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Renewable Energy Questions/Discussion => Solar (heating or electric) => Topic started by: MadScientist267 on April 07, 2013, 08:10:53 pm

Title: My first real array
Post by: MadScientist267 on April 07, 2013, 08:10:53 pm
 Here it is, 4x50W, measuring in at 56" x 50" with the sub frame attached.

This will be attached to an outer frame that holds it to the van and allows it to be propped up in any one of 4 directions to get optimal sunlight if parking does not provide for it naturally. That part is still in pieces... Pics of that to come in the next couple days and then hope to have the entire thing assembled and on the van by the end of next week.

[attach=1]
The front side.


[attach=2]
The back side.

Steve
Title: Re: My first real array
Post by: WooferHound on April 08, 2013, 10:05:09 am
Wow . . . Unlimited power now . . .
Will you be able to drive with that on the van ?

Able to tilt up in 4 directions . . .
That sounds like a fancy mechanism ?
Title: Re: My first real array
Post by: MadScientist267 on April 08, 2013, 07:27:25 pm
 Yep. It will lie flat for transport... About a total of 3" of additional profile on top in cruise mode.

I took a couple shots of it mocked up standing earlier just to look at some clearances. The angle in the photos are a bit steeper than the angle it will sit at once finished. Here it is between 40 and 45 degrees just because  that was the angle given by the 2 pieces of scrap angle I had handy. Design angle will be between 20 and 30 (possibly selectable) for the final version.

[attach=1]

[attach=2]

I was going to take a shot of it in transport mode laying flat, but by the time I got done tinkering and cleaning up, it was too dark to get a good one. I'll snatch one up before I go to move it tomorrow for posterity. ;)

Steve
Title: Re: My first real array
Post by: MadScientist267 on April 12, 2013, 12:00:28 pm
Well, they're up, at long last!

[attach=1]

It sounds like a complicated system, but it actually isn't. It almost seems to have taken a ream of paper to work out just exactly how to pull this off, but in the end, it comes down to a simple pin-hinge system.

Ironically, I don't have any of the drawings handy at the moment, but its easy enough to describe.

The array has a set of 8 bolts that screw into the inner frame, and ride in collars that are allowed to spin somewhat freely in the outer frame that is attached to the roof of the van.

[attach=2]
Detail shot of one corner showing 2 of the hinge bolts.

For transport, all 8 bolts are in place, locking the inner frame to the outer frame. Once parked, 6 of the bolts can be removed, leaving the 2 that form the hinge that the inner frame can then pivot on to be propped up in the desired direction.

I don't have any shots of the propping mechanism yet, but it its essentially a set of 2 angle aluminum bars that attach to the opposing bolt holes/collars via the extra bolts removed from other holes to lock the array into place. It can be propped as high as 45 degrees, but tends to bind beyond that at the hinge end.

There were 3 issues encountered that would be addressed in a future version of this mount system. None prevent the use of the propping system, but make it less than trivial to change modes.

First, and probably most significant, is an error made during the drilling of the holes for the hinge bolts. I didn't lock the inner and outer frames together to drill the holes, and despite best attempts to keep everything aligned, inevitably, things drifted slightly due to twisting and skewing while manipulating things. If I would have had a way to lock it all together on a workspace large enough, I would have done so and done all of them in one operation.

I also miscalculated the distance from each edge of the inner frame to the holes for the hinge bolts. I was able to compensate for this after the fact by modifying the outer frame, but it complicates transitions because it brought the margins much closer than originally intended.

The third was an oversight that makes it tricky to lift and lower the inner frame into and out of the outer frame. There is little to hold onto and the array is heavy enough that even with lubrication, the bolts drag significantly enough to make them difficult to insert/remove unless the stress can be taken off of the collars. I'm looking into a way of mitigating this issue, but for now, it just is what it is.

All in all, I'm happy with the results. For the price, the versatility is unmatched. There's less than $400 total invested in the entire array and it's framework/propping mechanism and does exactly what it's designed to do. I'm hoping to be able to work out most of the bugs for little or no cost... We'll see how that goes.

Steve
Title: Re: My first real array
Post by: DaveW on April 12, 2013, 01:42:36 pm
Congratulations.
Title: Re: My first real array
Post by: David HK on April 12, 2013, 05:27:12 pm
Have you checked the floor to ceiling heights of car parks, service centres and any other likely places you might visit in the future?

Have you also measured the new height of the vehicle and made a written note to keep on the dash board?

Just a thought that may save time and great irritation.

David in HK
Title: Re: My first real array
Post by: MadScientist267 on April 12, 2013, 05:39:13 pm
 That won't be a problem... In transport mode, it adds just a hair over 4" to the overall height.

It will still fit with plenty to spare on any normal road. It may be a decent idea just for extra insurance to have and make the extra height known, but I'm highly unlikely to run into a situation where it would pose a problem for me. My general target squatting grounds will be compatible with RVs and the like. ;)

Steve
Title: Re: My first real array
Post by: Wolvenar on April 13, 2013, 01:42:57 am
Yeah my guess is you won't visit many parking garages.
Those panels just are not terribly efficient/effective in them.

 ;)
Title: Re: My first real array
Post by: bj on April 13, 2013, 06:59:19 am
   Been away for a few days, and lots of changes.  Nice Steve.  The extra power is going to make life
a lot easier.
   Congrats.
Title: Re: My first real array
Post by: MadScientist267 on April 14, 2013, 01:08:31 am
 It most certainly will, and is. ;)

The van has been disconnected from "the umbilical cord" since the inner frame was built. They sat up top on the foam blocks while the outer frame was being built collecting light as much as possible.

So far, so good. I've had to revert to the skill I picked up in the wally world days of interpreting the following days weather patterns for myself all over again, but I'm not nearly as concerned about it now. The margin is much greater and I can be a little more lax about usage than I could then.

One option I see being put into place is a bypass for the MPPT. Under heavily overcast skies, I get ZERO output, but I've measured some useable output from the panels under these conditions that the MPPT just seems to want to discard. Next dark day I'll be investigating further.

All of the electrical is officially complete and operational, and aside from a single errant connector left over from the early days that I've just dealt with needing to be changed around to the opposite gender, everything is up and running as  designed and expected. As the sun gets higher and higher in the sky, my peak production steadily increases... Todays top end was 155W.

I still need to fabricate the prop rods, but with summer approaching, it's not at the top of the list; the tilt is primarily designed for fall/winter/spring less-than-ideal parking situations. Right now, it sits in a good location and gets a nice dose every day that the clouds don't interfere.

It is also notably cooler in there now during the mid day hours now... That's a lot of shade up there! ;)

Thanks again to all of you that have helped in various ways... I've learned a lot and continue to do so, and I ain't going anywhere...  Especially without giving more of what I've learned back to this awesome resource!

Got more to do aesthetically, but its really becoming something usable at this point... And starting to look pretty decent inside too!

Steve
Title: Re: My first real array
Post by: MadScientist267 on April 19, 2013, 02:50:13 pm
 Little update...

So far so good. Unplugged for just over a week, other than a quick plug in to make an adjustment to one of the grid charger settings while the batteries were full. I put a dump controller in so that I could have finer control over where equalization takes place, and simply needed to adjust the grid side of things so that I'm not dumping grid if I ever need to use it for that for whatever reason.

Other than that, I've stayed above 80% SoC, and so far, its exceeding my expectations. Today I caught it "edging" 180W, so it would appear that everything is intact and making good contact.

I've been intentionally laxing in the consumption department the last couple nights just to get a better feel for what it will and won't do... One thing I've found is that it would do me well to tighten up on how the big laptop gets its power... Its my big offender by far and running it via inverter/power brick is proving to be a little much...  Depending on what its doing, it doesn't leave much margin for charging the main bank.

I have a boost converter that is relatively efficient that I'm going to try out in place of running the inverter/brick combo, should help.

Steve
Title: Re: My first real array
Post by: WooferHound on April 19, 2013, 10:51:06 pm
Get it mounted on there right . . . and you will have a Spoiler too . . .

[attachimg=1]
Title: Re: My first real array
Post by: bj on April 20, 2013, 07:03:33 am
  Might be the world's first PV spoiler Woof.  Might make it into NHRA specs.  ;D
  Seriously though, coming along well Steve.
Title: Re: My first real array
Post by: ghurd on April 20, 2013, 09:37:21 am
One thing I've found is that it would do me well to tighten up on how the big laptop gets its power... Its my big offender by far and running it via inverter/power brick is proving to be a little much...  Depending on what its doing, it doesn't leave much margin for charging the main bank.

I have a boost converter that is relatively efficient that I'm going to try out in place of running the inverter/brick combo, should help.

Does the big laptop have the internal battery, and in decent working condition?
(or could you build a battery for it?)

Sounds like something a "ghurd timer" could help with.
Dump load goes high, meaning batteries are about full, timer turns the laptop charger on for a short time, resets every time the dump load pulses (without the off time to reset), power that would be dumped is stored in the laptop battery.

The controller will still control the battery.  The timer just uses some of the power that would have been sent to the dump load.

Small inverter with a rocker power switch, relay contacts bypass the switch, timer turns on the relay, which turns on the inverter.

Or relay in the 12V line to the boost converter.

Either way, it would automatically save power that would otherwise be lost.  And that reduces power that would have come from the house bank in the evening.

If you make one, can still do a small inverter for stuff I imagine you use.  Cell phone, rechargable shaver / flashlight / drill / camera / AAs / etc.

Links;  One less techie, other with the techie detail stuff.
http://www.fieldlines.com/index.php/topic,145170.0.html
http://www.fieldlines.com/index.php/topic,145256.0.html

FYI- I have all the parts here, even relays and sockets, just not packaged into kits yet.
Gimme a break!  I've been busy.  LOL
G-
Title: Re: My first real array
Post by: MadScientist267 on April 25, 2013, 10:44:37 pm
One thing I've found is that it would do me well to tighten up on how the big laptop gets its power... Its my big offender by far and running it via inverter/power brick is proving to be a little much...  Depending on what its doing, it doesn't leave much margin for charging the main bank.

I have a boost converter that is relatively efficient that I'm going to try out in place of running the inverter/brick combo, should help.

Does the big laptop have the internal battery, and in decent working condition?
(or could you build a battery for it?)

Sounds like something a "ghurd timer" could help with.
Dump load goes high, meaning batteries are about full, timer turns the laptop charger on for a short time, resets every time the dump load pulses (without the off time to reset), power that would be dumped is stored in the laptop battery.

The controller will still control the battery.  The timer just uses some of the power that would have been sent to the dump load.

Small inverter with a rocker power switch, relay contacts bypass the switch, timer turns on the relay, which turns on the inverter.

Or relay in the 12V line to the boost converter.

Either way, it would automatically save power that would otherwise be lost.  And that reduces power that would have come from the house bank in the evening.

If you make one, can still do a small inverter for stuff I imagine you use.  Cell phone, rechargable shaver / flashlight / drill / camera / AAs / etc.

Links;  One less techie, other with the techie detail stuff.
http://www.fieldlines.com/index.php/topic,145170.0.html
http://www.fieldlines.com/index.php/topic,145256.0.html

FYI- I have all the parts here, even relays and sockets, just not packaged into kits yet.
Gimme a break!  I've been busy.  LOL
G-

 Ugh... This one got away from me. Read your reply not long after you posted it, but didn't have time at the moment to respond, forgot to mark it unread, and well...  ::)

Unfortunately there are some "compatibility" issues with the two types of systems that, while not impossible to get around, might be impractical in the grand scheme of things. :-\

While I'm using one of your controllers in the system, it only engages during equalization to help the MPPT bring the bank closer to 15.5 sooner. It backs off too soon otherwise. The MPPT was given the task of regulating charge voltage for normal day to day charge cycles, so while not impossible, initiating a timer and such may be difficult to implement.

Another issue is that yes, while the battery in the laptop is good, it will only run it for around an hour, and less typically for what I use it for these days, video and music. That's long enough to say its there, but not long enough to say much else. Its been a point of contention for me for a while now, but there's little I can do about it ATM.

Sad part is, the small laptop with the mega battery sits in the drawer collecting dust while all of this is going on simply because the screen is so small. I've considered making the compromise and switching them out and just accepting the smaller screen. Might happen just yet. Thing there tho is, fully loaded (wifi, full bright, running YouTube, and charging the battery all at once), the power requirements don't break the 30W mark, and my electron woes would instantly go away, probably even in winter. But I'm such a sucker for the screen with ~3.5x the real estate. :-\

I did get the boost converter wired in, and there are some savings, but they're marginal and difficult to see just yet. I'll be doing some side by side comparisons with the boost vs inverter/brick to try and get some more concrete numbers. Computers are tricky to gather consumption info on, as the usage can vary widely depending on what they're doing.

Another thing that doesn't help is the idea that in order to get wifi, I had to resort to hacking an old Linksys WRT54GS to use it as a wifi "card".  On average, its pulling between 3 and 4 watts in and of itself. The sound system uses a little more  quiescent current than I wish it did too, amounting to about 4W in and of itself. Just how it is.

For the moment, I've shrunk all I can and still use the big laptop, so I've turned my attention to optimizing production. I've got an experimental yet simple method for prioritizing the aux SLA charging on the aux panel, and then snatching up what's left to boost the charge current into the main bank. Currently it's only good for another 15W, but I intend to  utilize the trick from the "pseudo MPPT" from days gone by to bump that up a touch if I can.  Even as is, it made a big difference today, so I'm optimistic of what yet another buck converter might be able to bring to the table. Time will tell.

If I end up succumbing to the screen and just going with the smaller laptop, the timer idea might be well worth the trouble... Charging lithium ion is more efficient than charging lead acid any day, and since I'm naturally nocturnal, I need all the help I can get LOL  ;D

I'm still unplugged, and hit a good long soaker float today, so all in all, it's working ;)

Steve

Title: Re: My first real array
Post by: MadScientist267 on May 06, 2013, 06:48:40 am
Figured a few might be curious as to what this thing all looks like on paper... There's nothing really super special about it really... Just the as it sits version I began working up to help me keep track of what is and what isn't.

 I'm pretty happy with the functionality of it all, so far it has withstood the test of time... Today makes about the 3.5 week mark, 12.7V first thing in the morning with no real useful sun in a couple days. Provided I pay attention to the clouds to come, it's certainly doable.

As soon as I finalize the console layout, I'll put up some pics of the cluster and wiring... Still deciding on whether or not the MPPT ammeter provides any real useful information - it's regularly in conflict with the "net" ammeter on the cluster due to a gain issue I really don't see much point in hunting down.

There are a few other little quirks about the layout, but nothing serious. I've pretty much got the information I'm after all in one place now, so it won't be long before I get tired of looking at the mockup props holding it all in place and finalize this thing. ;)

[attach=1]
 Click it for higher resolution...

Yes, I'm aware the file is a bit "pricey" for what it is... It's tricky to get a hand drawn schematic tweaked up and dialed in while keeping the resolution up and file size down. Blame the joint picture expert group for that. :)

Until next time...

Steve
Title: Re: My first real array
Post by: MadScientist267 on May 31, 2013, 11:23:51 pm
 Little update...

Still going... In fact almost TOO much...

Heat is becoming a problem now with the batteries, regularly hitting 100F core temp by the end of every day. Day time air ambient is hitting only low to mid 80s, and if this summer is anything like the last, I'll be working with lead soup that just happens to have sulfuric acid mixed in with it before August is up.

I have a master plan to deal with it, but only some of the parts at hand at the moment, and so after first reducing charge current yesterday and  micromanaging the charge process today with only a "gain" of 2F down to 98 or so and less than full charge at the end of the day, I implemented the parts I *do* have on hand to get the ball rolling.

[attach=1]

Next will come heatsinks along the "water lines" of the batteries to aid in heat extraction at night when it can pull it down easier. If its effective enough, I'll make another differential thermostat that shuts the fan down when it either wouldn't do any good (or worse, warm them more), or gets down to about 80F or so to save power. This fan is hungry, pulling about 7W by itself at full throttle (measured), but isn't afraid to move air either.

Its also a noisy little device, and the foam only amplifies it.

The cool air is sucked in at the bottom of the batteries through a 1" or so slot (currently implemented with cardboard as a test, the final will be the same 2" foam as everything else), and flows evenly across the entire front wall of both batteries, up over the top, and out. The gap between the batteries where the temp probes are has been taped over to prevent the cooler air from providing false readings/charge adjustments.

I'll put a better pic up when I put the heatsinks on, but for tonight, I just wanted it working, and this is all that's really visible.

Steve
Title: Re: My first real array
Post by: MadScientist267 on July 12, 2013, 02:21:53 pm
Little update...

The heat issue got out of control to the point that I had to go as far as reconnecting the grid to keep the batteries at float rather than let them add to the problem by generating more heat internally.

The heatsink solution hasn't come to fruition yet due to a lack of supplies, namely the heat spreader plate that will go between the heatsinks and the battery casings.

However, having the heatsinks in the cab waiting for the plate has illustrated that thermal mass needs to be removed strategically from the cab, and that shielding is a viable workaround.

 Cab ventilation is also going to be key but I don't quite have that implemented yet either, at least in the form I intend to use. A forced air exhaust is going to be critical before summer is over and done with, but for now, with shielding, there has been a marked improvement, and for the first time since late spring, I've managed to get the core temp down to ~78F, and it looks like I will be able to get it a bit lower than that over the next couple of days, as the weather has provided a break for the time being.

I also found that by removing the heatsinks before starting the fan, and placing them back in the cab before sunrise, that it helps significantly in keeping the ambient temp in the cab under control. Latest experimentation shows that about 14 hours in (12am to 2 pm or so) provides a decent level of passive cooling with minimal effort. For the remaining 10 hours, they are  outside and in the shade, releasing their heat to the atmosphere.

 The shielding is helping significantly and allows the heatsinks to absorb only ambient heat, rather than becoming hot due to incident sunlight. At certain points of the day, it is now more beneficial to have the doors closed rather than letting ambient temp breeze blow through.

I will still be putting the heatsinks on the batteries as soon as I locate a suitable spreader plate, but there for a while it was looking like there wouldn't be much point. Not anymore... ;)

Time will tell how well the concepts of shielding, "absorbing/displacing", forced ventilation, and sinking the batteries will work.

For the last couple of days, I've been allowing the solar to do a sort of faux absorption charge phase,  with the grid charger set to only allow a shallow discharge at night, to see if the temps stay under control. So far so good. Once I'm convinced the system in play will be effective, I'll drop the grid and go back to normal cycling with a watchful eye.

In the mean time, I've gotta find me a suitable chunk of aluminum... The quest continues. :)

Steve
Title: Re: My first real array
Post by: bj on July 13, 2013, 07:27:39 am
   So, the question would be " how big a chunk"?  I might have, or be able to find what you need.
   Shipping might be cheaper than paying retail where you are?
   Just a thought.
Title: Re: My first real array
Post by: MadScientist267 on July 14, 2013, 09:27:29 pm
 Well, still tossing around some ideas... But I might have found a very viable solution...  Time will tell. I appreciate the offer for sure ;)

Got a rudimentary forced air vent put in, passenger side window... Tomorrow it will get a good trial, and if all goes as planned and I see decent numbers, I'll be returning to normal cycling of the batteries.

A couple of pics:

[attach=1]
Inside


[attach=2]
Outside

Moves some decent air, nothing extreme, but is fairly quiet unlike its little brother pumping out the battery box. If this works as envisioned, it will eventually be replaced with a squirrel cage blower feeding a vent that will go in the roof.

Stay tuned, more as it comes.

Steve
Title: Re: My first real array
Post by: rossw on July 14, 2013, 11:38:36 pm
Moves some decent air, nothing extreme, but is fairly quiet unlike its little brother pumping out the battery box.

I used to put fairly large 24V fans in my old 4RU server cases, and ran them on 12V.
Such large diameter fans, at half voltage were almost silent yet still moved a lot of air.
Title: Re: My first real array
Post by: MadScientist267 on July 24, 2013, 06:36:10 pm
 Yep. Useful trick... There seems to be a growing trend amongst manufacturers doing that very thing. I do the 12V fan on 5V on many of my projects, and have seen it done many times in commercial equipment. The beauty of it is that they're quiet, have a longer life, and can potentially be throttled up if conditions warrant it.

Conditions have improved, the shielding and cab ventilation have brought the temps back into a normal range and things are back on track and running on solar.

In the next couple of days, I'll be putting the new heatsinks on the batteries (thanks DaveW!) and optimizing the battery box. I'll also be preparing it for use with a differential thermostat based on a 08M2 PICAXE, my first real experiment with a PIC from the ground up. Should be interesting.

More to come... ;)

Steve
Title: Re: My first real array
Post by: MadScientist267 on July 27, 2013, 03:43:53 am
 Had a decent post scratched up, phone managed to lose it for me... Grrrr

Anyway, the heatsinks are on, albeit without goop for the moment. Turns out this may have been a useful trial even before any performance is known. Installing these things in-situ is much more difficult than it would appear because of the tight fit they have in such close quarters. The lesson learned is that I should probably remove the batteries to do the final install, unless making a serious mess is part of my goal.

Even without the elusive goo, performance is decent. Without logging it has been difficult to tell exactly what conditions lead to which results, but the average drop with no heatsinks at all, 7F difference between ambient and core, and fan at full throttle, is about 1F/hour.  With the heatsinks installed, I'm seeing approximately 1.5F drop, all else equal. They may be performing better than this however, as the core is falling faster than the ambient, and as of last check, the difference was only 5F, yet they are still dropping at about the same rate. Time will tell, but it appears to be working well so far.

Adding goop of some form will only improve efficiency, resulting in less power needed to achieve the target temperature. With between 5 and 10% SoC being spent on cooling each night, every bit counts. I hope to reduce this to somewhere between 3 and 5% before this is over with. The differential thermostat will certainly play a big role in this as well.

[attach=1]
A shot from the top down. Not a common sight from what I can tell. At least not on lead acid. ;)


[attach=2]
Another view from the side. Each sink is 10" x 6.5" x 1 3/8" (3/8" substrate + 1" fins). Pretty good size chunk of aluminum.

That's all for now... They will likely run like this for a bit until I get the thermostat parts in and put together, as well as find a suitable heatsink grease that fits the bill. Might just end up going with plain old non-drying classic white stick-to-everything goo, even though the allure of finding a dirt cheap DIY solution is being sought out. Either way, I can't complain, this is essentially the final piece of the puzzle.

Till next time...

Steve
Title: Re: My first real array
Post by: bj on July 27, 2013, 08:01:18 am
   Those are seriously nice heat sinks.  Got to help.
Title: Re: My first real array
Post by: DaveW on July 27, 2013, 08:54:03 am
    Steve I'm glad to see them in use.  Still thinking on how to make a good heat sink paste on a budget that won't attack the batteries.
Title: Re: My first real array
Post by: MadScientist267 on July 27, 2013, 09:52:43 pm
Quote from: bj
Those are seriously nice heat sinks.  Got to help.

No fear, I'm sure the time will come. There are puzzles all over the place with this, and as I've mentioned before, you guys have all played a vital role in it becoming what it has. I'm certain the challenges will not end here. ;)

Dave, I've almost given up on the idea that its going to be all that cost/time effective to go the DIY route with the goop. Being a "gotta hold it in my hand to buy it" type, even a 2 oz tub of goop won't be all that bad, coming in at a touch over 20 bucks at the semi-local electrical supply joint. I could get it for 10 or so online, but... LOL

Last night the temps tracked fairly close, and the core bottomed out at about 72, intake temp for the sinks getting down to about 69. Tonight I'm running the fans at about 1/3 power input (total) to get a feel for how they perform with minimal flow. From what I can tell even already, things look promising.

The sinks didn't add much if at all to todays rise. I gained 12F,  bringing them to 84, which is a little elevated, but charge currents were also higher and ran for longer thanks to a deeper than usual discharge from running the laptop, stereo, etc while I was working on the heatsinks and batteries.

Tonight appears to be heading for similar temps as last night, so we will see. Anything less than 75 in the morning and I'll be ecstatic ;)

Till next time...

Steve


Title: Re: My first real array
Post by: MadScientist267 on July 28, 2013, 05:17:01 pm
Performance wasn't as good as expected, but I believe it was due to elevated cab temp.  With the vent fan throttled back, it the temperature didn't drop in there as far as they could have. To complete this, aside from the thermostat, a more powerful vent and/or a cool air intake down low in the cab will be necessary. This is also supported by the fact that the vent is much more effective if the driver door is cracked open to allow air to flow along the floor on its way to the batteries.

Since the thermostat will be set up to handle both heating and cooling, I am strongly considering a vent pipe of some sort that will be routed directly to the outside. Dryer flex vent comes to mind.

All of that said, the cooling at the minimal fan speeds was approximately double from what I have seen on average, bottoming out at 77.5F last night. Tonight I will be running the throttle for the cab vent at max power and the box vent fan at the same throttle as last night. Similar temps expected, so we'll see.

Steve
Title: Re: My first real array
Post by: MadScientist267 on August 03, 2013, 11:44:30 pm
Update time...

The outside temps here are fluctuating a bit, making it a little more difficult to keep track of what's what. Regardless, I have managed to keep the core temp in the comfortable range, not going above 86F, and typically bringing them down to between 74 and 80 depending on outside. So the heatsinks are definitely helping. I've caught on to a fairly stable constant - whatever the forecast low is for any given night, I seem to be able to get the core down to within about 4 degrees of it. Can only get better with the addition of the goop.

Which, is here. A whole pound of it. Sheesh. I should run out of solder before I ever use this tub of goo up.  ::)

Corner braces for the zip ties also cut. A plan for additional insulation to reduce heat influx from ambient temps in the cab, and an idea for directly taking in the outside air without breaching the firewall or floorboard is also on the table. I'm looking into cutting a vent into the passenger door with a screened louver on it to stop rain/bugs/etc. The cab has too much thermal mass, and is proving to steal precious cooling time away because currently it must be brought below core temp before actual cooling can begin. Should shave between 2 and 4 hours off the wait time by implementing this, depending on actual outside conditions.

Interfacing it with the door will be fun, as I don't want to have the vent hose directly attached, although it may come down to that for simplicity's sake. Currently (if I didn't accidentally throw it out on the last trip to the storage unit), I have a length of aluminum dryer flex vent that would be more than sufficient in terms of capacity, but probably wouldn't handle much repeated flexing. Opening the door is a fairly regular thing, as I also use that space as sort of an "attic", in addition to just checking on things and such. Maybe flex duct will be better at some point. Certainly, the added benefit of it being insulated can only be a plus as well.

As a stop-gap, I am also going to repurpose my existing differential thermostat to deal with the battery box fan. My whack sleep schedule isn't helping keep things cool. I currently go out each night, read a couple thermometers, flip a switch when it's time, and walk away until the morning comes. If I'm still up when the sun comes up, or if I wake up early enough, I kill it before the cab temp exceeds the core. When this doesn't happen, it continues to circulate air, undoing the progress made the previous night. I fully intend to have the thermostat controlled by a PICAXE chip before this is all said and done, but in the mean time, since there's still a few questions to be answered before I dig into designing it, the immediate issue of reheating needs to be addressed. The fans it currently controls are cooling a much less critical system and will tolerate being modulated by hand much more than the batteries can. They need all the help they can get!  :-\

The dryer vent interface will also be set up so as to minimize natural convection currents that might tend to flow, and will also make the changeover to the heating collectors that will lay over top of the batteries in the winter a snap. Keeping them warm was a challenge last winter, and even though I know I can do some of it with controlled overcharging, the energy might not always be available to do so, and is certainly not the ideal way to heat them as excessive overcharge can lead to positive grid corrosion, excessive water loss, and the like. So, I will have a more direct approach in place as the primary warming system. More to come on that as it comes to be.

With any luck, the weather will be useful and tomorrow evening I can put some of this into play. I plan to permanently mount the heatsinks with the goop, and put the differential thermostat in place, possibly cutting the additional insulation panels to add to the existing structure, bringing the total R value to 20 around the entire cab side. On the living space side, I will have to get creative to add the second layer - there's quite a bit of equipment crammed into the space immediately behind the batteries, although that space is itself insulated, forming somewhat of a double barrier. If only the components inside didn't generate their own heat... Having to run the aforementioned fans to keep that stuff cool kinda kills off the idea of it being "double insulated". Sue me, it wasn't really there as insulation to start with... it's just really easy stuff to work with and doesn't make a half bad surface to mount the instrumentation to.  ::)

Until next time...

Steve
Title: Re: My first real array
Post by: MadScientist267 on August 07, 2013, 01:30:03 am
Success!

Then failure...

... and finally, success!  :o ::)

Everything went very well, considering. Pictures are worth a thousand words, right?

[attach=1]
That's a quarter of a pound of your everyday silicone/zinc oxide heatsink compound. A layer on the battery, and a layer on the heatsink. The stucco appearance is from separating them after repeated mating checks to make sure there were no gaps. I figured 2 oz would cover both batteries... But that one pound tub sits right at about a half tank with all said and done, and there was very little oozing; maybe a half ounce total if I had to guess.  ???



[attach=2]
Anybody that's attempted to remove a heatsink from a CPU with a spreader plate on the die knows that the stuff gets a grip. It holds true in batteries as well apparently.



[attach=3]
Eventually, it would give way to fatigue and come off, or slide off to one side and become detached. Couldn't have this happening, so back on with the zip ties.



[attach=4]
On the back side, I used aluminum angle to spread out the pressure that would have been on the case of the battery itself. They are cinched down much tighter than they were for the dry test, and I didn't want to risk damaging the casing. Everything is much better off if the acid stays inside the cells.



[attach=5]
There has been a bit of debate as to the ideal location of temp sensors. Some argue that the sensors are best placed on one of the posts, the idea being that the lead conducts the heat of the core back to the post and provides a more accurate reading than if the sensor were placed on the side of the battery. For a battery/cell that is open on all sides for ambient temperature air flow, I'd agree. However, due to the way these two batteries are housed and insulated, the side of the case actually provides a more accurate reading than the posts would. Being forced air cooling, the posts would see a lower temp by the air flowing across the top of the batteries. In the pic above, there are 3 sensors, all within about 2 inches of each other in a V. A gasket 2" wide and 3/4" thick, sealed both on the inner and outer perimeters by tape provides an airtight seal and a chamber that completely blocks out errors caused by the cooling air. The original layout before heatsinks were ever a consideration involved only a tape seal around the outer edges of the batteries, and this did cause the measured temp to have some notable "play" in it when the fan was turned on or off. With this, it is now rock solid.



[attach=6]
Here is a shot of the heatsink <-> seal interface. This was very difficult to pull off, as it took forever to get the grease completely removed from the faces that needed to be taped. As you can see, it involved getting creative and using the most accessible faces of the heatsinks in combination with the structure of the tape itself, and the unbroken seal on the inner perimeter. The result is a good solid seal. At the very bottom in the center is the intake temp sensor for the differential thermostat.



[attach=7]
The much improved passage for the temp sensor wiring.



Everything worked exactly as planned once it was all put together. I stayed up with it to tweak the thermostat so it would cut off at the appropriate time, and checked on it from time to time throughout the day to find out the point at which it would bring it back to life.

Along about the late afternoon hours, I noticed the LED that indicates the power for the fan was on. At first, I only thought of it as a little early for it to engage, but a quick peek at the thermometers revealed that it was in fact on it's mark. The day began with heavy rain, and remained cool for almost the entire day. I had some extra insulation on the batteries and had actually lit off the SMPS charger to fill them back up as well as artificially raise the temperature when I realized the sun wasn't going to do it naturally.

But then I noticed that the LED was cycling, and had an odd flicker in it right before it would cut off. This definitely wasn't normal. A quick check of the fan revealed that not only was it not turning, but it's motor had become very hot for some reason. I have my suspicions, but I don't know for sure. Either way, it was dead at that point. One high performance 4" brushless fan, junk.

To get things back going again, I had no choice, I had to use the fan that had been venting the cab to pull air through the battery box. It's a very similar fan, slightly larger and has a thermister in it that I bypassed to make the motor run at full throttle all the time. It's knee isn't in the right spot, so it would slow down way before I needed it to.

To protect the fan, I ran it through a current limiting buck converter (it needed to be slowed down anyway, so this worked out). The batteries are now once again cooling and with 5 hours or so before even twilight, there's little left for it to do. It's drawing a fraction of the power that the other scheme was as well.

Both last night and tonight so far have demonstrated that the core temp can be brought within about 2F of the intake temperature, which (up until the fan failure) could generally be brought to within a couple degrees of ambient outside.

All in all, I'm pretty satisfied with how this has gone. Much thanks once again to DaveW for the heatsinks. ;)

Now on to reinventing the cab vent  :-\

Till then...

Steve
Title: Re: My first real array
Post by: MadScientist267 on October 30, 2013, 06:15:36 pm
 Well, its that time of the year again...

The cooling system has been working flawlessly in keeping the batteries cool.  Before I go into the next chapter, a little catch up is in order...

Not long after implementing the thermostat, I had the insight to make it reversible, and then put the controls for it on the instrument cluster. It now has the ability to run in reverse, so as to heat the batteries in the winter if necessary. There are two switches, one for off/on/auto, the other for heat/cool. In this particular instance, I didn't use any direct power control for any of the functions, instead, I manipulated the signal that the control chip sees. For forced on/off, the signal is biased high/low respectively, well outside the operating range of the thermistors, and auto of course is unbiased. Winter/summer mode is done by flipping the sensors electrically, so that instead of a warmer core pulling the signal toward high, it tends to pull it low. All in all, works well.

So, that led to the next piece of the puzzle. There's a significant difference between the roofline and floorboard temperatures in the cab, as much as 30F, and while the original cooling behavior was set up to pull air from as low as possible in the cab up across the heatsinks and through the fan, this wouldn't work for heat mode, as it would be rather inefficient. To deal with this, I've built an intake box out of cardboard and dryer vent line, to pull the warmer air from as high in the cab as practical. I also have moved the ambient temp sensor to the suction side of the vent (intake) tube.

Of course, its all held together with duct tape, but this is what I've come up with...

[attach=1]
I did have to peel the second layer of insulation foam off of the containment to pull this off. An Astro just isn't set up to  hold all of the things that need to be present to support all of this, but I made it fit.



[attach=2]
After installing the new intake (which as you can see required an in-place "hack"), there was barely enough room to get it past the doghouse. Most of the space issues were at the bottom, and having realized this after making the modification, it was clear that there was only one way to make it properly fit, and that was to remove the rear insulation and slide the batteries back about 2 inches. The entire box then needed to be trimmed by a similar amount. At this point, being low on materials, I noticed a significant gap at the top of the doghouse as a result. To keep the air gaps as small as possible where the batteries meet the  electronics container, I needed to put pressure on the box to help hold it shut. That's the job of the two wedges in the pic.



[attach=3]
A shot of the intake side, showing the roughly 3 inch gap between the tube and the headliner, along with the two sensors (the visible one controls the thermostat, the thermometer sensor is just inside the tube).



[attach=4]
A shot showing the routing of the whole thing.

Time will tell if this is viable, but in theory it works, as I've been watching the temps for a few weeks now. During full sun, the area where the intake is sees a full 40F rise above outside, so there should be no risk of freezing, unless I go to one of those horrificly cold places and beg for punishment ;)

Till next time,

Steve
Title: Re: My first real array
Post by: Wolvenar on November 02, 2013, 07:53:18 am
Wow man, people passing will start to fear the Borg have arrived and are starting to assimilate.
Title: Re: My first real array
Post by: MadScientist267 on November 02, 2013, 12:22:00 pm
Heh yeah, fair chance Wolv. Especially once they see all this... ;)

Get it mounted on there right . . . and you will have a Spoiler too . . .

[attach=1]

--- Almost Woof - LOL Here it is propped, first time I believe I've posted pics of it set up in winter mode. Its actually propped a little higher than it should be, pushed the limits of some things in the framework, but no real harm done. Here's what it looks like:

[attach=2]


Another few shots from various angles, and a couple extras showing the temporary setup for testing the two 100W/12V panels I got from Rover in the middle of last week...


[attach=3]
They are connected via the multi-purpose umbilical cord (10/3), used for everything from jumping the van cranking battery to other cars if the need arises, to charging via the engines alternator, and of course now, auxiliary PV connections ;)


[attach=4]
Another angle from the front.


[attach=5]
...from the back...


[attach=6]
And a close up of the "pseudo-MPPT" that Commanda et al on FL coached me through building several years ago. It was once speculated that the device wouldn't handle more than about 5A output @ 14V, but today it showed what it was made of and was pumping 11A in fairly lengthy runs into a 14.2V rail. Pretty respectable for a one off device that was meant more as an experiment than anything serious if I don't say so myself!

I wanted to get a shot of the total charge current going in today but the skies have been barely cooperating, and the times I did see totals of 21A and above, I was more concerned with noting the location and volume of any magic smoke events, of which there have been none. Skies are mediocre at the moment at best, still pulling 5A or so pretty steady.

Tomorrow is supposed to be clear and cold. I should have a pretty fair shot of getting some juicy numbers for a pic tomorrow.

Till then, Thanks a bunch more Rover! You know I owe you pretty big after this one 8)

Steve
Title: Re: My first real array
Post by: MadScientist267 on November 03, 2013, 09:59:56 am
 The money shot:

[attach=1]

430W "by the label", 382 of it realized. ;)

Steve
Title: Re: My first real array
Post by: MadScientist267 on November 06, 2013, 01:32:36 am
 Well, the numbers above look all nice and pretty, and of course are approximately doubled from the extra input from the external panels, but alas are only a snapshot, with conditions about as ideal as they can get for this time of year.

Reality is a much more grim prospect, with only about 10% of that under what is turning out to be a "normal". I of course knew that there was going to be a radical difference between summer and winter, but I'm a bit irritated with what I'm seeing. I calculated the 200W based on conditions I saw last year, and it would have roughly been enough, if carefully used. This year, I'm seeing different conditions, and while I don't have a quantified value to place on it, there's no way it's even close to what I was expecting. I'm not sure how much is actual difference and how much is due to estimation error, likely a solid mix of both. But either way, it ain't cutting it.

I regret to say that for the moment, I'm plugged back in, until I can come up with a way to reduce consumption and improve input. Both come with issues in the present setting, mainly input. Raising the panels to optimize incident light is not ideal, due to various concerns with having them elevated. The propping method I'm using at the moment isn't super secure, and while it has illustrated it can tolerate some wind, I don't know how far I trust it. It is also a very obvious protrusion into the sky since the entire array is more than 4 feet long, and it attracts a LOT of attention when it's raised, a fair amount of which I would not consider positive. There's also technically a 7 foot height limit for street parked vehicles, that isn't necessarily strictly enforced, but could become a problem if enough eyes fall on it over the course of time. I have no intentions of finding out.

On the consumption side, my load at night with only the phone, 2W overhead LED light, and ceiling fan running (via inverter) hovers right around 3.2A, which would be ok if the skies were cooperating during the day to any extent, but proved to be trending towards dead batteries (50%, and likely even lower) by the end of night 3. The fan is a requirement to keep the temperature homogenous in here, as stratification and drafts take over without it, and the heating fuel requirements go up significantly to keep it comfortable.

There's also more drafting than there was last year, the heat is working much harder for some reason. I've pretty much been left thinking door seals, but the physical configuration for air flow also changed when the bed frame finally gave way last year and I lost the ability to let the cooler air pool up somewhat underneath. I can't recall exactly when it was swapped out right off the top. I can probably get a clue from another post, but I'm thinking December. This would leave the coldest months still to have yet to come however, so I'm at a loss if that indeed turns out to be the case.

Today I also realized that the sliding door is trying it's best to reach the "I'm over it" stage, and pretty much solidified the idea that the van as it exists is at end of life. I have no complaints overall, it's been very good to me, was there when I needed it most, I don't have any real money tied up in it, and what I do have can be removed and reused. It's been an incredible learning tool, and I certainly don't regret anything I've done with or to it, but I think it's time to begin planning for version 2. More space, more real estate on top, and a reliable drivetrain (the computer that controls the engine has issues and I can't see dumping money into it given all of the other issues since it does still actually run).

I'll be continuing with some experiments that are currently in the works and running on PV as conditions allow, but I don't see anything major being started at this point in time in this version.

Thanks goes out to everyone that has provided input and components that have brought it this far, I can honestly say I wouldn't have pulled it all off without all of your help. No fear, it won't end here! I'll still keep the updates coming, just admitting that I've basically hit the wall on it and need to take it to the next level. You guys tried to warn me, it is certainly addicting! LOL ;)

Till next time...

Steve
Title: Re: My first real array
Post by: tomw on November 06, 2013, 08:20:58 am
Steve;

Well, you are not alone and it is not the size of your array. I am way behind this year even over the year before we upgraded from 820 watts to 2320 watts. Solar insolation varies widely from year to year here in the Midwest anyway.

I am convinced you need a massively oversized array in winter compared to summer needs mostly because you cannot assume this year will be like next year, etc. Been days and days here with our array putting out 10% to 15% of what I would expect on decent days due to no sun.  Not even including the short days near winter solstice. We heat water most days in summer as opportunity loads to use excess power rather than just let it go to battery heating or just shutting down the solar.

We have been running in "bypass" mode on the inverters more often than I like lately and unless the weather provides less overcast / clouds will be all winter.  Even running just the base loads of some lighting, 2 freezers and a fridge. :o

Just from here.

Tom

Title: Re: My first real array
Post by: MadScientist267 on November 08, 2013, 02:00:23 pm
 Most certainly seems to be the case here... :-\

Today was clear, and the entire weekend is forecast the same, so I'll "unplug" again (pronounced "kill the main breaker" and see how my estimations pan out each time I see expected conditions (not necessarily clear skies).

Tonight should be interesting, as we're looking at a new low for the season and I'll have a better idea of where any new drafts are coming from, and can seal them up.

I'm certain tho the catalyst has had it in the one heater, so I'm sure that's throwing my observations some.

More as it comes...

Steve
Title: Re: My first real array
Post by: Wolvenar on November 09, 2013, 06:17:52 am
I'm in the same boat it seems. I have the additional trouble that battery capacity is at an all time low, and the solar seems to have barely enough to bring the batteries to float on good days. It has been this way for about a month.

The offgrid system runs mostly just the site server here and all the network gear, but its been getting  grid help for about 2 weeks now.

I'm planning to take the array down for work as well sometime around the 13th of this month so, will be totally grid powered for a short time.
Title: Re: My first real array
Post by: MadScientist267 on November 12, 2013, 12:23:03 am
It's frustrating ain't it?

I've conceded long ago that it would be a never ending game if I decided to get into all of this stuff. But the challenges are a lot of the appeal for me. I'm all about a good challenge, provided it's possible to win. ;)

Another manifestation of the design "features" I've integrated into this thing reared it's ugly head earlier. Luckily, an apparently rather sensitive component exists that led to a flaky connector behind the driver seat before there was a serious problem. Every time the thermostat would engage the heat controller, the remote control DC light would shut down and leave me in the dark.  This was only a head scratcher until the phone was getting low and I went to plug it in and the light got noticeably dimmer. In the back of my mind, this ran to the front and  started yelling "a half an amp shouldn't be doing that", and the hunt began. 7 connectors later, I traced it to the one behind the seat which practically came apart as if they were just laying in one another... Easy enough to fix, but I'm starting to get annoyed at the increase in frequency at which I'm discovering these things. This would be round 3 of this type of issue... The first being the connector between MPPT and battery, the second being up top under the panels,  and now this one.

Rover had expressed concerns with the use of Molex connectors some time back, at which I half sneered, mainly because as a general rule, they haven't been much of a problem in previous projects. But with an estimated 50 or more of them scattered throughout, the odds that one will go a little whacky obviously go up, so it's cat and mouse till it's over haha.

Kinda puts me at a crossroads with them, but I think I've figured out a way to transition to a more reliable infrastructure in version 2 without having to completely rethink how the DC consumers get their juice. Being that I've established a "standard" that literally everything uses, I'll keep them on, but only as the interface that meets the wall, and of course keep the normal 120V plugs for the AC side of things.

The new DC infrastructure will probably be tied together by euro barrier, as I have found that format to be relatively easy to work with and fairly reliable over the years. The van was a victim of both nature and nurture, as it's evolution depended on the infinitely reconfigurable design that now plagues it in it's mature state. I'll use temporary wiring in the process of building version 2, but only to allow fine tuning of the physical location of various items, at which point a dignified distribution system will be carefully designed and installed to keep everything as clean as possible.

Till next time...

Steve