Author Topic: Neat Experiment  (Read 8002 times)

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Offline ghurd

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Neat Experiment
« on: July 29, 2012, 11:09:48 am »
Tinkering with some little stuff today.

VW PV (type with the factory regulator), 7AH SLA, lighter plug 12~24V input USB output switcher, and cell phone.

Removed the battery from the equasion.
PV to factory VW regulator to lighter plug USB to cell phone.

Rock solid voltage between the regulator and USB thing.
That was not expected.
G-

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Offline Laibsch

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Re: Neat Experiment
« Reply #1 on: August 04, 2012, 02:05:47 pm »
why were you surprised? wouldn't this be expected if the voltage regulator receives enough juice from the panel? Or am I missing something?

Offline Rover

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Re: Neat Experiment
« Reply #2 on: August 04, 2012, 11:46:02 pm »
Maybe because he is comming off a pV?
Rover
Location: South East Virginia US

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Offline WooferHound

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Re: Neat Experiment
« Reply #3 on: August 05, 2012, 05:23:08 am »
I think it's because he is using a VW panel which is 1.5 watt
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Offline Rover

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Re: Neat Experiment
« Reply #4 on: August 05, 2012, 10:16:15 am »
Ah, I think I get it, what was unexpected was that the VW panel controller combination actually being able to produce the voltage and maintain it.
Rover
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Offline ghurd

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Re: Neat Experiment
« Reply #5 on: August 13, 2012, 07:38:10 am »
Sorry for the delay. Had some more issues come up.

The VW regulator has a large hysteresis, maybe 0.3V on that one.  And it is kind of slow to react (don't need a 'scope!).

Not much space for filtering caps in the combined spaces of the 2 plugs.

Sun was not very good at the time.

Just expected the voltage to jump around by at least 0.4V, and as fast as a red squirrel on expresso.

However, the tiny filtering caps may be why the voltage stayed so solid.  Pretty sure that is why.  Didn't consider it at the time.
To test the VW PVs for a regulator, connect a meter and the voltage is fairly steady at about an SLA float voltage.  (those without a regulator in the plug have very high OC voltage because of the 42 cell design)

Was thinking the 42 cell PVs without a regulator would have Vmp at 20V.
10,000 uF cap.
Switching regulator 12~24V input to 5V output (USB).
Poor man's batteryless MPPT?
Looks like I can skip the cap.  LOL

I actually use the VW PV every day.  Its propped up against the railing facing either East or West, charging an abused 12V 7AH SLA (half of a bad "24V UPS pack"), dual USB output lighter plug, and then charge my cell and bluetooth every evening when I get home.  Hate to tell you how many mornings I can't find the phone in the house because it spent the night outside.
One day I'll have to calculate how much money it saves me over the course of a year.  hehe

Woof,
The "Red HF $10 PVs" (name may need changed to "Red HF $15 PVs") are 1.5W.
The VW PVs are rated 3.2W.  They will all do that easy enough, and some with larger cells will do close to 5.5W actually into a battery.
You knew that.
In fact, it's your fault I started collecting the VW PVs years ago after you posted a pic of a few above a window on your house!  That must have been 10 years ago?  More?
Geeze.  Now I feel old.
G-

Offline MadScientist267

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Re: Neat Experiment
« Reply #6 on: August 15, 2012, 11:30:00 pm »
Buck converter makes all the difference in the world...

I've found that if you use one that has current limiting, you can effectively "tune" it to the panel, and while it isn't technically tracking anything (of course), minus converter losses, you can get rather close to rated output from a panel.

This works particularly well where you need to split where the power is going, either because of differences in voltages, or because charging (or other) currents demand it.

For example, in the van, I limit the SLA to 600mA (C/20 rate), and rather than dumping, I divert the surplus into either charging the amp's battery (directly, 14.4 nominal NiMH) or alternatively, through a second buck converter limited to 1A going into maintaining/slow charging the van battery.

Works really well if you tinker with the output voltages on the bucks; regardless of SoC or sky conditions the following day (except for downright stormy clouds), the SLA is always full again by the end of the day, and if its been a particularly sunny day, the van battery has been boosted up enough that I'm not leary of lighting up the laptop for a couple hours or so. ;)

FWIW

Steve
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Offline ghurd

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Re: Neat Experiment
« Reply #7 on: September 13, 2012, 08:32:17 am »
I woke up too early, again.
Put the phone on the charger and SLA (that mess in the photo above).
Went out to get the phone later.

VW PV was facing West.  Sun was not making it past the trees and shrubs to the porch from the East.
But...
Dusty 2nd story window on neighbors house was (poorly) reflecting back onto the center of my porch.

Hmm.
Panel in the reflected light, sort of hazy sky, USB switcher, phone, no SLA battery... no way?
Wrong.
It still manages to put out enough to properly charge the phone.

Not sure how much power the phone needed at the time because the battery was "full" a few minutes before.  I don't know if this phone takes constant current for charging, or tapers the current as the battery gets closer to full.
Either way, I thought it was pretty cool.
G-

Offline ghurd

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Re: Neat Experiment
« Reply #8 on: October 14, 2012, 05:28:51 pm »
Update

Caution:
Do Not try this at home, with a cell phone you like.
I am a trained professional, with a cell phone I hate.

Today, busy watching engine oil drain.
Grab a couple solar assemblies I never really tinkered with.

AND the cell phone is almost totally dead.

Poor solar day.  Hazy.  Heavy cloud cover.  some patches worse than other patches.

10 x 1/2A cells paralleled with 10 more.
Voc =~ 6.5V.
Hmmm... straight into the cell phone's micro-USB port?
Yup.  That works fine.
Wind kicks up, leaves on the "assembly", still works fine.
This is with NO external regulation whatsoever.

Another "Hmmm" moment?
How about all 20 cells in series, to a Lighter-to-USB-switcher thingie?
Again, no issues... until I added a lot of leaves on the array... which caused the cell phone's "Poor charger connection!" warning on the phone.

I found the "Poor charger connection!" warning a bit strange, since I could not force it to happen without the USB switcher.
I have no explaination for that.

Also, once the phone's "Poor charger connection!" warning went off, it seemed that the charger needed unplugged from the phone before it would 'reset'.  The input voltage to the regulator indicated the PVs were operating at over Vmpp (basically unloaded).


The Good Stuff (if that wasn't good enough):

This is all for 20 cells.  Series for 10Vmpp, or parallel for 5Vmpp.

-  The 5Vmpp array was operating at between 4.6 and 5.8V.
It seemed to swing with the available solar intensity.  More clouds was less Vinput.  This was a smooth voltage fluctuation.
The phone was happy the whole time.

-  The PVout / Vin at the Lighter-to-USB-switcher thingie varied a LOT more.
PV tended to run about 7.8V, sometimes >8.3V.  It didn't seem to matter so much with the solar strength, which implies a fairly substantial load to the system.
BUT,  every so often, the PV voltage would jump up to >12V, even >13V, for a few seconds, which would imply Voc on the array.  Guessing that was related to the phone somehow, and the phone was taking '0' power from the charger.

-  A few notable things:

1)  Grid charging to 'full' at the condition the phone started takes about 3~4 hours (best guess) with the factory OEM parts supplied with the phone.

2)  Solar/USB/Direct took about 2.5 hours until 'full'.

3)  Part of the time the phone was charging, I was talking using the phone via USB headset, which I would expect would use a lot more power than if the phone was doing nothing.  But it still charged faster than via the OEM supplied grid charger (and no "battery is over-temperature" warning like was common this summer even when the phone was not charging).

4A)  I have far less money in this entire charging system (PVs, adapters, S&H, etc), than the cell company charges for a simple car charger (>$30 with tax where I got my phone).

4B)  Phantom loads are always an issue.  More so on tiny RE systems.
Seems like something like this would eliminate phantom loads, inefficiencies, battery costs...

Nothing ground shattering.
It is fun.
G-

Offline MadScientist267

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Re: Neat Experiment
« Reply #9 on: October 15, 2012, 12:41:06 pm »
Can't say for certain about every phone, but my Droid X has some odd power requirements and understandings of its own.

After the whole van incident started, I had to be very mindful of what got used where and for how long.

Android OS has a [very inaccurate] method of determining which components within the phone consume the most power, and so it wasn't any real surprise that the battery charging system was not exactly spot on either.

With a 12V nominal in at the "official" buck converter for the car, most of its charge life is right around 500mA, due to a current limiting sense in the converter. With losses, this makes For right around 1A going into the phone to charge the battery and do whatever else the user needs it to do in charge.

This 500mA holds true, all the way to 100% charge, and for another 15 minutes or so afterward. At that point, it does begin to taper off, with no other indication that there is still some charging taking place. Eventually, if left completely alone for about 2 more hours, the current will drop to around 40mA and stay there.

The insanely inaccurate reports from androids battery usage meter is useless at best... When I had extremely limited power available, I found out that even though android claims that 85-90% of the power consumed was by the display, this was simply not the case by any means. The highest consumption by far was the touch screen interaction, followed by video playback, then GPS, then voice calls, and THEN the back light for the display.

Moral of the story, a "charged" cell battery is anything but, unless you've either left it on solid power (grid etc) overnight, or have been able to confirm with a meter that its no longer drawing squat.

FWIW

Steve
Wanted: Schrödinger's cat, dead and alive.

Offline Wolvenar

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Re: Neat Experiment
« Reply #10 on: October 15, 2012, 08:37:59 pm »
I've done similar testing as MadScientist on our n900s

Discounting any app that uses the CPU heavily, it seems bluetooth is BY FAR the more power hungry thing that the phone can do, followed very closely by fm radio transmitter ( figures it uses the bluetooth hardware)
GPS is next, after that the  screen uses the next most power,  followed by audio if turned up loud using is speakers.

Another interesting aspect is I made a double battery for my phone, despite only being double capacity, the lower overall draw on each creates about 4x the usable time.
Trying to make power from alternative energy any which way I can.
Just to abuse what I make. (and run this site)

Offline ghurd

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Re: Neat Experiment
« Reply #11 on: October 16, 2012, 08:16:57 pm »
Another interesting aspect is I made a double battery for my phone, despite only being double capacity, the lower overall draw on each creates about 4x the usable time.

I see that all the time in other things.  It is one of the reasons my battery:charging system ratios and math vary widely depending on the situation.
Glad to know someone else noticed it too!

I have a feeling, maybe, this is part of what Norm is seeing with his LED lights in the difference between nicd and alkaline cells?
G-

Offline Norm

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Re: Neat Experiment
« Reply #12 on: October 23, 2012, 08:36:34 am »
4 LEDs + 1.....
How long has it been since I started that ?
Anyway ....my point is this....
the old alkalines can really solve an almost insurmountable
problem that you just can't do with NiCads.
example:
Scenario:
1 4LED lamp with 3 "D" size cells turned on at night.....next day
still burning bright as when I bought the cells about a month ago? (maybe longer)
next night (oops !) forgot to turn it off ...ah well (leave it on)
in the meantime 3 other 4LED lamps with 3 "C" size rechargables on each
that I've took the time to put quick connect fittings on so that I can put them
all in series and spend about 15 minutes every night to recharge.

Only  one lamp of the three has a 50 ohm resistor in series with it so
 it doesn't take as much juice, so it stays about the same brilliance 6hrs. earlier
 (quite a bit dimmer than the other two)
....and then I'm figuring what size resistors to be a compromise between lasting
longer or brightness......or maybe use a driver on each one to limit the current ?
......then an electronic circut to operate dusk to dawn?
All of the above is a continual challenge.


Meanwhile that ONE 4LED lamp with the 3 Alkaline batteries is still burning
nice and bright....even when I forget to turn it off in the morning once in awhile...
....Now if I were to hook a solar cell just almost large enough to replace the 'juice'
it used/using 24/7 ......SOC of the Alkalines staying about the same day or night
cloudy or sunny .....think about it awhile guys!


See how much easier with the alkaline? I think recharging these alkaline
batteries is really feasible when they aren't discharged very much and it's
all possible because alkalines have more internal resistance that the LEDs
were designed for ( I think it was designed/planned that way to use ....throw
away and buy $$more$$   ) Right?

 ....for $1 for the 3 batteries $1for the 4LED lamp plus 1 small solar cell in the
windshield of a vehicle you could have a nice bright reading light....I think !
figuring maybe a year for the $1 batteries if the price don't go up by then....?
Norm

Offline Norm

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Re: Neat Experiment
« Reply #13 on: October 23, 2012, 08:58:40 am »
Ghurd ....about that one panel with the canvas type back
cut in 4 strips (like there are 4 units there ?)
.....and hook to three "d" size Alkalines each 4LED lamp ?
4 lamps ....3 alkalines (each lamp) 1 strip solar (each lamp)
like I mentioned in this previous posting ?
well anyhow guess you can go ahead and send me one of those
solar panels that you spoke of.....
Thanks.....
Norm.
81 yr. old havin fun
with these "experiments"

Offline tomw

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Re: Neat Experiment
« Reply #14 on: October 23, 2012, 09:34:04 am »
81 yr. old havin fun
with these "experiments"

Norm;

They say you are only as old as you feel.

I calculate you qualify as "teens" the way you are having almost illegal amounts of fun!

Tom
Do NOT mistake me for any kind of "expert".

( ?° ?? ?°)


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