guess who bought a power jack inverter

[oztules]

I think the "cut if high" is part of the same voltage divider.. so you can push the limit the other way.

I had no joy with just changing the resistor value, as my charger is a home brew pwm. It sends very high/narrow current pulses when the batteries are nearly full... and this shuts down the unit.... if you have pwm, I expect you will suffer the same fate when the batteries near float. 5v6 zener works for me... but i needed to make a cut off device.

I had hoped that the batteries would stop the high voltage peaks.... but it does not suppress them for long enough for reasons i don't quite know...... so I did this.

Will do a story if necessary.


The IC 393 is actually a 339


Here it is on test. Set to 60v.
The grid tie active goes through the relay (normally open contacts)... so it simply monitors the voltage , and shuts the active off to the grid tie on tripping. Hysteresis is 4v so it will re-engage the grid tie when it drops to 56v. The grid tie will have about 2-3 mins before it retries then.



Here it is in it's margarine container for testing..








....oztules

[oztules]

Well by 11.30am, the relay tripped, grid tie stopped..... and the voltage dropped to 58v as the LV array was still active. The max input of the grid tie was 1520 watts. ( only one grid tie connected today). The LV array was around the 40 amp mark. (48v system )

It's 12.10 now, and the lv array has throttled back to about 25a...at around 60v so all working well  at the moment.
Now the days seem longer and brighter, will have to back the system down to 58-59v perhaps to keep over charging under control.

They are flooded cells.


................oztules

[Mike]

Hello Oz,
               How are you, can I ask a question but I'll give you some history first.
I'm not living off the Grid but the Gird is getting expensive when it's heading towards $4k a year.
I looked at putting the Pool on Off Peak but the quote was $600 for the rewire and it is estimated it costs $1000 a year in Electricity.
I looked at getting a Grid Solar installed but with no Feed In Rebate here in Qld any more, questionable pricing and workmanship on installation I kept looking around.

A small business close to where I work were selling 250w 60 Bosch Cell Panels for $130, OK for Off Grid.
So I am putting together a system firstly to run the Pool, then what ever excess is left over like the outdoor Beer Fridge, LV Lights using 9 Panels, regulated to 24v and some Batteries,
I looked at DC Pumps but Cost. I have Timer, Pump, Chlorinator. Then the Solar Heater has it's own Pump that does not get used much all 240v.

So now I am looking for an Inverter and I know the Pumps take a bit to start per the Davey Brochure, I have a 150 & 300.
I looked at the later 4 x start PowerJacks and when I contacted the sellers through Ebay they were pushing that I need over the top Start Ratings out to 40kW and near $2000.
Their pages say they will not start Inductive Motors but your posts show they should not have a problem.
You have given the 8,000/32,000 PJ a good rap.
I am thinking of buying a 5,000/20,000W for just under $500 as I believe this will do the job.
What do you think ?
 
regards

Mike

[oztules]

I assume the Davey is 150 and 300w pumps.
The LF units will start inductive loads without any fuss. The 5000w will run those loads all day without bothering the fan unless the weather is hot.

These things are both better and worse than the figures they claim. They are very tough, handle very high inductive loads and will run your stuff without complaint. They claim 5000w continuous, but really they mean 5000w for 12 seconds, probably 20000w for 1/2 second etc, Continuous is a function of the transformer size, and the one in that unit is good for 1.5-2kw max for continuous operation. The silicon part is easily good for 5kw continuous, but the transformer would need wicked cooling for that level long term.... and there we have it.

So it is a good honest performer with silly specs. As mentioned previously, you can mod them for anything you need to do.

I like the panel prices... do they send south?


For 24/7 you may need to use the inductor conversion, but the last 24, 5kw unit I bought for a bloke here already had that in it, so it's idle was already .7A@24v... or less than 18w... very good figures compared to their original units... by about 8 fold.

A solar pump would suit  very well if you can handle daylight operation only, as you will need to burn up 4-6kwh each night for continuous operation.... batteries?

You should pick up the 5000w unit for 400 or less if your patient.


So don't worry it will start it without noticing.


If they programmed the chip more sensibly, they would have the perfect unit really. The 12 seconds should be 12 mins... and I would be happy. Instead I need to bypass some power around the current sense to push the big mig welder up to draw around 5kw for the 8000w unit, which will do it easily ( and run the house at the same time)

Induction motors behave just like a short circuited transformer at start up... hence the big start currents they speak of..... add the inrush currents for the first few cycles, and it is easy to see why the HF inverters really struggle. These LF units seem to do it without any trouble at all.


...............oztules

[Mike]

Thanks Oz,
              I like to make sure I have explained the Details.
Davey 150 is 18 Amp Start & 4.4A Run. The 300 is 28A Start & 7A Run.
I even had the Brother In Law take a Log of the 150 with his good gear which is attached.
Brochure was very close.

I just rang the Little Business down the road http://batterycentralbrisbane.com.au and he still has Single 250W Panels for $150.
He will do a Deal for Qty and some that don't work but could be fixed for a lot cheaper but anyone interested talk to them.
He does not want to get involved in Freight but there are ways.
I checked the Models on the ones I purchased per Photo attached and they were not on the approved Federal List for the Grid if that makes sense.
I think they pick them up at Auctions so he has a mixed bag of Voltages & Watts, so be careful.

regards

Mike

[oztules]

ok looks like about 2000VA for the big one for 1650 watts.... power factor of maybe .8??for the motor... depends on if it is caps start cap run or just cap start... fiddling with the run cap may bring your pf closer to 1.... so VA can come down for the same power output.

This will be at the outer end of the heat range for the 5000w unit. Starting will be no problem, cooling might in your climate.
They had twin transformer ones in the 6000w range, and that would be fine, but I have also heard that the 6000w ones can come with a single transformer with an extra fan.
consistency is problematic apparently.

A fair chance you will get an 8000w unit for $600 if your careful in the bidding..... plenty of wiggle room there.... need a huge battery to run through the night, and more panels ( must run and charge at the same time )...... your looking at 24kwh to burn up each night ... so will need 29kwh of energy to charge that up each day.... but, gee...then you still need to run the power for daylight running

A solar pumping system may be a better option., no batteries, and up there a pretty fair chance of doing well with a 2hp motor on a mono pump, panels and controller... vastly cheaper and no maintenance but for brushes in motor.  I have built some pretty big solar pumping systems down here for cattle water, and they are simple and easy to make... particularly on the mainland, as big DC motors can be easily obtained from cleaning equipment repair places. Lots of floor scrubbers get retired each year, and a lot of them have 2hp 36v motors in them.... plum for the job...... especially Advance scrubbers.

The biggest to date is 120psi@60lpm.... thats a  fairly powerful system... you have no pressure to speak of comparatively, so if your at 35psi, instead of 120psi, up the volume accordingly.

Sent an email to those blokes for a pallet of panels and shipping, will see if they respond.

Am testing a standard 8000w unit at the moment, running 2 x 1500w grid ties into it every day, so 3kw loads for 5 hrs or so peak today I expect.

Transformers are still only 44C and power heat sinks are at 38C... air temp is 15C..... so the 8000w unit will do it without doubt... rarely hear a fan.., the 5000 I am confidant will run it fine, but 100% duty cycle will require watching the temps until your satisfied it is staying below 50C, maybe adding a fan if not happy.

...............oztules

[oztules]

Actually looking at it from an economics point of view,you would be better using a grid tie system of 4kw or so to provide the offset for running it for maybe 12 hrs per day.
No batteries or inverter, and just time switch the pump for daylight hours only. It would cover the pumps etc and the house use during the day, and would be better in every way I suspect.

................oztules

ps I bought a few pallets of those panels too....they will be used for water pumping over here, so CEC approval is not a priority... at all.

[Mike]

Hello Oz,
              My biggest concern was the Start Current with the 5/20K PJ Inverter.
You have settled my mind on that.
The Run cycle I'll do as you said keep and eye on the Temp until I am Happy.
One of those Pumps has a Noisy Bearing so when I have it apart I can check the Cap but I bet it is just Start.

The good thing about the Pool is in Winter, I only need to run the Filter Pump 1-2 hrs a day especially if I put the Bubble Wrap Blanket on it.
This time of Year 3 hrs is fine and Summer I go to 6-8 hrs a day and I'll time it to either side of Midday.
It's all Water Temp, Algae growth and Chlorine Production needed.

The Solar Heat Pump only cycles on when the Water Temp on the Roof is higher than the Pool.
The On time only needs to be a couple of Minutes to flush that Heat out of the Pipes/Mat.
Then you wait till it heats up again. I didn't even use it last year.
I have some Ideas to flush out where the Filter and Solar Pumps never come on together.

My 9 Panels on test are putting out 8 kW a day at the moment.
The Batteries are there to provide Start Current and I hope the Panels will then take over with a little left to keep the Batteries up.
As for those Cloudy Days I still have the Grid and I was thinking of a change over Relay on the 240v side controlled by Battery Voltage.
I believe I will need a timer circuit to control the Hysteresis so it does not keep switching Grid Inverter Grid Inverter in short cycles.
I was also thinking in the evening when the Panels stop producing I switch back to Grid just for the 24 hr Timer which must draw less than 10W.
That way the Inverter can go to Sleep and not draw much from the Batteries using the same change over Relay.
Still working on that Idea but a couple of my Regulators have a settable Load On Time for Lighting after the Panels stop producing.
A work in progress.

Hope the guy gave you a good deal on those Panels.
If you want I can take Photo's of what he is Shipping you.

regards

Mike

[oztules]

Yep start is not a problem, as we can overcome any shortage of high end control by fiddling the current sense. The difference between a 5000 and a 15kw control card is only the software settings, and the resistors across the current transformer for sensing.

The fets are big enough to look after themselves.... so if the original software is a bit wanting, a piece of wire or a resistor will solve the problem.

Continuous running is a transformer problem. A small transformer can pretend to be a big one... if it is cooled enough. or has a light duty cycle.

I had no idea of your duty cycle, but now you have clarified it, it is not in anyway near what I feared.... but 8kwh will be cutting things too fine for 6 hrs @ 2kw draw?? in summer.


..............oztules

[rossw]

My 9 Panels on test are putting out 8 kW a day at the moment.

They must be freekin' enormous panels! That's 889W each!!

(Or did you mean 8 kWh/day?  If so, why didn't you say it?  kW != kWh)

[oztules]

Ok, now testing the next generation of my powerjack conversions.
15kw power board and power card
Very big transformer. good convection cooling.

Here is the unit as testing.

the grid tie is running .... just as it is very overcast ( raining actually), so the two watt readings are very different.
Some of the grid tie is running the house load, so only a small power is adding to it.

The rest is coming from the normal array, and it is going to the battery.

This is the new transformer, up to 5kw tested so far... barely any sound at all.. Epoxied windings.


Here is the larger 15kw power card from power jack, it is the same elctrically as the smalle 8000w etc cards, but just bigger board and heat sink.

 The two temp gauges are on the very top, the RH side is the heat sink temp after running the house all night and into the day.... no fan so far.

The left hand side is the transformer after the last 24 hrs or more.
Can't ask for more than that, silent running and no fan thus far.






.....................oztules

[steve3]

Hi Oztules many many thanks for restoring my faith in the PJ. I’m retesting things again.
But I have been warned by her indoors, if this new TV dies I’m in real trouble, she will cut down my rations to 0, O dear. Once the pressure was off I did repair the old TV. The fault was one of those surface mounted dead fly things.

(1) One thing I will have trouble with is my PV connects to the grid via the link wire between the meter and my main S/W,
So just pulling the fuse on the mains incomer will get rid of the 240v feed, but the neutral will be solid to the rest of the grid.
With the grid they try to keep neutral at earth potential, but TRY is the right word to use don’t you think.
I can’t think of an easy way round this problem.
I just cant fit a double pole Isolator, as this position is no mans land over here, the meter man can get rather hot under the collar if you play with his wiring past your main box.

(2) I can’t for the life of me see how to get the lid back on without the choke pressing hard on the lid. I know what you are going to say, WHO said the lid has to go back on. So I rewound the choke using flat braided flexible strap the type used to connect say a car battery 170a 25mm rating, its flattish and winds very easily, from Ebay 221537256689 its 24inches long, the choke now goes in with little effort. Oztules that was a fantastic link you sent me, you in full flight butchering a TV. The comment you should never be aloud to own a soldering ion, well all I can say is keep the good work up, your a man after my own heart, great.

(3) I found this little plastic spacer (see picture) any ideas where it came from??.
Ps. I think I’ve found its home, at the back of the lower negative terminal next to c30 there is a screw missing, all other screws holding the pcb down have a metal washer and two fibre wasters, I suspect in this position no fibre washers should be used so you earth out one side of c30 can you please advise me.

Sorry for the novel, many thanks your a Gent. Steve.

[oztules]

1.
Over here we need a double pole switch for change over..... but the fact that the units are earthed.... and the neutral is earthed for the grid....... it is really a waste of time lifting the neutral... I still do, but it makes no difference at all.

So breaking the active only will not materially effect the isolation which you seek..... a double pole would only achieve the same thing if your grid tie is earthed anyway.... ie it is still joined at the earth.... hard wired in the meter box.

It is not practically possible to have dangerous voltages in the neutral with respect to earth... Even a double pole will not isolate the grid tie from the grids neutral, it is still achieved via the earth.... although the grid ties neutral would then be floating. The moment if connects to the PJ as the house circuit, it is automatically connected to the MEN earth system... back to square 1.

As a general rule, the innards of the PJ are floating with respect to earth, as will be the grid tie.... the boxes will be "earthed" internally, but not to the AC rails
They only get sorted to ground when connected to the MEN earth system via the feed cables.

2. I simply undid the transformer bolts, and shifted one forwards and one back, and the choke sits between them nicely.

3. no picture to be seen, but I assume your right . If you have 5 screws in, thats enough anyway... just make sure the washers associated with the screw are not floating around in there. There are two screws that should be grounding the filter caps, but they are only there for rf noise suppression... and won't effect operation is any other way if not done properly.

...............oztules

[steve3]

Thanks Oztules as normal you have put my mind at rest.
If any one goes down the route I suggested i.e. braided strap from Ebay, get the guy make you one 29 inches long, that would save a join.

Do you think I will have any troubles running my Sunny boy 3600w Hf inverter off grid, I know its a rubbish unit, but over here (England) we have to get all the gear installed by so called experts, (and as you know an expert is a drip under pressure), the rubbish they put in is what you have to live with, and they are Animals, no really they are.

That’s a very good thought about looking for the other screws and washers, I will investigate.

When I’m running on the grid I have installed a unit called a (Solamiser) Ebay this unit feeds proportionally only the power that would normally go back to the grid to say run an immersion heater, I have connected its output to a 13a plug socket, If there is only say 1000w of PV being generated, I plug in a kettle 2000w type, It take a little longer to boil but It totally free guys.

Many thanks Oztules for all your help. Steve.

[steve3]

Thanks Oztules for all your explanations, I have at last with your help fired up the PJ to wake up the sonny boy grid tie inverter and charge the batteries with pv power, But it wont kick it into gear, it comes up with a fault (PE connect missing). When I test things out I find there is about 240v on the grid tie live and neutral, but also 120v ish to earth on both the live and neutral, as you said its a crappy grid tie inverter, can you suggest a cure. Steve3