Powerstar W7 Inverter modification

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Re: Powerstar W7 Inverter modification

Postby Jimbo007 » Mon May 15, 2017 7:44 pm

Shayneo it is only the display riser board that varies. If you got the wrong one, you could probably swap with your existing riser board. the main control board is the same for a given specification.
the only active components on the riser board are the LED's and posibly some LED drive transistors. should be okay.
Cheers
Jim
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Re: Powerstar W7 Inverter modification

Postby shayneo » Tue May 16, 2017 2:20 am

Thanks Jim I will look into that !
Cheers. Shayneo
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Re: Powerstar W7 Inverter modification

Postby Jimbo007 » Tue May 16, 2017 4:15 pm

Graham,
do you know of any large toroids available ?
my search so far has been fruitless.
Despite buying a complete functional unit, I still love to build things for the satisfaction of doing so and this would give me a fallback in the event of a desparate collegue begging my new unit.
I don't want to have to fall back on the grid anymore and as I have two sets of boards, a failure (unlikely ) would not cause much inconvenience.
If you have any information, feel free to PM me.
Jim.
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Re: Powerstar W7 Inverter modification

Postby Graham_West_Wyalong » Tue May 16, 2017 4:23 pm

Hehehehe yep fuses are a good idea.

Like everything though it will be important to match your fuses to the expected max draw in amps with a low volts situation.

Ergo, if you have a 24 volt system and you are going to draw 12000 watts from it 500 amps of fuse capability may not be enough to deal with the lower voltage that would naturally occur when sucking this much current through the unit.

I worked out that the minimum I would want on my system was parallel 400 amp fuses.

Remember also to ensure the best electrical connection possible so you don't get yourself too many electric bar heaters in your powerhouse! Hehehehe

Don't be panick stricken about the fuses being so large! Once when tuning the current sensor for the maximum capability of my system I had 8.2 kW being drawn then my wife flushed the loo and caused the pump to start! Hehehehe those powerstar boards are amazingly robust!

Not so impressed with the old jack Chang boards.... Still cheap Chinese says it all there!

It is interesting that the 8kva and 12kva are identical (except presumably the programming) that is why we jumped the current sensor with loads (big loads) attached. As I said my 6kva would not handle the 6 without cutting out (probably specified higher than capable) but with the modified transformers, cooling and current sensing it easily delivered in excess of 8 continually!

Obviously thermal is an issue to be considered.

Good luck all.

And what about the battery details yunak?
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Re: Powerstar W7 Inverter modification

Postby Jimbo007 » Tue May 16, 2017 4:42 pm

Graham,
I did notice Yunak said it was 1010 km round trip to his remote location.
Hopefully, he has some kind of load tester to check his batteries or at least a meter he can check each battery with while under load.
I got the impression he had just a couple of batteries rather than a bank.
My own battery bank consists of 16 x 200 ah SLA configured for 48 volts so gives me a total of about 40 kw/h to 100% depth of discharge ( which will never happen ).
His best bet, given the distance, is probably to take a new set of batteries out there and hope that's the solution.
Jim
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Re: Powerstar W7 Inverter modification

Postby Graham_West_Wyalong » Tue May 16, 2017 6:08 pm

Yep. One thing people always do is underestimate the capability of batteries....

I have been fortunate enough to have scored 4800ah at 24 v (fla) old forklift batteries which salvaged up nicely and clearly I have been able to hammer them with no issues. This is for the 240v system.

The 12v (light system) consists of 440ah at 12v (sla) Trojan forklift batteries. Again because people do not understand batteries and simply go by cycle count they were presumed to be on their way out. A few bucks worth of diesel and single cell balancing brought them back to balance and they have done a marvellous job for three years now and I would not expect them to die in my lifetime given the maximum demand over 7 days with no charge is under 10% DOD. Hehehehehe definitely worth being friendly and helpful to people.

The flooded S are lucky to drop to 3% overnight if the wife cooks a roast at night!

Buy big batteries is my motto! Oh and make sure you charge them enough.

People also don't seem to understand that 1kwh used in the house equates to more than 2kwh charging for lead acid, (especially the slow soak charge after the 80% bulk charge). Oh well the information is out there.

I was looking at upgrading to lifepo4 and worked out (with the new chemistry and DOD capability) realistically our 13.2kwh at 10% capability would be delivered by 8 200ah lifepo4 at 100% DOD (give or take a beer or two).bthis extreme figure factors in the charge rate being in excess of 5c and the discharge rate of 3c (the only real problem with lifepo4 for me is the discharge rate! Would have to change to 48v to deliver the power I am used to using or double the size of the bank!

Needless to say we don't use 13kwh daily... Actually it is less than 5. And obviously there is wind generation and abundant winter sun also!

This is the one thing people forget about lead acid. If you never let them stratify and never discharge them beyond 5-10% they will outlive you! (Typically). (Assuming your system is large enough). Imho.


G.
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Re: Powerstar W7 Inverter modification

Postby Graham_West_Wyalong » Tue May 16, 2017 6:10 pm

Just realised it is 2017, I have been using those batteries for more an six years! Wow and they were going to be melted down for the lead! Hmphhhhhh.
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Re: Powerstar W7 Inverter modification

Postby Jimbo007 » Tue May 16, 2017 6:38 pm

You did a good dead saving them from the scrap heap. I must agree, lead acid will take a flogging as long as you don't over chatge/discharge them. I've lost a few due to overcharging. fortunately a thing of the pasr with modern smart chargers.
The battery in my car is now 10 years old and despite the freezing winters in Canberra and having completely self discharged on four occasions during extended absences, continues to bounce back for more.
I would find it hard to justify LiPo4 batteries particularly as my experience with lithiums is that the BMS always eventually fails even though the individual cells are okay.
Next time you get a dead laptop battery, open it carefully and check the individual cells. always okay from my experience. just the BMS is lying. I have some early lithiums from the early laptops that are more than 20 years old and use my own charger. They still work like new after disposing of the internal BMS board.
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Re: Powerstar W7 Inverter modification

Postby Graham_West_Wyalong » Tue May 16, 2017 8:23 pm

Yeah, Jason and I are/were looking at making our own bms. Not too difficult, there are some dedicated chips that do balancing and such.

Beauty of being an old nerd I guess!

Hehehehe
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Re: Powerstar W7 Inverter modification

Postby Yunak » Tue May 16, 2017 11:17 pm

Hi Jim and Graham. To set your minds at rest the 535ah battery bank in the shed is old but in good order. It is kept charged with 560watts of PVs controlled through a PL20. All cells are even and they get equalising every 30 days by the PL20. Up to when the inverter spat the dummy they were charged after a run of cloudy days by my 4kva diesel generator. The shed setup is completely separate from the house Solar. The replacement (spare) inverter in the shed is a 24v to 240v 50Hz single phase pure sin wave without shore power switching (read no battery charger). It is made by Yueqing Reliable Electric Co. Ltd. http://www.powerreliable.com
I have wired it up to the batteries with the same 15mm diameter multi-strand leads that the PSW7 was connected with. It works very well and yes, it is 240v ac not 220v.
Now back to the PSW 7 problem.
When I returned from the property I tried the inverter on my 24v source at home and it performed the same as it did at the property i.e. no LED lights and the display erroneously showing the battery voltage as 18v counting down to 10.8/11.0v.
I dismantled it and thoroughly cleaned both the boards. I checked both for signs of discolouration or loose joints, all appeared OK except one of the caps on the base board seemed rattly. As they are in parallel I removed the rattly one and tested it rudimentarily using a voltmeter as the Ohm meter decided to have a hissy fit. Both these caps checked out OK. One of the blue electrolytic on the top board felt as though it moved towards the board when I applied a little pressure to it, it had no sideways movement and the soldered joints looked good.
I gave both boards a thorough cleaning as before, checked all for mounting firmness cleaned and checked all plugs and sockets and reassembled it and connected to the 24v source as before.
There was the usual spark as the caps charged, with fingers crossed I switched the inverter on.
The LEDs lit up and went out except the one showing we were on battery power.ie normal indication.
Then less than 2 seconds later the alarm gave a beep and the LED went out and the display showed the battery voltage erroneously counting down to 10.8/11.0v. I switched it off disconnected the 24v source waited a few minutes and tried again. No joy, back to the no LEDs lit and the battery voltage count down. I tried the switch off, disconnect, reconnect, switch on routine numerous times, once the inverter hummed and then the LEDs flashed rapidly for 2 or 3 secs and then back to count down.
My rudimentary knowledge of electronics is pointing me towards the bigger blue cap on the top board. I will take the cover off and try running the inverter with some pressure on that cap,( with a wooden dowel and one hand behind my back of course) I will let you know what happens. Have you any other suggestions. I have not yet had a reply from China about purchasing the boards.
Know any one that is in the market for a 20kg anchor?? Only joking.
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