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Forum Index : Electronics : Good money after bad - Solar upgrade time
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| oreo Regular Member  Joined: 11/12/2020 Location: CanadaPosts: 69 |
So in order to charge my batteries, I need about 82v and I have 8 hours each night at the lowest hydro rate. So I figured that I needed about 2kw. So I purchased these power supplies.  The HEP600-24 can be adjusted up to about 26v, is ~95% efficient and has an adjustable current limit from 12-25amps. The C3KX-PWR-715WAC is 56v, 12.5A and is about 88% efficient. A better choice would have been the PWR-C1-715WAC-P which has the same rating, but with platinum efficiency (94%). So I have the 2 56 volt power supplies feeding into .025ohm resistors into the 24v supply (so the 56v units share the current) feeding into a schotkey diode to ensure the battery does not back feed into the power supplies. I stuck it into a old inverter box and put in a Voltage/current/power measuring meter.   It works well, and right now I have it charging at 20amps and have it controlled with a mechanical timer. I will get more resourceful in time with this. Some other interesting power supplies which at times can be purchased cost effectively. (12v server power supplies like the HP one below are really cheap)  This website has data on the efficiency of many different power supplies You can download the whole list into a spreadsheet. Power supply efficiency numbers Greg |
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| oreo Regular Member Joined: 11/12/2020 Location: CanadaPosts: 69 |
I also use these bench supplies for charging the main battery during testing etc.  The upper supply uses 1pc of C3KX-PWR-715WAC, while the bottom supply uses 3pcs of HP HSTNS-PR28. The project cases are from amazon, and while they are made with the thinnest of materials, everything seems to be just ok.  Unfortunately these HP 12v power supplies connect the gnd of the supply to the case, and also have a few caps running from the 240v line back to the case. So you need to remove the connection to the case and the caps for all but 1 of the supplies. Greg |
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| oreo Regular Member Joined: 11/12/2020 Location: CanadaPosts: 69 |
So I packaged the second battery. This gives me about 14-15kwh to play with in total. This is prior to adding the covers   And I ended up getting a used automatic transfer switch. It's really designed to be used with a generator, but I changed that up so that if solar dies, after a minute the switch connects to utility. I have to manually move the switch back to solar should it trip. This way if there is a failure when I am away, everything will continue to run. So far I have moved about 14 circuits over to solar, using breakers in the ATS.   Greg |
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Revlac Guru  Joined: 31/12/2016 Location: AustraliaPosts: 1088 |
Quite an impressive battery build.  Cheers Aaron Off The Grid |
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| oreo Regular Member Joined: 11/12/2020 Location: CanadaPosts: 69 |
^thanks Aaron. I do wish the packs I am using were smaller. These batteries take up a lot of room. Greg |
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| oreo Regular Member Joined: 11/12/2020 Location: CanadaPosts: 69 |
So I just had my first major explosion. Actually it was pretty muted, with not even any FET packages getting blown off. Not sure what happened, although it was running at about 6kw for an extended time. Half the FETs, one driver transistor, the 8010 chip, the 80-12v DC-DC converter and 1 voltage comparator were all sent to the promised land. Surprisingly the 8010 and voltage comparator were being powered off 5v and the 5v regulator was still outputting 5v. I replaced the 5v regulator, "because". This gave me the opportunity to fix some things I had been putting off. 1. When I built this inverter board 5 years ago I didn't use particularly good substitutes for the TIP41/42's. I had purchased some TIP41/42's so I upgraded those. 2. I didn't document the additional windings I put on my donor transformer, and also had mistakenly used the wrong gauge wire (smaller) on some additional HV windings I added to it. This was fixed along with adding more isolation tape between the HV and LV windings. The transformer is now slightly quieter, and the HV winding resistance is now 10% lower. The transformer still weighs in at 35lb, and I have an additional transformer that I plan to make these modifications to. 3. I had ordered some MS225060-2 cores off EBAY so I could rewind my inductors. The vendor ended up shipping me MS184040-2 cores and indicated they actually did not have the correct core in stock. These cores were not really going to be much better than what I already had, but ended up building 2 replacements. They are in series with each winding, and each has the same equivalent wire gauge, but 1 is built with multiple 20awg windings while one is built with normal stranded welding cable. We will see what measurable difference in temperature there is during operation. So everything is back up and running... .jpg)  Greg |
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