24V to 12V DC Power Supply

Setting up a 12VDC power supply to run off the 24V lithium ion battery bank to power DC loads around the house.

Motivation for this was to free up a 335W solar panel to allow a more efficient series-parallel combination to feed the 24V charge controller more efficiently. I also wanted something to keep the old 12V lead acid batteries in workable condition. Added benefit of the system is getting a free 12VDC uninteruptable power supply) UPS. I can also retain the old 25A - 12V power supply I have as a backup, and that was used in this video while I swapped over the charge controllers. At 20A output and ~13.8V, this can deliver approx. 275W of DC power, which is enough for my needs at this time.

With 4 solar panels feeding the 24V charge controller, I can set them up in series/parallel for a better performance. I can't run all 4 in series, as the 164Voc would exceed the 145V charge controller maximum rating. With the series-parallel setup I get 68.2 Vmp x 19.66 Imp or 1340 watts. With the current 2.7KWH battery bank, I've seen 1050W maximum so far, but the battery bank is usually topped off long before the sun hits the peak angle. Time to add to the battery bank, which will be in upcoming videos. Later, with 7.5KWH battery bank, I now have seen about 1.3KW from the 4 panels.

I was thinking of changing out the 12V circuits for 24V, but that gets messy as I have some 12V loads, then there are 15V loads driven through a step up converter as well as 24V loads again via a step up converter. I would have to add many small step-up-down converters all over the place. I could of course pick up a 24V DC power supply to use as a backup, but I already have the 12V supply and it works just fine. This is the only time in over 7 years that I actually used the backup power supply, so it's not a high priority, but having working backup systems are nice to have

More to come...
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Intro/Outro:
Louisiana Fairytale by Austin Rogers
https://web.archive.org/web/20170402222425/http://drfiddle.com/show_tune.php?id=94