Posted March 16, 20205 yr With prices souring and availability on the decline, I was wondering what the limitations of the old reliable 12V 7AH could be. I have heard that there is a limit of 3 parallel strings of batteries. I know that the cycle limit of the 7AH will not be great, but at R5,000 for 8 x 48v strings yielding a 50AH it could be an option. with monthly checks of the batteries to insure consistent charging. Replacing a few 7ah batteries every year is cheap enough. We all want omni's or pylontech, but at the moment beggers can't be choosers... Just wanted to know if it is a viable temporary solution.
March 16, 20205 yr it works out expensive in my view rather buy the royal batteries 105ah at R1500 or so R6000 for 48v 100ah vs R5000 and simpler wiring and less monitoring of the batteries
March 16, 20205 yr Author @scrarfussi Good suggestion, but I had some Royals and the Axpert just didn't want to charge them AT all. Went to some 12ah's that worked and onto Omni's. Now I am looking for replacements.
March 16, 20205 yr There are UPSes that use small lead acid batteries in long strings (96V I think) and do well enough, but for backup purposes, not for daily cycling. So in principle doable, but the cycle life is not going to be that great. 200-400 cycles according to some random specsheet I googled into. I think the biggest issue is going to be when one cell goes short circuit and that string starts to pull current from the other 7 (plus charge current), cooking the rest of the cells until one of them blows up like a balloon and then potentially explodes. Odds of that happening is 8 times greater than with a single string... Severity of things going bad... also much worse. Risk = likelihood x severity. I agree with @scrarfussi, if you're going to cheap out, cheap out on the Royals. Though of course... you may not be able to find stock of those 🙂 Or.... design a RAIB... random array of inexpensive batteries 😛 Edited March 16, 20205 yr by plonkster
March 16, 20205 yr Ohh ok that's weird i got some vision Batteries they seem to be charging OK mine is a synapse
March 19, 20205 yr On 2020/03/16 at 2:56 PM, scrarfussi said: it works out expensive in my view rather buy the royal batteries 105ah at R1500 or so R6000 for 48v 100ah vs R5000 and simpler wiring and less monitoring of the batteries You have a source? Gauteng preferably? my google fu is not revealing something with stock at the moment.
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