Hey Wrenches, I just did a site visit for a client who's had a few iterations of PV installed. The main reason for the call was that the battery bank would never charge to 100%SOC but rather appear to charge to 100%SOC and actually hover around 70%SOC. At the end of the day the client would top it off with the generator for 30-60min. This has been happening since October, I just got the call the other day.
The site is less than code compliant to say the least and the programming of the 3 charge controllers were not equal. Array 1 South Facing 4-Canadian 250w (one string) Flexmax 80 Absorb 29.3V 6hrs Float 27.3 End Amps 10A Rebulk 25V Array 2 South Facing 6-205w 2-195w (one string) Flexmax 60 Absorb 29.3V 6hrs Float 27.3 End Amps 10A Rebulk 25.6V Array 3 North Facing 8-295w Renosola (4 strings) Flexmax 80 Absorb 29.4 1hr Float 27.3 End Amps 0 Rebulk 24 20-Trojan Reliant L16 12V (5 parallel to a bus) purchased the end of 2017 Apart from the not so great design to say it lightly, the bank is consistently showing a stepping voltage of about 70%SOC up to 100%SOC from negative to positive. I changed the charge controllers to an equal absorption voltage and time (28.8V and 4hrs) to try and slowly bring up the lagging side of the bank. I was cautious not to raise them all to 29.4 at 4+hrs because I don't know their history and didn't want to cook them further if they are indeed headed that way. At the time of inspection the batteries were about 84F and the thermal camera showed no variations or hot spots. I asked the owner to report back if it gets better, worse, or the same. He reported back and said that the total kWh production daily is gradually going down over these past few days. Any suggestions on how to bring this bank back to 100%SOC would be appreciated. Jon Siegenthaler
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