Lead acid capacity in freezing temps
mountainman
Registered Users Posts: 145 ✭✭
My batteries specs are 208 amp hr but only 50% at 0 degrees. Question since at 50% on capacity do I charge on 10% of 208 or 104 amp hrs. One more thing which is worst on a battery bank discharging to 50 soc and charging at c10 or discharging to 75% soc and charging at c 5. On cloudy days charging with generator at c8.
Blue ridge mts. Renogy 400 watts manual tracking . Epever mppt 30. 2 GC 208 ahr. 300 watt psw inverter. 2 kw genny. Iota 45.
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But I know of nobody who changes charge rates with temps. The BTS (battery temp sensor) with many high end charge controllers, adjusts the charging setpoints + & - according to temps, but not the amps. So I dont think I'd worry about it.
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Some have argued that both of those are 1x charging cycle. So, from a pure $/ah cycle cost, a 50% discharge is supposed to be more cost effective.
Personally, use the system the way you need it. Don't drive yourself nuts trying to be perfect.
Bill
> So keep it at as is. Any thoughts on which is worse on battery bank daily 75% soc at 5% charge rate. Or 50% soc at 10% c rate?
A 75% SOC is probably marginally better, BUT there are other factors to consider. Assuming a cold bank (0°f?), sulfation will take much longer than it would with a hot bank, so going to 50% may not be so bad as long as it doesn't stay there for long (like many days/weeks). Also, charging with a generator from 50-80% or so can be more fuel efficient that charging from 75-100%.
IMHO, you should give a cold (FLA) bank all the current it will take, assuming voltage is compensated for temp by a RTS. The only reason I limit current is to prevent overloading the generator in use. I don't change the limit based on reduced winter capacity.
Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
900W 3 × 300W No name brand Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal as a backup system.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergencies and welding.
And not much to bring them back up.
FLA at about 0F.
900W 3 × 300W No name brand Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal as a backup system.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergencies and welding.
900W 3 × 300W No name brand Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal as a backup system.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergencies and welding.