Lead acid capacity in freezing temps
mountainman
Registered Users Posts: 377 ✭✭
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 pwm 4 100 watt and 2 190 evergreen on Epever mppt 30. 4 Gc 208 ah @12 volts 300 watt psw inverter. 2 kw genny. Iota 45.
Comments
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.
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
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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
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
And not much to bring them back up.
FLA at about 0F.
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
Second system 1890W 3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah FLA 24V nominal used for water pumping and day time air conditioning.
5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.