Calculating Ah

[kfulmer]

If I have 4 235Ah 3.2V cells in series for target 12.8v, what is my final Ah calc? is it 1/4th or the same?

Probably a dumb question but having a hard time finding info on it. Trying to make a 36v pack to replace golf cart battery.

Side note - i know you can order these cells for like $120 a piece. Which seems like a lot when you can buy a full batter for around $400. Would there be a scenario where you would buy the battery, rip the packs out and configure your own battery (knowing you would need a new BMS that is golf cart friendly).

Thanks!

 

[MrThisIsME]

235Ah

Series increase voltage not amps.

 

[kfulmer]

235Ah

Series increase voltage not amps.

Ok. so these would be, from a $ per watt hour. be better than ripping a 100ah 12v generic battery. A 12.8 V version would be 235ah and 3000 ish watt hours.

 

[MrThisIsME]

I am confused. What are you trying to accomplish? Creating a 36v golf cart LiPo battery? If it is as simple as that, there many premade and most likely at the same cost it would take to build one, or rip apart other batteries.

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[offgrider]

deleted... was way wrong

 

[OffGridInTheCity]

If I have 4 235Ah 3.2V cells in series for target 12.8v, what is my final Ah calc? is it 1/4th or the same?

Probably a dumb question but having a hard time finding info on it. Trying to make a 36v pack to replace golf cart battery.

Side note - i know you can order these cells for like $120 a piece. Which seems like a lot when you can buy a full batter for around $400. Would there be a scenario where you would buy the battery, rip the packs out and configure your own battery (knowing you would need a new BMS that is golf cart friendly).

Thanks!

235ah * 3.2v = 752wh - e.g. run a 752watt load for a hour.
If you series these, the voltage increases but the ah stay the same.

For example a 4s1p battery is: [235] -> [235] -> [235] => [235] = 12.8v @ 235ah. The volts increase but the ah (per cell) stay the same. However, since the volts increase at the same ah, the overall capacity increases. The capacity is 235ah * 12.8v = 3008wh - e.g. you could run a 3008w load for a hour instead of only 752 watts for an hour.

To recap:
Series = volts increase, ah stay the same (assuming the cells are the same ah).
Parallel = volts stay the same, ah increases (assuming the cells are the same voltage range / same chemistry)..

 

[kfulmer]

235ah * 3.2v = 752wh - e.g. run a 752watt load for a hour.
If you series these, the voltage increases but the ah stay the same.

For example a 4s1p battery is: [235] -> [235] -> [235] => [235] = 12.8v @ 235ah. The volts increase but the ah (per cell) stay the same. However, since the volts increase at the same ah, the overall capacity increases. The capacity is 235ah * 12.8v = 3008wh - e.g. you could run a 3008w load for a hour instead of only 752 watts for an hour.

To recap:
Series = volts increase, ah stay the same (assuming the cells are the same ah).
Parallel = volts stay the same, ah increases (assuming the cells are the same voltage range / same chemistry)..

Thank you! this is perfect.

 

[Danke]

Nvm

I thought you had 12v batteries, not 3.2v