One 12 volt AGM battery, double AMP hour capacity?

**Ziptrekker** · 04-25-2021, 03:54 AM

Hello. I have one 12 volt AGM 85 amp hour battery. I want double my amp hours. How do do that? Buy another one and connect them in series or parallel?

**jmbopp** · 04-25-2021, 06:25 AM

Parallel. + to + and - to -

**el Rojo** · 04-25-2021, 07:35 AM

I hope the battery is relatively new. It's not good to mix an old battery with a new one.

Red

**Ziptrekker** · 04-27-2021, 05:16 AM

Thank you for the advice.

**xrated** · 04-27-2021, 05:49 AM

Originally Posted by Ziptrekker

Thank you for the advice.

In a nutshell.....Hooking batteries up in series, double the voltage of the batteries, but retains the amp hours....assuming that both batteries are the same. Hooking up batteries in parallel keeps the voltage the same, but doubles the Amp hours, and again, assuming that both batteries are the same.

**Ziptrekker** · 04-27-2021, 08:37 PM

Originally Posted by xrated

In a nutshell.....Hooking batteries up in series, double the voltage of the batteries, but retains the amp hours....assuming that both batteries are the same. Hooking up batteries in parallel keeps the voltage the same, but doubles the Amp hours, and again, assuming that both batteries are the same.

Does it matter what connections from rig go on what battery?

**EsquireRV** · 04-28-2021, 12:26 AM

Originally Posted by Ziptrekker

Does it matter what connections from rig go on what battery?

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Wire them in like this. +ve from one battery, -ve from the other.

**RV Sailor** · 04-28-2021, 12:35 AM

85 ah battery means 43 usable as it’s not good to draw below 50%. 43 amps is minuscule in terms of RV amp hours. Even by doubling you only have 86. Better getting 2. -6 volt golf cart batteries in the same space and wiring in series. Usually means 240 amp hours at 12 volts or 120 usable in the same space as your undersized group 24 batteries.

**Ziptrekker** · 04-28-2021, 05:47 AM

Originally Posted by RV Sailor

85 ah battery means 43 usable as it’s not good to draw below 50%. 43 amps is minuscule in terms of RV amp hours. Even by doubling you only have 86. Better getting 2. -6 volt golf cart batteries in the same space and wiring in series. Usually means 240 amp hours at 12 volts or 120 usable in the same space as your undersized group 24 batteries.

Right. I'd rather do that but it's the $ I have to work with ��. Thanks for explaining it.