Need batterys.

pnichols wrote:

BFL13 wrote:

prichardson wrote:
Sounds like you are worried about recharge time. Charge time is dependent on how much amperage has been removed from the battery bank. It does not matter if it is 2 12s in parallel or 2 6s in series. As far as the charger is concerned it is one big 12vdc battery.

You do faster time if you remove more! :) By doing 50-80s instead of 70-100s (both 30AH)

But then your bank is lower in AH (higher R) while camping so voltage drop is more. Try to still have enough AH at 50% to run the inverter loads and do 50-80s for fast charging too.

That can mean four 6s instead of just two. And a bigger amp charger and gen to run it to still keep the time down. And a bigger Rv to carry the four batteries. And a bigger truck to pull it.

Interesting concerning your comments above on battery "R" (internal resistance?)!

Can you provide a technical link talking about lead acid battery (6V or 12V) internal resistance changing much at all based on how far down they are discharged?

I've always thought that internal lead acid battery intrinsic internal resistance depended entirely upon such factors as physics, chemistry, and construction - but I could be wrong.

I am going with how you can run the big things on the 2000w inverter down to 75% SOC on two 6s before the inverter hits the 11v alarm with voltage drop, compared with how you can run the same load at 50% SOC if you have four 6s.

Four 6s have less R (What I call it :) ) than two. So I ASSume the two at 75% have the same R as four at 50%, which means the two have more R below 75%

OTOH--I remember from Salvo days that R of a wire stays the same and it is the amps variable that affects voltage drop.

You are invited to explain all this! :)