Originally Posted by Greydennyhawk
What is the advantage of replacing a size say, group 31 , 12 v battery with two 6 volt types?
I see a big difference when I compare on the Trojan battery website.
Group 31 battery (commercial vehicle battery)
- 12V, therefore only need one for TT
- 69# of lead plate
- 177 minutes @ 25amps
- 100 ah over 20 hr rate
T-605 6V golf cart battery
- 6V, therefore need two for TT (voltage is additive for batteries in series, discharge rate is not)
- 116# of lead plate (total)
- 383 minutes @ 25amps
- 210 ah over 20 hr rate.
Brands might make a bit of difference in overall performance. But as shown above, the discharge (boondocking) capacity of your TT battery pack is proportional to the total amount of lead plate the battery pack contains.
Two group 31 batteries will give you similar capacity as two 6V, given that the total lead weight would be similar. 138# of lead, 344 min @25amps, 200 ah over 20 hr rate. Discharge rates are additive for batteries in parallel.
With your checkbook in mind, which is cheaper? (2) 6-v or (2) group 31? In my case, a 6V Napa GC battery was the same price as a 12V gp 24 deep cycle marine. So I replace my two worn out gp 24 batteries with two 6V GC batteries. Then spent $25 on Amazon for two new battery boxes, and have been happy since.