T-125 (6v) vs T-1275 (12v)

tenbear wrote:

BFL13 wrote:
...But to be fair, if you intend to run a steady 11a load, you want to know the 1275's AH for an 11a rate, same as the 105s, not the 15a rate. That 11a would be more than the 300AH say 350?...

Would you not want to use the 5.5a rate for the 1275s since with 2 in parallel the total would be 11a?

This means more coffee! :) You could also compare the lower than 225AH of the 105 at 15a with the 1275's 15a rate in AH.

The first thing is to get them both at 12v, so you need two 6s. I wasn't trying to equate two 105s with two 1275s, just line up their amps rates to get comparable AHs

The idea would be the cost per AH calculation would be using the comparable AHs at the same rate, not their unequal 20hr rates.

Be hard to do it in actual number of batteries too since you have to buy the 6s in pairs, but the 12s are single.

Of course, then you go and use all sizes of amps draws for various durations in the RV, so how do you know which is the appropriate rate to compare the battery to your usage?

Easy for my pair of 1275s, being on the inverter as their only job, where the load is always around 100a more or less. Just varies by duration among MW, kettle, and toaster. I would want the AH for 100a, not 15a.

In real life you can't use those Peukert times to DOD you can find in battery tables either, since they go to dead battery. In real life you don't go that low and there is bounce back after each short duration draw, so you get longer total times than the tables indicate.

Anyway, somehow you have to get your cost per AH figured better than just comparing the 20 hr rates worth of AH which don't line up where the rates are all different.