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

Interesting. Maybe the differences have something to do with the total number and size of the individual cells.

Maybe some of the ambiguities have everything to do with the active surface area to acid relationship. Always been a sensitive point with scrubbers.

what about aH per $$$.
myself I would be interested in getting the most AHs that fit the space, assuming cost is not outlandish.
bumpy

for a comparison though remember the 12's are in parallel, the 6's in series.

so for comparison do your numbers reflect that for the 12's each of them is supplying 1/2 the total current vs. the 6's in which case each supplies ALL the current.

So when each BANK is supplying say 25A, for the 6's each is supplying 25A while for the 12's each is supplying 12.5A which will increase the AH rating slightly from the 12's 25A AH rating.

And the likely real differences are:

1) what is the voltage drop of the 6's vs. 12's when supplying say 150A?
2) what is the rated cycle life at 50% DOD and 70% DOD for each.

I'll bet that's where the REAL differences would show up.

Unforetunetly, I have never found (1) on the trojan web site. And while (2) exists on the trojan website for the 6's and many 12's, I don't recall seeing it for the 1275.

Bumpyroad wrote:
what about aH per $$$.
myself I would be interested in getting the most AHs that fit the space, assuming cost is not outlandish.
bumpy

The point is that it seems not all AHs are created equal for cost comparisons. Peukert plus plate/electrolyte ratios, whatever.

so it seems you first need to know if you are a low amp guy or an high amp guy so you can figure what AH performance you can get from each type of battery (not sure about that---maybe we will learn more here) THEN you can do a cost comparison?

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I wonder if the battery heights make a fair comparison. How does it work out for T-105s and L16s on the 6v side? I don't know if there is a short version deep cycle 12.

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Mex says the T-1275 is a scrubber battery but they are used in golf cars (four make 48v) as an alternative to using six 8v ones.

Local forklift guy swears T-105s work better in his forklifts because they do not shatter inside like some others do when getting pounded around.

Bumpyroad wrote:
what about aH per $$$.
myself I would be interested in getting the most AHs that fit the space, assuming cost is not outlandish.
bumpy

A STRICT interpretation of your request points toward group 31 engine starting batteries.

ktmrfs wrote:
when each BANK is supplying say 25A, for the 6's each is supplying 25A while for the 12's each is supplying 12.5A

Ideally, you get the 50% current split with double 12s. In practice the wire resistance, contact resistance and internal battery resistances tend to be slightly different, so one will provide more than 50% of the current and the other less. Over time, one battery works harder and wears out faster, or at least that's conventional wisdom as I learned it and explains the common preference for double 6s over double 12s.

MEXICOWANDERER wrote:

Bumpyroad wrote:
what about aH per $$$.
myself I would be interested in getting the most AHs that fit the space, assuming cost is not outlandish.
bumpy

A STRICT interpretation of your request points toward group 31 engine starting batteries.

not to be quite so strict, I am talking about batteries suitable for House use.
bumpy :)

What is best in a house battery seems to depend on how closely your typical draws are to the battery's 20 hr rate.

Two T-1275s-, 300AH = 15a rate
Two T-105s--, 225AH = 11.25a
Two T-125s--, 240AH = 12a
Two Trojan L16E-AC, 370AH = 18.5a

Before you calculate the cost per AH, you need to line these up using Peukert. Mena must have done this, but what would be the AH for his L16s at 11 or 12a rate? More than 370.

Then you need how many batteries of each size comes to the same AH at that rate, then compare the costs of those batteries per AH.

You'd have to plot some curve to figure out those Ah's at alternate rates. Not sure that would be accurate though. I did do 5 and 20 hr rate calculations (amp draw). The 5 hr calc is what sold me on these but MEX says L16's aren't designed for 5 hr draws, they're designed for 20 hr draws (18.5A).