The original 6V battery is Group Size 1 - 9-1/8 (L) x 7-1/8 (W) x 9-3/8 (H).
12V Group 25 & Group 35 batteries are just slightly smaller at 9-1/16 x 6-7/8 x 8-7/8.
I own 4 6v 8Ns and 2 6v 1929 Fords. All use the same battery, a Deka, model 901MF (made by East Penn) or the Duracell equivalent, Ultra BC1.
I always run the vehicles to operating temp every 3 or 4 weeks if they haven't been used. To make sure the battery doesn't discharge, all now have hard wired
Battery Tender float chargers. (And that will extend the life of any battery because it stops them from discharging.)
I also keep everything "clean, bright & tight", use the braided strap & 00 gauge negative cable.
So, in addition to it being a well made battery, doing everything else right gets me on average, 8 years out of a battery. I had one battery that I replaced in
October, 2020 that was 12 years old.
I like the idea of a gel battery..as in the Optimas. But, my Model A friends tell me that the newest versions, made in Mexico, are no where near as reliable
as the ones made 10 years ago. As further proof of that, Batteries + Bulbs no longer stocks them . Further, being a gel battery, they require a higher charging
voltage so the average charger will not work on them.
Got a Batteries + Bulbs store near you? They sell Duracell 6v batteries.....also made by East Penn. $82 w/ exchange, 640 CCA. They also sell Group 25 & 35
Duracell batteries for $119, and Battery Tender 6/12v float chargers ( DBT022-0209-DL-WH ) for $85.
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