1951 John Deere A Electrical System

JDAdriver

New User
Does anyone know why John Deere used two six-volt batteries ganged together in series, instead of one 12-volt battery? Can one 12-volt battery do the trick?
 
Back in the day a 12 volt battery was hard to find and if you did it cost 3 times what 2 6 volt one would cost. Yes now days one can use a 12 volt battery in place of 2 6 volt batteries. Try to find the highest CCA that fits
 
that is because one 12 volt battery had about 550 cranking amps. so they used two 6 volt in series to give you more cranking . sure they would start in summer, but they needed to cover their azz for winter starting. it is not only john deere tractors, international did the same thing, same with case, plus minneapolis moline 705 and such tractors used three 12 volt batteries in parallel to get that big engine started. in summer time one battery starts it easy also. i know those batteries are 550 cranking amp batteries, as i just bought one for my minnie U. but nowadays batteries come in 1000 and 1100 cranking amps so one is quite sufficient.
 

As mentioned, 12 volt batteries were not that common back in those days, so they used the two 6 volts in series. I have 12 volt batteries in my 2 cylinder tractors (two 50's and an A).
 
You have to look at the times and what was available back then and what it took to crank the engine over in cold weather. For sure when I was a used tractor dealer and farmed using those tractors I replaced those batteries with a single high rated heavy duty high CCA, say maybe a 1000 CCA or so not a small weak wimpy 500 or so CCA.

NOTE use an adequate hold down method to avoid the battery slipping or sliding around.

NOTE insure you have a good solid clean frame ground and not any thin wimpy rusty seat box type of connection.

John T
 

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