Just bought a 49 M

greener351 · May 2, 2011

I just bought a 49 M and I have a concern about the battery and electrical system. The guy I bought it from had a 12v battery in it when it is clearly a 6v system. How much damage was/can be done by doing this?

I've already bought and installed a new 6v from TSC and immediately noticed much slower cranking. I couldn't get it to fire on the 6v, but I think that was due to running out of gas (and daylight).

Thoughts?

soybeanjoe · May 2, 2011

No big deal as long as it had a resistor between the coil & points to keep from burning them. Even then worst would be the points would burn shut &you'd have to replace them. Bigger problem is that the 6v generator won't keep the battery charged so you'll have to recharge it often.

I've seen several tractors settup that way. In fact the SMTA I bought a few years ago was that way. One thing is that the 12v battery will turn it over a lot quicker. Won't hurt the starter as long as you don't "grind away" on if it won't start

armand tatro · May 3, 2011

That is why the tractor had a 12 volt battery in it when you got it. You say it was clearly a 6 volt system with a 12 volt. How do you know this? As was said the 6 volt starter will work good with a 12 volt battery as long as you do let it crank too long at a time. in the late 50"s and 60"s after those tractors were upgraded with higher hp overhauls 6volt systems did nor haave enough power. The 8 volt batters and that oddball 6/12volt battery were a joke. A 12 volt upgrade with neg. ground was and still is the only way to go. (If postive ground is such a good deal why is not in use on new vechles and has not been for some fity years?) Return the 6 volt battery, renew the wiring harness if needed(it might be orig. to tractor and in need of replacemant) use it and enjoy the easier starting of a 12 volt system esp. if this is to be a working tractor. BTW All my M"s are working tractors and are converted to 12 volt neg.ground. Armand

Dave_Id · May 3, 2011

6 volt battery system needs heavy battery cables. Someone probably replaced the cables with one from their wifes Mazda. Make sure the cables are 00 gauge, and you'll find that the starter turns over much faster.

Faster346 · May 3, 2011

I've always been curious, what would happen if you you put a 12v battery in? Left it Positive ground and all? With a 12v coil still wired for +?

rhtx55 · May 3, 2011

(quoted from post at 17:33:03 05/03/11) I've always been curious, what would happen if you you put a 12v battery in? Left it Positive ground and all? With a 12v coil still wired for +?

The amp gauge would work backwards, points, cap & rotor wouldn't last very long, the lights will all blow as soon as you turn them on bright, and the generator would never be able to charge the battery, you would have a 6volt battery in a 12 volt case.

Rich'sToys · May 4, 2011

Why would the amp gauge work backwards if he left it positive ground? Amp gauges don't care what the voltage is.

rhtx55 · May 4, 2011

Sorry, I mis-read his post.

glennster · May 4, 2011

i have an m and a w-9 they were converted at some point in the past to 12v. they are 12v positive ground and use a 12v generator of an early chevy car. works fine, no problems.

mkirsch · May 4, 2011

If the tractor has a magneto ignition, it would start and run just fine on 12V because the battery has nothing to do with the spark.

The lights probably stopped working decades ago. The charging system probably stopped working decades ago.

All the 12V battery is doing is running the starter. Odds are good that the previous owner simply charged up the 12V battery once in a while.

Just bought a 49 M

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