Starter cranking amps

Farmall H, HV & Super H, 300 & 350, 1939-1958

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Starter cranking amps

Postby pokitisme » Tue Oct 23, 2018 7:14 pm

I'm pretty sure I got a weak battery with dead cells. I'm almost 100% sure of it. What I'm curious about is with a voltmeter how do I determine the cranking amps for a starter on a 1948 Farmall h. Or does somebody have the actual listing for the amperage for the starter. I've charge this battery over and over and it reads 12 volts. But I suspect it's a pretty damn damage battery. I have not yet hooked up the voltmeter to it while I tried starting it I plan on doing that tomorrow. I checked all the connections and everything is pretty tight and I've cleaned everything when I hit the starter button it does attempt to turn just a little bit. but like I suspect I don't think it has enough volts to kick in. I know it's a screwed-up battery but the Curiosity part got the best of me so what is the starting and running amps for a 48 Farmall h
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Re: Starter cranking amps

Postby John *.?-!.* cub owner » Tue Oct 23, 2018 8:23 pm

I have never measured the cranking current on my old H, but typically on a 12 volt conversion you could expect 50 to 75 amps. The current drain will vary, rising as a piston comes up to TDC compressing the fuel air mix and drops off as it passes TDC, to repeat the cycle as the next piston comes up on TDC. Running current will be about .5 amp for the ignition, but I do not know what size alternator you installed when you converted to 12 volts. You cannot measure cranking current with a typical multimeter, you will either need an inline ammeter capable of handling that type current, or a clamp on DC meter.

Read voltage directly across battery, and then with lights on if you have them. See if it holds 12 volts. Then with lights off, read battery voltage while cranking. with a 12 volt system it should stay above 8 volts. Having a 12 volt system powering a 6 volt starter can make readings unusual though.
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Re: Starter cranking amps

Postby tst » Tue Oct 23, 2018 8:48 pm

a fully charged 12v battery should rear 13 to 13-5 volts so your battery is not fully charged or could have a bad cell, on a volt meter while cranking the engine it shout not drop down to less than 9 volts, a battery with low voltage will kill a starter if you continue to use it long enough

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