I inherited a 1946 H when my father died. I'm confused about the battery hookup. I've seen info that says these are "positive ground" systems. I'm a mechanical/electrical idiot so don't know what this really means. Put a new battery in and hooked cables one way and it started/ran. Swapped and it started/ran. I'm not sure what is right and don't want to damage the thing! Should have asked Dad when I had the chance. Help the dummy and explain this and the right way. Thanks
- Thread starter New H-boy
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Bob M
Well-known Member
Not to worry about causing permanent damage by running with the battery polarity reversed. Those old generator systems pretty much could care less about ground polarity.
Suggest you do this (assumes your H still has the original generator - not a 12 volt alternator conversion):
1 - Hook the battery cables up so the POSITIVE post is grounded.
2 - Now turn on the lights and note which way the ammeter needle swings.
3 - If it swings left (discharge) skip to step 5.
4 - If the ammeter swings right (charge), REVERSE the cable connections at the battery.
5 - Polarize the generator: With the engine stopped, momentarily jumper between the BAT and GEN terminals at the voltage regulator. (Soon as you make contact - you may see a small spark - you have successfully polarized the generator)
Your tractor is now set to run positive ground - like it did from the factory.
Suggest you do this (assumes your H still has the original generator - not a 12 volt alternator conversion):
1 - Hook the battery cables up so the POSITIVE post is grounded.
2 - Now turn on the lights and note which way the ammeter needle swings.
3 - If it swings left (discharge) skip to step 5.
4 - If the ammeter swings right (charge), REVERSE the cable connections at the battery.
5 - Polarize the generator: With the engine stopped, momentarily jumper between the BAT and GEN terminals at the voltage regulator. (Soon as you make contact - you may see a small spark - you have successfully polarized the generator)
Your tractor is now set to run positive ground - like it did from the factory.
ScottyHOMeY
Well-known Member
So I was slow (well, busy with other stuff, actually), but that's okay as Bob M got here first with excellent advice.
What I was gonna say was it depends whether you've got a generator or an alternator. Bob mentioned it right at the front, but it's important.
Make that determination and go from there.
You say you replaced the battery. Was the old one (if it was even there) a six-volt (three cells, terminals at opposite corners)? If so, did you replace it with a 6-volt? And, if so, I'd charge (pardonnez le pun!) right ahead just like Bob described
The only things that might make any trouble for you are having a 12-volt battery on a 6-volt generator (issues with charging and, unless the tractor fires off a magneto, ignition), or an alternator or a very rare 12v generator on a 6-volt battery.
Other than that, hook it up, polarize the generator and go, like Bob said.
What I was gonna say was it depends whether you've got a generator or an alternator. Bob mentioned it right at the front, but it's important.
Make that determination and go from there.
You say you replaced the battery. Was the old one (if it was even there) a six-volt (three cells, terminals at opposite corners)? If so, did you replace it with a 6-volt? And, if so, I'd charge (pardonnez le pun!) right ahead just like Bob described
The only things that might make any trouble for you are having a 12-volt battery on a 6-volt generator (issues with charging and, unless the tractor fires off a magneto, ignition), or an alternator or a very rare 12v generator on a 6-volt battery.
Other than that, hook it up, polarize the generator and go, like Bob said.
Thanks guys for the help. Couple of additions. Yes - it is a 6V system and I bought a 6V battery - from Tractor Supply there are 4 caps for adding water and battery post are on one side - not diagonal. As far as I know the starter, etc are still the original equipment. Bob mentioned lights - unfortunately they were removed at some point - I remember them there when I was a kid. Plan to replace them at some point. Is there another way to test without lights?
ScottyHOMeY
Well-known Member
If you've got a battery/coil ignition, you should see the ammeter move to discharge when you pull the ignition button out to the run position. Whether battery or magneto ignition, the ammeter should swing to discharge when you hit the starter button.
Bob M
Well-known Member
No lights? Then do this: Have an assistant observe the ammeter while you do the polarize step. If the needle kicks hard to left when the jumper makes contact you are all set.
However if the ammeter kicks to the right swap the battery cables, then repeat the polarize step.
----
If the generator's working the ammeter should deflect noticably to the right (indicating the battery is being charged) when the engine's running faster than slow idle.
However if the ammeter kicks to the right swap the battery cables, then repeat the polarize step.
----
If the generator's working the ammeter should deflect noticably to the right (indicating the battery is being charged) when the engine's running faster than slow idle.
ScottyHOMeY
Well-known Member
Oooopppsss!
Thanks, Bob. I had that very thought just a ffew minutes ago and checked back in to see if it got caught, so thanks on that point too.
Related question, now that I'm almost confused again. . . Is the same true of the setup on As, Bs and Cs (which is what I was thinking of when I answered) that have the starter mounted switches, or just the Hs and Ms with the starter button on the panel.
Thanks, Bob. I had that very thought just a ffew minutes ago and checked back in to see if it got caught, so thanks on that point too.
Related question, now that I'm almost confused again. . . Is the same true of the setup on As, Bs and Cs (which is what I was thinking of when I answered) that have the starter mounted switches, or just the Hs and Ms with the starter button on the panel.
Bob M
Well-known Member
Yeah Scott - the same is true for ALL engine electrical system. Ammeters are rated for 20 - 60 amps max current. Sending 300 amps or more of starter through them will bend the needle and set 'em to smoking every time!
Note: If the manual pushbutton starter switch (and hence starter cables) are located close to the ammeter it CAN cause the ammeter to deflect one way or the other when the starter button is pushed. But it's the strong magnetic field surrounding the cable when starter current is flowing that causes the deflection - not the current itself.
Note: If the manual pushbutton starter switch (and hence starter cables) are located close to the ammeter it CAN cause the ammeter to deflect one way or the other when the starter button is pushed. But it's the strong magnetic field surrounding the cable when starter current is flowing that causes the deflection - not the current itself.
ScottyHOMeY
Well-known Member
Thanks, Bob. I need to look at your diagram for the H and M again and compare it with the As, etc, to make sure I've got my head around it, but it makes sense.
Anonymous-0
Well-known Member
If it has 4 caps its an 8v batt. Hook it up for pos ground and polarize the gen before starting by using a jumper just touch the batt term on the reg to the A post on the gen. A quick touch will produce a spark and thats all thats needed. Just make sure the term on the gen is marked with an A as the F terminal is field.
Anonymous-0
Well-known Member
You say the reg will have to be tweaked to use an 8V batt. What has been your experience using an 8V batt it didnt charge or what.?
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