12v Problem on 8N

My problem: the battery drains/dies after turning off the ignition.

I bought the tractor and the last owner had a 12v system put on he claimed cost him $600 because he forgot to ask before he turned over the tractor to them. The way it is assembled, it certainly does NOT look like a professional job. However, I am not an expert, so what do I know?

In any event, I can jump start the tractor and it runs fine (now that I have put a new carburator and air filter on). The ammeter shows it is charging. It starts out very high charge, in fact, if you remove the battery cables for the jump too quickly, the engine dies. After running it for about two hours raking hay, the charge decreases considerably, but does not show that it is charged. If you turn off the tractor and immediately try to start it, it starts fine. However, if you wait one hour - it is dead.

Does this sound like an electrical problem or a battery problem?

Also, on a 1949 8N, where the air cleaner leaves the top of the hood, there is supposed to be a louvered vent. Is there any source for this small sheet metal part?

---Mike

Here's a few tests to do to narrow it down. If it is a bad battery and then it will charge up and discharge, like you say, try this. Charge it up good on the tractor.. ( The way you mentioned it is charging is typical.. a high charge at first, then it tapers off as the battery gets charged... also, the tractor dieing if you take the cables off too fast may indicate that your alternator is not charging immediatly. If that is so, then usually indicates a '1' wire 12v conversion.. and in some of those cases, the alternator doesn't 'self-excite' untill the rpms go high.. like above 800, etc.... this usually means no external voltage regulator.. in which case I would guess that the 12v conversion wasn't so 'professionally done'.. nor should it have cost 600$, unless he just plain got 'taken'.)

In any case, charge the battery, and then disconnect the battery cables. Check the voltage on it every hour for a couple hours.. see what it is doing. After a couple hours, re-attatch them.. if it starts fine... battery is probably ok. If it is dead as you mentioned, battery has a bad cell or internal short, etc...

( A store that sells batteries usually has a 'free test' they can run to check this )

If it isn't the battery, then my next guess is that the battery is discharging back thru the alternator sense wire, or something to that effect, depending on how they hooked it up.. or in the case of an external regulator.. perhaps a bad cutout.. or a bad (shorted) diode in the diode trio/rectifier pack, letting the alternator back-discharge.

All depends on the method your 12v conversion was done by.

To check this, again, charge the battery, and then disconnect all wires going to the alternator ( mark them! ).. try the voltage checks for a couple hours, then hook back up and try to start.. if it starts, there is a good bet the alternator is sinking some serious current in that hour you mention it takes to kill the battery... If so, when you reconnect the alternator.. you might notice a spark, denoting current daw.

If that isn't it.. check the rest of your wiring.. there must be a resistive short somewhere. ( If it was a direct short, surley it would be very noticeable.. with sparks and melted metal and wires... and wouldn't take an hour to kill the battery. )

Sources of restive shorts can be bad insulation, coroded wires, or lots of corrosion onthe battery, terminal to terminal, etc.. something like that.

let us know what you find, and we'll try to help.

Soundguy

If I touch an ohmmeter to the empty battery cable while everything is turned off, should it read like an open circuit? I was thinking if there is any conductivity, that would tell me if I have a short or not.

Also, I noticed the 12 vole kits sold here don't include a 12v starter or a 12v condenser for the distributor. Are those not necessary for the conversion?

An easier way to check unknown loads, is to set your meter to amps.. many have a 10 amp setting, and then hook up the ground cable to the battery, and then hook the meter inline with the positive cable... if anything is using current.. the meter will show it a sthe current is flowing thru the meter... if it analog, mind your test lead polarities.. digitals usually don't care..

6v starters spin faster on 12v. And as long as you don't sit there and grind on them forever, they seem to hold up fine... same with the starter solenoid on the 8n and NAA's.

Though you can get a correct condensor for the ignition from a 12v kit.. most ignition caps are probably rated high enough that 12v isn't an issue... besides, if your ignition has a dropping resistor, and the original 6v coil, it isn't an issue anyway, as the dropping resistor is dropping some of those 12v before it hits the ignition circuit.

soundguy

John A