Back again with battery drain

[rooftrussman]

I have a Ford 1210 1986 3 cylinder diesel. This has been an ongoing problem. The previous owner said he had battery problems and had bought a new battery. For a while, the tractor started if I left the battery disconnected when I wasn't using it. I got tired of that and assumed a short which I guess it still is. I pulled all the wiring and redid the harness. It's not very complex. I checked the starter solenoid and found it lacking so I replaced that. I had the starter and alternator checked and found the alternator bad so replaced that. The starter was OK so they said. It was bench tested. It does have lots of power and starts the tractor (which runs fine) when the battery is OK. I put the whole thing back together but the battery still drains when it sits. I got a new battery because the abuse of the other ine did it in. When I check the resistance between the two battery cables, without the battery, I get about a half ohm in resistance. I guess it is no wonder the battery drains. When I was checking the starter per the book, it says there should be high resistance between field coils and the case. This starter has a design that has the field coils directly connected to the case so there is little resistance but the starter part seems to be what is called for in the parts manual. Does anybody have any experience with 1980's Ford tractors (Shiabura) of the 1110, 1210, 1310 etc series that would indicate different starter types that would be wired differently? I'm concerned I'll burn out more things again if I don't deal with this. Alternators, solenoids and batterys start to get expensive the second time around. I don't know if this is the original starter but the tractor is 20 plus years old. The manuals don't mention this but I have about run out of other ideas. Everything else checks out. I hate to spend the money at the dealer for what has to be a simple fix. The wiring just isn't that complicated. Thanks for any help or ideas.

 

[RickB]

Take a good look at the key switch and the fuseblock.

 

[mattman]

How long does it take for the battery to run down? Does the battery create a spark when disconecting the battery with everything turned off? If the battery runs down quickly then an easy way is to unhook one electrical componet at a time and allow tractor to sit and see if the battery drains down. If you have a digital voltmeter it is fairly easy to check for a draw and unhook one elctrical componet at a time while watching the reading on the voltmeter. I would not think there would be more than 10 miliamps of draw on a tractor of that age. To set up the voltmeter unhook the negative battery cable and connect one lead of the voltmeter to the battery post and the other lead to the negative battery cable. Set the meter to DC amps and see what kind of number you get. Some meters you have to sawp holes in the voltmeter with the red lead wire to read in amps. It usually says on the front of the meter.

 

[jinman]

When I check the resistance between the two battery cables, without the battery, I get about a half ohm in resistance. I guess it is no wonder the battery drains.

If you have 1/2 ohm load for 12 volts, you are pulling 24 amps. That's huge! Your DC ammeter may not be able to read that high. I think I'd follow Mattman's procedure, but rather put your ohm meter between leads on the resistance scale and disconnect until that low resistance goes away. A short of 1/2 ohm should be very easy to find by disconnecting components until it disappears.

 

[Soundguy]

Another way to do it is to install a test lamp between positive lead and battery, and pull stuff till the lamp goes out..

soundguy

 

[CCWKen]

Ditto on the checking but a 24A draw is HUGE! That will easily cause smoke for small wires and you should see sparking when connecting the battery. I'm thinking it's a chaffed power lead shorting against the chassis or a coil with that resistance.

Be careful putting your ohmmeter in series with the battery. Most will only handle 10A.

 

[Soundguy]

'OHM' meters will probably smoke when you hook them up to power.. 'ammeter' will handle it based on their fused / unfused rating...

Be sure what you are putting inline.. if you have a multi-function meter.. make sur ethe correct function is selected for the required test...

soundguy

 

[CCWKen]

You're right about that. What I meant to say was multimeter. The AMP range on most will only handle 10A maximum. In any case, don't allow that 24A draw to let the "Good Smoke" out of the wires. Once it leaks out, you can't put it back in.

 

[J_J]

Something is not right here. If something is using current of 25 amps, I think you would know it. About the only wire that could handle 25 amps would be the battery cable. With the engine running, A current leak of this size, would not let the battery charge. With the solenoid disengaged, the battery cable is sitting there to cross feed the voltage and current to the starter windings.

If you can not find the problem, a battery disconnect switch is called for.

 

[jinman]

Something is not right here. If something is using current of 25 amps, I think you would know it. About the only wire that could handle 25 amps would be the battery cable.

I'm afraid I may have biased some of the responses because of the math I did based on rooftrussman's saying he read 1/2 ohm between the battery cables when disconnected. I think the average ohmeter would struggle to measure 1/2 ohm accurately; however, if it did and 12 volts was applied, the circuit would draw 24 amps. That is purely hypothetical and I'd suggest that it is not accurate. However, using an ammeter in series or disconnecting one lead and using a test light as Soundguy suggested or disconnecting completely and using and ohmeter are all valid troubleshooting techniques based on what you have available to do the job. This is a problem that should be relatively easy to trace and isolate on his tractor.