Battery discharge mystery

[capefarm]

Somehow my battery is discharging when the tractor is not in use. The ammeter, on the dial from 0 to 20 plus and minus, shows about +1 to +2 when running, but -1 when not running. Everything on this tractor is original except for new wiring and a rebuilt generator. Not good at electrics, I'm baffled by the discharge. It's easy enough to disconnect the ground cable from battery when not in use and preserve the charge, but if anyone has an idea of what's happening, I'd be delighted to hear it.

[Eugene]

Disconnect battery, fully charge. Multimeter connected with one lead to disconnected battery cable and the other lead to the battery cable. Multi-meter set on lowest (10 amps) DC scale.

Disconnect battery lead at the voltage regulator/cutout. Amp meter drops to zero, voltage regulator/cutout is the problem.

Not the problem, disconnect one switch at a time until you find the problem circuit. Once you find the faulting circuit you will need to further determine if the switch is the cause or a switch controlled appliance.

[Jim Becker]

First off, are you sure the battery holds the charge when the ground is disconnected? Does the ammeter read 0 when the battery is disconnected? If those are both no, you have a bad battery. If they are both yes, you have a leak somewhere. Find the leak by disconnecting things to see when the leak stops. For example, disconnect the "BAT" wire from the cut-out to see if the problem is in the cut-out or generator. Disconnect the wire to the light switch to see if the problem is in that switch. etc.

[capefarm]

Bought a new battery yesterday (now looking as though unnecessary), and battery discharged over night. Ammeter does show 0 when battery is disconnected.
Very cold in this part of the world, and I might wait for warmer weather to try these good suggestions, which I greatly appreciate.
I have had for a long time a Triplett handheld VOM, but unsure how to use it. It has two small, uncommon batteries in it which may no longer be good.

[phill_mi]

For Triplett 'analog' meter (with a needle indicator in contrast to a digital display) the batteries are for the Ohms (or continuity) settings, and do not affect using the meter on either the Amps or Volts settings as suggested above.

[capefarm]

It is an analog meter and I'll put it to use as suggested. Thank you so much.

[capefarm]

Problem Solved! The advice here encouraged logic, and remembering the rear light stopped working about a year ago (initially thought it was a bad bulb) I tested the wire to it first. Sure enough, vibration had worn the wire insulation where it passed through a tight spot near the battery box, touching the foot plate and body causing a short. Easy enough to repair.
Again, my appreciation to you three.

[Glen]

Hi,
I don't see how that would cause a battery drain when the light switch is not turned to D or B, so the lights would be on.

The lights on a 1949 Cub originally have no power in the wires when the light switch is at L or H, there is no power in the rear light wire unless the switch is turned to D or B.

If the light wire has a place that is bare, and is against metal, it would blow the fuse, when the lights were turned on.
The light fuse is on the rear of the light switch in 1949.
Maybe you have replaced the light switch with another switch.

Below is a pic from TM Tractor of the rear of the 4 position charge and light switch used in 1949, showing the fuse.

[Eugene]

I don't see how that would cause a battery drain when the light switch is not turned to D or B, so the lights would be on.

Conduct the amp draw test I previously suggested.

[outdoors4evr]

I suppose it would be easy to have a discharge overnight if the lights are left on.

[tst]

the headlight wire if shorted would probably blow the fuse probably, suspect you may have more of an issue yet

[capefarm]

Of course you all are right, and this brain fog continues. The Cub came with its original wiring, and it's amazing it ran at all. I took it to a mechanic to rewire it. He did a good job which included replacing the back light which does still work, except for the red to which the switch was set. Anyway, the heavy cable from the battery to the starter had some slack, and I pulled on it together with the wire to the light, and the ammeter stopped showing discharge. Today I noticed the main cable was being pinched by the clutch pedal and pivot below the floor plate. This seems the likely source of the short. Yes, the lights only come on when their switch is turned on, but the fuse is in a separate holder lower on the instrument panel. When the days get warmer, I'll remove the cable, repair the insulation, and make a clip to keep it away from the clutch pivot.

[tst]

there are two clips from the factory to keep the cable from being rubbed by the clutch pedal
this link shows the main one
http://www.tmtractor.com/tm-tractor/gel ... ip_001.htm

[capefarm]

Easy enough to fabricate.
Thank you!

[Dale Finch]

Or TM Tractors sells them...
Early cub:
http://www.tmtractor.com/new/el/522fp.htm
Or later cub:
http://www.tmtractor.com/new/el/534fp.htm

However, the other clip is simply a flat band the wraps around the battery cable and taillight wire and is wedged right there between the pedal and clutch housing at the platform. This one takes the brunt of the rubbing.

The last two photos show both clips in place.