Toubleshooting help - battery won't stay charged

SuperCDon · Jan 13, 2014

I have a 51 super c, converted to 12 volt. All new wiring harness, Delco 10SI alternator and battery. The battery will not stay charged and the alternator checks out fine. When running the ammeter reads 10-12 amps. The system is wired per BobM's 12volt conversion for a Super M, but without the warning light or diode. I have the battery out so I can access the backside of the electrical box. Any suggestions for debugging or corrections?

Joe Scribner · Jan 13, 2014

You'll need to wire in either the warning light or a diode. Without it you will experience a backfeed and possible drain on the system.

teddy52food · Jan 13, 2014

If the battery goes down when it is out of the tractor, the battery is bad. Otherwise you have a drain on it. How are you exciting it without the diode?

SuperCDon · Jan 13, 2014

If I have the alternator converted to a 'one wire' can I eliminate the diode/warning light?

old · Jan 13, 2014

Well if you have no diode or light bulb is it a 1 wore or a 3 wire set up?? If it is a 3 wire you if the alternator is working as it should be not be able to shut it down with the ignition switch so sounds like you have the excite circuit wired hot all the time but not threw the ignition switch which will drain a battery in a day or so. So answer this is it a 3 wire or a 1 wire set up then if we know that we might be able to help you help your self

ken house · Jan 13, 2014

how much time does the battery take to discharge?

in a 12 v conversion, the battery will discharge, over a period of time, unless you have a way to disconnect. i take off the battery cable, if i am going to let the machine sit for a few days.

Joe Scribner · Jan 13, 2014

(quoted from post at 19:19:33 01/13/14) If I have the alternator converted to a 'one wire' can I eliminate the diode/warning light?

The short answer is yes. The only issue I've ever had with a one wire set-up is sometimes you have to rev it a bit to get it to charge initially. Other than that never had an issue.

IH fan · Jan 13, 2014

I have a 1 wire alt. system on my 240 and for a long time (years), it would not discharge sitting for a long time. Then all of a sudden it started discharging in a couple of days, even with a new battery. I suspect a diode went bad somewhere, but a friend had an extra battery disconnect switch, one you unscrew to loosen a connection on a post and that's what I use. I think the diode is internal to the alternator because I do not see one outside of it.

mkirsch · Jan 13, 2014

1-wire alternators are a hit-or-miss proposition on discharging.

Some will discharge the battery while sitting, some won't.

With a 3-wire setup and a proper diode, you are 100% guaranteed that the alternator won't discharge your battery.

The diode is EASY, all you need to do is go to radio shack and buy the biggest diode they have in the electronics drawers. They come in packs of two.

Back at the tractor, cut the wire running to the #1 terminal on the alternator somewhere convenient, and strip the ends. You don't have to solder the diode. Use wire nuts and tape if you want. Connect the diode with the end that has the line pointed toward the alternator.

SuperCDon · Jan 13, 2014

It can take a few weeks to discharge to the point that it won't turn it over if the battery is fully charged. I usually try to start the tractor at least once a week. I use the 'engine start' feature on my battery charger if it won't turn over to get it going and then run the tractor for half-hour to charge up the battery, but the next day it won't turn over. My alternator is a 3-Wire 10SI

JMOR · Jan 13, 2014

(quoted from post at 17:56:30 01/13/14) It can take a few weeks to discharge to the point that it won't turn it over if the battery is fully charged. I usually try to start the tractor at least once a week. I use the 'engine start' feature on my battery charger if it won't turn over to get it going and then run the tractor for half-hour to charge up the battery, but the next day it won't turn over. My alternator is a 3-Wire 10SI

K, so you have it wired according to BOB's diagram except without lamp or diode..............then where/how is alt #1 connected?

S2710 · Jan 13, 2014

I had one on a tractor and one on a truck that was doing that and I would wait till dark and take the ground cable of the battery and it would show a little spark. I then unhooked the alt. and then checked at the battery and no more spark. The alt. was working but had a short or something in it. Changed alt. and no more problem. Your mileage may differ.

Bob

old · Jan 13, 2014

Bet you have the excite circuit hooked up so it is hot all the time and that will cause that problem and also can cause the life of the alternator to be short

SuperCDon · Jan 14, 2014

Thanks for your help. It's clear I need to add thte diode/warning light or convert the alternator.

SuperCDon · Jan 14, 2014

Thanks for your help. It's clear I need to add thte diode/warning light or convert the alternator.

mkirsch · Jan 14, 2014

Add diode: <$5
Convert alternator: Dunno, but gotta be a lot more than $5, and doesn't guarantee that it won't discharge.

JMOR · Jan 14, 2014

The lack of a lamp or excite diode is NOT the reason for the alternator discharging the battery. We don't even KNOW if the battery is discharging via the alternator yet. Way to early to start "fixing" before source of drain is identified.
Never saw an answer to "......then where/how is alt #1 connected?"
Have you looked carefully for a spark when connecting/disconnecting battery cable to a charged battery? Inserted a small bulb between battery post & battery cable to see if it lights? An ammeter in same position?

old · Jan 14, 2014

Yes but if it is hooked up with the excite circuit hot all the time the diode or bulb will still not help you fix the battery drain problem. The excite #1 wire off the small plug should go to the ignition side of the switch. On a lot of the ones I have done to save wire I just hooked it up to the ignition side of the coil

SuperCDon · Jan 14, 2014

#1 terminal on alternator is connected per BobM's wiring diagram: to the same terminal of the ignition switch as the ignition coil. As mentioned, there is no warning light or diode in this connection. Battery is fine. #2 terminal is connected the BAT terminal of the alternator. The BAT terminal connect to the ammeter.

SuperCDon · Jan 14, 2014

#1 wire is connected to the coil side of the ignition switch...without the warning light or diode.

JMOR · Jan 14, 2014

(quoted from post at 13:52:28 01/14/14) #1 wire is connected to the coil side of the ignition switch...without the warning light or diode.

ypically that would cause engine to keep running after key turned off as alt feeds coil, but it will not result in your battery drain. As I outlined, verify drain & that alternator is cause of drain. If it is you need a new alternator.

Owen Aaland · Jan 14, 2014

A bad diode in the rectifier bridge in the alternator could cause the output to be low enough at idle that the engine still shut off and cause the battery drain when the engine is not running.

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