Is it a bad battery?

[rod]

I need your CUCV guys to help me narrow down a problem and confirm my suspisions that I may have a batery going bad.

Here the facts of the problem

-1984 M1009
-Using Military Bateries, marked "US 6TMF" unknown age
-Both Gen 1 & Gen 2 lights come on when you turn on the ignition
-As soon as I crank the M1009 the lights go out so I think the alternators are charging


The problem is that if I let the M1009 sit for a couple of weeks the batteries get weak and won't turn over the M1009 enough to crank.

I can charge the bateries up and the M1009 cranks fine. As long as I drive it every few days I do not have a cranking problem.

I do no see any obivious reason that there would be any kind of draw on the battery.

Things I will do tomorrow -
-Charge batteries so I can crank the M1009.
-Once I get the M1009 cranked I will check the output on the alternators using a voltmeter.
-Check to see if here is a draw on the batteries


What does this sound like to you? Opinions and input is welcome.

 

[CCATLETT1984]

yeah, sounds like you have either a week cell in one of the batteries, or you have a bad diode in one of the alternators that's slowly draining them down. Next time you let it sit, disconnect the ground cable from the front battery, this will break the circuit. If you have a issue starting the truck next time, then its the batteries. (Always try to replace them both at the same time)

 

[M725]

When you disconnect the ground, connect a voltmeter to the battery and a good ground. If there is a draw you will
see it on the voltmeter, and how much. If there is none than one or both your batterys are bad.

 

[Fred431]

Battery

Why not install a Solargizer. My M1009 came with one already installed by the military. If you check the specs its supposed to eliminate battery sulfation and prolong the life of the battery and revive older batteries if you want to believe that. Their selling for around $45 on epay Just an idea

 

[Irv]

You could also have a bad starting switch. As a general test to determine if it is the batteries or something on the vehicle, insert an ammeter in the line to the batteries. Do this with all systems turned off. The instant you attach the ammeter, you might get a spark. This doesn't mean anything by itself, since you're likely charging a noise suppression capacitor (condenser, in wrench terms). The current will jump up as it charges the condenser and then fall off once the condenser is charged and will not further drain the system. If you do see a drain of more than a few milliamps, then something is causing a small discharge path. Could be a light, corrosion somewhere to ground from a hot lead, or even the starter switch. That seems to be a common problem on deuces. The action of making and breaking the starter switch causes a small spark as it breaks because of all the inductance in the starter solenoid.. That vaporizes a small amount of metal off of the contact, and it deposits itself on the nominally insulating interior surface of the switch, leading to a weak conduction path to ground and hence, your dying battery over a few days time.
If you do not see any significant current drain in the battery circuit, you can assume it's the only thing left, and that is internal conduction between the plates due to old age, which means the end of the line for those batteries.

 

[M725]

Re: Battery

Why not install a Solargizer. My M1009 came with one already installed by the military. If you check the specs its supposed to eliminate battery sulfation and prolong the life of the battery and revive older batteries if you want to believe that. Their selling for around $45 on epay Just an idea

Military took them off all their trucks. They were creating alot of problems with the batteries. They are in the stage of testing something new.

 

[CCATLETT1984]

Re: Battery

Why not install a Solargizer. My M1009 came with one already installed by the military. If you check the specs its supposed to eliminate battery sulfation and prolong the life of the battery and revive older batteries if you want to believe that. Their selling for around $45 on epay Just an idea

I wouldnt put a solargizer on a cucv, since the main load is not spread across both batteries, this will cause one to be over-charged and the other battery to be under-charged.

 

[Bozor1000]

RE: Re: Battery

It sounds like you have some kind of parasitic draw. Meaning that the batteries ae getting drained from some unknown source.

 

[M725]

Re: Battery

Why not install a Solargizer. My M1009 came with one already installed by the military. If you check the specs its supposed to eliminate battery sulfation and prolong the life of the battery and revive older batteries if you want to believe that. Their selling for around $45 on epay Just an idea

I wouldnt put a solargizer on a cucv, since the main load is not spread across both batteries, this will cause one to be over-charged and the other battery to be under-charged.

The one's the military used where 24volt and where wired so.

 

[cranetruck]

RE: Re: Battery

Get a specific gravity tester and check all the cells after charging. If the readings don't agree with the voltage (see tables for pecentage of charge showing voltage and specific gravity).
IMHO, your batteries suffer from sulfation. There should be a date on the label on the side of the batts.
If you keep your batteries fully charged at all times, sulfation will not occur, so that's my choice, a charger like Chargetek 500 (no, I don't own stock in that company, it's just a good product). Kind of wish they made a solar powered one....
A solargizer should not be needed if the batteries are kept in good condition from day one. The solargizers I have seen, have been 24 volt types, two each used on 4-battery installations and this should be okay since they are not charging, just exposing the batteries to this particular current. Charging should be done on an individual battery for its individual need not in series with other batteries.

 

[devilman96]

RE: Re: Battery

Fred431 wrote:
Why not install a Solargizer. My M1009 came with one already installed by the military. If you check the specs its supposed to eliminate battery sulfation and prolong the life of the battery and revive older batteries if you want to believe that. Their selling for around $45 on epay Just an idea

CCATLETT1984
Military took them off all their trucks. They were creating alot of problems with the batteries. They are in the stage of testing something new.

CC is correct, you would need to install 2 12V units to charge the truck correctly...

The one's the military used where 24volt and where wired so.

Incorrect... the truck runs on 12V and starts on 24V