Battery Dying!

[Croatan_Kid]

I'm not entirely sure when this problem started, but something is seriously wrong with my electrical system. It's not reading in the green on the voltmeter like it should be, just barely in it when it used to rear dead in the middle. It's like the rear battery isn't getting charged or something. So at work today I had the mechanic help me out some....we checked BOTH alternators and they were both putting out good voltage, around 14.5 I think. However, at the rear batter we could only read 12.4-12.65, whereas the front would read around 14.3. I can charge the rear battery off of the truck and start the truck, cut it off after driving a few miles and it will turn over about 4 times and that's it. I'm hoping that it's only a bad battery. It sounds logical, like it lost all CCAs. Anybody have any ideas on what to check?

 

[mangus580]

Take your alternators off, and your batteries out. Have them both tested by a reputable place. Make sure they are aware the alt's need to be grounded via the terminal on the back.

 

[Croatan_Kid]

I was kinda thinking that I had messed up one of the alternators when I replaced the belts. I forgot to disconnect the batteries until it was too late and the passenger side alternator slid in the bracket and grounded out against it..... I'll take the to be tested tomorrow I suppose.

 

[Rocco]

Test it yourself.
Get a screwdriver While the engine is running and touch it to
the back of the alternator in the center and if it sticks magnetically than it is still good
if not its bad.

 

[Rocco]

Or you might have a dead cell in the batt.

 

[CCATLETT1984]

I would guess its a bad cell in the battery

you could also try swapping the batteries front to back. and see if the issue follows the battery or is charging related.

 

[pa.rich]

Pull the batteries and have them checked.

 

[Croatan_Kid]

I took the batteries to Auto Zone and had them tested today...the front one was fine, but as I suspected, the rear was really low. Front voltage was 12.48, rear was 7.6....of course they say charge them and keep going. It's been charging since noon out in my shop, a very slow charge. So for the time being, I stuck my Optima Red Top in there so I could still drive it and it's still showing the same voltage on the voltmeter and still reads the same voltage at the batteries...14.5 front and 12.4 rear and this is while it's running. So apparently the rear battery is not getting a charge from the alternator. What do I go check out next?

Thanks,


Jake

 

[mangus580]

Alternators. I would have taken them together, and saved myself the extra trip.

 

[Croatan_Kid]

I tried the magnetic thing when I got home, driver's side was good, passenger side was iffy. Reckon I'll be looking into getting my alternators rebuilt.

 

[rottiedog]

No help from me but you just happen to be in the same town!!!

 

[tsmall07]

Which alt is Gen 1 and which is gen 2?

 

[CCATLETT1984]

gen1 is the 12volt alternator and is on the drivers side of the engine.

gen2 is ran in series with the positive pole on gen1 connected to its ground lug, and makes 12volts (combined 24 volts) and is on the passengers side of the engine

 

[bottleworks]

So, you have aprox 14.5 volts @ the heavy stud on each alternator, correct? But when you check the voltage at the rear battery, it reads low. Yes?

To me, that sounds like you have a battery cable causing a voltage drop. Check your battery cables and connections.

 

[Croatan_Kid]

So I should get 14.5 from Gen 1 and around 28 from Gen 2, right? I don't understand why I'm getting 26.7 from Gen 2, unless is just isn't charging very well. Luckily my rear battery wasn't dead this moring, I put my Optima in the rear location. If this keeps up, it looks like 12 volts are in my future.

 

[mangus580]

Why not just have it tested, rebuilt/replaced?

A lot easier to just put another alternator in, than to rewire the truck for 12v, and replace the starter!

 

[Croatan_Kid]

I suppose I could do that for now, but I am going to make it 12 volt. It's such a pain not having everything the same voltage.

 

[1956_4x4]

If you shorted the alternator out, I'd bet the diodes are toast inside the alternator. These alternators are pretty easy to rebuild. Like everyone's saying above, have it tested and make sure they hook the ground wire of the test machine to the insulated ground terminal or it will test bad regardless.

Smitty

 

[Croatan_Kid]

I took both alternators to a local starter and generator shop and had the guy test them. They came out fine on all tests. So if they're both charging good, that means that the charge isn't reaching the battery....right? I reckon I need to keep tracing wires.

On a side note, I left the batteries hooked up last night and they didn't die at all and I've driven it quite a bit today too. The Optima is holding up so far.

 

[Somemedic]

I know it sounds elementary but my old man was an electrician. He rambled on all the friggin time about connections, contacts, dirt, and dust. He always said bad connections whether they were loose or corroded would always cause heat and resistance. It was like a blocked pipe, you could have a 5" diameter supply hose with a 3" reducer in the middle. Theres a restriction someplace and that more than likely means a connection. My guess is at the batt terminals or a alt ground is nasty or frayed or loose. Check em, dont cost a dime.

http://www.steelsoldiers.com/Project 5.htm