Engine/Transmission (1994 - 1998) Same battery problem /1995, 5spd, 106,000 miles

[jsjaastad]

Posted month ago about battery problem.

Two Napa Legend #7527 batteries. Month old. Truck sits 7-10 days and batteries are stone dead. Advised possible cause could be diodes in alternator, as I could not find any draw on batteries. Had alternator re-built, new rectifier & diodes. Still have the same problem.

Charged batteries, drove 25 miles, came home and again charged both batteries for one hour.

Need assistance with my findings, please.

Alternator charges (both batteries) 14. 38 volts at idle.

Motor stopped, both batteries tested 12. 78 volts

Disconnect ground from both batteries (one at a time) and have NO amp draw.

Measured specific gravity on FULLY charged batteries.

Driver's battery measures 1200 to 1180.

Passenger battery measures1200 to 1210.

Directions say: 1300-1250= good. 1250-1225=fair.

1225-1100=recharge.

Batteries are one month old and fully charged.

Specific gravity says to re-charge the batteries, but, they are fully charged.

I measured amp draw on the 200m scale. Right/wrong?

What to do? Go to NAPA or what? Recourse at alternator repair guy is not an option as I burnt that bridge. Once again any assistance is greatly appreciated. Thanks, Tom/Idaho

 

[hsmith]

With the grounds disconnected for a few days check them individually for full charge and load test. If they both pass, then you have a parasitic drain somewhere. If one shows weak, then that is the problem with both.

 

[B.G. Smith]

Tom, just some observations/suggestions. 25 miles won't charge the batteries, might put back what power it took to start engine. Depending on what battery charger you are using, it could take 24 or more hours to fully charge the batteries individually. The 14. 38 voltage you are showing at idle will probably taper down when everything heats up so that could be on the low side. You need to check the battery voltage with engine off after the truck has sat for a while and cooled off. The 12. 78 you got would be good after every thing has cooled off but the hydrometer test indicates the batteries are not fully charged so I would put each battery on a chaerger, at least 10 amp and charge until the electrolyte checks in the charged zone. Check the battery voltage on the battery while the charger is on, it may not be getting the voltage high enough to fully charge the battrery. Should be 13. 8 to 14. 4 volts. I would check for unknown drain with a 10amp amp meter, if you check continuity from the disconnected battery cable to the battery post with volt meter and you show 12 volts then there is a drain, you just can't tell how much. Good luck, bg

 

[JoeBioDiesel]

For the batteries to be stone dead, you must have a parasitic draw.

Check to see if the fuses are blown in your meter.

Disconect one battery. Measure the draw of the other one.

Start on the 10A scale. If the draw is under 200mA, switch to the lower amp scale.

If your draw is over 70mA, you need to find what's not turning off.



Joe

 

[SRath]

Have you ever had the headlight switch melt down, Tom?

Mine did twice. The plug on the wiring is pretty crispy and deformed now. I could see where it could easily cause a short (but not leave anything on) or even carbon track to ground now, though my batteries are over 10 years old and still going strong.

Just a thought since I was worried about a short-circuit after the last switch replacement due to that burnt plug.

 

[GaryOwen]

Had the same problem on my 95 a few months ago. After reading on TDR about a lot of members having a problem with the glovebox light staying on, I pulled my glovebox bulb. Sure enough, that was the problem. Haven't tried to fix the switch yet, need to do that someday. If you have the glovebox light, you might give it a try.

 

[B.G. Smith]

There is a fuse in the panel at the end of dash labeled IOD which is (Ignition off drain), things like the radio memory etc. You can pull that fuse to eliminate false readings while looking for the problem. Also have read of people having problems at the receptacle for trailer hookup, especially in areas where salt is used on roads in winter. bg

 

[SFPADGETT]

We had a similar problem, and found that the "under hood" light was staying on when the hood was closed. (We found it one dark morning when we could see the light coming out from under the hood by the cowl)



We did have not had good success with the NAPA brand batteries. Our trucks have GPS tracking devices on them and if not started over the weekend, then by Monday they were having to be jumped off during the winter. Changed to Optima's (Red top and Yellow tops--depending on the truck and its use) and have not had the problems and the batteries are lasting much longer (5 years plus with the Optima's vs about 30 months on the NAPA)



The Optimas are more money, but less headaches!

 

[Joe G.]

When I used Optima batteries they didn't last too long. I'm using the biggest Interstate batteries that will fit in the battery boxes now. I don't know how long they will last yet.

 

[jsjaastad]

Up date on batteries

---hope I do this right---New fuse makes the meter work...



Batteries have been unhooked for a week. Use a 50 amp load tester.

passenger battery: 12. 51v before test. 11. 66v during load test. 12. 25v after test.

Drivers battery: 12. 53v before test. 11. 67v during load test. 12. 27v after test.

Hooked passenger battery up and meter in line with drivers pos cable. Use 200m scale.

Meter reads -03. 3 and builds up to -06. 0 during test. Removed the IOD fuse with negative results.

I pulled all the fuses one at a time under the hood and by drivers door. Are there any more?

Any and all advice is appreciated.

Thanks again, Tom/iDAHO

 

[B.G. Smith]

Try removing the big wire at the alternator, it could be a diode I guess? bg

 

[fest3er]

... I pulled all the fuses one at a time under the hood and by drivers door. Are there any more?

Any and all advice is appreciated.

Thanks again, Tom/iDAHO

*All* the fuses? Did you unscrew one under the hood? If not, you missed the 140A alternator fuse. As BG said, it could be a bad diode in the alternator. Several of those have been reported in here in recent months. I imagine mine may be ready to fail, then (12 years, 260K miles, original alternator).



Aside, I would think it's safer to remove the alternator fuse that to just pull the big wire on the alternator; less chance of an unintended short circuit. We wouldn't want to have to change your name here to 'Sparky'.

 

[jsjaastad]

I had the alternator rebuilt a couple weeks ago, so one would 'assume' it was good. I will pull the alternator fuse today and see if there is a drain.

When I did the test yesterday the drain went from -03. 3 to -06. 0 in the short time it took to pull the fuses. Why would it do that? Or, do I need a new meter? If it doubled in less than 5 minutes, what would it be in a weeks time?

Thanks again, Tom/Idaho

 

[JoeBioDiesel]

If that's 3 to 6 milliamps, that's fine. You can have 50-70 milliamps and be just fine. If that's 3-6 amps, you've got a heck of a draw. That many amps would make the alternator warm to the touch after a while.