Dead Batteries

[dlmetzger]

I have a 2008 Ram 3500. In the past 3 years, I've had 3 incidents of a no start condition which can be attributed to drained batteries. The 1st case can be explained away because of a draw from bad wiring on a trailer. The 2nd & 3rd cases I can't explain. The truck sat in the driveway without a trailer. Both times it sat for 2 -3 days. However, the truck has sat unused for more than a week on several occasions and started just fine. I've purchased a clamp on ammeter. I had to open the hood and the under-hood light is on but everything else should be off. I locked the truck and delayed 10 minutes. I checked the negative wires on both batteries. The passenger side total draw is . 53 amp and driver's side total draw is 1. 0 amp. What is normal?

 

[dlmetzger]

I forgot to mention that once the truck is jump-started, there were no further issues. The truck would start the next time it sat for a day or two. The water levels on the batteries are also OK.

 

[Prairie Dog]

It's a shot in the dark but I remember some posts about brake lights coming on by themselves. You may wan't to verify they're off when you get home or before turning in for the night.

 

[JMetzger]

I have seen the glove box light stay on & you would not know it. I would pull fuses & check the amp draw to see if that will tell you anything.

 

[JJPage]

Grid heater relay(s) will stick shut and drain a battery pretty quick, but that really does not sound like your problem.



Turn everything off, get a decent DC clamp-on amp meter, place around your positive battery cable(s), should be no draw. If there is, start pulling fuses until it goes away.

 

[dlmetzger]

battery Ground (return) current readings

Initially I thought that my 3 year old batteries couldn't be the problem. It turned out to be a failed cell on the passenger side battery that was taking both batteries down. I didn't need to use the ammeter. I replaced both batteries with Sears Diehard Platinum batteries. Anyways, I used a clamp-on DC ammeter (Klein Tools CL2000) to check what should be a nominal draw from the batteries. The vehicle had not been running (took photos in morning). See photos.

Pass Battery
Body Grd (1) - 0. 30 amp
Eng Grd (2) - 0. 00 amp

Drivers Battery
Fass fuel pump (1) - 0. 00 amp
Body Grd (2) - 0. 50 amp
Starter/Eng Grd - 0. 05 amp
Grd (4) - 0. 00 amp
Grd (5) - 0. 00 amp

 

[Prairie Dog]

Thanks for updating us. I bought new batts from NAPA and before I could even put them in, I found one had a shorted cell.

 

[HBarlow]

I was reading down through the earlier replies with the intention of telling you one of your batteries may be dead.

My '08 had a failed battery last year and I think it was dead for some time before I realized it. Quality control on batteries installed in new Rams in '08, at least during a short period, must have been poor. Both batteries in each of my earlier Rams lasted for years.

 

[SRadke]

FWIW, my truck will be dead in 4 days if I leave the key in it. Not "on" but fully inserted into the ignition in the off position.

 

[MChrist]

FWIW, my truck will be dead in 4 days if I leave the key in it. Not "on" but fully inserted into the ignition in the off position.

I can leave my keys in for weeks with the key in, and starts right up. You must have an electrical gremlin. . fun.