The batteries on my 96 have been loosing charge for about the last three weeks. It doesn't get driven much, but the last time I used it a couple of time in a week. Then all of a sudden it would barely crank over. I had the batteries and alternator checked and they are good. I checked to see if there was any parasitic draw and it came up as 0.035 amps. I'm assuming that's not enough to cause the battery drain.

Looking for suggestions as to what could be going on. It wouldn't start yesterday and and the batteries had 10.5 volts.

Bob

 

One battery may be bad. That's what was going on with my 01. The one would drain down the other in a short period of time.

 

Cougar,

I had the batteries and alternator checked the first time it happened. They said all was good. We'll see tonight when I go home I checked the battery voltage last night after unhooked both ground cables. Will check it again tonight to see if anything has changed.

Bob

 

I would say .035 amps is excessive, unless I read that wrong, it is 350 Ma?

I think the number is closer to 30 Ma for a normal power draw.

Start monitoring the draw while you pull fuses, when it drops, that is the circuit you have to troubleshoot. Could be a million stupid things from a glove box light staying on to a keyring light module failed........

 

Patdaly,

It should have read 30 mA's. I think I found the problem though. I jump started my truck and ran it for 30 minutes. Batteries both read 12.5 volts, disconnected both grounds and tonight one battery still had 12.5 volts. The other had 10.3 volts. Even though both tested good I think the one is bad.

Bob

 

Yep, definitely sounds like you got a bad battery. And to clear up the draw current, Dodge's maximum ignition-off draw spec is generally 30 milliamps (.030 amps). On a vehicle with two big batteries, I would accept a draw of 35 milliamps without a moment's worry as it would take several weeks to drain those batteries enough to make a difference.

 

Bob, upon reflection, you had it right, my math was off by a factor of 10......... .035 amps would be 35 Ma.

Sounds like when you had your batteries tested they did not test each one by itself. Very common thing, it is not intuitive that each needs to be disconnected to test.

 

When a start battery looses more than 10% of it's charge, it becomes damaged. Depending on the amount of charge lost you may not noticed anything but the damage adds up with each occurrence. If it happens too often, you'll begin to notice.

Deep cycle batteries can lose more. Most can lose 40% without sustaining any lasting damage but their voltage drops too much with high current draw to work well as start batteries.

When the headlights have been left on overnight on my spouse's car, I replace the battery asap.

I never change just one battery on my 02'.

Marc

 

Your right they didn't test each one seperately. I didn't even give it any thought until you said that. I don't feel too bad about replacing them, they've been in the truck for 10 years. And I don't very often plug my truck in during the winter unless it gets below zero.

Bob

 

If you got 10 years out of them, you aren't wrong when you say they don't owe you anything. I think a lot of us are happy to get 5 years out of a pair in northern climates...

 

Replaced both batteries last night that should take care of the problem.

Tallguy67,

Like the "Sausage Aficionado (In training)" under you name.

Bob

 

UnionBob, that handle got given to me by one of the admins because my wife and I are sausage makers as a hobby. It is a fun hobby and the end result is tasty food. Glad you fixed your battery problems.

 

Tallguy,

I know what you mean about making sausage. We would make some every fall when we butchered while growing up on the farm. Now we try to make sausage every 6 month with our grown kids so they can learn. We're of German descent and sausage is a German thing.

Bob