Hey all, I have a nagging problem with my batteries. It seems there is a battery drain. I have new batteries, neither older than 2 years. Replaced 1 of the batteries about a year ago and I thought the drain was that battery being a bad battery. But it looks like the batteries continue to run down within a few weeks or so. The X sits for weeks at a time and now I keep it on a tender. If I take it off of the tender, the battery voltage reading dropped to about 12.4 within 2 weeks. Is this normal?
What should I expect the battery draw to be after engine is off for 20 minutes or so?
Thanks for the advice
Kevin
'02 7.3

 

what is the voltage when you park it. I had an issue like thin in my 02 f350 came to find out it was the alternator it was not putting out enough to fully charge the batteries I ended up replacing both batteries and the alternator and have not had the issue return. If you take your truck to autozone to test your alternator and batteries make sure they disconnect both batteries and test 1 battery at a time.

 

First of all...it is not unheard of to have batteries in these diesel beasts last for only two years. Secondly, you MUST REPLACE THEM AT THE SAME TIME. I don't care if they tell you one is dead and the other is perfect...after six months, you will be replacing the other, then the other again, and so on and so on and so on.

Your alternator could be vampiring your batteries if it's going bad. It's been known to happen. If you still have the OEM alternator, it would be preferable to have a good rebuild shop rebuild the OEM, as they are beefier than the other aftermarket alternators. Cost? Well, about $100 to rebuild...so it's the inconvenience factor that's the biggest issue.

 

Okay update, the voltage from the batteries reads 12.58, reading was taken after 30 minutes of the engine being off and everything sleeping. After starting the engine another reading of the voltage came in at 11.8.
Can I assume the alternator needs replacing or rebuild?

Anybody have any recomendations in the denver area for who can rebuild alternators?

 

Got mine at autozone...

Gold Duralast/Alternator (DLG3659-8-2) | 2002 Ford Excursion 4WD 8 Cylinders F 7.3L Turbo Diesel | AutoZone.com

$189 lifetime warranty new not rebuilt.

I would replace the batts too a bad alt can kill batts.

 

You need to check 2 things first.

1. Voltage when the engine is running. It should be above 14volts if you don't have 14 or above the chances are you need a new alternator.

2. The amp draw when everything is sleeping. This can be done with a multimeter and you can pick them up real cheap from harbor freight.
If you need a walk through let me know. I just did this and it is pretty easy. You should have no more than 50 ma showing when everything is asleep. That would be .05 on the multimeter. If you have more you will need to start pulling fuses and trying to find the circuit that is drawing the power. Any questions let me know.

I agree replace both batteries at the same time never just one.

 

1.5 years ago I replace both batteries and hte alternator. I'm experiencing dead batteries again, or slow to crank on cold mornings. It's really annoying and really time consuming to figure out htese issues.

 

Thanks Bergy. The reading when the engine is running is 11.8. I also checked for ac leakage in got 0, So I think that's good. I know how to do a current draw test so I'll give that a try. Also, I just checked the chilton's manual. It says any current drain over 500 millamps Is a problem, But 100 milliamps is typical.
it's looking more and more like I need a new alternator.

 

BFT, Thanks for the advice. There are no alternator rebuild places near me, so I think I'll be buying a new one. How long have you had that one? I want to avoid replacing this every couple of years if I can.

 

You should see around 250 ma right after shutting her down. That would be .25 amps. My chilton says anything over 100 ma is excessive. From What I have read anything over 50-70 is a lot. I currently draw 30 ma +- after everything is asleep and that's with the scan gauge plugged in as well as the p2 brake controller. The alternator may. Also have a bad voltage regulator which can drain the battery when not running.

 

my experience has been anything over 200 mha.... just depends on what all is going on in the vehicle and what has memory. anything plugged in to your cigarette lighters is a draw. I thought mine had a slow drain and turned out it was an old cell phone charger that had a slow short in it that was plugged in to one of my plugs. Its a good idea to unplug everything when you shut the truck off, though I am guilty of leaving my sirius tuner on all the time because I forget.

 

I had a battery drain issue a couple years ago, if I ran every two weeks everything was OK but after three weeks I had slow cranking and four weeks just click. Turned out to be a bad battery, replaced with a Red Top Optima and all has been good since. But 11.8 volts running does point to an alternator problem.

 

If you replace the alternator...DON'T FORGET to trickle-charge the batteries to full strength BEFORE you start the truck with the new alternator installed. If you don't, you are putting a heavy load on the alternator when it's brand new, and many believe that leads to shorter overall alternator life.

 

Update: the alternator passed a bench test.
The battery drain test produced the following reading: 1.6 on the DMM (200ma setting). Does that mean 160 milliamps?
I was honestly hoping the alternator test would have been a fail, and thus problem solved, easy fix. But nooo... not my lucky day. I don't understand why the alternator passed the bench test, but the voltage reading at the batteries when the vehicles running is only 11.8v.

I guess my next step is to have the batteries load tested.

Note: strange noise when you spin the alternator, sounds like there is a leaf in there or something. Going to get a flashlight on it and have a good look.

 

Going on 3 years 75k miles.