Need some guidance on my battery issue. A little background. I recently took my 1999 F150 on a road trip from Green Bay to the Outer Banks of North Carolina, roughly 3000 miles round trip. On the way there I noticed my Battery light flickering on and off, but the gauge stayed steady. Shortly after arrival the battery light came on steady. Found a parts store, had the battery tested and replaced. Not fixed, so I ended up replacing the alternator. The rest of vacation was good, trip home was good, and a trip to Milwaukee the next day was good. Then it sat for a day and the battery was dead. Over the past month it seems about every three days the battery is dead. I have checked all the grounding and alternator connections I can find, cleaned them up and reconnected them. Today I hooked up a meter between the negative battery post and negative battery cable, with the truck off all doors closed and the light pulled out of the hood, I had roughly 200 milliamps of current. Anyone know if this is normal or know of anything else I should look at?
Thanks

 

Do the same test between cable and post, but check the volts. I think that'll be a better indication. When you say every three days, it's dead, are you driving it the other two, but on the third it's dead, or does it sit there for 3 days then you try to start it?

 

Roughly every three days driving. Truck runs great when it running, seems like after a few days of driving to/from work, about 20 miles 1 way, I park it in the garage overnight and then it's dead. Usualy when it's dead I can put a charger on it for a few minute's at 75amp start mode, and it will start and be fine for a few more days. I'll recheck for voltage when I get home tonight.

 

I would think having the Alternator that you replaced in NC checked for:
1. a high resistance path to ground
or

2.It might not charging the battery correctly, and the 2 days of driving take the battery down far enough. This would be a case of it is using the battery to run too much, and the alternator is not keeping up with it, and it dies after the 80 miles.

You never had dead betteries prior to changing the alternator, and now you have a dead battery every 2 days. What changed...the Alternator and the battery.

I just put a Fluke 336 clamp meter on my '06 neg cable, and it is about 500 mA of draw on the line, without anything turned on ( goes to ~ 900 mA with the interior lamps on ). I tried to center best I could without moving any of the factory wire placements, this could be off a bit, if I was I not perfrectly centered on the cable.

My truck I know does not have a problem, it just sat at ORD for 4 days in the parking garage, and it started fine, after a little use over the weekend ( most on the motorcycle this past weekend ).

 

200 mA sounds about right with everything off. That seems to eliminate any kind of high resistance leakage to ground (including leakage through the alternator) unless you have an intermittent problem. I had a similar problem with a new battery several years ago and ended up disconnecting the battery overnight and the battery would still go dead. Turned out the battery was bad. To prove to the battery store that the problem was the battery, I had to take the car to the store and TELL them to disconnect the battery and let it sit overnight in their store and then check the battery the next morning. Sure enough, it was the battery, surprise, surprise. Mine went dead overnight, every night. Also, you can take your vehicle to Auto Zone or Advanced Auto and have your charging system checked to be sure the battery is being charged while the engine is running.

Good Luck!

 

Checking voltage from the negative post to the negative connection gives me 11.24vdc. Post to post on the battery gives 12.5vdc. Everything off doors closed, only thing I could tell that was on was the hood light. I have been disconnecting the battery whenever I park and leave it for more than a couple hours, so far no problems. Unfortunately this leads me to think there is something with the truck draining it.

Thanks,
Jeff

 

If I understand you correctly you are measuring the voltage drop between the negative battery post and the cable terminal connected to the negative battery post. If that is correct, it sounds like a high resistance connection between the battery post and the terminal. A high resistance connection can prevent the battery from being fully charged by the alternator when the engine is running and can limit the current when cranking the engine. Clean the battery post and the mating surface on the negative cable terminal and recheck the voltage.