Battery drain

[pamster868]

Hello!

We have a parasitic drain on our engine battery and can't figure out what's causing it. We have a 2002 E450 V10 with a good battery and we ruled out fuses and relays as a source . The battery will die in about 3 days with a 50mA continuous drain. We put a kill switch on the battery until we figure it out. My husband is now thinking the alternator diodes are bad. Wanted to get some input first before we replace the it. Thanks for the help!

P & J

[SeaKing1]

Maybe start here:

https://www.fordforum.com/forum/general ... ain-36918/

[pamster868]

Thank you for sharing the link to this Ford forum video. It's actually what we used to help us troubleshoot prior to our original post. We are now considering putting in a new alternator. Has anyone experienced this issue and resolved it by replacing the alternator? We appreciate any and all input.

[Mike Jean Bandfield]

Remove one of the cables from the battery and put an ammeter in series with the battery and the removed cable. The meter should now show the drain. Start pulling fuses, one at a time, until the meter drops to ~0 amps. One of the devices on that fuse is causing your battery drain.

[pamster868]

Thanks for the input. We tried that with the ammeter and we pulled every fuse and relay for the engine compartment and inside the cab. The ammeter never dropped to zero. We checked the alternator ourselves and verified it was good with Auto Zone. There is a 50mA draw and the most confusing thing is the draw continues even when the engine is running. We are perplexed and getting ready to take it in to a pro mechanic. Unless there's something else we haven't thought of...stay tuned.

[tomzleapin]

A 50ma drain is minor. You could go a month without killing the battery. With the engine running you would be measuring a charge current of several amps. It sounds like your meter is not working right or hooked up incorrectly. I use a clamp meter to measure current. It allows you to measure current without disconnecting the cable. If purchasing one, make sure that it can measure DC. Most cheap ones can only measure AC. Here's one available on Amazon:

https://www.amazon.com/KAIWEETS-Multime ... hdGY&psc=1

[pamster868]

Our battery was dying within days, not weeks, so we got a new meter and the draw was significantly higher which explains that. We went through the drill (twice) of pulling fuses and relays, but the meter never dropped, so we still can't figure out what is pulling power from the battery. Right now the rig is in the shop, so we hope they will figure it out. I'll send an update as so as we get a diagnosis/fix. Thanks to everyone who offered suggestions.

[pamster868]

I've been meaning to update this post. We took the RV into a local mechanic. Turns out it was a bad radio fuse causing the draw on our battery. We still engage the kill switch on the engine battery when we store the rig. So far, no more issues.