Yet Another Battery Drain
 

Hello, Used to be a member but couldn't remember log in. So new again.

Read a bunch of posts on battery drain.

Bought a 1995 Eddie Bauer F150 4wd off Craig's. I think I know why I got such a good deal. Four day +/- battery drain. If it's driven every day, it's no problem.

I have removed all fuses while watching volt meter connected between cable and battery. Shows battery voltage with every fuse, breaker, and flasher module. Disconnected all wires from the alternator. Still shows drain.

Not sure which wires are normally hot with ignition turned off. I would think it would just be a hot wire to the ignition that would run a relay to turn other stuff on.

Unless someone has a suggestion, I'm thinking of just installing a high amp relay at the battery with an on/off switch at the dash. Don't know what else to do at this point.

Thanks, Harold

You really need to use an Amp meter to find the draw. This is a great step by step video. Watch the whole thing then test and I'll bet you can find it.

THANK YOU SIR!! One of the best if not the best well done instructional videos I have watched.

Problem found. Problem fixed.

Harold

Awesome, Harold. What was it?

Long story, sort of. When I bought the truck, I noticed the driver's side courtesy light button was missing. I mentioned I had done the same to my truck as I didn't like the light coming on.

The seller said the only interior light available to the driver was to reach up to the interior dome light.

So when I pulled fuse #8 (think it was 8) which controls everything from the radio, interior lights, door locks, to the mirrors, most of which have no power with the key off, except the interior lights,. i suspected the door switch.

Used a 1" hole saw to be able to fetch the wiring. Nope. That wasn't it.

Someone had abandoned the removal of the radio and that was going to be my next test as it was listed on the fuse.

For some reason I decided to check the interior light switch located at the headlight switch first. It was in the on position but the interior light was not on. I clicked the switch clockwise to the right and had my "voltage" drop.

Voltage because I had burned out my 10 Amp circuit on my 40 year old Radio Shack unit and only had 500 mA available. Dug up a resistor from a set of handle bar heaters that measured 2.2 ohms. Showed 2.64 volts with the probes across the resistor with the resistor wired is series with the battery cable and terminal. Dropped to .02 volts when I pulled #8 and also when I turned the interior light switch on the headlights.


I checked the battery voltage during the day as confirmation and it dropped nary a bit.

And another big thank you! Didn't spend a dime.

Glad you found it. The idea of using a resistor as a shunt is creative. I'll bet a low watt automotive light would also work.

I bet you'd win that bet.

Hi you should measure current in amperes.Use amperemeter like an open circuit.And you can disconnect your battery for several days.The battery may cause problems too

Harold's post is a bit confusing but he couldn't use the ampmeter because he burned out the high current fuse in his meter. So he put a resister (2.2 Ohm) in series with the circuit and used the voltmeter function with it's low current fuse to measure the voltage across the resister. In effect his resister was acting as a current shunt. Even though it was not calibrated he was able to find what was pulling the current because the voltage across the resister dropped dramatically when he pulled the fuse. He was originally pulling (2.64volts x 2.2 ohms) or 5.8 Amps and it dropped to (0.02 volts x 2.2 Ohms) or 0.052 amps after he pulled the fuse.

Harold, Amazon or E-bay is a good place to pick up some fuses cheap and in addition you won't have to go anywhere to get them. I've been ordering a ton of parts that way lately.

FYI I'm currently in the process of permanently installing some current shunts and a dash mounted meter in my F-150 just so I can keep track of what's going on electrically in my truck. I haven't had any problems yet but I keep hearing horror stories about electrical problems in them so I want to be able to tell what's going on.