Battery and Alternator Experts Please Help!

I've been having low battery problems lately. I got the low battery warning light on the dash last week, and just the other day I had to jump start the truck. I had just driven it the night before, so it wasn't sitting around for a long time.

So I went to Sears figuring I needed a new battery. They hooked it up to their test machine and it said too low for testing. So they charged the battery for 45 minutes and then retested it. The test machine said the battery was fine. They also tested the alternator and the starter and said those were fine too.

Well the next morning, the truck wouldn't start again. I tested the voltage on the battery and it was around 9 volts dc.

I jump started the truck again and retested the voltage while it was running. This time I got around 14 volts.

I drove around for a while, came back home, turned the truck off and remeasured, 12.6 volts this time.

With the truck still off, I hooked up the multimeter in series and measured the current draw. After about 10 minutes, the electronics settled down, and I got a consistent 0.5 amps reading. I then proceeded to pull every fuse and relay I could find both in the engine bay and the passenger kick panel. I also disconnected my speaker amplifier and my alarm system. Still got 0.5 amps. Something is causing the battery to drain but I can't figure out what it is.

I read online that the alternator could have a bad diode and drain the battery. They said to measure the AC volts while the truck is running. I did so, and this is what I got:

https://www.youtube.com/watch?v=nWKqMYtXyME&feature=youtu.be

I don't know what that reading means. It seems to be jumping all over the place.

On the positive side of my battery, there are two main connectors. One goes to the fuse box, the other goes towards the alternator, see picture below. The connector with the red rubber cover is the one that goes towards the alternator.



As soon as I disconnected that cable, the current draw dropped from 0.5 A down to 0.03 A. This is with the truck turned off. So it seems something on that line is causing the drain. I'm not sure if that cable is actually going to the alternator or not. It's hard to tell with the Whipple sitting right on top. Here's another pic of the wire bundle.



It's the bundle of wire right between the Whipple and the alternator, the one wrapped up in tape.

What do you guys think? Is the alternator draining my battery? Do I need a new alternator? Does the Whipple have to be removed to replace the alternator?

Please help me guys! I want to get this fixed so I can go to SVC Day in the Dirt.

Strange that everything tested fine, but still having an issue.

Yukon Joe
www.RUNRAPTORRUN.com

Well, according to Sears, everything tests fine. But I don't have much confidence in them. And I doubt the dealer would do much better. Based on what this guys says, you shouldn't have more than 0.05 amps drain when the vehicle is off. I have 0.5 amps drain. Ten times as high as it should be.

https://www.youtube.com/watch?v=zdIKNnwEjIs&list=FLgDtq5gsbUxI1ppNOrW__AA&index=1

Try a new battery I know it's not cheep but probably what you need.

I would charge the batter to full, disconnect it over night reattach it in teh morn check the voltage and see if it starts. Its the cheap way to test it. Did tehy load test the battery?

The 0.5a draw is way to high the 0.03ma is perfect. With out looking at a wire diagram I would follow the wire that is causing the draw to each component disconnect 1 by 1 and watch for the draw to drop to 0.03ma. Also if your battery is over 3-4 years old it may be time to consider replacing it after the draw is fixed

When I pulled out all the fuses and relays, shouldn't the current draw drop to zero? How many fuse boxes are there? The truck manual only shows 2 and I removed all those fuses. I also disconnected my stereo amp and my alarm. Are there some components in the electrical system that are not fused?

I'm thinking about just getting a new battery, but I'm concerned that this current draw will just kill the new battery.

mike.s said:

I'm thinking about just getting a new battery, but I'm concerned that this current draw will just kill the new battery.

Click to expand...

Hockster said:

I would charge the batter to full, disconnect it over night reattach it in teh morn check the voltage and see if it starts. Its the cheap way to test it. Did tehy load test the battery?

Click to expand...

what hockster said is the best way to tell if its the battery at this point. if the battery is bad USUALLY it will lose voltage all by itself without any draw. so if u disconnect it and u still have a problem its the battery. a good load test is a very good way to check it, if they didnt do that already

If you have more than .050 amp draw "50 mA", then you need to chase that down first. A new battery would not likely get rid of a current draw.

If you have removed the fuses and the draw is still there, it is possible that something aftermarket is hooked into the harness you are referring to. If you want to see if it is the alternator, there should be a connector on the alternator that can be removed. Then check your draw (spec is less than .050 amps).

Keep in mind it may take a while for the modules to go to sleep before the current reading is accurate. Some modules can take up to 20 min or more to go to sleep. Every time a door is opened or closed, the modules can wake up. It is easy to trick the door switch with a screw driver (to think the door is closed).

There are a few components that are not fused hence the draw still present with all fuses removed. You said that the one cable under hood that you disconnected caused the .5A to drop to 0.03ma. Trace that wire to the end and note all elect components that are on that wire and disconnect 1 by 1 while watching the meter it drops then that elec component is that source.


The best way that I have found to accurately do a draw test on a vehicle is to start with a known good battery, roll down all windows close all doors open the hood jump the hood switch so the alarm system thinks the hood is closed, connect meter in line with ground cable setup for amps, then lock vehicle with remote control and watch the amp reading. It will start off high then as time passes anywhere from 5mins to 30 mins the reading will settle and that will be the final at rest amp draw. Once that number has been determined you can then start pulling fuses to locate that source if it is over 0.05ma.



Disclaimer I can not beheld responsible for an individuals actions this is just a guide that may help understand the processes.