Random Battery Death?
Tuned
Joined: Dec 2013
Posts: 458
Likes: 2
From: The Northwoods, Wisconsin
Testing
This is not going to fix anything, but it is awesome for testing your battery, alternator and starter. Napa wanted over $100 for it, so I got it at Amazon.
Again, doesn't fix things, but I can't imagine going without it now.
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New User
Joined: Aug 2014
Posts: 22
Likes: 0
The computer doesn't draw THAT much! Not even close. You shouldn't see much more than 300ma, if all lights are off, and the computers have gone to "sleep".
The alternator is a likely suspect. You can disconnect the batteries, and alt, then re-test to verify. I assume you have a DMM, and the leads are being placed in series with the battery cable? How hot is the alternator getting 10mins after a cold start, with no load?
The alternator is a likely suspect. You can disconnect the batteries, and alt, then re-test to verify. I assume you have a DMM, and the leads are being placed in series with the battery cable? How hot is the alternator getting 10mins after a cold start, with no load?
Lead Driver
Joined: Nov 2007
Posts: 5,139
Likes: 209
At least its not cooking, yet. Have you disconnected the alt charging lead, and taken any measurements? Remember its connected to the positive terminal of the battery, so disconnect the battery and protect any exposed connections accordingly. If no change, it's fuse pulling time.
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New User
Joined: Aug 2014
Posts: 22
Likes: 0
I did disconnect the alternator last night and checked the diodes, I got a reading of 428 on way and nothing the other way. I'm keeping the negative on the battery disconnected until I figure out what's going on.
Lead Driver
Joined: Nov 2007
Posts: 5,139
Likes: 209
I had a buddy with an 03 6.0l, and the same problem. I went through this same procedure to identify the problem. It ended up being a bad battery. The bad battery was only two months old.
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From: Houston, Texas
I topped the batteries off and they did what they were supposed to, but I think all I did was buy myself some time. Gonna run them by Autozone after work Friday.
Just didn't want to have to spend money on two new batteries
Lead Driver
Joined: Oct 2010
Posts: 5,420
Likes: 16
From: Ouray, CO
Disconnect one lead from battery A - while measuring the current draw from battery B. Read the voltage on battery B.
Re-connect battery A's cable.
Disconnect one lead from battery B - while measuring the current draw from battery A. Read the voltage on battery A.
Re-connect battery B's cable.
IF one battery is pulling the other down because it has a bad cell (or two) - this should determine which battery it is..
Re-connect battery A's cable.
Disconnect one lead from battery B - while measuring the current draw from battery A. Read the voltage on battery A.
Re-connect battery B's cable.
IF one battery is pulling the other down because it has a bad cell (or two) - this should determine which battery it is..
Lead Driver
Joined: Nov 2007
Posts: 5,139
Likes: 209
The OP has had his battery tested, and it checked okay. If it is, something is pulling it down. All the troubleshooting can be done in an hour if you move through it efficiently.
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New User
Joined: Aug 2014
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Ya I had the alternator disconnected completely. A friend of mine was sure that it was the source of the draw that he helped me take out of the truck. Retested and still got the same 8 amp draw that dropped down to about 6 amps after a few minutes.
Lead Driver
Joined: Nov 2007
Posts: 5,139
Likes: 209
Now its time to pull fuses, and relays. Having a buddy with you here really speeds things up. One guy watching the meter, and the other pulling and replacing until you see a dramatic change. It helps to identify the constant sources first(PCM/radio memory/etc) first. Get them out of the way, and note how much of a load they contribute. Hopefully in the 20A setting on your meter, you still have resolution down to at least hundreths (x.xxA).When the offending circuit is identified, leave its fuse out, bring the constants back up first, and verify the load is similar to what was noted when they were pulled. The PCM can draw a higher initial load when first energized(as it's basically rebooting), and will stabilize to a lower reading after it sleeps(can be several minutes).
Postmaster
Joined: Mar 2013
Posts: 3,066
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From: Over There
http://www.harborfreight.com/7-funct...ter-92020.html
My suggestion pickup a cheap buzzer and a couple alligator clips. Clip it in place on the battery post and cable clamp. This way you don't have to be anywhere near it, not even see it. Then pull/unplug things until the buzzing stops.
Lead Driver
Joined: Nov 2007
Posts: 5,139
Likes: 209
Is it the one with the red plastic housing? If so, I have IDK 8 or 10 of those HF gave them away for a while, they SUCK. I bet if I was too hook up all the ones I have to the same battery at the same time I'd get 8 different readings. I am a HF fan but have HORRIBLE history with all of the CEN-TECH products, I don't even take the free ones anymore. My point, you can not rely on it for this.
My suggestion pickup a cheap buzzer and a couple alligator clips. Clip it in place on the battery post and cable clamp. This way you don't have to be anywhere near it, not even see it. Then pull/unplug things until the buzzing stops.
My suggestion pickup a cheap buzzer and a couple alligator clips. Clip it in place on the battery post and cable clamp. This way you don't have to be anywhere near it, not even see it. Then pull/unplug things until the buzzing stops.