Battery Drain...Problem

[82ABNMP]

The M1008 has all new GP system/plugs/card/switch,starter relay upgrade ect... and the batteries are 6mos old group 31 Exide made in 2012.


Previously the volt meter has always been dead on the hash mark and Gen lights work correctly.
The truck has been sitting for a few months with weekly checks and start ups with no problems...until now.
The other day it’s 45 outside and the truck starts fine,but while driving the volt meter goes low into the yellow.
Park the truck overnight INSIDE and the next day...complete blackout no juice at all. So I switch out the batteries with known fresh ones and the truck fires right off with the volt meter in the greenon the hash mark. Parked the truck overnight with the second set of batteries OUTSIDE and try to start in the morning temp is 14...batteries have some juice but not enough to spin the motor over to start they are mostly dead.

One thing I have did notice (and have noticed before on other trucks with a short/drain) when I went to hook up the second set of batteries (fully charged) there were some sparks when attaching the cables...yes they are hooked up correctly. Is this normal? Or is it because there is a draw on the batteries? Which means I have a short/draw somewhere?

No wires are hot to the touch.

Why suddenly after months one day would it start to kill the batteries? How much of a draw would it take to mostly kill a set of batteries overnight? Did the cold kill them?
Thanks, David

 

[MarcusOReallyus]

1. There is a draw on the batteries somewhere in your system. You need to find it.
2. Your black font is very hard to read against the dark SS background. Please reconsider it.
3. The phrase is "all of a sudden", not "all the sudden".
4. There are spambots for phone numbers, too.

 

[Warthog]

Have the alternators been rebuilt?

I have seen a bad alternator drain the batteries.

 

[82ABNMP]

1. There is a draw on the batteries somewhere in your system. You need to find it.
2. Your black font is very hard to read against the dark SS background. Please reconsider it.
3. The phrase is "all of a sudden", not "all the sudden".
4. There are spambots for phone numbers, too.

Fixed, i wrote it in word. That's why the black font. Also, cutting and pasting into the forum does strange formating things to the text. Thanks, David

 

[82ABNMP]

Hey Joe, I was hoping that you would chime in. the funny thing is that the truck sat around for weeks then in one night the batteries were dead?

So am I correct in thinking that there is a draw on the system when hooked up because of the sparks when hooking up the battery cables correctly? This happend once before on another truck when the GP switch went bad.

The alts have NOT been rebuilt because they have been working correctly, both lights and volt meter in the green. But I will have to test them with my meter.

Even with everything off a bad alt will drain the battery?

No wires hot to the touch.

Thanks, David

 

[MarcusOReallyus]

So am I correct in thinking that there is a draw on the system when hooked up because of the sparks when hooking up the battery cables correctly?

You are correct.

Now the challenge is, to find out what is creating the draw. You don't need warm wires to have enough draw to kill the batteries overnight.


Here's a quick test you can do if you have a test light:


Disconnect the batteries. (Leave the ground in place.) Now connect a test light to the + terminal of the battery and the cable that should attach to it.

I'm betting it will light up. Maybe dimly, but it will light.


To find the problem, you are doing to have to start disconnecting circuits one at a time. When you get the right one, the test light will go out.

OR, you can use a voltmeter the same way. When you get the right circuit disconnected, the meter will go to 0 volts (or pretty close).

 

[82ABNMP]

You are correct.

Now the challenge is, to find out what is creating the draw. You don't need warm wires to have enough draw to kill the batteries overnight.



Here's a quick test you can do if you have a test light:


Disconnect the batteries. (Leave the ground in place.) Now connect a test light to the + terminal of the battery and the cable that should attach to it.

I'm betting it will light up. Maybe dimly, but it will light.


To find the problem, you are doing to have to start disconnecting circuits one at a time. When you get the right one, the test light will go out.

OR, you can use a voltmeter the same way. When you get the right circuit disconnected, the meter will go to 0 volts (or pretty close).

Ok, thanks. So disconnect thet rear pos + and test that battery with the test light/volt meter? To check for draw? Could I then remove fuses to test the circuits?

 

[MarcusOReallyus]

Yep, you've got it. You want the test light or voltmeter to be in between the battery and whatever might be drawing current. When there's nothing drawing current, you won't have any voltage across the test light or voltmeter. So, go one at a time, and disconnect fuses, and see which circuit has the draw.

 

[cpf240]

um, are the blackout lights on?

 

[MarcusOReallyus]

Here's a good video on the process. He recommends using the ammeter function, and disconnecting ground. Same idea, though.

I prefer the voltage measurement because you don't need to worry about excessive current wrecking your meter.


http://www.youtube.com/watch?v=KF1gijj03_0

 

[82ABNMP]

Here's a good video on the process. He recommends using the ammeter function, and disconnecting ground. Same idea, though.

I prefer the voltage measurement because you don't need to worry about excessive current wrecking your meter.


http://www.youtube.com/watch?v=KF1gijj03_0

Ok, tested per above and this is what I got:

test light from - neg to +pos on rear battery the light came on (test)

test light from pos+ battery cable to Pos + post of rear battery no light

Voltmeter from Pos+ battery cable to Pos+ post = 12.82v (key off not running)

with voltmeter connected I went through every fuse and no change to the 12.82 reading?

 

[diesel583]

As mentioned earlier use a test light or amp meter, voltage is not a measure of current flow. Most current draw problems I have found on CUCVs have been on the 12 volt side. Good luck

 

[82ABNMP]

As mentioned earlier use a test light or amp meter, voltage is not a measure of current flow. Most current draw problems I have found on CUCVs have been on the 12 volt side. Good luck

Ok, thanks, I will try again with it set to amps. Also, when hooking up the batts again this time no sparks of any kind.

David

 

[cpf240]

May I ask why you are testing from the rear battery? There is very little that runs off the full 24v, so the rear battery doesn't see much load. I'd think it would be more likely that it is the front battery that is being drained. Perhaps run the test light between the front battery negative post and its associated cable?

The front battery being dead will give the symptoms you described, ie no dash lights at all, etc, even if the rear battery is fully charged, since the front battery pretty much runs the entire truck, including the relays that switch the 24v side of things.

 

[MarcusOReallyus]

First step - make sure BOTH batteries are fully charged!

 

[82ABNMP]

First step - make sure BOTH batteries are fully charged!

Yes, both batteries are fully charged and load tested. I will check the test light from the front battery neg- post to neg- cable.

Thanks.

 

[bshupe]

So I was working on narrowing down the battery drain tonight. I pulled the negative cable and inserted a test light between the neg cable and the neg terminal. The light came on for a moment and faded out. The way it faded is about how I would expect if there were a capacitor in the circuit and it just drained out. I tried a bunch of different things but never got the light to come back on.



I also was looking at the connections on the back of the alternator and the main terminals are all very clean. There is a plug on the back though that has two wires on it and the connection was very, very soiled. It looked like when a car has a real bad oil leak and oils is in everything. I couldn’t quite tell if this was some kind of sealer or something or if it is soiled as it looks. The way the connector connects to the alt is through an opening in the alt body so spraying a cleaner or anything will go right into the alternator.

Im stumped on the test light. I don think the battery was too terribly low tonight but I put it on the charger anyway. I am hoping I will have a minute in the morning to put the test light on it again or maybe even my meter to see if there is a draw that isn’t big enough to light the light but is still there.

 

[82ABNMP]

May I ask why you are testing from the rear battery? There is very little that runs off the full 24v, so the rear battery doesn't see much load. I'd think it would be more likely that it is the front battery that is being drained. Perhaps run the test light between the front battery negative post and its associated cable?

The front battery being dead will give the symptoms you described, ie no dash lights at all, etc, even if the rear battery is fully charged, since the front battery pretty much runs the entire truck, including the relays that switch the 24v side of things.

I think you are on to something...because the test light didn't come on when I tested the rear battery. Should I test the front battery Neg - post/cable and if the light comes on go through the fuses again?

 

[82ABNMP]

So I was working on narrowing down the battery drain tonight. I pulled the negative cable and inserted a test light between the neg cable and the neg terminal. The light came on for a moment and faded out. The way it faded is about how I would expect if there were a capacitor in the circuit and it just drained out. I tried a bunch of different things but never got the light to come back on.



I also was looking at the connections on the back of the alternator and the main terminals are all very clean. There is a plug on the back though that has two wires on it and the connection was very, very soiled. It looked like when a car has a real bad oil leak and oils is in everything. I couldn’t quite tell if this was some kind of sealer or something or if it is soiled as it looks. The way the connector connects to the alt is through an opening in the alt body so spraying a cleaner or anything will go right into the alternator.

Im stumped on the test light. I don think the battery was too terribly low tonight but I put it on the charger anyway. I am hoping I will have a minute in the morning to put the test light on it again or maybe even my meter to see if there is a draw that isn’t big enough to light the light but is still there.

The plug you are talking about is the 2 wire plug on the back of of the Alts. The red wire is hot 12v and the brown wire is the exciter wire that is connected to your Gen light in the dash.

What I am interested in is what Joe said the other day...can a bad Alt. pull a draw with the key off?

David

 

[doghead]

Yes it can. One of the diodes in the diode trio can go bad, it can still charge, but it will have a draw and kill a battery with the key off. It(the alt) will even test good on a tester.

Same thing can occur with the rectifier.

I feel this has been your problem all along.

Spend $80 and rebuild both alts, and you should be good for a long long time.