Battery drain - cause?

[cngodfather]

My truck does this randomly sometimes. I can not drive it for months and it'll startup fine. Other times it is a week and won't turn over. Also, Optima doesn't make the batteries like they used to. FYI -

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[Pinger]

When you’re using the multimeter you are disconnecting the positive and putting the multimeter between the battery and cable correct?

Yes.
Your 0.12A draw sounds high. On another forum I'm told 65mA (0.065A) is as much as there should be. You are twice over, mine is four.

 

[Chewy11B]

So a couple things to think about. Parasitic draw should never be above 50 mA, which would read .050 if your scale is in amps. If you simply tape the door jamb switch down you can allow the computer's to all sleep. Give it atleast 15 minutes. Pull one fuse at a time and watch for a drop. The other thing to test on a battery is the parasitic drop across the plastics itself. Leave one lead on either positive or negative and run other lead across battery case. You should not get any voltage at all. I have had batteries test good all day long, have disconnects on and the battery still drains itself.

Good luck and make sure to post back results!!!!!

 

[Edward Case]

Anything on a fusible link that avoids fuses how about the starter cable, disconnect it and isolate it from any potential grounding.

 

[Erik the Awful]

Optima batteries are great on equipment that's going to sit for a year with no draw. I'll even say they're better than your standard car battery. They are not better enough to justify 2x the price, especially considering that once it's been drained it never works right again. After years of buying Optimas, I've gone back to standard lead acid batteries.

 

[Pinger]

deleted - double post

 

[Pinger]

Try disconnecting the + cable on the alternator.

A bit more....
Car has sat with battery disconnected since Saturday and with a Fluke multimeter is showing 12.4V on its posts.

Disconnecting the only sizeable lead I could find on the alternator makes no difference to the current draw. None whatsoever - so I think that rules out the alternator as a cause. If, I've got the right cable that is - biggish one on the back of the alternator at the top that comes forward to a junction box mounted on the radiator fan upper shroud - yes?

Current draw is ever present - ie with everything that could be energised by the ignition key not. Next on my mind to check (as suggested) is starter motor cable. What might I expect to find? Conductive dirt permitting a path to earth? There's not much more that isn't switched via the ignition key to check. Three ciggy lighters in the front (maybe another two further back) and the interior lights (working fine). Double checked the interior lights - they all go out together and lights in sun visors also. All fused circuits have been checked - fuses pulled one by one. Any further suggestions anyone?

 

[RawbDidIt]

A bit more....
Car has sat with battery disconnected since Saturday and with a Fluke multimeter is showing 12.4V on its posts.

Disconnecting the only sizeable lead I could find on the alternator makes no difference to the current draw. None whatsoever - so I think that rules out the alternator as a cause. If, I've got the right cable that is - biggish one on the back of the alternator at the top that comes forward to a junction box mounted on the radiator fan upper shroud - yes?

Current draw is ever present - ie with everything that could be energised by the ignition key not. Next on my mind to check (as suggested) is starter motor cable. What might I expect to find? Conductive dirt permitting a path to earth? There's not much more that isn't switched via the ignition key to check. Three ciggy lighters in the front (maybe another two further back) and the interior lights (working fine). Double checked the interior lights - they all go out together and lights in sun visors also. All fused circuits have been checked - fuses pulled one by one. Any further suggestions anyone?

Power cable on the alternator should be pretty obvious. It's 6ga with a fusible link, should be connected directly to the positive battery terminal. The wire that goes over the fan shroud should be the main power for the engine fuse box, try removing that from the fuse box, and the power wire from the alternator. That should leave only the starter connected, if there's still a draw, then the starter is the issue, and you did the diagnosis without getting under the truck, double check your work by disconnecting the starter and checking the voltage, then adding the alternator power, check again, then add the fuse box and check yet again. Those should be the only the loads directly connected to the battery unless you have something aftermarket. If you do have something aftermarket directly connected to the battery disconnect that first, and check draw, as that's usually at fault. Motors and alternators can fail and draw current through the coils, best fix for that is rebuilding or replacing.

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[Pinger]

Can't get a proper look at the back of the alternator as a load of LPG associated trunking is in the way - and hard sometimes to know what in the engine bay was put there by GM and what later by the LPG installer.

My wiring is different from your description. The lead that runs across the fan shroud at one end connects to the engine fuse box, the other end into that junction box. On the same terminal another lead goes to the alternator. It was that lead I disconnected. Beneath that terminal on the junction box (which I think also carries fuses) there is another terminal (connected internally presumably) and from it there's a lead that connects to the battery's +ve terminal.

Need to have a look in Haynes for that 'junction box'. Maybe it's an LPG thing. Definitely needs checking for source of drain.

An oddity is that the MM (multi meter) in series (between battery post and lead) doesn't register interior lights being switched on or off. Only the 1/4 Amp parasitic drain. The lights don't come on either with the MM in place. Ditch the MM and reconnect and they work fine (but for one in the driver's door).

 

[RawbDidIt]

Can't get a proper look at the back of the alternator as a load of LPG associated trunking is in the way - and hard sometimes to know what in the engine bay was put there by GM and what later by the LPG installer.

My wiring is different from your description. The lead that runs across the fan shroud at one end connects to the engine fuse box, the other end into that junction box. On the same terminal another lead goes to the alternator. It was that lead I disconnected. Beneath that terminal on the junction box (which I think also carries fuses) there is another terminal (connected internally presumably) and from it there's a lead that connects to the battery's +ve terminal.

Need to have a look in Haynes for that 'junction box'. Maybe it's an LPG thing. Definitely needs checking for source of drain.

An oddity is that the MM (multi meter) in series (between battery post and lead) doesn't register interior lights being switched on or off. Only the 1/4 Amp parasitic drain. The lights don't come on either with the MM in place. Ditch the MM and reconnect and they work fine (but for one in the driver's door).

Not sure what LPG is, but sounds like that's aftermarket. Disconnect that junction box from the battery and see if the battery still registers a load over .05A. At that point, the only thing connected will be the starter. If that gives you nothing, disconnect the alternator and fuse box, reconnect that junction box and check again. Not sure what's in the junction box, but it may be causing the issue. Sounds like it may be a low voltage cutout (the added resistance of the MM may cause enough of a voltage drop to trip the disconnect), I've thought of adding one myself, but found it to be unnecessary when everything is running correctly. If the draw is still present with the only load connected being the starter, remove the power wire from the starter and perform test again, should remove the draw and you have your answer, if it's still present remove the positive terminal from the battery and test for current from the ground terminal to the ground wire, that will show you if the battery itself is leaking power to ground from the case as mentioned in above comment.

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