Parasitic battery draw

[Rrent]

I’ve been keeping an eye on front battery (about 5 months old) - occasionally having to jump it from another vehicle. The #1 alternator has been rebuild - dash lights show both alternators to be working. The morning after my 40 mile trip the battery was dead, but jumped off easily/quickly.
I did a load test on this battery - seemed to barely “pass”. I broke out the multimeter. I believe this reading shows an 83/84 milliampere draw. Removing each fuse caused no change in this reading. I’ve replaced the battery had the old one tested at an auto parts store. Was told it is “good, but needs a charge”. I’ll put it on a charger.
Any ideas how/where I should look next or should I just drive (or at least start and run for awhile) more regularly? Maybe a battery tender?

 

[dependable]

I'd try to find the draw, there is no reason for it to be there. Truck does not normally have any systems that take current when key is in off position. If you have an aftermarket stereo or something, sometimes they draw a bit.

A common thing to cause draw is faulty alternator diode, but usually the alt light will glow a bit when key off. You could elimiate that by unhooking alternator.

See if there is any draw with service light switch in off position, this would eliminate light switch & horn relay, a place to start anyway. Make sure blackout lights are off, though I belive they would draw from both batteries.

 

[Tow4]

Are you sure the alternator works? The battery shouldn't be dead after you have been driving the vehicle. I can't tell what scale your meter is on but assuming it's showing 830mA load, that would take a day or two to kill the battery.

 

[Rrent]

Are you sure the alternator works? The battery shouldn't be dead after you have been driving the vehicle. I can't tell what scale your meter is on but assuming it's showing 830mA load, that would take a day or two to kill the battery.

I think it was set to 20m (I guessed milliamperes). I have a new aftermarket alternator. I’ll probably install it while I have the #2 alternator rebuilt and see if that fixes the draw. And yes - it was taking a day or two to deplete the battery, enough to need a jump start.

 

[Tow4]

Why don't you try using that meter to check the battery voltage at each battery while the engine is running instead of looking at the idiot lights? The battery voltage should be over 14 with the engine running unless it is dead.

Alternator #2 has nothing to do with alternator #1, which you say was rebuilt. I don't see how rebuilding alternator #2 will help. Since you don't know if the problem is in the vehicle wiring or the alternator(s), maybe instead of throwing money at it, you should try and diagnose the problem. Follow the link below.

Testing The Alternator On the Vehicle.

 

[Skinny]

Definitely need to know both battery charging voltages at idle and higher rpms.

My M1031 has sat outside for months in freezing weather and started with the blip of the key. Granted it runs like shit without a block heater but the batts aren't supposed to drain down even for months.

If you removed all the fuses and still have the draw I second the motion for a faulty alternator. It's the only thing really left directly connected to the battery.

 

[Rrent]

Definitely need to know both battery charging voltages at idle and higher rpms.

My M1031 has sat outside for months in freezing weather and started with the blip of the key. Granted it runs like shit without a block heater but the batts aren't supposed to drain down even for months.

If you removed all the fuses and still have the draw I second the motion for a faulty alternator. It's the only thing really left directly connected to the battery.

Alternator(s) are next on the to do list

 

[Mullaney]

Definitely need to know both battery charging voltages at idle and higher rpms.

My M1031 has sat outside for months in freezing weather and started with the blip of the key. Granted it runs like shit without a block heater but the batts aren't supposed to drain down even for months.

If you removed all the fuses and still have the draw I second the motion for a faulty alternator. It's the only thing really left directly connected to the battery.

.
Nice idea @Skinny !

Removing the fuses when on a quest for a power drain. Naturally any hack jobs in the wiring for oddball or non-military additions could get overlooked but it is a nice "polite" way to look in one spot for everything drawing juice.

 

[DeadParrot]

Swap the batteries so #1 is now #2 and #2 becomes #1. If the problem follows the battery, then the battery is bad. If the problem stays in the #1 spot, then its a wiring/device fault.

2nd what Skinny said about sitting. My M1008 can sit for a couple months and still start fine.

 

[Rrent]

Are you sure the alternator works? The battery shouldn't be dead after you have been driving the vehicle. I can't tell what scale your meter is on but assuming it's showing 830mA load, that would take a day or two to kill the battery.

I tested both alternators - good voltage at idle. After the 40 mile trip, I did start it (to be sure it would), but turned it off almost immediately. Might the, hot, starter (if not at 100%) have sucked the batteries down? Is there anyway for the starter to cause/contribute to the drawn down when the vehicle is not running?

 

[Mullaney]

I tested both alternators - good voltage at idle. After the 40 mile trip, I did start it (to be sure it would), but turned it off almost immediately. Might the, hot, starter (if not at 100%) have sucked the batteries down? Is there anyway for the starter to cause/contribute to the drawn down when the vehicle is not running?

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If the bushings / bearings in the starter are worn badly - yes, the starter could be drawing power where the armature might be touching (or almost) the fields inside the starter.

Have you tried all the other things like removing all the fuses and seeing if the drain is still happening?

 

[vanaisa]

Might have solved parasitic drain problem

Tested .83-.84. Thought maybe it could be the battery. Bought/installed a new battery. Took the one that was in the truck to an auto parts store where a young fellow told me - “it’s good just needs to be charged”. Tested the alternators- both good. Just for grins re-ran the above… this time .03.

www.steelsoldiers.com

 

[Rrent]

.
If the bushings / bearings in the starter are worn badly - yes, the starter could be drawing power where the armature might be touching (or almost) the fields inside the starter.

Have you tried all the other things like removing all the fuses and seeing if the drain is still happening?

Yep- no change as I removed the fuses. Might the starter have been (and will be again) the problem/draw. Armature ending up touching vs. not touching the fields, as it stops spinning?

 

[Mullaney]

Yep- no change as I removed the fuses. Might the starter have been (and will be again) the problem/draw. Armature ending up touching vs. not touching the fields, as it stops spinning?

.
I am not a starter repairman, but I have been told by folks who ARE skilled in those repairs that could indeed be the case. The big thing is that repairing the starter before the armature is badly damaged will save you money in the long run.

 

[Rrent]

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I am not a starter repairman, but I have been told by folks who ARE skilled in those repairs that could indeed be the case. The big thing is that repairing the starter before the armature is badly damaged will save you money in the long run.

That would make sense as the battery need-to-jump-situation came on very unexpected. Plus it might also address vanaisa’s above concerns. I’ll plan on pulling the starter and dropping it by the same place I had the #1 alternator rebuilt.

 

[Squibbly]

I assume that when you charge the battery on a charger check the voltage and leave it disconnected over night and check it in the morning it isn't dead? The parasitic draw could be the plates in the battery.

 

[Rrent]

I assume that when you charge the battery on a charger check the voltage and leave it disconnected over night and check it in the morning it isn't dead? The parasitic draw could be the plates in the battery.

The questionable battery is on the charger (at home now) I will disconnect and check tomorrow. Hopefully it was the problem.

 

[Squibbly]

The questionable battery is on the charger (at home now) I will disconnect and check tomorrow. Hopefully it was the problem.

I've got a 24v system in my Bass Boat, and I have a Genius Batter Charger that charges all 3 batteries (starting battery and 24V (two 12s) trolling batteries) on a trickle charge. Probably one of the best purchases I made for that system, because those batteries aren't cheap., and that Genius battery charger can bring some batteries back from the dead.

I may do the same thing on this truck if I'm going to be letting it sit for long periods.

 

[MarcusOReallyus]

That's a very good idea.

 

[Rrent]

That's a very good idea.

It seems these can also be had- solar powered.