Batteries Draining Overnight. What could draw so much?

[KevinDIY]

hey guys, I am trying to track a heavy amperage draw on my truck that manages to seemingly kill the batteries quick!

The batts had a full 100% charge from the batt charger @ 8 amps over a weekend. The batteries were weak enough this morning that the truck was completely dead. Ive got a Shuriken medium battery upfront, and 3 NSB 90's (big) in the back. They have alot of reserve, so to completely drain them to me must be a huge drain.

I really dont know how to track a drain, and dont know what setting to use on my meter to do so, I do have a current clamp to but Ive never used it. The truck has alot of wiring from myself, big 3, power/ground runs to the back batts, auto electric rad fans, aftermarket heated seats, various switches, 2 amps etc. So Im not really sure were to start. Everything appears to be off, and still connected properly.

The truck was stored for about 18 months (but was started weekly, and always on a battery tender) and I just put it on the road again (but some maintenance/audio work was done)

Where would you guys start tracking this?

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[jrdnhsnbrg 10+ year member]

Unhook all batteries besides main starting batteries. That would be the first thing I would do.

 

[Roland 10+ year member]

With the battery charged and the engine off, clamp on your DC amp meter around your battery cable and check for amperage draw. if you have more than one pos cable, you could try each cable separately if you known where they lead...

You could also clamp the ground (you should see your amp draw ether way) and start pulling fuses. Pull one at a time (put the fuse back before going to the next) until you see a drop in amps being drawn you should be able to narrow down the culprit fairly quickly...

 

[Side Show 10+ year member]

check wiring on any audiowork that was done.

 

[KevinDIY]

With the battery charged and the engine off, clamp on your DC amp meter around your battery cable and check for amperage draw. if you have more than one pos cable, you could try each cable separately if you known where they lead...
You could also clamp the ground (you should see your amp draw ether way) and start pulling fuses. Pull one at a time (put the fuse back before going to the next) until you see a drop in amps being drawn you should be able to narrow down the culprit fairly quickly...

So I just pulled my clamp out of the box for the first time, never used it, but I think with the manual I can figure it out. When you say to check the amperage of each cable, do you mean ac current, ac voltage or dc voltage

 

[jrdnhsnbrg 10+ year member]

So I just pulled my clamp out of the box for the first time, never used it, but I think with the manual I can figure it out. When you say to check the amperage of each cable, do you mean ac current, ac voltage or dc voltage

Gonna be DC current

 

[trumpet 5,000+ posts]

How to Find and Stop Car Battery Drains – DIY Car Battery Drain - Popular Mechanics

As shown in that article, a more accurate way to measure current draw with the vehicle off is to put a multimeter in series with the battery post and the terminal. Use your troubleshooting skills(or develop them now) by disconnecting your additional circuits one at a time to see how the vehicle off current draw changes. If it's not caused by the extra wiring you added, then it's probably something original to the car that's acting up.

 

[marcos65]

one bad battery in the bank can kill the rest of them.

 

[KevinDIY]

^^^ funny that you were the last to post, heres what I found

So I havent had a chance to do any of the tests yet as Im still at work, but I went out for lunch today and after turning the truck off I heard an INTERMITTENT fizzing sound, I jumped in the back and sure enough, one of my batteries is making a fizzing noise from the case on the negative side. Makes a fizz noise for 1 second, quiet for 1 second, then fizz etc. It was louder with the car on aswell.

Then I even noticed that battery was warm, while the other 2 rear batteries were COLD, as its -15C outside. Battery toasted? My batteries are in a line against the back of the seats, and the fizzing battery is the farthest right, its the last one to get a positive cable run, but its ground runs to the frame and the front battery ground. Would that kill it?

I havent had a chance to do any of the other tests, but this seems pretty damning

 

[brian84corvette 10+ year member]

sounds like its a bad batt.

i would un hook all of your rear batterys and find time to take them to autozone or wherever to be hooked up to a load tester.

also charge them up individualy. let them sit for 48 hours - take voltage readings on each one.

if they all read above 12.6 they are ok to use still. if any battery has fully charged but drops to below 12.4 in 48 hours sitting its most likely shot

 

[bgowdy 5,000+ posts]

^^^ funny that you were the last to post, heres what I found
So I havent had a chance to do any of the tests yet as Im still at work, but I went out for lunch today and after turning the truck off I heard an INTERMITTENT fizzing sound, I jumped in the back and sure enough, one of my batteries is making a fizzing noise from the case on the negative side. Makes a fizz noise for 1 second, quiet for 1 second, then fizz etc. It was louder with the car on aswell.

Then I even noticed that battery was warm, while the other 2 rear batteries were COLD, as its -15C outside. Battery toasted? My batteries are in a line against the back of the seats, and the fizzing battery is the farthest right, its the last one to get a positive cable run, but its ground runs to the frame and the front battery ground. Would that kill it?

I havent had a chance to do any of the other tests, but this seems pretty damning

yea i was going to say check batts because 1-bad will kill them all. I had a problem and couldnt figure it out. When i started my truck the batt had got bad enough(down to like 9v, i had no idea until i finally checked it by it self because tied in with the rest it reads the same as the other) and was acting as a load on my alt. My alt voltage never got above 13v at max. Then my friend said to check the batts individually. i had just got a new smart charger and pulled them all out and charged them one by one. The last batt i charged ended up being bad and would not charge up over 11v at max then my charger would kick of and give a bad battery message.

 

[Side Show 10+ year member]

always try get new batts all at the same time

 

[KevinDIY]

Wish I could afford 3 new batts, but a grand on my winter beater isnt an option