Aggressive battery drain.. thoughts?

So i bought a 2010 platinum 6 months ago and it started and drove fine. Then I had to move to another city for 3 months so the truck just sat there. The truck is mint with 150k on it so having it "sit" shouldn't be an issue.

I came back home yesterday and it's now -20C, so when she wouldn't start I figured it was just a weak battery. I put it on the conditioner for 90 mins and then tested it and it was at 12v. I let the battery sit on the bench over night and tested again this morning and it's the same voltage so it holds charge..

As soon as I connect the battery to the terminals on the truck I read like 6v and it rapidly loses .1v every second or so.. at first the car alarm went off but I dont know if that was a tamper defense because of the voltage issue or not. I removed the neg terminal and re connected and the alarm didn't trigger this time but I hear a faint tick o a one second interval of what could be a relay signaling the horn to sound.. the truck has a compustar starter fob.

Seems like the issue could be the automatic starter or something related to that? But why would it just happen all of a sudden.

Any tips on how to troubleshoot would be appreciated, thanks

 

battery draw, so you will need a multimeter and start pulling fuses 1 at a time until you find the culprit... I'm sure someone on here has done something similar, so you can find it on this site. Highly suggest you start there.. OEM Toyota batteries don't do very well, should probably upgrade, but first find the draw or you will be standing in the exact same place you are right now....

 

When you say 12 volts, do you mean 12.0 volts? If so that's too low. A good battery should be about 12.8 volts fully charged. As suggested either have it load tested or if you have a Harbor Freight close by you can pick one up for about $20.

 

This is the likely answer. Going from 12 to 6 with a load usually means a bad cell.

 

Thanks boys, I'm not a battery expert so wasnt sure if that was the problem or not.. when I bought the truck the guy told me he put a new bat in and it looks to be in pretty good shape so I believe him.. still could be faulty but doubtful. The only reason I would lean on a faulty bat is that it just happened all of a sudden with the change in season/temp and its not like I did any work on it electrically.

Just to clarify, I did pull all the fuses and hooked my meter up to monitor voltage. Then periodically put them back in and found 3 that caused the voltage to dwindle. 5A met-b, 15A rad no.1, and 7.5A ECU-b1..

At this point the battery is at 10.8v but it's all good as I just want to find out what circuits are drawing this load. Even if I put the key in with the fuses pulled the voltage drops.

I'm not sure how to load test the bat but that's a google search away.. my question is would my suspected fuse circuits draw that much under normal conditions, and a strong battery have the voltage to supply and not die? Thanks

 

If you did a full charge and the battery only reads 12.0 volts, you need a new battery. I’m pretty happy with the Costco Interstate ones. Made by Johnson Controls (who made my factory battery that lasted 5 years). $93. And correctly sized at 27F (unlike Walmart which no longer stocks that size and recommends a 24). Good luck!

 

Sounds like a bad battery to me as well.

 

Same for sure.
This sounds like classic dead battery symptoms to me.
Again though this is simple enough to have tested for free at most parts stores where they will be happy to sell you the new one too!

 

**problem solved**

For anyone having similar issues.. buy a new battery and presto loll

Sometimes 12v doesnt mean 12v

 

Yup. The only time 12V really means 12V is when there’s a load applied and you still have 12V.


Glad you got it solved.