I installed a radio from a 2001 tahoe the other day, and I woke up the next morning to a dead battery. competely drained, my dome light wouldn't even turn on. The battery was old and too small for the car (was in there when I bought the vehicle) so I put a new one in and disconnected the radio. Woke up this morning to a dead battery yet again, though not as wiped as yesterday. What would be a likely cause of this? The radio hooked up to my factory harness so I didn't have to splice anything. But why would it drain again after I disconnected it? The radio seemed to turn off when the car turned off, the clock wasn't on anyway. Would the fact that I didn't have the separate CD player connected have anything to do with it? I'm stumped.

 

Now I'm really stumped. I put a one month old battery in with a full charge after driving all day, and disconnected the positive cable from the post. Go to start my car this morning and I still had enough juice to turn the engine a few times slowly, but it wasn't enough to start it. Now what in the hell would do that. I couldn't do a proper draw test because my meter had a blown fuse but I could see the voltage dropping at an alarming rate. I watched it go from 12.6 down to 12.3 in under 30 seconds.

 

alt, terminals, grounds, all wiring really, only way to find it is with a continuity tester (test light, dwell meter, multimeter) and alot of time. keep in mind if something is getting power, it needs to be grounded

 

Check alternator. Regulators sometimes stick in charge position when the ignition is off and drain the battery. One test you could do is leave battery hooked up and disconnect alternator over night then check again in the morning. Make sure it is good and charged before doing this test.

Sounds like that battery needs tested if it loses charger overnight while being completely disconnected.

 

I have the same issue at the moment as wehn I did my LS swap the wipers never worked and the radio power wire always had a .72v going to it all the time. I pulled the wiper fuse and it went to 0v so I left it that way and my barrty still died a few days later. I recomditioned my red top since then so I will try it again as soon as I can to see if that was the issue as I know optima's are retarded and finicky when they lose a charge

 

I'd definitely have the battery load tested. Sounds like a bad cell or two. Then I'd have the alternator tested. Good luck with it!

 

The battery I put in was a month old and never had a problem in the car it came from. I still haven't gotten around to testing it yet but my bet would be on the alternator. If it was that sticking in the charge position couldn't it still do that with the negative side connected? I'm going to charge it tonight and see if disconnecting the alternator does anything. I'm still waiting on a good meter since my crappy Walmart one can't do the test without overloading

 

Finally got a DMM with load test capabilities and and and amperage rating that can handle an automotive application. Parasitic draw test showed almost exactly 50mA. battery also passed the load test. what the hell is happening here then? The batery I put in after the first old one died was only a month old and worked fine in the previous vehicle. should I check for a current draw from the alternator to the battery? I would think that would have shown up in the initial draw test though, but I'm just trying to cover all my bases. I drove the car for a few miles today to make sure it was stil charging and listened when I shut everything off and to the best I can tell, nothing is staying on as far as fuel pump, hatch motor, etc. the radio definitely turns off, including the clock, except when I press recall to illuminate it. I'm leaving everything conected tonight and see what happens when I go to start it tomorrow. The starter is almost brand new as well so it shouldn't be putting any stress on the battery.

Edit: Wow I don't know why i didn't mention this before, but I did notice when I installed the radio the first night that my headlights would dim slightly when I hit the brakes, and (luckily) when I was in a parking lot, I flicked the toggle switch for my fans and it killed the car. just shut everything off immediately, although when i tok the key out and started it she fired right up. Never had any problems like that before, when I looked under the hood, the crappy lead terminal on the negative side was half broken off, which would explain the crappy charging it got that day. I fixed that after the second battery died the next day, today was the first day I jumped and drove t since then which is why im leaving everything connected tonight to se what hapens.

 

Yeah try a new or different one, deep cycling car batteries plays hell with the electrolyte.

 

Found the problem lol. Not sure how I didn't notice it but the crappy lead terminal on the negative side was cracked, which would explain everything.
nothing to see here haha problem solved