Losing battery juice when sleeping.

[s.u.p.r.a]

So I've had this car for a couple years now. When I bought it, it came with a switch to toggle power and a push button start. I just finished my GTE swap and I now realize that the switch was installed because the battery drains when the car is off. All the switch did was to break the connection of the (-) terminal.

When I turn the car off everything appears to be off (int. lights/ext. lights/ radio etc.) but if I leave it the battery will drain and die.

I know the alternator is working fine and the battery is brand new and working (tested).

Where do I start looking for the cause of this drainage?

 

[akito]

So, do you still use the switch? It is still in place like the way it was when it came with the car? U might have a short somewhere thats draining all the juice out of the battery.

 

[s.u.p.r.a]

I removed the switch + button start. Know of any time-savers when looking for the short? =]

 

[buckshotglass]

I would start in the fuse box. Test both sides of each fuse with a voltmeter when the car is off.

 

[slidebabyslide]

disconnect the negative cable from the battery. Get a multimeter and set in in mA Dc and place the + lead of the multimeter to the disconnected - cable and place the - lead of the multimeter to the - battery terminal. This will allow you to see how much power your getting drain.

Thats the only way i know how.
And if you see a draw disconnect the things that you think are the culprit

 

[s.u.p.r.a]

Thanks for the replies. :icon_bigg

I'll do some testing overnight.

 

[foreverpsycotic]

Do you have an aftermarket system or electric fans? I need to pull the fuse to my amp and my fan relay when I turn off the car or the battery will drain.

 

[suprastanger507mgte]

The car I recently bought has the same problem. It drains a fully charged battery overnight if not used. I tested for a battery drain as mentioned above and pulled each and every fuse, but did not see anything out of ordinary. I still haven't figured it out but I suspect my Alternator could be the culprit. Eventhough it charges and no charge light is on, I think it may have an internal short. Maybe a diode is dead or something causing current to be drawn. Maybe this weekend I will test this. Only reason I say this could be a possible cause is because I know of instances where an alternator was the reason. Not on a Supra though.

Maybe you can pull the alternator wires off and tape them off so it does not short out. Put in a fully charged battery and see if it drains overnight.

 

[iwannadie]

Ive been having the same problem and cant figure it out. Kills my fully charged bat over night. I hooked the multi meter inline with the battery and pulled each fuse with no drop. So its gotta be something thats not fused?

 

[jetjock]

Nobody said what they actually measured. A stock car shouldn't have more than about 15-20 ma of parasitic draw total. Off the top of my head the keep alive loads are ECU , clock, and radio. If the alarm is activated it'll be a bit more. Even then I use Priority Starts on all my cars. They've saved my ass on more than one occasion:

http://tinyurl.com/gs7w5

There's also the Battery Brain:

http://tinyurl.com/q86ky

Try ebay for cheaper. Course, they're not going to help if the battery itself is at fault.

 

[iwannadie]

Nobody said what they actually measured. A stock car shouldn't have more than about 15-20 ma of parasitic draw total. Off the top of my head the keep alive loads are ECU , clock, and radio. If the alarm is activated it'll be a bit more. Even then I use Priority Starts on all my cars. They've saved my ass on more than one occasion:

http://tinyurl.com/gs7w5

There's also the Battery Brain:

http://tinyurl.com/q86ky

Try ebay for cheaper. Course, they're not going to help if the battery itself is at fault.

When I checked mine it was reading .777, someone in another thread told me theirs reads .001(normal).

 

[jetjock]

That's way too much but nowhere near enough to drain a fully charged battery overnight. I have one car that pulls about 250 ma and it takes a week to bring the battery down to 40%. If the battery isn't fully charged though (and few are just from driving) the time will be less.

 

[iwannadie]

That's way too much but nowhere near enough to drain a fully charged battery overnight. I have one car that pulls about 250 ma and it takes a week to bring the battery down to 40%. If the battery isn't fully charged though (and few are just from driving) the time will be less.

Ive taken the battery and had it charged(not quick charge), put it in the supra(didnt turn the key) and left it over night. The next day the battery was so dead the lil green light around the ignition wasnt even on. I took the battery back to be tested and it was totally drained, they also said the battery is good and tests fine.

If I pull the negative terminal I can leave it for 2 weeks(just happened to be how long it sat), then connect it again and it starts as strong as ever.

Im tempted to go buy another battery and just see if that fixes it, mine is only about 14months old though. I just dont see the battery as the problem since it holds charge when unplugged.

 

[dbsupra90]

what is totally drained? what is the voltage?

 

[iwannadie]

what is totally drained? what is the voltage?

I forget(its been like over a month lol) but it was Really low/dead, just cant recall the number they said. Dead enough to have no green ignition light or any dash lights...

 

[dbsupra90]

11.4v is considered fully discharged. if it discharged lower than this it can seriously harm the battery.

btw, i bought a battery tender for mine and never looked back. no matter how long it sits, it is at 13+ volts. if it goes below, it will kick on and bring it back up.

 

[iwannadie]

11.4v is considered fully discharged. if it discharged lower than this it can seriously harm the battery.

btw, i bought a battery tender for mine and never looked back. no matter how long it sits, it is at 13+ volts. if it goes below, it will kick on and bring it back up.

I still need to fix whatever is sucking down the battery though lol. I cant take the tender with me every where I go after all

 

[suprastanger507mgte]

I still need to fix whatever is sucking down the battery though lol. I cant take the tender with me every where I go after all

Anyone got anywhere with this? I changed out my alternator but that is not it. Battery is brand new and fully charged.
I can leave mine overnight approximately 24 hours and it will start. If it is more than a day, then no way it will start.
I would like to get one of those products listed in a few threads earlier, but would definitly like to fix the root cause as well. Wiring harness and connectors look great, no frays or splices or grounding anywhere I looked.

If anyone has anymore thoughts..I'm all ears. Ofcourse I've done the drain check and it was around 42 mA or somthing close to that.

Thanks,
Moe

 

[c_ronius]

This may help...

I also have had battery/charging problems since I got my swap running (Soarer 1jz custom wired into my truck). I get no error codes nor a charge warning lamp. If I let it sit for 2-3 days the battery would drain.

A fresh battery with a voltage of 12.8 would drop to 12.5 within 2 minutes when connected to the system. A test for mA through the battery will pop the 500mA fuse in my multimeters everytime...but a check of each fuse showed only a total around 100mA.

I have a relocated battery and a BUNCH of re-wired systems, and I have spent some time on here and elsewhere researching proper battery and charging systems. I'm no expert, but I'm fairly confident I have things wired properly. I have tons of trust in the physical wiring and connections I have changed. ...Neverless I have checked and doublechecked my wiring both in theory and physically and I couldn't find anything wrong... till today.

Took the alternator connection (3-wire) off today and no more drain! So I took the alternator off and noticed the pin associations in the 3-wire connection were marked different than the Soarer FSM stated. I originally wired it up according to the connector layout in the FSM, but 2 of the wires were mixed up according to the alternator. S and IG were switched...both are 12V sources, but S is always on and IG is with the ignition switch.

I switched them around and viola... all is great. No more drain on the battery when off, and the alternator is charging stronger too.

Lesson learned... Don't trust connector pinouts in the FSM diagrams for the alternator connection, check what is on the alternator itself.

Good luck all.

 

[suprastanger507mgte]

This may help...

I also have had battery/charging problems since I got my swap running (Soarer 1jz custom wired into my truck). I get no error codes nor a charge warning lamp. If I let it sit for 2-3 days the battery would drain.

A fresh battery with a voltage of 12.8 would drop to 12.5 within 2 minutes when connected to the system. A test for mA through the battery will pop the 500mA fuse in my multimeters everytime...but a check of each fuse showed only a total around 100mA.

I have a relocated battery and a BUNCH of re-wired systems, and I have spent some time on here and elsewhere researching proper battery and charging systems. I'm no expert, but I'm fairly confident I have things wired properly. I have tons of trust in the physical wiring and connections I have changed. ...Neverless I have checked and doublechecked my wiring both in theory and physically and I couldn't find anything wrong... till today.

Took the alternator connection (3-wire) off today and no more drain! So I took the alternator off and noticed the pin associations in the 3-wire connection were marked different than the Soarer FSM stated. I originally wired it up according to the connector layout in the FSM, but 2 of the wires were mixed up according to the alternator. S and IG were switched...both are 12V sources, but S is always on and IG is with the ignition switch.

I switched them around and viola... all is great. No more drain on the battery when off, and the alternator is charging stronger too.

Lesson learned... Don't trust connector pinouts in the FSM diagrams for the alternator connection, check what is on the alternator itself.

Good luck all.

C-roniuos, thanks for posting up. I will look to see if the alternator connections are messed up inside the loom.

One thing to note is that I do not have a swapped car. It is the stock engine and original harness . battery is brand spanking new. I have already done a alternator swap just to eliminate that as a culprit.

I also do believe it has to do with something in the wiring. I know since it is original, i will rip the wiring loop apart and see if anything is grounding .

Your post definitely helps. Thanks.