Battery keeps draining

IOWABARON

MEMBER
2002 TOYOTA AVALON
3.0L
6 CYL
2WD
AUTOMATIC
127,000 MILES

Bought the car listed above from a relative's estate about two years ago for use as my daughter's school car.

Battery was dead when I bought it so jumped it and it started right up. Drove it a few times, no problem. Changed oil and some other maintenance leaving the hood and door open for maybe an hour. Went to start car and a rapid clicking noise and the gauges bounced around. Jump started it and everything was fine. Bought a new battery and installed it cleaning the terminals and connectors. Everything was fine until I cleaned/detailed the car before my daughter started to drive it. Again the doors were open for maybe an hour and the car would not start along with the rapid clicking.

This has happened several times since, door not quite closed, headlights left on, forgot to close the trunk. Something on any other car it would not drain the battery so quick. Today after school a friend didn't close the door tight and the car would not start. I jumped it, started right away (the jumper cables were on for maybe a minute), and pulled it into the garage to hook my battery charger up to it. The car ran maybe 3 minutes after I started it. Hooked my automatic digital battery charger to it (it displays % charged) and it said the battery was at 97%. So it went from too dead to start the car to 97% in less than 3 minutes of run time. Either I have an extremely high output alternator or what else is going on?

3 Replies

SQM

MECHANIC
6,383 POSTS

Hello,

You might have a high parasitic draw (current drain) on this vehicle.
Every electrical circuit with battery will have parasitic drain however it can become excessive due to a light staying on or having a short in the circuit which can draw more current.

You can check for the drain on the battery with all the equipment turned off.

Here is a helpful guide:

https://youtu.be/z5F7WpgjaRs

https://www.2carpros.com/articles/car-battery-dead-overnight

Please let me know of any questions.
Thank you.

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Thursday, September 2nd, 2021 AT 7:58 PM

IOWABARON

MEMBER
5 POSTS

So only a high drain when a light is on? The car can sit for a week or more with no issues yet a door is open for less than an hour the battery cannot start the car. I am more concerned that a newer battery with a 90%+ charge cannot start the car.

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Friday, September 3rd, 2021 AT 5:43 AM

SQM

MECHANIC
6,383 POSTS

It will depend on that electrical circuit of the lights. You can check the drain with the door open and with the door closed to see being the light on or off how much difference does it make. The drain can be at a level certain level that it lowers the battery charge just enough for it not to start.
Also a battery with 90% charge should start the vehicle. Unless of extreme temperature or if the battery cold cranking amp is lower than the recommended level.

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Friday, September 3rd, 2021 AT 9:32 AM