Battery dies after long idle

I have a mystery problem w my 2009 tundra. This has happened 3 times with a good battery. Each time I have the truck idling in park, waiting. Say 25 min then have shut the truck off and kept waiting. When I go to start the truck again the battery is dead. I’m stumped. Any ideas?

 

Sounds like the alternator is going bad. The battery only starts the vehicle. Once running, the alternator supplies running voltage to keep it running. If the alternator isn’t functioning, power is drawn from the battery. Sitting in idle is just pulling power from the battery so when you turn it off and try to restart, there isn’t enough amperage

 

^^This^^

 

You can hook up a volt meter to the battery and check the voltages, but my bet is the alternator as well.

 

If you are still sitting in the truck after its turned off, but no one has gotten out of it. Most likely head lights or DRL is draining the battery. The lights won't auto off unless a door is opened after shut off. (DRL stays on even if lights off) found that out the hard way. If this sounds like your situation/scenario it could be the cause. (Maybe also leaving key in ignition after off with out doors opening was part of it)

I didn't think about it till it happened to me at a park since I was use to auto off. Played with my dogs some then started my truck to get it warm enough shut it off and toke a nap to pass the time waiting on a random inspection to be done. Woke up freezing and went to start up and realized I never opened the door since it was turned off. Had to wait for AAA to come jump me so I could get home.

 

That's some good info, didn't know that. I wonder if there's a purpose for it behaving that way?

 

Sounds like Toyota has changed a few things on this platform over the years (duh).

A couple weeks ago I was unloading materials with the truck was running, as I thought I was going to have to move afterwards. Turns out I didnt have to move and ended up opening the passenger door and reaching through to shut off the truck... About 3 hours later I noticed my lights were still on. So, at least on my 2012, it is specifically the driver's door which needs to be opened after shutoff or the lights will remain illuminated.


Also think the OP's issue is a gracefully dying alternator.

 

The purpose, I believe, is for "courtesy lights". Should start the countdown (1 minute?) for the auto off feature. Some people dont like walking in dark parking lots

If you hit the lock button twice it will cancel the courtesy lights and they will turn off upon the second click... In my 2012 anyway.