What can Drain the Battery ?

I think if you leave the car "running" it's ok for the 12 volt, but other problems arise, lol.

Just sitting is going to wear the battery down. Regular multiple-day hiatus, and that's our situation. Try to drive every second or third day, monitor, and periodically hook up to a charger.

 

Leaving a door or hatch ajar will kill the battery within 3 days, even if all interior lights are off (or unplugged in the case of the bottom-of-door lights). Current drain in that case is about 0.7 amperes, roughly equivalent to a single dome light.

 

Yeah I set the dome light to completely off, but there's the front door courtesy light, the illuminated door, and there's 2 sneaky little lights under the dash, illuminating the footwell. One time unloading grand kids I got distracted, left driver's door ajar for about 18 hours, battery was down to 11.9 volts.

I recharged it in that case, and replaced it about a year later, it was coming up on 5 years.

 

Car unresponsive, didn't even bother trying to start. That time I hooked it up to my smart charger (CTEK 3300 at the time), and it ran about 12 hours before it completed, battery restored but I'm sure a bit compromised. I replaced the battery about a year after that.

 

I actually had the car run for 11 days in my detached garage while I was out of the country. A friend drove me to the airport, parked my car and never hit the power button. Fortunately I had just filled up and upon my return still had 1/4 of a tank left. No issues with car since then.

Posted via the PriusChat mobile app.

 

Wow! I remember when we did our first test drive of a Prius, learning, with some reservations, how the fob worked. The deletion of the need to insert/remove a key has some downsides, especially for the uninitiated.

 

About a year ago the 12V battery went completely dead on my 2014 Prius after not driving the car for about 5 - 6 days. All displays, indicators, lights, etc. were completely dark. I checked the 12V battery (at terminals in the fuse box) and it was reading 5.1 volts. I thought for sure the battery was wasted. The only thing I could find was the rear hatch may have been ajar. I always keep all interior light switches in the "off" position. I can't remember whether I jumped the car or put a charger on it, but I got the car up and running (I had to go somewhere). I assumed that I'd done some serious damage to the battery with that 5 volt reading, but it has been well over a year with 100 - 200 starts since then and all is good. I have a Scangauge on the car and the battery reads in the low 12's (volts) when not being charged. I frequently go 3 - 4 days without starting the car and have gone maybe a week or slightly longer once or twice without any further issues. Original battery, 2 1/2+ years old.

 

welcome! good info, as testing is the only way to determine a batteries health. they don't appreciate being run down, but it isn't always a death sentence, especially on newer batteries. all the best!

 

Yes. A system that simply prevents screw-ups is superior, to one that issues "warnings". The latter are the refuge of lousy engineering. As an example: a conventional car key that can't be removed from the steering column, until the car is in Park and Off.

 

The Prius is a very advanced vehicle, it would be nice if there was an "automatic off" feature, where all accessory lights would turn off after a couple minutes if you happen to walk away and leave the door ajar, etc.

 

I would like a car that stores all settings to a built-in RAM drive (aka jump drive), then completely disconnects the 12 volt battery , with some sorta servo/relay. Then at startup reconnects the battery and restores settings.

It's probably complex to do tho.

 

My wife proved yesterday that if you turn the headlights back on after turning the car off, they will stay on and drain the 12V battery...

2010 with the original battery, I'll probably just get a new one.