Did I leave the car on or door ajar?

[rocketdoctor]

I tried to start my car today and the electric system was dead. When I jumped the car it started right up. At first I thought my wife had left the car running all night but I noticed their was still alot of gas in. Their was a door slightly ajar so maybe a light was left on?

If a car is left on will it keep the battery charged enough until it runs out of fuel?

Does the Prius know to shut off power ahead of time when the 12V gets low? soon as I jumped the car I was able to turn it off immediately and start it up without a jump. This is unlike other cars I had where you had to drive them around immediately or you would have to jump start it again.

[firepa63]

Most likely a door was left ajar and ran the small 12v battery down. The system will not prevent the 12v battery from depleting. If the car was in the READY mode the ICE would cycle to keep the traction battery charged. In turn, the 12v battery would be kept charged from the HV system. You should drive the car for at least 1/2 hour after jump starting to give the 12v battery a chance to recharge. Keep in mind that a deep discharge of the 12v battery will shorten its life.

[David Beale]

It doesn't take a lot of power from the 12V battery to "start" the Prius. Just a 50A pulse for 1/2 sec. will do it. So a battery you just "boosted" will probably restart the car.

But that battery is nearly fully depleted, and will sulphate if left in that state. You should run the car for at least an hour to give it a reasonable charge. It actually takes about two to three hours in "ready" to charge it well. Note that with the Prius the engine doesn't actually have to be -running - to charge the battery. It's charged from the "traction battery" (the high voltage one) through a charger built into the inverter. The engine will cycle on and off as required to keep the traction battery charged. If the A/C system is on and calling for heat the engine will also run for that.

As noted above, the 12V battery has now been "stressed" and will probably have a slightly shorter life due to that. Expect another two to three years life out of it if you don't fully discharge it again. Owners are averaging 3-5 years of 12V battery life.

Beware of things like a door not fully closed, the interior light switches being left "on", and especially the hatch light, which is dim and very hard to see if left on with the cargo cover closed. Note that the interior light switches have two "on" positions. One keeps the light on even when all doors are shut.

[Eoin]

If you lock the car every time you leave it it would be hard to leave a door ajar.

[Auntmimi]

14K miles on my 2006 Prius because it has set in a garage on and off two years while we were away, but always started right up when the battery was re-connected.
I just drove it from PA to FL and after setting in the garage a few days, there is no power at all. I tried inserting the fob.....no go.

Do you think it just needs charging or would it be safer to have it towed to a dealer? There is a possibility that the hatch was not closed entirely.

Feel free to email me at auntmimi12@ymail.com. Thanks so much, The Villages, FL

[rocketdoctor]

Originally Posted by Eoin

If you lock the car every time you leave it it would be hard to leave a door ajar.

I know that but try telling that to my wife over and over again. in addition not locking the car makes it easy for someone to enter our house through the garage and its not uncommon for my wife to leave her Phone and wallet in the car.

I read this interesting article on how much power is needed to jump Prius Startup Current so it makes a little more sense how my dead batter could start the car so easiliy after a jump.

I had a long commute after jump starting so no problem recharging car.

[BAllanJ]

With winter coming you should also be aware that a depleted 12v battery will freeze if it gets below 0 C and that will break the insides of the battery...ok, maybe that won't happen in lafayette... but we have a frost warning here for tonight.

[kenoarto]

When is a door not a door? Whenn it's a jar!

Originally Posted by rocketdoctor

...Their was a door slightly ajar so maybe a light was left on?

[Patrick Wong]

Originally Posted by Auntmimi

...Do you think it just needs charging or would it be safer to have it towed to a dealer? There is a possibility that the hatch was not closed entirely.

You could start by trying to charge the 12V battery. If that doesn't work, then replace the battery.

[richard schumacher]

But be careful when jumping. As with many modern cars if you reverse the polarity it can do hundreds of dollars of damage. If you're not certain, have a dealer send someone to jump it, so that if they get it wrong there will be no question about warranty coverage.

And get in the habit of always locking the car, no matter where you park or for how long. It will warn you of the most common battery-draining conditions.