Left Interior Lights On 10 Hours

[Grumpy Cabbie]

If you're really bothered or concerned you could install LED sideline and number plate bulbs. They cost more but use negligible power. Dunno, but might be worth a pop.

[kithmo]

If your interior lights had been on all night then the 12V battery should have been dead.

I certainly would have expected it to be flatter than it was.

I don't know for sure, but I believe what you said earlier may have happened. According to the manual the interior lights are on a 20 minute timer if left on so, as you said, probably turned off after 20 minutes and came back on as I approached the car with the smart key.

No harm done (touch wood).

the twenty minute timer is only for leaving the door open not if the switch has been moved to on if you read page 350 of the prius+ manual. i have a 2013 prius plus and tested it today.

i went to tescos so left the interior light switched to on and went to do the shopping, after more than half an hour had passed i sent my son without the keys to check on the lights and they were still on.

it had been at least 45 minutes when we got back to the car after shopping and again i sent my son ahead to check because as you said the lights would light up if the key was detected and spoil my test but again they where on.

i personally believe your lights must have been on all night,but our cars have a 45ah Battery maybe another hour and you would have been in trouble, we will never know

On page 344 in my manual (must be slightly different to yours)

"To Prevent 12-volt Battery discharge

If the interior lights remain on when the door is not fully closed and the interior light switch (door position on/off) is on, the lights will go off automatically after 20 minutes."

I read it that if the switch is on it switches off after 20 minutes, but I now guess it means that if the switch is in the door position and your experiment proves that, thanks for trying it out.

I just checked the Battery voltage at the terminals and it's reading 12.83 V, still connected to the car, 3 hours after I turned it off, the footwell lights were on, interior lights off and it's currently 3 deg C here, according to the manual (page 540 in mine) that's fully charged so it seems to have fully recovered now.

[mrmooa]

If your interior lights had been on all night then the 12V battery should have been dead.

I certainly would have expected it to be flatter than it was.

I don't know for sure, but I believe what you said earlier may have happened. According to the manual the interior lights are on a 20 minute timer if left on so, as you said, probably turned off after 20 minutes and came back on as I approached the car with the smart key.

No harm done (touch wood).

the twenty minute timer is only for leaving the door open not if the switch has been moved to on if you read page 350 of the prius+ manual. i have a 2013 prius plus and tested it today.

i went to tescos so left the interior light switched to on and went to do the shopping, after more than half an hour had passed i sent my son without the keys to check on the lights and they were still on.

it had been at least 45 minutes when we got back to the car after shopping and again i sent my son ahead to check because as you said the lights would light up if the key was detected and spoil my test but again they where on.

i personally believe your lights must have been on all night,but our cars have a 45ah Battery maybe another hour and you would have been in trouble, we will never know

On page 344 in my manual (must be slightly different to yours)

"To Prevent 12-volt Battery discharge

If the interior lights remain on when the door is not fully closed and the interior light switch (door position on/off) is on, the lights will go off automatically after 20 minutes."

I read it that if the switch is on it switches off after 20 minutes, but I now guess it means that if the switch is in the door position and your experiment proves that, thanks for trying it out.

I just checked the Battery voltage at the terminals and it's reading 12.83 V, still connected to the car, 3 hours after I turned it off, the footwell lights were on, interior lights off and it's currently 3 deg C here, according to the manual (page 540 in mine) that's fully charged so it seems to have fully recovered now.

our car is only three weeks old and is reading 12.86v so I think you have got away with it ,

have the other hybrids got a smaller battery I know ours is 45ah but I am sure I have read some of the others have 35 ah perhaps that's why they seen to drain fast

[timberwolf]

If your interior lights had been on all night then the 12V battery should have been dead.

.......as happened to me!

When the 12v eventually dies - kaput - are there any particular warning signs to watch out for in advance of this happening? Thinking here particularly with the Prius/hybrid in mind.

In the worst scenario I've always accepted that a car Battery can be like a light bulb - one day it works, next day it's a gonner - but then most cars' batteries aren't supported by a HV biggie. Does that make a difference at all?

I have an older Prius model to your car and I normally only use the car at the weekend therefore with long periods not being used. In my case, there were warning signs of a sort, but they were when it became iffy about unlocking the doors and then whether I would be able to start the car i.e. it could take 3 or 4 attempts to get the car to go into READY. On the failed starting attempts, I could hear the 3 relays try to connect the HV Battery but then the exclamation warning triangle light would display on the dash and if my recall is correct various other warning symbols as well.

I have a Scangauge II and a digital volt meter, and although I could see the 12V Battery gradually fade over time, I wasn't successful in predicting before hand when it would become unreliable. The dealers were worse than I was at determining the health of my 12V battery and on a couple of occasions would fast charge the 12V battery and then pronounce that it had passed as healthy on their tester.

If you rely on the dealer to determine when the 12V battery needs replacing, you are likely going to have put up with a few events where the car is either going to fail to start and then need jump starting, or is going to be iffy at starting as in my experience.