[drbenson]

My wife just had a scary experience in her brand new '04 Prius. She stopped at a rest stop on her trip back from California to Washington. used the facilities, crawled in back to sleep for a couple of hours (it was 3am). When she woke up and tried to continue, she said she saw a very dim 'engine malfunction' light, and the car refused to start.

She called Toyota Roadside Assistance. They sent a tow truck, and the driver and she learned together how to jump start a Prius. The driver said the Roadside Assistance covered only up to $100 towing, so she decided to drive to the nearest Toyota dealership. In the morning they checked the car, put it on diagnostic, and found nothing.

Now she's afraid to turn the car off, trying to get home on caffeine, and swears she hates the car and will never take it farther than around town again. Any ideas from the assembled collective wisdom as to what might have caused this debacle? Any similar experiences?

 

[john1701a]

With all due respect, you've got a good thing going now. I know quite a few husbands that no longer get to drive their own Prius anymore... because the wife has become hooked on the hybrid and now forces him to drive the other vehicle. Bummer, eh?

Anywho, the odds of accidently leaving the lights on at a bright rest stop when you are really tired is quite high. That's likely what she did.

 

[AgentElrond]

I know quite a few husbands that no longer get to drive their own Prius anymore... because the wife has become hooked on the hybrid and now forces him to drive the other vehicle. Bummer, eh?

We had the reverse situation here. My wife never drove the 2003 until we completed the tag transfer; she even (jokingly) complained to my salesperson about it. She hasn't driven my 2004 - and isn't about to anytime soon. 8)

 

[drbenson]

Just revised my signature tag to reflect the real situation. She liked mine so much that we had to go out and get her one of her own, which is the one she was 'breaking in' by going to visit our daughter.

Lights on is one plausible scenario, though she insists not. My thought experiment is this: Pulled up to the rest stop, lights on. Got out of the car, lights off automatically when car door opens. Got back into the car, turned aux on to lower a window a bit for ventilation. Turned car back off. Would this have turned the lights back on? If so, we may have found the problem. Haven't had a chance yet to test this scenario on my car.

Is it the concurrence of opinion that a once-discharged 12v should be replaced?

 

[Daniel]

I don't know if the lights would come back on with AUX. You could try that and see. I do know this: when you shut the car off without manually turning the lights off, they stay on until you open the door. If AUX did allow the lights to come on, shutting the car off would have left them on.

I'll let wiser folks than me comment on the battery, but I have read comments to that effect. There should be a way to test the battery.

 

[ehurtley]

Leave the IG-ON.

Personally, if I was going to sit in the car for a few hours taking a quick nap, I'd just leave the ignition on. I'd have all accessories off (except maybe heat or A/C, as warranted by the weather,) and just let the gas engine cycle on and off as needed. It should be able to sit for many hours before it uses any appreciable amount of gas. (I plan on driving my new Prius to Arizona for my yearly trip this fall. I'll probably end up doing just this, since I can't make the trip non-stop anymore.)

As for the lights? Testing... Yes, indeed. If the light switch is in the 'ON' position, turning the car to Accessory mode turns on the lights. (Which will drain the 12v battery VERY fast, I've heard 10 minutes or less.)

 

[RSnyder]

Is it the concurrence of opinion that a once-discharged 12v should be replaced?

No. Especially since the battery is still very new, it was recharged soon after discharge, and it was summer. It's very unlikely that you need to replace it. If it starts tomorrow after leaving it off overnight, don't worry about your battery.

I accidentally drained Pikachu's 3.5 year old battery last month, but recharged it within 1 hour and it's been fine since.

Now if you leave it drained for a week in the winter three years from now, you'll likely need to replace it.

 

[richard schumacher]

I would replace the battery for peace of mind at least. I've drained more than one (although never a Toyota battery) and they were never the same afterwards. (If you do you might look into an "Optima" deep-cycle battery. These have a superior internal construction. I don't know whether one of the few sizes available would be an easy fit into the Prius battery box.)

The simplest explanation for the initial problem is operator error. The 12V battery is not very big. Leaving one of the interior lights on for a few hours would be enough to drain it.

 

[richard schumacher]

Re: Leave the IG-ON.

Personally, if I was going to sit in the car for a few hours taking a quick nap, I'd just leave the ignition on. I'd have all accessories off (except maybe heat or A/C, as warranted by the weather,) and just let the gas engine cycle on and off as needed. It should be able to sit for many hours before it uses any appreciable amount of gas.

Making a *very* rough estimate: 50 MPG at 50 MPH means the fuel consumption rate while moving is 1 gallon per hour. In my (short) test parked at 90'F with the A/C set to 70'F the engine cycled on about 1/4 of the time, so you might burn a gallon every 3 or 4 hours running the A/C. It would probably run a lot more to keep the heat on continuously since it has no way to store energy needed for the heater. And of course your MPG for that tank will really suck :_>

 

[Bob Allen]

I did manage to leave my lights on. I was working on my car and needed to use the aux function to power the vacuum cleaner. I didn't push the button the correct number of times to shut everything down and came out a hour later to notice my lights were on. Fortunately, nothing happened and the car started right up.
The Prius has a smaller than normal 12v battery which could run down quicker than a conventional car.
My suggestion: since you both have Prii; swap. Drive hers for a month without problem and show her that it was a freak anomaly. You might try leaving stuff in her car too, which would motivate her to want to get hers back.
If the car is running ok now and the service people couldn't find any fault with it, then I'd assume it's ok to go.
B

 

[frenchie]

The only bad things to do when you stop for a while in a Prius is to put the transmission in "N" instead of "P" if your car is in the "READY" mode, or to use accessories (radio, etc.) when the car is *not* in the "READY" mode. Otherwise, neither battery should discharge.

 

[drbenson]

My wife and I went over my 'scenario' above, and she agreed that's exactly what happened- the particular sequence of actions led to leaving the lights on, thus dead battery.

The upside is that she learned to nap with the car 'on' and in park- better ventilation, and an automatic one-hour wakeup nudge when the engine turns on.

Thanks to all for the help and advice. Hope her experience will save someone else from a drained Prius!

 

[BIF]

...an automatic one-hour wakeup nudge when the engine turns on....

This turn of phrase made me smile. I like that. "Wake up nudge" indeed. Glad you and your wife figured it out!

PS - tell your wife to make sure she locks the doors during those naps.

 

[mrv]

The only bad things to do when you stop for a while in a Prius is to put the transmission in "N" instead of "P" if your car is in the "READY" mode, or to use accessories (radio, etc.) when the car is *not* in the "READY" mode. Otherwise, neither battery should discharge.

However, note that if in "N" the ICE cannot recharge the HV hybrid battery, although in READY the HV hybrid battery can recharge the 12v accessory battery...

 

[hyperion]

I like the scenario about getting back into car and lowering a window but not knowing about "aux" turned on ignition to get power for windows. (was car equipped with "smart key?)

 

[flare]

If you have smart entry/ smart start and leave it in the car while its off... that's gonna drain the battery too

 

[Sonikbaby]

BEEN THERE DONE THAT!!


The lights most likely were left on...


All it needed was a simple jump start...


I have jump started my prius several times...


Poor poor prius..


Nothing to worry about though...

she should relax