Weird Problem Starting My Gen 3 Prius.

[Chris Dance]

My Gen 3 had not been used for a week. Went to start it this morning and the internal lights came on when I opened the door which indicated to me the Battery was OK. I made sure I had fully pressed foot brake and pushed the starter button but the whole of the dash electronic indications were dead. I tried 3 times and the on fourth time everything was normal and the engine started and ready mode was indicated. I used the car for the rest of the day without any problems. It was as if the elecronics had gone into a sleep mode. Any Ideas on what might have happened????

[Grumpy Cabbie]

I'm surprised at this on a 2011. Have you been doing loads of short journeys and leaving the car for days at a time? I'd double check that the boot/hatch clicks shut properly and also turn the boot light off if you don't really use or need it.

Have you left the lights on without the car in Ready or has someone else been driving the car who could have inadvertantly run the 12volt Battery down?

Failing the above it could be a switch on the brake pedal but that's unlikely as the car started on the 4th attempt. If there's a problem the car will often take more than 3 attempts before starting. It is likely a minor issue but probably one that will log up as an error code if you get the dealers to check it.

[Chris Dance]

Thanks GC. I have only been doing local journeys recently and the car had stood a week. The boot hatch is positively closed as I double check that after expierincing a flat Battery on my previous Gen 2. Brake pedal switch sounds a possibility!!! Car goes in for its first service next month so I will get them to check it over then unless it occurs again. I will give the car a good run up the motorway tomorrow. I also think it would only be a minor problem as the car has only done 5,000 miles.

[timberwolf]

IIRC you're the second person to post with those symptoms recently, coincidence or a faulty batch? (http://www.toyotaownersclub.com/forums/index.php?showtopic=133041)

On a new car, with a healthy 12 V Battery, I'd expect the Prius to be able to last for at least four weeks and still start normally at the end of that period.

[Grumpy Cabbie]

Makes you wonder if there's a software issue on these later models that's causing the 12v to run down quicker if stood? Perhaps the keyless ignition is more aggressive on the 12v or something similar? Were both these cars the t-spirit model? Is there something obviously new on these newer cars?

Replies on a postcard :)

[Chris Dance]

No problems today with starting. I did a good motorway run today and the car performed great. I am beginning to think it is when the car left for a week or more in cold weather!!!. I will let you know if it occurs again.

[inspiredron]

I had the difficult starting problem about a year ago on my early Gen 3 Oct 2009 Prius. My dealer could not diagnose the problem and could not reproduce it either. When I collected the car it refused to start. Back to reception and returned to car with a mechanic. It strated immediately. Talking to the mechanic he mentioned possibility of 12V Battery problems. A couple of days later, having used the car normally (short runs mainly) I put a voltmeter on the Battery. It showed just over 10V!

I returned to the dealer who replaced the Battery under warranty. Now, 1 year into th enew battery I have a scanguage and I am just beginning to experience the beginning of difficult starting - it takes a few seconds for the raedy light to come on instead of almost immediate. Scanguage shows about 11.5V on first switch on, jumping to 14.6V as Hybrid battery cuts in (which is when I can put it into gear) and then settling at around 13.6V after a few minutes of running. On switching off voltage drops to about 12.4 and then falls off slowly to around 12.2.

My warranty expires in a couple of weeks. When I took the car in for its service I reported the fault - I was told that low mileage Prius owners ahould expect this as the car's electronics put a very heavy load on the car when starting. I asked how this compared with the 300amp drain of a starter motor but got no response other than a replay of this is what I should expect!

Has anyone else had this very poor 12V battery life? I have asked them to advise me of power down battery drain curent.

[timberwolf]

<snip>

My warranty expires in a couple of weeks. When I took the car in for its service I reported the fault - I was told that low mileage Prius owners ahould expect this as the car's electronics put a very heavy load on the car when starting. I asked how this compared with the 300amp drain of a starter motor but got no response other than a replay of this is what I should expect!

Has anyone else had this very poor 12V battery life? I have asked them to advise me of power down battery drain curent.

Yup, the low usage will do it. The 12V Battery is relatively small precisely because as you say it doesn't have to crank a starter motor. I think their explanation isn't the whole story. The problem with it being a smaller Battery is that when the car is used infrequently and low mileage, the Battery is using relatively more of its capacity just delivering a standby current for the Alarm and the keyless entry. The other consequence is the low mileage is not sufficient to fully recharge the 12V battery.

For low mileage usage, one option is to buy a CTEK charger.

BTW I've always thought it ironic that a supposedly slightly more environmentally friendly car wasn't designed for people who don't drive that much:)

[Opifex]

........Scanguage shows ........ On switching off voltage drops to about 12.4 and then falls off slowly to around 12.2.

To be able to see the voltage fall off the Scanguage must be still on. Does it stay on permanently? If so this will be another drain on the Battery.

[Chris Dance]

Since the time I first started this thread I have not had any starting problems. I only do about 5,000 miles a year but some of that is long motorway journeys. I was told by the dealer Battery life is usually about 4 years. I always ensure internal lights and rear hatch lights are switched off when parking. I do what GC advised ie do not listen to the radio on small Battery power only.