Battery

[Chris Dance]

Last week got up early to go to N. Wales I went to start my 57 plate gen 2 Prius T spirit and a warning triangle weird noises and other warning indicators came on. Luckily I had not put on the anti theft on the day before as the car was in a fairly secure garage so I could get into it the car. I rang the local dealer he said you left something on and the 12v Battery is flat. Rang RAC and the RAC chap arrived 2 hours later. The boot had locked even though the doors could be opened. He put power to the front point in the engine compartment and got the boot to open. He then put jump leads directly on the 12v Battery from his vehicle and got the engine running. At first he said the Battery was not accepting charge but that was a false diagnosis. He did a battery health check and thank goodness it was OK. What had I done to cause all this trouble? The answer: I had not put the boot lid down fully; when the boot lid is not fully down the interior light remains on and the 12v battery goes flat. When the battery is flat the boot locks itself. (RAC man said it is witchcraft!!)

Tip for all Prius owners make sure you shut the boot lid firmly.My car is OK now.

Thank goodness for an RAC chap who knew about the Prius. He advised not trying to do any DIY on the electrics inc the 12v battery on the prius. He said he had been called out to a member who had the same fault as I had but that member had tried to do a jump start from a mates car and it had mucked up the Prius computer system.

[Fujisan]

A few years ago one of the lads at work was having trouble with the Battery on his brand new Vectra going flat all the time.

Took it back to the garage, they couldn't find anything wrong, new Battery fitted, everything. Still it would go flat.

Then one evening he was walking past the car, just about to give it another kick, when he noticed a small chink of light above the passenger seat.

Turned out there was a faulty switch on the passenger sunvisor mirror cover, so that the light that was only supposed to come on when the mirror cover was moved back, was and always had been on.

To add insult to injury, because the light was on with the sunvisor in the normal stored position, the heat had burnt a nice brown mark into the sunvisor and discoloured the headlining around the light!

Glad your sorted Chris.

[timberwolf]

The Prius hatch is always locked. There is no mechanical linkage between the switch (under the rubber strip) on the outside of hatch and the hatch catch/lock mechanism. There must always be a 12v supply for the hatch to be opened from the outside.

I am guessing that your 12v Battery will fail again soon. :crutchy:

[ormi]

The Prius hatch is always locked. There is no mechanical linkage between the switch (under the rubber strip) on the outside of hatch and the hatch catch/lock mechanism. There must always be a 12v supply for the hatch to be opened from the outside.

I am guessing that your 12v battery will fail again soon. :crutchy:

he's right you know......its hard to get a propper diag on the prius 12volt bat as its a lesure Battery and doesnt work the same as a normal one....

[Chris Dance]

You are right timberwolf about the boot catch. We learn something every day. The RAC chap did do a Battery health check and he said it was fine. Dealer said if it needs a new Battery it is under warranty but this should not be necessary.

[JohnD2]

Hi.

He put power to the front point in the engine compartment and got the boot to open.

I would be grateful for a clear description of this 'front point', please.

Also, note that the mechanical key buried in the remote fob, will enable unlocking of the driver's door if/when the 12v Battery is discharged. (H T H)

J

[Chris Dance]

JohnD2. Refer pages 362 and 363 of the owners manual, titled "IN CASE OF EMERGENCY". It is referred to as the exclusive jump start terminal.

Cheers Chris.

[ian rooke]

Hi did the same with my Gen11 twice had not shut the boot properly, Battery will flatten in about 4 hours I now carry a small booster Battery which is enough to run the computers while the 200v Battery starts the car (keep the air con on or the engine can switch off before there is enough charge in the 12 v battery to maintain the computers)

[JohnD2]

JohnD2. Refer pages 362 and 363 of the owners manual, titled "IN CASE OF EMERGENCY". It is referred to as the exclusive jump start terminal.

Cheers Chris.

Chris. V grateful, thanks. J

[Chris Dance]

I am informed each time the 12V Battery goes flat it shortens its life. So I am being very cautious about closing the boot and doors and ensuring all lights are off. I am also given to understand you can successfully jump start the Prius by using just the positive jump start terminal and a suitable negative "post".

Is it safe to charge the 12V Battery on the car using a normal Battery charger or would it be safer to remove the battery from the car and then charge it?

If you do charge it on the car are there any special precautions to take? I notice the manual says something about disconnecting the "earth"????

Chris.

[JohnD2]

I had need to recharge the 12v Battery on two occasions. On the first I did disconnect the -ve terminal; on the second I recharged with both terminals still connected. On both occasions I used a standard (small capacity) charger. I did use an ammeter to check that the current stayed below 3.5 amps. The Battery compartment lid was off, there was no noticeable smell during the recharge. These occasions were over a year ago. I haven't experienced any ill effects on the car's performance. The recharge period on both occasions was less than an hour, (I can't remember exactly), for a successful re-start. J

[Jolly English Gentleman]

On a couple of times I have not shut the boot properly, my Gen II has refused to lock, which is obviously a blessing and I will be more careful in future.

It seems strange that the Prius has not got the feature from the 1998-2002 Corolla that beeps at you if you have not shut something properly when you try and lock it which seems an odd thing to miss out in a newer model.

[Chris Ray]

Interested in this thread, as my Gen 2 has done 75000 miles in the two years I have owned it with no Battery problems,even leaving it at airports for over 2 weeks

However, last weekend I went to Scotland for the weekend and when I returned to Ebbsfleet two days later, the Battery was completely flat and what fun it was getting the hatch open in the dark and rain so the RAC man could get to the 12v Battery.

He also said never try to jump start a Prius, despite the "dedicated" point under the bonnet, so not sure why the manual says you can

I did not open the boot when I parked, and the doors were shut because the car locked fine off the fob.

Also, no interior lights were left on!

Toyota have said it is "just a one off thing", and the battery is fine, but as I am going away for a week or so in the summer, I am a bit worried about getting into the car when I get back and calling out the RAC has cost me some of my good customer discount!

Will probably get a new battery to be on the safe side, but would love to know what caused it to go flat, it certainly wasn't lack of use and charging!

[ian rooke]

Hi you can start the Prius from the Battery in the boot or from the dedicated point under the bonnet with no adverse effect on the engine or electronics,I have done it twice when the Battery was so flat the green light on the start button would not light the only problem I can see is if the 200v Battery is flattened then its a trip to Toyota I suppose.

[Chris Ray]

Thanks for clarifying Ian

I have just been testing the door locking from the fob, as I thought they would not lock unless the doors and hatch were completely shut.

However, I have now found that you can lock the car when a door is slightly ajar, so could well have been that which caused my flat Battery!

Will have to double check everything in future and not rely on seeing the flashing indicators and assuming all is locked OK!

[Chris Dance]

Hi Chris Ray,

I was also adamant I had locked everything properly when my Battery went flat. The RAC chap proved it was the boot not shut properly. Local dealer also told me it was due to me leaving lights on etc. I check everything now; I find myself firmly closing the boot twice after removing stuff from the boot.

Did you know that if you become a Toyota Club member you get full AA membership. You would not then have to worry about your RAC good customer discount.

Cheers Chris.

[Chris Ray]

Thanks for the advice Chris, I was a club Toyota member for the first year and my son is now with his Aygo, but have been with RAC for 20 years on a family policy, so tends to work out cheaper ( I did check with Club Toyota at renewal)

Agree with you re double chacking now, as with over 35 years of driving an average of 30000 a year, I have never had a flat Battery!!

[Jolly English Gentleman]

Thanks for clarifying Ian

I have just been testing the door locking from the fob, as I thought they would not lock unless the doors and hatch were completely shut.

However, I have now found that you can lock the car when a door is slightly ajar, so could well have been that which caused my flat battery!

Will have to double check everything in future and not rely on seeing the flashing indicators and assuming all is locked OK!

Interesting results.

I must have been extremely lucky when my car refused to lock after not closing the boot properly. I am surprised that no one has raised this as an issue with Toyota, as I would have been hopping mad if it had happened to me. You should not be able to lock a car when all the doors are not properly shut! Especially if it results in a flat Battery!

[Ancient Nerd]

I'm surprised by these problems, as both Gen II and Gen III have refused to lock when any door has not been fully closed. Has anyone affected got their dealer to check, as it sounds a lot like a warranty fault.

Both cars also refused to lock when the key was left inside. Although I guess this is mainly a problem because of the Gen III hands free operation!