Flattened My 12V Battery

[GreenJuice]

The hatchback wasn't closed properly over one of the recent long bank holiday weekends. There are many postings on Priuschat, but I thought I should share my experiences here as some aspects are not intuitive.

Firstly, I could have avoided this by always locking the car when in the garage as I would have been warned that the hatch wasn't completely secured.

When the 12V is flat, the hatchback won't open to let you inspect the Battery. This doesn't matter as the charging points are in the engine compartment. I plugged on a trickle charger to the terminal points as indicated in the manual. After about an hour of charging at slightly less than 4 amps, dropping down to about 2 amps, there was enough charge to Start the car. As indicated by others, the 12V is basically only needed to provide the initial booting of the computers. After that, in Ready mode, the HV Battery takes over and also completes the recharging of the 12V Battery over time. There is no need to take the car for a run.

The SatNav system is rebooted almost like a new installation. Daylight savings setting and speed settings had to be reset, however, saved destinations and bluetooth settings were retained.

All trip readings and consumption figures are lost and reset to zero. A pain if you monitor these closely. Lucky for me, I have a ScanGauge which retained all its memory.

All radio channels were lost and had to be reset.

An odd and unexpected problem is the failure of the driver's power window auto-open and auto-close. This has to be reset by half opening the window, then fully closing and holding the button up for several seconds.

I had previously disabled my seatbelt beep alarm. This was turned on again and I had to go through the disable procedure again.

Reassuringly, the car appears to be fully recovered after this event. In this warmer weather, I managed a personal best on one of my 80 mile commutes (two-thirds motorway, one-third urban) clocking 72 mpg.

If there is anything else I should have checked, let me know!

[timberwolf]

What Prius generation?

Personally, I would top off the 12V Battery with the trickle charger at some point, I'm not sure that the Prius on board 12V charging system is sophisticated enough to fully charge the 12V Battery, but I guess it might not be so important if you do a high daily mileage.

[GreenJuice]

What Prius generation?

Gen 2 T-Spirit

[timberwolf]

Ta.

I think if I recall correctly, it was in John's Prius Owners Guide that recommended slamming the hatch down, and it was one thing I've always tried to remember to do to make sure that is shut properly, if I think I haven't pulled the hatch down quickly enough, I'll open it and give it another slam!

[GreenJuice]

Certainly paranoid about doing that now!

I did do a trickle top-up overnight afterwards. I expect someone might be able to work out how much time to fully charge one of those small batteries.

[Chris Dance]

Leaving the hatch open is easily done. I have done it once and my son has done it twice. If the hatch is left open the interior lights stay on. That is is if you have not set them to the off position. The lights in the vanity mirrors can also flatten the 12v Battery if left on.

[sjrainsford]

Is this a uk car? I didn't realise you could turn the annoying seat belt alarm off. Shame we can't turn the reverse alarm off too!

I've often considered disconnecting my 12v Battery for a bit to see if these cars learn like other Toyotas I've had in the past do. I physically can't get over 55 mpg.

[Jan&tone]

Is this a uk car? I didn't realise you could turn the annoying seat belt alarm off. Shame we can't turn the reverse alarm off too!

I've often considered disconnecting my 12v battery for a bit to see if these cars learn like other Toyotas I've had in the past do. I physically can't get over 55 mpg.

Strange... I regularly got 60mpg from my gen2 and 65-68 so far on the gen3....

And I still can't fathom the problem people seem to have with the seatbelt and reversing beeps? The seatbelt only beeps if it's not being worn and who reverses for miles? 5 or 10 yards at most, max 20-30 seconds....

[cbcdesign]

I would have thought that a quick tug upwards after closing the hatch to make sure the latch has engaged properly would avoid any possibility of leaving it open. I do this as a matter of course on car boots and hatches just to make sure.

[capnbirdseye]

The first thing I did when I got my car was turn off the boot light after reading all the Battery problems, after all how often do you actually need it & how simple is it to turn it on & off again if you do

[Jan&tone]

The first thing I did when I got my car was turn off the boot light after reading all the battery problems, after all how often do you actually need it & how simple is it to turn it on & off again if you do

Lol, I've done that for 20 years, ever since I got caught like that with a Carina!!

[Grumpy Cabbie]

Is this a uk car? I didn't realise you could turn the annoying seat belt alarm off. Shame we can't turn the reverse alarm off too!

I've often considered disconnecting my 12v battery for a bit to see if these cars learn like other Toyotas I've had in the past do. I physically can't get over 55 mpg.

My understanding is that you CAN'T turn off the seat belt alarm on the UK model. I'd be interested if anyone else was able to do this following the instructions given. The reason I say this is that I have begged and pleaded for the seat belt alarm to be turned off (as some customers refuse to wear their belts) and my dealer said it absolutely can not be done.

The reverse beep and rear seat belt alarm IS a dealer fix though.

[timberwolf]

Oh, isn't it a law that passengers have to wear a seat belt?

[acetip]

Oh, isn't it a law that passengers have to wear a seat belt?

any person sitting in a vehicle seat fitted with a seat belt must use them.anyone above 14 years is resposible to use the belt,failure to do so is up to £500 fine.

[Grumpy Cabbie]

Oh, isn't it a law that passengers have to wear a seat belt?

any person sitting in a vehicle seat fitted with a seat belt must use them.anyone above 14 years is resposible to use the belt,failure to do so is up to £500 fine.

You got it :) And note it says the person is responsible and not the driver. It is against the passengers human rights for me to impose on them to wear the seat belt if they choose not to. They will be liable to be fined but I can't force them. A child 14 or under must have a responsible adult to make the decision for and travel with them. I do not carry children under 14 years old on their own other than certain regular runs.

Oh and just to rub it in a little more - a taxi driver doesn't legally have to wear a seat belt when with a passenger and doesn't have to wear one at all in a purpose built taxi. I however, always always always wear mine. Seen too many messy accidents not to.

[GreenJuice]

I am in the UK and you can disable the seat belt beep on UK Gen 2 Priuses by following the instructions on the link in my earlier posting. It disables the beeping sound but not the red flashing light which for me serves as a sufficient and more pleasant reminder.

[Seamaster73]

One taxi drivers' trick I read about is cutting a buckle off a matching car in a scrapyard — stick this in, and the beeps are silenced.

[Grumpy Cabbie]

lol I know of one or two who do that but couldn't possibly tell :!Removed!:

The other trick is plug the seat belt in behind you and sit on it, but why not just put the seatbelt on?

[Jan&tone]

lol I know of one or two who do that but couldn't possibly tell :!Removed!:

The other trick is plug the seat belt in behind you and sit on it, but why not just put the seatbelt on?

Just been out in mine deliberately (it's not raining so I used mine instead of 'hers'

No sound from the seat belts for about 20 seconds then a slight beep for another 20 seconds when it then gets more strident... By which time you should have it on!

Having seen the result of not wearing a seatbelt I NEVER travel more than 10 feet without it... The exception is getting on to the IoW ferry at about 5mph when I put up with the beep for the 2 or so minutes it takes.

- bit like motorcyclists wearing shirtsleeves and shorts at the moment... Idiotic IMO.

[Grumpy Cabbie]

I thought the beep goes off when you go over 11 mph. Well it does on the gen3.

[Jan&tone]

I thought the beep goes off when you go over 11 mph. Well it does on the gen3.

Dunno Grumpy... Only time I ever use it without seatbelt on is getting it out the garage or going on to the IoW ferry max 5 mph!

[dwilson]

I would rather have the momentary annoyance of a buzzer than forget to put a seat belt on myself.

The only time it has been a problem to me was in my Subaru (sorry if that's swearing) and my heavy laptop on the passenger seat set the alarm off intermittently and I didn't know why! Yes I know it wasn't a good place for my laptop!

David

[johalareewi]

I thought the beep goes off when you go over 11 mph. Well it does on the gen3.

I have had it go off below 11mph when I was crawling round the supermarket car park. Seems like it is time for an experiment

[timberwolf]

I would have thought that a quick tug upwards after closing the hatch to make sure the latch has engaged properly would avoid any possibility of leaving it open. I do this as a matter of course on car boots and hatches just to make sure.

To be honest, I prefer the slamming, and I can't remember if there were cases where the hatch could be latched but still not closed properly.

[timberwolf]

Oh, isn't it a law that passengers have to wear a seat belt?

any person sitting in a vehicle seat fitted with a seat belt must use them.anyone above 14 years is resposible to use the belt,failure to do so is up to £500 fine.

Ah, thanks, I was being a bit lazy, I thought there must be a law by now, I can remember we had to use rear seat belts in Canada probably 25 years ago or more, and it just stuck in my head that it was a good thing and I wondered why we didn't have the same sort of law in the UK.

You got it :) And note it says the person is responsible and not the driver. It is against the passengers human rights for me to impose on them to wear the seat belt if they choose not to. They will be liable to be fined but I can't force them. A child 14 or under must have a responsible adult to make the decision for and travel with them. I do not carry children under 14 years old on their own other than certain regular runs.

Oh and just to rub it in a little more - a taxi driver doesn't legally have to wear a seat belt when with a passenger and doesn't have to wear one at all in a purpose built taxi. I however, always always always wear mine. Seen too many messy accidents not to.

It doesn't bother me, it feels weird to me not to wear the seat belt, and I put it on even if I'm moving the car a short distance. When I was learning to drive, I always tried to do an emergency stop with the aim of getting the instructor or examiner to hit their head on the windscreen... I don't think I managed it, but I seem to recall I got pretty close (or maybe I like to think I got close).