Removing 12volt battery

No, the brake power supply does not need to be removed. Unhook the wires with white connectors from the 12V+ terminal, pull them forward and out of the way (you'll lose radio and other preferences). Then remove the black plastic vent duct. It's tricky since the screw that holds duct into the fender on the right side is quite low, but you'll see a notch in the fiber trim panel for your socket wrench extension. Use a magnetic socket or put a piece of paper towel/tissue into your 10mm socket while unscrewing....you don't want to drop the screw into the battery well. Once duct is off and battery hold down clamp out of the way it is fairly easy to finagle the battery out.

 

Also, why don't you install a small battery maintainer permanently in the car, just plug the car in when you don't use it for long periods.

In the US this is a great unit, under $25 and suitable for AGM batteries like the Prius
http://amzn.com/B000CITK8S

Not sure if they have a European voltage model.

 

It is helpful to unbolt the brake power supply and move it aside (not necessary to remove the wiring harness connectors) to provide better access to the 12V battery.

I assume that you need to remove the battery because you do not have a way to provide AC power to the charger, while at the car. Otherwise, you could charge the battery while it is installed in the Prius.

 

GRRtinybattery,

As to removing the GenII 12V battery, info here should be helpful:

http://priuschat.com/forums/gen-ii-...2v-battery-replacement-preemptive-strike.html

 

The extension cord comment is probably just because of their lawyers...that way if your car burns up it's not their fault. I would certainly be comfortable using an extension cord with a battery maintainer, especially one that only uses 750ma.

The Prius battery is sealed with a vent to the outside via the small tube. It is safer to charge "in the car" than in your house...since in your house the gasses will not necessarily vent outside.

 

There are also 12V battery disconnect swithches which can be installed in series with the negative lead to ground. Whether a battery would stay charged for 6 monthis or not is questionable.

 

You can easily disconnect the 12V battery without any tools. Remove battery area cover and red plastic cover over the positive terminal.

Unhook the heavy gauge black cable with the white connector from the positive terminal block by pressing the small release tab on white connector and pulling it out and away from battery.

There will be no power drawn from the 12V battery if you do this.

The method above is also good for "resetting" ECU's etc when error codes won't clear.

You will have to use the hard key to open drivers door and crawl through rear seat to re hookup since hatch doesn't open without 12V. You will also lose radio preferences and all other preferences (window down mode etc) but this is a good solution if not using car for many weeks.

A good 12V battery should hold charge without a current load for at least 6-12 months.

 

I can't say, but they should be available in any tool or hardware store. They are only about 3" square, with several types available. Right now my 12V is disconnected while I am in Germany.

 

Can you charge the battery from the jump start place (in front of car)? That way you don't have to take battery out. I am just guessing...

 

Absolutely.

That is the easiest place to charge the battery....especially if it is dead since you cannot open the hatch when the 12v is flat.

 

There's a caution in the 2010 manual to alway remove the battery for charging. That said, I think it's butt covering: I've done maintenace charging a few times on ours, not touching the battery, and hooking up at the jump-start terminal in the fuse box under the hood, without incident.

 

Yes, the Toyota repair manual also suggests that it is necessary to remove the 12V battery. Toyota doesn't want to be held responsible if your 12V charger provides a higher charging rate than needed and the battery blows up while installed in the car.

 

"Crawl thru rear seat" Part of your exercise program! Remember to leave hatch ajar.

 

Just FYI, do not take your 12V battery into AutoZone, Napa, Kragen or any other store to get your 12V battery charged, they tell you that the terminals are too small. When I took mine into Autozone, the guy had no idea what it was, he thought it was for a motorcycle.

 

1NZ-FXE Charging.pdf. This seems to help if you put it in google.

I don't like the idea of jump starting with another 12V battery in parallel. Charge current tends to be very large. This may explain why people think flattening a 12V battery is bad. I've found that if you do this slowly and don't keep it flat it improves the battery. By slowly I mean as slowly as possible. Don't discharge below 10V. (You can discharge lower, but I'm not sure of the benefit/risk). The main thing is to charge at lower than 5 amps or whatever it says on your battery and limit it to 14V. (Higher voltages can be used with current limit to desulphate if you know what you are doing) Start the discharge at 10-20 amps and then work your way down. Each time you reach 10V give the battery a rest and then halve the current.
I'm not sure what damage is done if you leave a large load on for a long time. I have recovered a battery that was completely flat for a week. I just keep the charge current below 5amps. The prius will do a constant voltage charge at 14V which may be around 20A. I don't see the point in that. There is not usually a rush to get the battery back to full charge. The car only needs 10V to run, more volts could be supplied when lights are in use. But the current would mainly go to the lights, rather than the battery.

It seems starnge that Toyota go to so much trouble to protect the Drive Battery and then take so little care of the 12V one. Laptops tell you how long the battery will last, why doesn't the Prius?

And why doesn't it switch off the load before the computer fails, or the battery gets to 10V.

I would have thought that these days it should be possible to tell the user how long they can expect battery to last without use.

Still I'm out of date. Bsc Electronic Engineering 1970.

 

...consider Optima Prius battery from eLearnaid.com ( I realize you are overseas) but I am in reference to their instructions for battery removal which may be helpful may be avail on website.

One point Optima/eLearnaid make if you are going to sit your car for long periods, if your car is like my 2006, you might want to disable the smart key system which is constant small drain on battery. There is button under steering wheel.

 

Just a thought -- does the 12v have a fuse in the engine bay that could be disconnected instead ?