Hybrid Battery Dead if PRIUS OFF for long time?

Use a trickle charger on the 12V battery (small solar panel type works if you don't have a garage etc.) and you can leave it as long as you need.

 

I thought the 2 weeks battery life was due to the SKS system, and if you turned that off it'd last longer...

 

Please define how long is a "long time".

The main hybrid battery will lose its charge slowly, and will deplete itself completely if you let it sit for mebbie half a year to a year or so (timeframes are guesses, consult others for better numbers)

 

That won't help w/the big HV battery.

 

But that also won't be *needed* with the big NiMH battery. Unlike the 12V lead acid battery there are no power consumers draining charge from it when the car is off. The computer, the clock, the remote locking system etc. are all powered by the 12V system.

One of the purposes of the 12V battery is to power a solenoid to reconnect the NiMH battery to the rest of the car - by default it is disconnected.

There is some limited self-discharge of the NiMH battery, but that won't be a problem if you only leave it off for a couple of weeks. When a Prius doesn't start after being off for too long, the reason is almost always the 12V battery having lost its charge. A trickle charger will take care of that.

 

While I was repairing my '08 I did not turn the car on for over 2 months and the main hybrid battery charge did not change at all.

 

A few months is fine, but anything longer then a half a year I'd start worrying about the HV battery. You'll want to keep the 12v battery on a float charge or disconnect it if longer then a few weeks.

 

Is the solar charger the type you plug in the fag lighter socket or one you need to attach to the battery directly? Also, if its the latter do you disconnect the 12v first?

 

Yep, I tend to agree that there should be no issue w/the HV battery after leaving the it for 2-3 weeks. I just haven't left mine any longer than ~1.5 weeks or so.

 

I have to point out that the cabin 12v lighter socket is disconnected when the car is off... so don't plug the solar charger into the lighter socket.

 

Many misconceptions.

The SKS system will shut down by itself after some time. It's in the owners manual.

A -healthy- 12V battery will be fine for 3-4 weeks IF all lights are off. Do check the cargo area light. It can be left on and not noticed during the day.

If you are parking the car in a garage or somewhere there is AC power, get a "battery tender". Then you don't have to worry.

If you are parking the car where there is no AC power, but it's not under cover, then you -could- use a solar charger, but you will have to wire it to the 12V circuit. Be sure there is a diode in series. You don't want the solar panel discharging the 12V battery.

If you may be parking the car under cover with no AC available (car park garage for example), then you will have to live with the 2-3 week gamble. Disconnecting the battery is not easy, as you have to open the hatch to reconnect it, and you either will have to use power (hatch lock is power operated) or crawl over the rear seats and dig for the release.

IF the battery does go dead, you can "jump" the Prius from under the hood. The jump point is clearly indicated in the owners manual and the hood can be opened without power to the car.

A better solution than the solar panel would be a portable "jump starter". These are readily available and are small enough to carry in the car (don't put it in the hatch area when you park the car, as you will have trouble getting in there if the battery dies). The only disadvantage with this option is you would probably loose the 12V battery from sulfation if it goes dead too often. The advantage to this option is if asked, you could actually boost other cars with it (NEVER boost another car from the Prius).