2010 II 12 Volt Battery Dead After 17 Days of Parking

[indianapens@msn.com]

Left my 2010 Prius II at a parking facility in Chicago for just over two weeks. Upon return, the 12 volt battery was completely dead. After a $50 jump start, returned the car to the dealership for assistance. Their report:"everything is fine and this is common for the Prius as there are numerous computers that are running as well as SKS". BTW, SKS can not be easily turned on and off in the 2010 series.

According to the dealer, Toyota's position is that anything over 10 days of storage with no driver activity will result in a discharged 12 volt battery. Both the dealer and I looked in the owner's manual and could find nothing describing this situation, but apparently they have a service bulletin that covers it.

One possible solution when parking the car for an extended period is to disconnect a lead from the battery but that would require me to climb through the back seat area and manually open the hatch door to gain access to the battery to reconnect the lead. Another idea would be to pull a small fuse called the "short pin" located in the center of the main fuse box. Both ideas are rather cumbersome to say the least.

Anyone have any other ideas?

[Vaughn]

I don't have the owners manual with me but if I'm not mistaken the switch next to the tire pressure reset switch may serve to turn SKS off.

[LulzChicken]

That's very interesting. I'm worried about this.. Anyone have any tips on how to improve the 12V battery's storage/life capacity while in storage for quite some time? Also, can I use a "battery pack" jump started to jump start the prius? I have one of those, and not jumper cables that hook to another actual car. the "battery pack" has + and - terminals. I assume I'd hook the + on the jump start location and the - on the chassis and try to start like normal eh?

[tumbleweed]

Originally Posted by Vaughn

I don't have the owners manual with me but if I'm not mistaken the switch next to the tire pressure reset switch may serve to turn SKS off.

I don't think so, that button turns off the pre-collision system in ATP cars. The Gen2 has a switch to disable the SKS but for some reason they eliminated it on the Gen3.

[DavidA]

no switch. That was genII cars. The III is supposed to have an automatic shut off if it sits 3+ days. It's in the manual.

[RodJo]

Originally Posted by indianapens@msn.com

One possible solution when parking the car for an extended period is to disconnect a lead from the battery but that would require me to climb through the back seat area and manually open the hatch door to gain access to the battery to reconnect the lead. Another idea would be to pull a small fuse called the "short pin" located in the center of the main fuse box. Both ideas are rather cumbersome to say the least.

Anyone have any other ideas?

How about replacing the stock batter with a higher-capacity battery? As I understand it, the Prius battery just boots the electronics so you don't have to worry about cranking amps.

EDIT: Although moved to a Gen 2 forum, this thread (12V Battery Replacement? Opinions Please) includes a Technical Service Bulletin for the Gen 3 that discuss what to do prior to storage and also warns about replacing the battery. You may want to read the rest of the comments.

[3PriusMike]

A couple of months ago I went on vacation for 14 days. Both my Gen 2 and Gen 3 started right up when I returned. The load needed to start the car is pretty small so its hard to imagine that just 17 days really drains a normal battery.

3PriusMike

[rachaelseven]

It may sound elementary and I certainly don't mean to insult anyone's intelligence, but I'd be looking for a dome light or trunk light that was left on during the trip. There shouldn't be enough parasitic losses to drain the battery that badly in 2 weeks. As was pointed out previously, the 12V battery only has to close a contactor and boot the computer, hardly high load. So for the battery to get that flat, that quickly, it seems like it would either have to be a defective battery or some un-accounted-for power drain.

[indianapens@msn.com]

Originally Posted by rachaelseven

It may sound elementary and I certainly don't mean to insult anyone's intelligence, but I'd be looking for a dome light or trunk light that was left on during the trip. There shouldn't be enough parasitic losses to drain the battery that badly in 2 weeks. As was pointed out previously, the 12V battery only has to close a contactor and boot the computer, hardly high load. So for the battery to get that flat, that quickly, it seems like it would either have to be a defective battery or some un-accounted-for power drain.

I thought that I had to have left something on too............but no! Believe me, I checked once the car was jump started and nothing was left on. Most worrying to me is Toyota's apparent position that after 10 days the battery will most probably be drained. Has anyone seen a copy of the service bulletin?

Thanks for everyone's responses!

[a priori]

Originally Posted by indianapens@msn.com

I thought that I had to have left something on too............but no! Believe me, I checked once the car was jump started and nothing was left on. Most worrying to me is Toyota's apparent position that after 10 days the battery will most probably be drained. Has anyone seen a copy of the service bulletin?

Thanks for everyone's responses!

I understand your position, but I have to agree that leaving something on or a defective battery are possible answers to the problem. The third is that there is something wrong with the car's "new" system of automatically disabling the SKS to prevent a battery drain.

I would press this one much more with your dealer. If you are absolutely certain there was no light left on, you can go this route with some impunity. If you are willing to say to the dealer: "Look, I'm as positive as I can be that nothing was left on, but one never knows . . .", well then you can ask them to check both the battery quality/capacity and the auto disabling system, while still having the dealer feel like you could have caused the problem.

Sorry, but I haven't seen an applicable TSB.