2010 II 12 Volt Battery Dead After 17 Days of Parking

[Indyking]

What is SKS?

I'm worried now. I'm planning to leave my Prius stopped and parked in Wisconsin for at least 10-15 days in December. I was planning to find a covered garage to protect it from the snow but the cold will be intense.

Should the auto-off SKS system be enough to prevent the 12V battery from draining in that situation?

[a priori]

I followed the link earlier provided to another thread discussing the replacement of the battery. One of the posts provided a copy of a Toyota TSB (Technical Service Bulletin) describing the activities to be undertaken to protect both the HV and auxilliary batteries during storage. Here is that TSB:

Tech Serv Bulletin re Battery Maintenance during Storage.pdf

For some reason I cannot understand, there is reference to a maintenance activity should the Prius be stored for 10 days or longer. It involves disconnecting a harness under the hood. Not difficult to get to, but kind of odd to do it for a 10-day storage.

Remember, though, that this TSB addresses the handling of a brand-new Prius just delivered to the dealer and being prepped for initial delivery to a customer. It tells the dealer how to handle long-term storage and then delivery to the customer. It is not a TSB designed to address ongoing operational issues.

[TKY]

Originally Posted by Indyking

What is SKS?

I'm worried now. I'm planning to leave my Prius stopped and parked in Wisconsin for at least 10-15 days in December. I was planning to find a covered garage to protect it from the snow but the cold will be intense.

Should the auto-off SKS system be enough to prevent the 12V battery from draining in that situation?

Indyking, Smart Key System (SKS) or the key fob.

According to my owner's manual (p.48), if the SKS entry system is not used for five days, then it disables the entry function to prevent discharging the car battery. If the entry function is not used for nine days, then the unlock function is disabled for all but the driver door, where you may need the mechanical key. This implies to me that the battery should not be dead in two weeks because the car takes preventive actions to conserve the battery. At the least, it contradicts the TSB that the battery may be dead in 10 days. --TK

[a priori]

Originally Posted by Indyking

What is SKS?

Smart Key System. This is what allows you to unlock or lock the doors and start or stop the hybrid system simply by having the key (key fob) in your possession.

Originally Posted by Indyking

I'm worried now. I'm planning to leave my Prius stopped and parked in Wisconsin for at least 10-15 days in December. I was planning to find a covered garage to protect it from the snow but the cold will be intense.

Should the auto-off SKS system be enough to prevent the 12V battery from draining in that situation?

Yes, it SHOULD be enough to protect you. This thread, though, is all about a time when it appears the system didn't protect the owner. There is a possibility, of course, that it could have been something else that went wrong. Still, it is valuable to know what the system is supposed to do:

This is from page 49 of the Owner's Manual:

Battery-saving function

In the following circumstances, the entry function is disabled in order to prevent the vehicle battery from discharging and electronic key battery from depleting.

l When the entry function has not been used for 5 days or more
l When the electronic key has been left within approximately 6 ft. (2 m) of the vehicle for 10 minutes or more
l If the entry function has not been used for 9 days or more, the vehicle cannot be unlocked by a door other than the driver’s door. To unlock the vehicle, grip the driver’s door handle or use the wireless remote control or the mechanical key.

The system will resume operation when...

l The vehicle is locked touching the door handle lock sensor area.
l The vehicle is locked/unlocked using the wireless remote control function (→P. 63) or the mechanical key. (→P. 541)

[a64pilot]

Dark current is the term used to describe the parasitic loads on a battery while the vehicle is not in operation. Very easy to measure, just simply disconnect the battery and have a multimeter in series with the battery with the multimeter measuring amps. Without measuring this dark current every thing is just speculation. Once you know what the load on the battery is when the vehicle is off, then you can determine battery life. And you may be able to find out what's pulling current when it shouldn't be if anything is.
Has anything electrical been installed in the car?

[indianapens@msn.com]

Originally Posted by a64pilot

Dark current is the term used to describe the parasitic loads on a battery while the vehicle is not in operation. Very easy to measure, just simply disconnect the battery and have a multimeter in series with the battery with the multimeter measuring amps. Without measuring this dark current every thing is just speculation. Once you know what the load on the battery is when the vehicle is off, then you can determine battery life. And you may be able to find out what's pulling current when it shouldn't be if anything is.
Has anything electrical been installed in the car?

NOPE! the car is just as it came from the factory with no modifications of any kind. To me, the technical bulletin T-SB-0152-09 kind of tells the story..........."To store for 10 days or more, disconnect wire harness from exclusive jump starting terminal"

[RodJo]

Originally Posted by a priori

Remember, though, that this TSB addresses the handling of a brand-new Prius just delivered to the dealer and being prepped for initial delivery to a customer. It tells the dealer how to handle long-term storage and then delivery to the customer. It is not a TSB designed to address ongoing operational issues.

I'm not sure what the difference would be. A 10-day storage at the airport shouldn't be much different than a 10-day storage at the dealer.

That also doen't explain why it warns about replacing the battery with a regular car battery -- not something that would be done pre-delivery. Unless the dealer stores the car for years.

Originally Posted by indianapens@msn.com

NOPE! the car is just as it came from the factory with no modifications of any kind. To me, the technical bulletin T-SB-0152-09 kind of tells the story..........."To store for 10 days or more, disconnect wire harness from exclusive jump starting terminal"

But it does seem kind of silly. I'm not sure the Prius has more electronics running while off than many other cars. It seems to be just a side effect of the small battery.

[radiocycle]

I just called the service dept. at Lompoc Toyota, where we bought our '10 II and told them we're going on vacation for 3 or 4 weeks. I asked if that would run the battery dead. He said yes it would and here is what to do: In the cargo area there is a small door that gives access to the 'small' battery. Disconnect the neg. terminal.

I asked if we simply reconnect the battery when we return. He said, yes it should fire up, no problem. So that's what we'll try.

[RodJo]

Originally Posted by radiocycle

I just called the service dept. at Lompoc Toyota, where we bought our '10 II and told them we're going on vacation for 3 or 4 weeks. I asked if that would run the battery dead. He said yes it would and here is what to do: In the cargo area there is a small door that gives access to the 'small' battery. Disconnect the neg. terminal.

I asked if we simply reconnect the battery when we return. He said, yes it should fire up, no problem. So that's what we'll try.

Isn't the problem then getting to the cargo area to reconnect the battery?

[jayman]

I would suggest wiring a VDC Battery Minder directly to the 12 vdc battery, like I did with my 2004 Prius. However, that doesn't do you much good if parked outside at airport long-term parking