2010 II 12 Volt Battery Dead After 17 Days of Parking

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.

 

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?

 

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.

 

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.

 

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 (http://priuschat.com/forums/gen-ii-...-12v-battery-replacement-opinions-please.html) 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.

 

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

 

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 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.

 

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?

 

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:

View attachment 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.

 

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

 

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.

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)
​

 

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?

 

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.

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.

 

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?

 

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