I have a hybrid Camry and am going to be traveling abroad for about 4 months. What, if anything, do I need to do to my car so the batteries don't die while I am gone?

 

You could drop it at my house...I would make sure that it gets good care while you are away....

Failing that, make sure the traction battery is fully charged and disconnect the 12 volt battery in the trunk. That should work for just a 4 month trip. 6 months or longer and I would prefer someone to take care of it for me.

 

Batteries loose charge while just sitting, even if they are disconnected. I have another vehicle that sits for 2-3 weeks at a stretch. I keep a trickle charger on the battery in that vehicle. Before I got the trickle charger, it often needed a jump. The TCH has two batteries. The little 12 volt battery is no problem -- a trickle charger should work just fine. (Don't use a high-rate charger, though, because it could damage the battery.) But we don't have a way to charge the big traction battery other than by operating the car. So, it seems the vehicle actually needs to be operated periodically.

NIMH batteries lose, if I recall correctly, something like 5 or 6 percent of their charge for each day they sit idle. I have some other NIMH batteries (on power tools) that seem to lose their charge much more rapidly than that, just by sitting unused. So, an idle period of just a few weeks could result in a completely flat NIMH battery.

If I understand correctly, Toyota does have a charger for that big battery. But I think it would be rather a major PITA to flatbed a car to the dealer just to have the battery recharged. And I don't have any clue how much a dealer would charge for the service.

So probably the best approach is to get a relative or neighbor to operate the car once a week or so, and keep a trickle charger on the little battery in between those weekends.

 

Another possibility: I recall reading a note in this forum last summer -- someone returned from a 5-day business trip, and discovered his car in the airport parking garage was cool. The air conditioner had been running the whole time, after he forgot to turn the car "off" before leaving on his trip. It was locked up just fine, and the motor only ran occasionally when the battery got low, so the one tank of gas was enough to last the whole time. That makes me wonder: If you turn off the AC, radio, lights, etc., how long would one tank of gas keep the battery charged? It seems to me the car would just monitor the battery state, and start the motor for a few minutes each time the battery got low. If there are no other loads, that might not be very often.

 

Oh my! Certainly creative thinking...pragmatist indeed!

 

Best advice is to have a friend/neighbor/relative drive it once a week.

 

Toyota doesn't recommend going over 2 months without recharging the traction battery. If the Camry HV is put into storage, the state of charge (SOC) of its HV battery and auxiliary battery will gradually decrease. To prevent the batteries from deteriorating during storage, proper maintenance is necessary and required.

See TSB PD020-06 MAINTENANCE FOR HV & AUX BATTERIES for more details.

In brief, the HV (traction battery) must be charged every 2 months by powering on the TCH (Ready light on) for at least 30 minutes. Toyota also says to disconnect the negative terminal of the 12V auxiliary battery if stored 30 days or longer.

My suggestion is to have a trusted friend run the TCH every two months for 30 minutes while you are gone, and use a regulated battery tender to keep the 12V battery from discharging.

One interesting hint about charging/reconnecting the 12V battery I don't recall seeing elsewhere is:

After recharging the auxiliary battery, the hybrid system may NOT start. Follow the proceedure below to initialize the system.

• Put the shift lever in the "P" position.
• Open and close any of the doors.
• Restart the hybrid system.

 

Longest mine has sat is 3mo, when we were overseas. After that amount of time the large battery was only down a shade over the half way bar and the small battery also evidently had enough to operate the computer.

 

I had a similar thought process for when your car might be exposed to very cold overnight conditions. Turn off everything except your heater, crank that down to minimum temperature setting. Power up your car and lock your doors. I would think that would temporarily replace the need for an engine block heater and have your cabin temperature at a reasonable level when you got in the next morning. Not great mpg results but at $1.70/gal not terrible.

 

....just make sure you don't do this in an attached garage.