I am considering the purchase of a Hihy and was wondering about the effects of cold weather on the system. One of my use models has the hihy
sitting for several days outside in the mountians in winter. The temps can go sub zero for several days and I might have to start it under these conditions. Anynoe have any experence with this situation. Also the hihy may have to sit in the parking lot at the airport for a week and a half (Denver) . Anyone have any experience with these situations.

Andy

Toyota recommends disconnecting the small auxiliary battery if the vehicle will be stored for an extended period to prevent the small auxiliary battery from slowly discharging. However, you can reasonably maintain the small auxiliary battery's charge state by running the vehicle at least once every 60 days.

Starting the vehicle in cold weather should not be a problem at all as the large electric motor/generator used to start the engine is much more powerful than any conventional starter motor and this motor uses power from the very large hybrid battery to start the engine. The small auxiliary battery is not used to start the engine.

I have never had problems starting in cold weather. The coldest start with my Highlander this winter was Feb 5 of this month with -10 degrees F in the morning - started with no problem after sitting in the cold for 13 hours since it was last used.

For sub-zero operation, use a fully synthetic motor oil such as Mobil 1 5w20 or 0w20. The synthetics typically have better flow properties at extremely low temperatures than conventional oils with the same rating.

5w20 is the Toyota-recommended oil weight for all temperature use.

Thanks for the reply.This leads to one more question. If the high voltage battery pack is used for starting can the HiHy be "jump started" if necessary ?

Thanks
Andy

If the Highlander appears to be dead, the small auxiliary battery is likely discharged. This small battery is needed to power the Hybrid controls that allow the vehicle to operate. Very little power is needed from this battery to operate the vehicle or to start it.

You can jump start the Highlander in a conventional manner by connecting jumper cables to the small aux. battery positive terminal and a ground point on the engine. The Highlander Hybrid will be capable of being started immediately upon connecting the jumper cables -no need to wait for the battery to charge.

Note that the large Hybrid battery can not be jumped as the voltage of this battery is 288 volts DC which is obviously too high to be getting anywhere near. However, this battery will not fully discharge. The hybrid battery is carefully monitored and protected from deep discharge. In the very unlikely circumstance that the Hybrid battery ever did discharge to the extent that it did not have enough power to start the engine, the only option is to have it towed to the dealer.