New owner of a used HiHy. As a carryover from my gasoline engine days, I only run the AC when the weather gets unbearably hot. I see checking around that the hybrid battery must be cooled.

My question is, is the battery water cooled, like a typical engine, or does the Highlander use A/C to cool the battery, so that my not running the A/ C is a pointless exercise in masochism, since the A/C must run anyway? Or are they separate cooling loops?

Thanks in advance for any answers.

 

The battery has an independent cooling system with an independent fluid chamber and pump. I found this out when it was time to flush and replace the engine coolant on my '06 Highlander. Both are typically flushed at the same time.

 

Turning off the AC may save you some MPG at stoplights (ie engine shuts off in EV mode) but at speed there's no reason not to run it for comfort. The AC compressor is actually electic too (ie not accessory belt driven) and only used for cabin temp control. As was mentioned above the hybrid traction battery also has a separate cooling system to deal with heat production as well. Long story short, turn on your AC and don't worry about it.