Battery fan

Yes, your HV battery was warm. That's how it works.

Tom

 

Where do live and how do you drive that you managed to get the fan to start? Half my grill is blocked all year and even "fully" blocked at 70F it hasn't turned on.

 

Ahh, Jim, blocking the grill will have no effect on the battery fan use.

The battery fan will run if you heat up the battery, from EV use, for example (whether switch induced or not). Or from charging a discharged battery with the ICE.


If you've never heard it before, but just noticed it, that's for sure normal. When I first got my car I didn't notice much of the car's operation. After awhile you get "tuned in" to the sounds you never heard before.

 

Make certain that you never block or cover the battery vent.

 

Driving in mountains is a good way to make the HV battery warm enough for fan-on. It moves lots of energy in and out of the battery; both processes generate heat.

 

One of the most common reasons for the battery fan to operate is driving in hot weather with the windows open and no AC. You have to remember that the battery is cooled by inside air and the warmer it is, the more the fan will run. Keeping the battery comfortable will actually improve your mileage.

 

If the noise seems a bit louder than normal, you might want to take a look inside the fan housing. I recently saw a Prius with a strange rattling noise from the HV fan. Turns out a frog had gotten inside and was causing a noise when the fan would come on.

 

Hi PGE...,

Are you sure the air was coming from the vent, and not being sucked into the vent ? If it was coming from vent (correct me if I am wrong Bear) that seems to indicate a blockage of the exhaust duct. The exhaust duct blowes out the passenger side wheel well. A blocked duct and a operating blower (fan) would make more noise than an open duct and an operating blower.

 

You are not wrong Dontee... I agree with your thoughts... A blocked exhaust could also cause excessive noise...

 

Glad to come across this thread. I was not aware at all that there is a fan back in the HV battery.

 

Hello
I have a 2006 prius with an undioagnosed pop sound which comes from the rear (leftREAR) of the car
It is so intermittent I cannot duplicate the problem but it is there
What would the fan noise sound like?
Thanks
Deva
PS toyota service could not isolate or fix the problem even thos they had the car for 8 days

 

The fan will give a whirring sound of at least a few seconds duration, not a single or repeated "pop". By the way, is your "pop" single or repeating? Is there possibly something rolling around in the trunk?

 

Hi Deva...,

The pop sound might be the brakes at when you use the brakes below 7 mph. Above 7 mph the braking is electric, and thru the front wheels only. Below, the car switches to friction brakes, and there is a hydraulic pressure resouvoir (called an accumulator). It has allot of pressure just sitting. If there is any hangup in a drum (rear brake) mechanism, it will catch and then get pushed through, making the pop. Drum brakes are like this in my experience. They have a loose fit, and the shoes are not solidly guided. So, they can rub against the inside of the drum, and catch at times.

 

I had this exact thing happen today. I have a 2007 prius and have never heard this sound. it was realy loud and was drawing air, not blowing. Is there a filter?

 

This answers a question I had about regen braking. So all the braking power is provided by the front wheels above 7 mph? (Assuming gentle driving and no emergency) That's cool.

 

"All" is too loose of a term.. only x amount of energy can be reneged through the front wheels at any time. turning that figure into pedal pressure brings you somewhere between 15 and 20 percent.. last time i read about it ( on here with all these gurus ) the numbers were all over the place.. and this only applies to the GEN II.... this gen III may be two to three times more efficient... so.. any non panic stop under 50% brake pressure? shrug...

btw, the easiest way to turn that fan on is go up a really long hill right after a cold start. since the electric side does most of the assisting during warm up, the batteries usually call to get cooled.

as for the "air going in or coming out" ... it's a fan.. it blows in 1 direction. you shouldn't get a breeze if it's blocked.. it should simply stay on longer since it's not doing it's job.

 

Only the cabin air filter. It's a good idea to use recirc most of the time to keep the dust down.

If the fan starts running a lot, see a dealer. Every now and then is just happenstance, the battery system being warmer than it wants to be.

 

I think it catches everyone off guard the first time it happens. I have only heard it once, and it required driving around town for half the day then driving down and back up a really large hill that I don't normally take. Sure enough the ScanGauge was reading a battery temp well above 50C whereas I rarely see it much above 45C during normal driving. At least I know the fan works! For a while I was starting to wonder.

 

I have a 2007 Prius III 60,000 miles. I live in PHX. I have only heard the fan come on three times (Never in Summer). The weird thing for me is that when the fan is on, its screws with the performance of the vehicle. The throttle response is terrible. It doesn't rev-down on deceleration, rather stays at higher RPM like its in "B" mode. Does this sound bad? Should I trade it in?