Battery Cooling Fan Question

The fan doesn't run at all until the battery reaches the upper-90's F. I believe 96 degrees may be the exact number but don't quote me... The fan has 6 speeds which are based entirely on battery temp, although the higher speeds are rarely seen in normal operating scenarios. Speeds 1 and 2 are very normal.

 

No the hybrid battery fan always runs at a very low speed. I see it as speed #1 on techstream. But you will not hear it if you listen to the air inlet. Always on.

If the fan is on so high you clearly hear it the hybrid battery is over heating which usually means it’s failed.

In 11 years of owning the car only heard the fan on full once. Left the car out in the sun top of parking garage blazing hot day no windshield sun shade. Interior was blazing hot. Fan is loud at top speed.

Never did that again.

 

No. The fan isn’t running at all if the hybrid battery is cool enough. At least on mine it’s not.

Fan might turn on to the lowest speed when battery temperature reaches something like 35c or 95F. You can’t hear the fan at lowest speed but you can feel the air flow at the vent. You can also check it with Techstream. Fan is not on with cold battery.

 

Ok my battery is never cool. Every time I looked at my battery on a never driven car its always on #1 in techstream.

 

I monitored ours (albeit 3rd gen) for a few years, with a ScanGuage II. Cold starting the car, fan speed was always zero (off). Somewhere around 35C it'd start up, run fan speed 1, sometimes tick up to 2. The most I saw I think was fan speed 4, with battery temp sensor #2 (the middle of pack sensor, tends to be hottest) reading close to 45C. This was in prolonged stop-and-go traffic, hot day.

 

I suppose given your climate, the pack never gets below the mid-90s F? It must in the winter though, eh?... Perhaps voltage variation in an older, heat-stressed-it's-entire-life pack triggers the fan to always on?... Not saying this is the case, just thinking out loud.

Up here in your home region, I've observed fan off behavior first thing in the morning in all 4 Prius I've owned/maintained. This includes an original pack '07 with 180k miles and three turds. Takes about 15 minutes of driving to kick on speed 1 in the summer and up to double that during meat locker season.

 

I am living in cold climate but never heard of the noise from vent , is it normal or need to see a specialist ?

 

Normal.

There are dash lights and trouble codes present when there are.

Keep the battery fan inlet clean (mostly important if you carry hairy pets) and you’ll be good in this regard .

 

I have searched and can not find an answer.
Is it normal to go into my unheated garage several hours after parkingand find the hv/batt. fan running. 40degrees, it shuts off in a few minutes.

 

How often has this happened, and how sure are you it's the battery fan?

If it is something you hear several hours after parking, car off, and it stops in a few minutes, I suspect you are hearing the fuel system evaporation control test. Different fan, under the car, back by the fuel tank.

 

Thanks for the reply. I hear the fan by the right rear corner . I suppose it could be the fuel system evaporation control test. Is that normal after a long shut down??

 

I think it's on a time delay, five hours or so after shutting down. Maybe to ensure that things are at normal, parked temperatures and pressures.

If they did the time delay hoping to avoid making owners go "huh?", well that kind of backfired then.