I have been searching this topic for some time and I have seen conflicting information regarding the operation of the HV battery cooling fan. Does the fan operate continuously, or does it only come on when a certain temperature is reached? Thank you for any light you can shed on this.
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.
Thank you for your reply I have the cooling fan exposed now and I was concerned that it is not running right now, but it is rather cool right now in so cal so I have not had battery on for very long open like this. Thanks again, feeling better about it now. Thank you for your reply, this is what I was hoping. I see that there are still conflicting views on this subject, so I think I will perform an experiment with the fan exposed. Run for a while to heat up the battery and see if/when it comes on. Thanks again
Ok my battery is never cool. Every time I looked at my battery on a never driven car its always on #1 in techstream.
again, thank you all for your replies. I have owned my prius for over 13 yrs now & have gained so much valuable information here on pc,so thanks to the entire community. This is the first time I have posted a ? as I could not find a definitive answer, but I will now do some more digging & I will let you all know what I find.
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.
Update: With the fan exposed I drove the cold car (68 F) for almost 20 min until I heard a faint whirrr in the back. I stopped to be sure and yes the fan finally came on. I can now close up all of the panels and put the seat back, confident that my cooling fan does work as it was designed, plus the fan is much cleaner now. Thank you to all that provided information that got me back on the road.
Thank you for your accurate information. I was able to prove that the cold battery will not call for the cooling fan until it is warm. Thanks again Yes, thank you, this was very helpful.
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.
