Traction Battery Fan LOUD

Lots of people report being able to hear the fan. I have never heard it in mine. I believe it's probably normal but at 400 miles you should query your dealer.

 

The HV battery fan exhauts to the outside of the car next to the 12V battery and in to the right rear tire well.

I cannot hear my battery fan but I think the road noise that I hear by the right rear is coming from the battery vent. The vent is only rubber strips that move outward when the battery fan comes on.

 

Only time I've heard mine was in 100' heat in city traffic. Keeping the cabin cool and avoiding recirc mode on the A/C will help. I don't think it comes on under normal conditions, the battery has to get extra hot to trigger it. Normally the usual cabin circulation is enough to cool it. Make sure you have nothing blocking the vent openings under the seat and in the rear.

 

Honest question here. Why does avoiding the recirculation mode with A/C help?

If you want to keep the cabin cool, recirculating the air through AC is the quickest way. And if you are using your A/C on a hot day, I don't think your battery or traction battery fan know the difference as to whether you are in recirculation or fresh intake.

I just don't see where the connection between the two exists. There are times when Recirc with your A/C IS the most efficient way to keep you cabin cool.

 

Because the battery ventilation is designed to take advantage of the "flow through" cabin ventilation. Recirc eliminates 80% of the fresh air intake. Turning recirc off increases the natural flow of air through the battery vent. Most of the time it shouldn't make any difference, but if the battery is extra hot it will.

 

Hmm....I agree that the battery ventilation fan is drawing air from the cabin. But I don't exactly see how turning off recirc or turning on recirc for that matter increases or decreases the "natural flow of air through the battery vent"?

Where I'm hanging up on the picture, is the battery fan itself, and the vent itself, have no direct connection to the operation of the AC. So "It" doesn't know whether the AC is on Recirc or Fresh Intake. It only knows how hot it is, and whether it should turn on or not.

So to me logically, if Recirc is keeping the cabin air "Cooler" than it would be, with the AC on BUT on Fresh...then it would actually be better to be in Recirc. The battery fan system, doesn't know or care whether it is drawing cool recirculated cabin air, or cool fresh cabin air...it's just cools the battery.

By definition the "natural" flow of air through the vent is going to be the natural flow of air through the vent regardless.

So I'm just not getting the recommendation to keep the AC out of Recirculate.

I could see some arguable benefit to saying when you are NOT running the AC stay in fresh intake. But when you are running the AC....I'd say, just use the AC in the most efficient manner possible. Whether that be fresh intake or recirculate.

 

i think recirq is all happening up front. you're either pulling outside air in and cooling it and it's going out the back, or you're pulling cabin air (mostly) and cooling it and it's going out the back. but i have no idea really.

 

"Flow through ventilation". Air comes in the front and goes out the back. (exhaust vents in the rear of the cabin) In recirc mode, 80% of that air flowing through the cabin is eliminated. The battery vents are designed to take advantage of that, so less air coming into the cabin means less air flowing through the battery vents. The battery vent fan ONLY runs when the temp of the battery reaches a set point. (or at least it only runs full blast). Recirc mode also decreases the cooling in the rear of the cabin for the same reason: less coming in means less going through. Toyota is apparently confident in the over-all ventilation being adequate for the battery, but the addition of the battery fan is the safety.

 

o/p, do you live in a hot climate?

 

I think I understand what you are trying to say about the flow through ventilation. I keep my AC on Auto so when first cooling the cabin it stays in recirc most of the time. I monitor my battery temps with SGII and when the battery fan comes on it seems to reduce the temps fine when in recirc mode. I will have to try to pay attention between recirc and outside air and see if I see any difference in battery cooling.

The battery fan actually has six different speed modes and steps up in speed beginning at 97F for speed mode 1, 100F for mode 2, 104F for mode 3, 110F for mode 4. I have never seen mine above mode 4 and cannot hear my fan even at mode 4.

The car seems to do a pretty good job of controlling battery temps if I just leave the AC in Auto and keep the cabin cool.

 

I'm sure its doing a good job. My point was just that avoiding recirc mode *should* help keep that battery fan from running full blast as often or as long. I've only heard the thing once, as I posted above, when it was blistering hot outside and it was getting a workout in traffic. Obviously, keeping the vent intake free of obstruction is critical.

FWIW, recirc mode is default on auto A/C when the outside temp is above 75'F. (72' in ECO mode).

 

I hear mine from time to time. I just ignore it as it is not obnoxious. Usually my music drowns it out so no biggie.

 

I live in Florida, and I hear the vent fan kick in from time to time, more so on my Gen III then in my Gen II. However, if you are not experiencing any problems, I wouldn't be concerned since the car is doing its job and the fan is working...

 

I've barely heard mine too. I think it's a lhd/rhd thing. For us in a rhd car the vent is directly behind us and thus harder to hear. For the lhd driver, the vent is over their shoulder and more likely to be heard. I suppose if the vent was on our passenger side we might hear it more to?

 

I hear it in the afternoon sometimes when it is hotter out. At first I thought I had a windshield leak or something.

 

The next time you hear the battery fan try this. With the car stopped, turn off everything - radio, AC blower motor, etc. See if you still hear the fan.

Every time I have thought I heard the fan I have tried this. My wife got out one time and put her ear up to the vent by the rear passenger seat and said that she could just faintly hear it. It was on a speed mode 3.

 

With recirc on you are creating a slight vacuum because little air is allowed to be drawn in and consequently the volume of air you can push over the battery is lessened. A fan might spin like crazy but simply cavitate because no pushable air is available.

 

Uh...now you guy's are just being silly.

 

No, it's just Physics. Remember the fan is tying to push more air over the battery and through the exhaust vents than can be drawn in.