Why doesn't the hybrid battery fan run while when sitting still

The software works fine even in abnormally hard use, i.e. autocross. I dare say I have pushed a Prius far beyond what 99.9% of owners have or will ever do to their cars and it's performed flawlessly. If nothing else, hook up a Scangauge, put in the xgauge for max HV battery fan speed, and run it on high all the time to keep it cooler. I do this during my competition runs to KEEP temperatures lower but no other time during normal driving, I let the ecu handle it. Hot summer days on course and between runs I've seen 120 degree+ battery temps and 150 degree inverter temps. Most of this though is due to heat soak between runs and no AC use except after each competitive run. Cabin temps get pretty high so the fan sucks in hot air. Between runs I'll run the AC but not real cold due to using HV battery capacity. Plus I'm force charging at this time, which also increases temps quickly.

SM-G900V ?

 

If you used something to monitor your car battery and fan parameters you would know what is happening rather than making such false assumptions based on your hearing.

The battery fan runs above a battery temperature of about 96.7F and shuts off below about 93.2F. This is battery temp and not ambient temp. It varies fan speed as the temp rises and also varies speed according to vehicle speed. So the fan will be running slowest when sitting still, but if above temp it is running. The fan is very quiet.

It would be nice if the fan would run for a period of time after stopping with a hot battery but the software is not designed for this.

 

Could it be something else, gas system venting? I mean, when monitoring fan speed, seeing at 3~4, I couldn't hear it at all.

 

Meh...
Toyota warrants their hybrid battery for 8 years, 100,000 miles or 10 years, 150,000 miles respectively. CARB or non-Carb.

IF-big if- the parameters are set that the fan doesn't run unless the vehicle is moving? I'm just going to trust Toyota engineers on that one.
To be honest? When I owned my Prius I barely ever heard the fan...running or otherwise, it was pretty quiet.

But given the auditory standards most Prius owners want to try to reach and maintain?

Exhibit A: Oh My God! The Reverse Beep is KILLING me!

Exhibit B: Help me disable the Vehicle Proximity Notification System. I don't like that mild humming sound.

I'm going with far more people would complain about the fan running at stops...than will would complain about it shutting off...and how that only "might" affect Hybrid Battery Life.

 

I monitor battery temp and battery fan level with a Scangauge and have never heard the fan when it is at levels 1-4, although I might have heard a light hum once when it hit level 5, not sure. But NEVER saw the fan go to level 0 (stopped) when when we stopped and the battery temp was over 35 Celsius but the ignition was still ON. The fan does, however, stop when the ignition is turned completely off, which in my experience causes a spike in the battery temp on hot summer days after a short stop.

 

Below is some recent data from my 2013, logged with EngineLink. My battery fan does run while stopped.

I looked at observations where:

• TB 2 greater than 97 F (battery was hot enough for the fan to run)
• Speed = 0 mph (stopped)

The chart below shows the span of battery temperatures (TB 2) for each fan speed under those conditions. I did not have any observations where I was stopped, the battery was > 97 F, and the fan was off (fan speed 0).



Note, I also excluded observations in the first 90 seconds of a trip because the fan speed appears to step up at the beginning of a trip. In other words, even if the battery is hot enough to warrant a higher fan speed, the fan will run at speed 1 for the first ~minute of a trip, then will step up to the appropriate speed. See the end of this post for examples.

 

that has been my observation too. the OP's concern is valid in a sense that fan speed goes down when stationary for cosmetic reasons, and i don't understand all that hostility here. being too defensive is a sign of weakness.

 

And I don't understand those who feel compelled to analyze the motives of others.

I think you mistake genuine concern for hostility.
I also think that commenting on it is unnecessary and unproductive.......even if it is true.

Doing that probably is a sign of something too.

 

Huh??

 

I don't mean to sound hostile.
But I am saying...regardless of what you might think about the fan stopping when the vehicle is stopped, most people aren't going to care that it is NOT on.
Where as, I believe if Toyota set different parameters, and had The Battery Fan run when the vehicle was stopped, the amount of people that would complain about hearing it...would be far greater than the amount of people concerned about it NOT running.

I also trust Toyota engineering. I have to believe that they did factor into battery life what their decision to apply the "off" parameter to the fan would translate into being.
Toyota is the one that have to replace the battery if it fails under warranty, so if NOT having the fan run at stops made a huge difference in potential battery life, I'm pretty sure Toyota would not of chosen the parameter the way they did choose them.

 

so, explain to me what sign it is when someone feels compelled to comment on the "unnecessary" (but true) comment.

"i'm pretty sure," or is it more like hope/believe?

 

Pretty Sure.

 

I remembered this thread tonight, because we had some higher-than-usual battery temps (130 F), so the battery cooling fan was loud enough to hear while driving. We noticed that we couldn't hear the fan when stopped at a light. The battery temp continued to decrease while stopped, and a napkin held up to the intake vent was sucked against the vent (so we knew it was still running).

I downloaded the log data when we got home, and here is what we found:

• The highlighted sections below are times when the car was stopped (speed = 0 mph)
• We can see that fan motor voltage (red) does vary with speed (gray), but it is never zero, even when stopped.
  
• The low point of fan motor voltage (when stopped) was 1.6 - 1.8V. It was 1.8V during the first highlighted period, and 1.6V in the following two.
• Fan Mode (blue) does not vary with fan motor voltage (red); i.e., even when the motor voltage drops, the Fan Mode does not change.
• Fan Mode does vary with battery temperature (green).
• In the highlighted section #1, Fan Mode = 5, and TB2 = 121-122 F; in section #2, Fan Mode = 4 and TB2 = 114-115 F; in section #3, Fan Mode = 3, and TB2 = 105-109 F.

 

Last week, weather temp were average of 103 to 111 degrees all week here. I rarely turn on AC on all my cars and previous ones, my current Prius 2012 blizzard pearl IV with solar sunroof HUD package was no exception either. It sat in the sun for 8 hours with solar powering fans for 7 hours non stop under no shade. Drove it home, all windows down with sunroof fully opened, NO AC. One of the 5 days commuting back home EV led never came on, but the other 4 days EV did come on. The thing is that I hear the HV fan turn on, or spinning up loud enough to hear anything, but the other 4 days when EV was working as it is. Now I'm thinking is the HV fan even working heh.

So if you hear very audible noise from the HV fan than make sure the vents are clear of any debris and the HV fan bearing spindle is spinning freely, that I will first suggest to look into.

 

The same thing happened to us - we noticed that the engine wouldn't shut off at the usual time. I track battery temp with an OBD2 app, and saw that it was very high (130 F). I guess the car limits using the battery when the battery is too hot. It looks like it went into full electric drive again once the battery got below 120 F.

My pleasure, and thank you for asking the question last year! Without this thread, I never would have known that this was normal behavior for the battery cooling fan.