Controlling HV battery fan with Torque App.

Hello. I have a 2012 Prius 4 that I have owned and driven for the last 40,000 miles or so over the last two years. I got it with 160,000 miles on the odometer, and have just rolled over 200,000. I already had the dubious pleasure of replacing a blown head gasket, I had already cleaned the EGR pipe and cooler. While down for the head gasket, the whole intake system was cleaned very well and the rings got a week or so to soak in seafoam.
But enough background, on to my current concern:
I have been running the Dr Prius app. Initially at about the 165,000 mile mark, I did a full battery life expectancy test and got about 68% condition, according to the app that is the higher end of "fair" I did it about a year later at around 190,000 miles and got around 65%, and just recently at 202,000 I got 63%. I know this pack wont last forever, but I want to get as much life as I can before I am out getting a new pack. I noticed the Dr Prius app has a battery fan override option, and one can set the base temperature that the battery fan uses to start ramping up its speed, but this option only works while the Dr Prius app is actively running. I use Torque a lot of the time and wonder if there is an option in the Prius PID set that would give me manual control over the fan speed, or at least the ability to cool more aggressively. This is my main question and the real reason for my post.

However, some people may need the following information before they start madly typing away:
I have seen the people scratching their heads wondering why anyone would think that they know better than whatever software the car is programmed with and don't mess with things that are not broken. Well, I am not an average user. I live in Arizona. I have a major trip planned up to Washington State in a week or so, and I have noticed that when the temperature goes up on the battery, the car starts limiting how much power it will attempt to either charge or draw from it until it gets cooler. I can be sitting still in Phoenix where the outside temperatures are in the 110-118 degree range and start up, and I have less than 5 hp of battery power available to me until the battery gets cooler. The car drives noticeably sluggishly. I used the Dr Prius app and noticed that the car will allow more current draw or charge as the battery cools, until you have 30 ish horsepower of capability from the battery once it is right at or just over 100F. Cruising down the road with the A/C on, the car will take care of itself. I would like to be able to proactively cool from a "hot startup" such that the battery is more capable. If I am not abusing that capability, I also think the cooler temperatures might extend battery life enough to matter. I think even if I wear out a HV battery fan or two, they will be substantially less expensive than a battery pack, and probably not too hard to source used. Also worthy of note, I have already cleaned the battery fan. It was only slightly dusty. I am not the first owner, but I can tell that this vehicle never had a pet in it that was capable of shedding hair.

Thanks for taking the time to read this.

 

The problem with the solid state peltier cooling devices is they are only about 5% efficient. To cool down a roughly 100 pound pack I think I would need about 1.21 gigawatts of power. Of course, If I had that, I would just find a Tesla with a bad battery pack and leave flaming burnouts as I hit 188 mph (upgraded from the DeLorean). But you make a good point, there is no need to run the fan much at all until the cabin temperature is at least a few degrees cooler than the battery. Other than the wonderful fun to be had mixing water and electricity, I wonder if a practical miniature swamp cooler that would be rigged just to work for maybe 5 minutes on startup until the cabin temperature was more reasonable. A real engineer would probably add a tiny condenser from the existing A/C system into the inlet side of the battery fan to chill the intake air. I suspect that might cost as much as just buying the new battery. The other thing to think about is if any of the aftermarket batteries are more heat-cycle tolerant than the original equipment HV battery and could be run any hotter without decreasing service life. (something I need to look into before I get to the point that I have to buy a battery somewhere)

 

The Dr Prius app seems to just change the critical temperature where the fan first starts operating, not so much just setting the fan on high and leaving it. I am thinking even shifting that critical temperature down 10 degrees F might accomplish something worthwhile. The app lets you choose a wide range of temperatures down to maybe 60F. The default temperature seems to be about 97F. It can only spoof the temperature while it is actively running though, I suspect it just continually writes a correction to whatever the battery thermometer outputs are. I have played with the Torque app, and I have found control buttons in the PID's I have for mundane things like changing the song the radio is playing, but I must not have the exact right PID that gives any deeper control into things like fan speeds. What I am hoping is somewhere in this collective knowledge base of the members, someone can point me to the right PID, or can point me into a relatively fail-safe way to achieve the same goal with minimal programming. The last thing I want to do is brick a whole ECU by writing a faulty line of code. I did find a tutorial on how to basically add a "full power" battery fan switch, but it just draws 12v power and adjusts it with resistors to what the fan needs (I think 6v) with a DPDT switch. Switch one way for regular computer controlled fan speeds, and flip the switch to disconnect from that and connect directly to voltage modified (again resistor only, but with a known fan load that can be adequate) to run the fan at full speed.