My 07 FEH has been reluctant to drop down into EV mode after it's been driven for around 15 minutes. Today was a 90 degree day and it only lasted maybe 7 or 8 minutes before EV gave out. When i got home I left the engine running and disassembled the battery to see if the fans were running. They weren't. I then took to removing them so i could test them directly to battery. They didn't spin up, but i imagine they needed signal on the two low voltage leads.

The fans have 5 leads:
RED - 14v (on even if car is off)
BLK - ground
BLU - 0.11v
TAN - 0.07v
YEL - 13v (0v if car is off)

EDIT: i think i flipped the blu/yel numbers here. I am confident the values are right, but had uncertainty on the color association by the time got back to the computer. I was too lazy to head back to the car and repeat the test so i assumed yel was the higher voltage since yel is typically 12v on car stereos. Later testing is indicating my uncertainty was justified and that blu was actually the line with higher voltage during this test.

My assumption is that YEL = ignition and BLU/YEL are battery temp / vehicle speed. I'm basing this off of a bit of info from http://www.eaa-phev.org/wiki/Escape_PHEV_TechInfo :
Here are some tear down images from one of the fan motors just for fun. They could be useful if you have a failed bearing and want to replace it.
1. After removing the plastic housing you're left with just the motor itself.
2. The squirrel cage is held on by a retention clip (removable via twisting with some pliers)
3. Then you are faced with a metal plate. This has a few screws holding it down. After removing those you can pry up a bit. You'll then be able to slip a screw driver into the gap to pry some thermal adhesive loose from the top of a heatsink. The plate is then free.
4. You now have a circuit board. I pried up on mine to try to dislodge the motor from the metal housing, but this was a poor idea as there are 6 copper leads that go to the windings and have _zero_ slack. The proper way to remove it is to desolder the 6 copper leads that go down to the windings. You'll then be able to just pick up the circuit board.
5. Now you just have the permanent magnet rotor with 2 bearings.
6. The stator appears to be glued to the metal housing and is not removable.


Immediately after metal top plate is removed. note the heatsink with the white thermal adhesive is opposite the input cable.


Here's when i was prying up the board. Note that the windings had zero slack and are actually broken free in the picture. Desolder them from the top instead of prying up on the board.


Bottom of board and a view of the rotor+stator


rotor pulled from stator. Stator is glued down.

 

My plan is to buy a couple generic 12v blowers from amazon. I'll use the YEL 12v ignition wire as a relay trigger so they don't run when the car is off. Then use whichever of the BLU/TAN wires is the battery temp to throttle the fans. I'll ignore the speed wire since i don't care how loud the fans are.. i'd rather they just do their job cooling when necessary.

Anyone have any input on this before i get going? I don't have a ton of experience here, but I imagine i can figure out what i need via some google research. The trouble is that I haven't been able to find any specs on those BLU/TAN signal wires anywhere so i just have to work off of assumptions.

 

Can't say I know a lot definitively, but I can't see why you're drawing your conclusions, or taking this course of action.

The fans are the fans. They do what they're told to do. They make no decisions on their own. The temperature sensing is at the main connector on the front of the battery, driver's side - not the fan.

The fans are PWM controlled. Yellow is likely the speed sensor and blue is likely the PWM signal. They likely won't spin up if you apply 12V directly to them.

You're likely seeing deterioration of the battery itself that's unrelated to temperature. What was the battery temperature?

IMHO, you're going down a rabbit hole for the wrong reasons and all possible outcomes are negative.

Good luck.

 

I think you might be underestimating the logic that's incorporated into the fan itself. With 5 leads and multiple ICs on board, the fan's have a significant amount of decision making of their own.

I conducted another test on the way into the office. I plugged in one of the fans so that I could see it from the driver's seat. The fan never once turned on. As per normal, the EV worked at stop lights for roughly the first 10 minutes of the trip. I set up torque to display the battery temp and state of charge so i could screenshot it at every stop light. EV stopped working when the temp surpassed 100F. The state of charge was between 53-56% throughout the trip (was lower at the start due to me having the car on prior to the trip while i was setting up torque).

At the start of the trip with the car running but still completely cold I read these values:
RED- 13v
BLU - 0.05v
TAN - 0.0v
YEL - 0.05v

At the end of my trip with the car still running i read:
RED- 13.4v
BLU - 12.5v
TAN - 0.11v
YEL - 0.11v

I'll try stopping a couple times on the way home today to get voltage readings at various levels of battery temperature to see if I can confirm that BLU is signal for battery temp.

I could just buy a new set of fans for $300, but it really seems undesirable that the stock fans slow down to 10% when you're at a stop light. I'd much rather engineer a solution where they run at whatever speed is necessary based on battery temp and ignore the vehicle's speed.




my view of the fan.. i would look back at every light and occasionally while at speed. I also experimented with turning on the cabin AC. it never once spun up.

 

Why on earth would they put that logic into the fan? Ford would be the ONLY ones that do it. The link you provided confirmed that the temperature reporting is NOT wired to the fan, so I'm not sure why you keep asserting that it is.

Have you tried it with the A/C running? With A/C off, you're not giving the battery it's most important life-extending resource - chilled air for battery cooling - the key reason why the FEH battery has been as reliable as it has been.

I don't know what the FEH logic is, but if your T_in value isn't significantly lower than the battery temperature, it may not attempt to cool the battery. I can tell you the Prius will NOT run the fan under any circumstance if the INLET temp registers higher than the battery temp.

Try giving it some cold air from the A/C to actually cool the battery. If you're dealing with 90°F+ ambient, it's likely the T_in value is the same as or higher than the battery itself.

Here's a good philosophy for hybrids:

"If the driver and all passengers are NOT cool and comfortable, the battery is being damaged."

 

Sorry for the misunderstanding. I hadn't meant to imply the fans were reporting the temperature.. only that they are reacting to it. Though, i do agree that it's bizarre to put all that logic onto a fan. Even more absurd is that there are two fans and each of them have their own. Though, this does help to explain the ridiculous price of $300 for 2 small fans.

Yea, i tried turning the AC on/off at various times throughout the drive and it didn't have an effect on the fans.
Good point on the temp comparison param for engaging the fans. The cabin temperature was around 85F and that the fan compartment was disassembled and exposed directly to the cabin atmosphere. All should have been well even if that param check exists since 85F is significantly better than 105F

On the way home today i'm going to stop periodically to measure the voltage on BLU to see if it truly is tied to the battery temp.
On a similar note after i get home i'm going to install some back probes so i can measure the other 2 signal lines to see if one of them is tied to the vehicles speed. I'll share my findings once i have them.

 

The fans aren't reacting to temperature. They are reacting to the computer telling them how fast to spin based on the computer's thermal management rules.

Those "small fans" are very powerful for their size, and they have to be extremely reliable. $300 is pretty much on par with the industry. The Gen2 Prius is a very simple fan. It's larger, but has far less circuitry, and it's about $230 MSRP.

IMHO, the blue starting out at near 0V with the battery "cool" vs. 12V when the battery was warm was the PWM signal increasing it's duty cycle to command the fan to run at near max speed. Your VM isn't sensitive enough to see the pulses, so it's reading an "effective" voltage. I would conclude your fan(s) have failed.

I would expect continued operation will throw a code related to cooling.

 

I also agree the fans have failed. I was rather sure of that before starting this project (which is why i wasn't too concerned with wrecking one during the experimental disassembly). The fans have been broken since before i bought the car a 3 weeks ago. it's pretty safe to say that there isn't a related code for the failure.. though i think there should have been one added. Sadly, I can drive without any fans connected at all and there are no codes thrown. The only observable behavior is the lack of full EV once the battery time rises above the threshold.

The project at hand is to buck the standard trend of simply spending 300$ to replace a relatively common-fail part. Rather, I'm trying to determine what information is available at that connector so that i can create my own fan that costs significantly less and doesn't spin down when the vehicle slows.

 

Unless you're using more advanced diagnostics, it's not safe to say there are no related codes. If all you're using is Torque and a bluetooth OBDII reader, there are LOTS of codes you can't read. Get Forscan, preferably with a MiniVCI cable and a laptop.

IS YOUR WRENCH LIGHT ON?

Fan failures are NOT common, but they do happen. One shouldn't expect infinite life from any component, particularly when you have no history with it, and you're starting with something 11 years old and likely well over 100K miles. You are not likely to come up with a better solution if you assume that your time has any value. You've already wasted a lot of time and are no closer to a solution. You've also concluded that you can build a better mousetrap than the Ford engineers who designed it. The FEH has one of the best batteries ever made due entirely to its cooling system. If you want continued reliability, replace the fans with stock units and be done with it. I don't get the impression that you have an in-depth understanding of the workings of the FEH system, nor do you project competence in the skill set necessary to improve on the best hybrid cooling system ever made.

I recommend you run with the A/C full time. Battery temperature codes tend to occur after the car confirms on multiple occasions that cooling is not effective, i.e., for a given set of conditions (ambient temp, battery inlet temp, fan speed and battery temp), the battery is not cooling as expected - this can be pretty fuzzy. By running the A/C, you are ensuring the source air is VERY low temp, and the car should be able to figure out. Also, drive a little more aggressively than usual to insure the battery is generating some heat. If your wrench light is on, then you already have codes (that you can't read with torque).

 

You sure are an aggressive fellow, aren't ya? I attempted to be tactful in my replies to your aggression, but my patience has waned. I intend on continuing with my little experimental project since I find it to be fun and interesting. It seems you might want to unsubscribe from the thread in order to prevent some sort of meltdown.

This isn't intended to be a project that i expect many other people to embark on since simply buying the stock fans is the way most people will go. However, now that these cars are depreciated to the point that they're practically free, there will be people acquiring them that don't have lots of spare funds to throw at repairs. Perhaps they'll find this useful for their own solution.. Or perhaps they'll see it and decide to reconsider saving up and buying the stock fans. Either way, I think you can consider it time to turn your caps lock off, disable the bold button, and calm down a bit.