I'm sorry you see me as aggressive. I'm just not one to stroke a stranger's ego. I'm not hear to make you feel better about your choices if I think they're bad ideas. I'm honest and direct. It's likely that you're a bit too sensitive and took my observations as a criticism. That's on your side of the fence.

I typed ONE thing in caps, and it was to get your attention. You didn't answer. It's a very important question as the wrench isn't a maintenance light, it's a "you've got a problem" light. Ford stashed a bunch of codes under that umbrella vs. codes that turn on the CEL. The only upside of that is that a wrench isn't an automatic emissions test failure, where a CEL is. The big down side is that only some readers can pull those codes - typically only professional stuff, or Forscan.

Unfortunately, the demographic you describe is exactly the type of folks who shouldn't be buying high mileage used hybrids. High-mileage used hybrids have a very low benefit to risk ratio. Far more chance for frequent and expensive repairs than when new. As a result, any savings associated with improved fuel economy are likely going to be negated and likely surpassed by additional repair costs.

Regardless, I wish you no ill will with your endeavor even if I see nothing but headaches and failure ahead of you. Good luck!

 

Personally, DIY threads like this are the some of the best things to be found on Internet forums.

Perhaps some are forgetting that Ford's original response to battery fan failure was "It's a sealed unit - replacing the entire battery pack is the only remedy." This was obviously ridiculous and once it became clear that this was a higher than expected failure point (and enterprising forum DIY'ers started tearing down the packs to see what was up) Ford relented and issued their much more affordable but still rather steep $300 repair kit.

It remains to be seen whether the OPs investigations will yield useful results, but what's the harm? So long as he doesn't subject the battery pack to extreme conditions he should be fine.

Also I'll somewhat disagree with the contention that the robust cooling system is the reason for the admirable reliability of the Ford battery packs. It's certainly a reason but I'd argue that the extremely conservative operating range for the batteries (~40-52% SoC) was just as important.

 

Feel free to disagree, but there's a point you're missing. There is NO balancing of the cells within the pack. Thus they have to maintain 250 cells in nearly the same state of charge for their entire operational life. What do you think the likelihood of 250 individual cells all being at exactly the same SoC for their entire operational lifetime? Pretty low. What do you think the likelihood of all 250 cells each individually losing the exact same amount of charge as they sit for days or weeks? Pretty low.

What improves the above? Charging. Regenerative braking at the higher SoC range helps this because as NiMH fills, it becomes less efficient, e.g., 30A of charge to a cell at 55% SoC takes on a tiny bit less charge than a cell at 50% SoC. This is MORE effective at higher SoC - particularly around 70%. According to the OP's link, the FEH uses 35-60%. If this is true, the FEH benefits LESS from this phenomenon.

What helps the above? Cooling. Cooling helps everything. It minimizes SoC drift, it minimizes cycle damage, and it minimizes capacity loss.

So sure, reduced SoC range helps, but cooling is the holy grail.

FWIW, the exact same cells are used in the 06-11 HCH2 - the WORST hybrid batteries ever made. Their cooling design is horrendous.

 

I'm not trying to minimize the benefit of cooling, just trying to put it in perspective with the entire system. And I acknowledge your greater expertise in battery chemistry.

And I can understand the OPs reaction to your post - posting in BOLD ALL CAPS is not the best path to productive discussion, regardless of your intent.

But hopefully such raw nerves can be put aside and we can have a productive discussion going forward.

 

And I do agree that the OP, if he's not already done so, should do a Forscan check of his modules for undisplayed codes. Though for scanning, as opposed to programming, an OBDLink MX BT should be more than adequate and cheaper than a quality USB interface. I have an ELS27 in addition to my OBDLink and TBH I never use it - the OBDLink works well and is far more convenient.

 

OP, curious if you did a thorough pressure/leak test of the cooling system and A/C lines that run the length of the vehicle? These have been a point of failure on some early FEHs, as the lines can be exposed to road salt or other corrosives. As the other posters indicate, modifying/repairing the fans will likely not make up for a weak A/C system.

 

At the recommendation of keith & elborak I ran forscan and found that it did throw an internal-only code for each of the missing fans (P0A81-60 P0A96-60). Though, it still feels silly that these codes are never broadcast to the end user.

I have not done a pressure check on the AC, but I did confirm that my fans are definitely bad. A friend of mine preemptively replaced his fans a few years ago. I borrowed one of them and connected it to my car and it immediately spun up. I unplugged it and connected mine and it does nothing (switched again and his worked).

It's worth noting that the bearings in both of my fans were both perfectly fine and i could not see anything that was obviously burnt out on the board. I presume the board had failed in some way since all 3 of the windings tested ok. Each board had some areas that got a bit crusty. I'm guessing they got too warm, or perhaps it is just flux remnants from when they were made. Either way, the crusty schmoo doesn't seem to be conductive.

 

Did some testing today:

• RED - constant 12v
• BLU - is not a pwm line. Rather, it is 0v when the fans should be off and a constant 11-12v voltage when the fans should be on.
• TAN - is a 200mv pwm that signals the fan speed. It is affected by battery temp and possibly vehicle speed
• YEL - I have yet to see a meaningful reading on this line. It doesn't appear to be pwm. Its around 2khz 180mv in EV and around 7khz 280mv with ICE. It might react while driving, but i was testing by myself so i couldn't use the scope while moving. Maybe i'll recruit the wife to drive tomorrow.

The fans turn on at 75F.
At 90F they begin to increase their base speed and continue to increase in speed until 100F.
Once the battery exceeds 100F the car will not go into EV mode.
When under 25mph, the fans will spin 10% slower when in EV mode.

Here's a breakdown of TAN's pwm and the current draw on RED. These are all at 0mph (had to turn off car and put key in ON position to read EV at over 100F)

As you speed up, the fans will increase in speed as well. All temps over 90F will be at 100% fan when over 25mph. Here's the breakdown when at 93.4F when in EV:
1.8A - 0mph
3.2A - 10mph
6.7A - 25mph

The highest reading i saw throughout the testing was 6.7A, even when going 60mph at 100F. I presume this is the max value.


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My plan is to re-use the motor itself and simply replace the controller. I disassembled one motor nicely by desoldering. The other motor ended up getting its leads broken so i'll unravel 1 wrap from each winding so they're all even and all have enough slack to tie into. For the controller I'll likely give one like this a try to see how it goes. I'll omit the potentiometer and just wire it to be 100% speed. I think it might work to omit the pot and wire TAN to the pot's center pin to retain the car's former speed control. Though, since i always have music playing anyway, it seems preferable to just run 100% and have stronger cooling.

To make it so that it doesn't always run, I'll wire in a relay based on the BLU wire and situate it ahead of the controller. This way the fan should always be running 100% whenever the temp reaches 90F and will turn back off whenever it cools back down.

 

Nice sleuthing.

Just a reminder... You can bypass the need for any supplemental controller by running the A/C and giving the battery cool inlet air instead of relying on high ambient temps.

Harking back to post #5:

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

 

While both of those points sound good, I don't think either one is actually correct.

>>You can bypass the need for any supplemental controller by running the A/C and giving the battery cool inlet air instead of relying on high ambient temps.
The fans contain a brushless DC motor that has three-phase coils. A controller is absolutely required in order to make the motor spin. Though, if you meant 'supplemental' as in additional logic on top of the required 3ph logic then I'm not sure what you're referring to since I haven't proposed using any kind of enhanced controlling. Rather, my proposal is entirely based on making a solution that removes the enhanced logic from the stock system.

As for running the AC, well that is impractical during winter when the blend door opens to use external air instead of cabin air. Aside from that, as far as i know, the AC is split into 2 systems. The battery portion can run without engaging the cabin's ac. The battery portion turns on automatically based on battery temp.. so why would I ever bother to force the battery AC on by making myself suffer the effects of the cabin AC? It's also worth pointing out that the battery AC has zero impact if the fans aren't running since there wouldn't be any air passing over the exchanger.

If the driver and all passengers are not cool and comfortable, the battery is being damaged.
The fans for the battery never have a situation where they pull from the cabin air. When the blend door is closed, the system is completely sealed and just cycles the air in the sealed battery and passes it over the heat exchanger. This entire air path is sealed by gaskets to avoid mixing with cabin air. During winter, when the door opens, it pulls air from the exterior of the car, but still restricts the air to the sealed battery passage (otherwise you would freeze in the cabin). The temperature in the cabin has an extremely minimal effect on the temperature of the battery during cooling stages.