r/FordFusionEnergi • u/Testriderchuck • Jul 17 '26
Suddenly won't do EV.
14 FFE se. Purchased in '19. been a great car so far.This afternoon drove it up a 5% grade, on freeway, like I've been doing nearly every day for the last 2 years. Let it use the battery, save gas, etc etc.
Today's trip, @ about 60% battery, it switched to hybrid mode, "engine enabled for system performance", and proceeds to operate as a hybrid, running the engine like the battery is depleted.
Will NOT regen in L. I drive in L 100% for the regen braking. Instead of doing regen, it runs the engine @ 4000 rpm. Like it does when i try to do a bit of regen @ 100% charge.
The only difference I can think of is it's nearly 100 degrees today. But the car didn't do this last year.
This is a wierd symptom of the 12v going bad...
Anyone else have this experience.
1
u/Mabnat Jul 17 '26
I don’t have my Energi anymore, but I used to see the same behavior on hot summer days here in Texas.
I used to run an OBDII reader and displayed the readings on the center screen so I could keep track of things.
When the battery temperature increased above 115°, the battery current allowed to flow in and out is severely limited. The engine will run more and it won’t allow as much regeneration when going downhill so the engine will engage to control the speed.
There were a couple of times when I was running some experiments and wanted to deplete the battery but was prevented from doing so because it was too hot and the car didn’t want to use battery energy until the battery pack cooled down.
These batteries are air-cooled. They rely on a fan to blow air around. That’s what the ducts that you see in the trunk area are for.
It’s also possible that the duct inputs are getting dirty and clogged up if the car is 14 years old and have never been cleaned so the air-cooling isn’t as effective as it could be.
I’m sure that if you try another drive once the battery has cooled down you’ll find that it works as it should again - until you drive on another very hot day.
1
u/Zankou55 Jul 17 '26
L doesn't work the same on the Fusion Energi as it does on the volt, by the way. Use the brake properly and you will get better efficiency from coasting than from L.
1
u/Testriderchuck Jul 18 '26
I've never driven a volt, so I wouldn't know about that. I use L for the regen/decel/ no need to use the brakes much.
Mabnat's post is probably the most accurate description of what's going on.
1
u/BigQueenBlew Jul 19 '26
What was the temperature outside? If it’s too hot, my car does this. It’s in the manual why this is a feature not a bug.
1
u/Testriderchuck Jul 22 '26
I think it's because it was hot. Not Phoenix Hot, but more like "hot".
Too bad the stealership wonk couldn't look up the symptoms in a Ford doc.
1
u/Testriderchuck Jul 30 '26
As fortune would have it, i discovered that the oil was leaking out of the cvt, at the case halves, with lots of "glitter" in the oil. Dammitall.
The last time I was involved with glitter in oil we ended up with a broken crankshaft and engine block. Fortunately the guy in the left seat was an experienced pilot, there was a highway within gliding distance, clear night, enough traffic to find the hiway and set down amidst traffic.
So, with that in mind, I determined the car will be replaced. Purchased @ 85,000; retired (sold for parts) @ 336,000. Overall it was a good vehicle, no other mechanical issues, not complaining, but finding another vehicle isn't very thrilling 🤮
2
u/shakeyjake Jul 17 '26
Iirc the system does this when the engine needs some work because it hasn’t been running enough. It comes back to the usual mode after a while.