SnowStorm

Our 2013 hybrid (not Energi) is past 246k miles and is doing fine. There are others with similar mileage and no problems. I expect to keep it another 10 years - although it won't get a lot of extra miles. The HVB (high voltage battery) is simply not a problem in these cars.

I thought you could force the ICE to run by pressing (flooring?) the accelerator while parked.

Do you plug it in at night to charge the main hybrid battery? If so, that might keep the 12V charged too (I don't have an Energi so don't know the answer). Otherwise, you should be able to connect the tender to the two posts under the hood (driver's side) where you jump-start if the 12V is dead.

Well, I keep seeing this complaint about the turning radius but even after 245,000 miles and almost ten years I could hardly care less. I'm not even sure I would have ever noticed it if I hadn't read about it on this forum. We all have different things that annoy us and different driving/parking situations but for most folks it shouldn't be a significant issue. I sure wouldn't let it rule out selecting a C-Max over another car.

I don't have an Energi model and have no experience with the TCU but here are my thoughts based on the understanding that the car has a 12V battery drain problem somewhere. There could be a drain somewhere else - replacing the TCU wouldn't help. The dealer may not know about it, simply sees that the TCU is out of date so says you should replace it. You should find out exactly what is happening with the 12V battery over time. Get a voltmeter and a jump starter (the small lithium-ion ones are great). Use the 12V "jump-start" posts under the hood on the driver's side. (You can also plug the voltmeter into the 12V jack in the back since it doesn't turn off.) When the car is ON (Ready-To-Run), you should have over 13VDC - the 12V battery is being charged by the DC-DC converter. When the car is OFF the voltage will be below about 12.8 volts. Check the voltage with the car OFF, first in the evening and again in the morning. If there is a drain, it will go down a lot. A 12V battery is considered fully discharged at 10.5 volts but it might go a lot lower than that and the car will still turn ON. I've seen mine down around 4 volts! Of course at that point you have to use the jump starter. You should have the 12V battery load tested and replaced if it fails. (Be sure the mechanic knows how to reset the battery age counter.) You still need to perform the above step or you may end up eventually ruining the new battery. Repeated discharges of the battery to a low level will damage it. Can't the TCU be simply unplugged if it is the culprit? I understand its no good anyway with 3G dead. You can also get the Forscan software and a compatible OBDII adapter and investigate lots of codes and issues that way if you want to get into the guts of everything. I would think using a trickle charger should also keep you operational but still keep the jump-starter in the car when away from home.

These cars are fantastic in winter - you'll waste money staying with ICE. As mentioned, ICE only runs as needed to keep you warm, not generate gobs of extra heat to dump into the environment. We got caught in a snowstorm in Wyoming, spent the whole night 'sleeping' in the car, stayed very comfortable and only used about 0.7 gallons. The ICE only runs about a minute out of ten. its wonderful. Seat heaters are a great help too - try and find one with that option. Use recirculate as much as possible (when humidity isn't too high to fog things up). Its true that gas mileage goes down in winter but with an ICE car its "down" all year!

Interesting, as that appears to be the problem with the early transmissions with transfer shaft failures. Mine failed, I tore down the old tranny and what appeared to be a pressed on ring had slipped which then allowed the shaft to move sideways causing the problems. My 'pet' theory was that a software glitch caused a severe jolt after a long down hill run using engine braking and that jolt drove the ring out of place. (It was quite an awful noise when it happened.) Or, it was a design or manufacturing problem. I suppose any of these could be aggravated by too much heat but I would doubt that heat is the root problem - if at all. I think there are a number of posts where folks have tracked transmission temps under various conditions. You can certainly get the data with Forscan. For me, I'll never use engine braking again!

Slight correction: the transfer shaft is directly geared to the differential so only turns when the car is moving. When sitting still with the ICE running, the only things spinning are the planetary gears and one of the electric motors (and I guess the oil pump) so your sound would be from one of those. If yours is truly out of fluid, its more likely due to a leak as described in TSB 15-0174. Read about it here. Maybe fill it with fluid and see what happens - see where the leak is???

Forget about that plug on top. I used the check plug hole on the side as described here. Turn the wheels full left then reach in front of the left tire, pull up a mud flap and you can see it. A bit cumbersome but not that hard.

What happens when you try the link? It still seems to work for me. It should go to: https://ford.oemdtc.com/1696/15b04-12-volt-battery-test-and-module-software-update-2013-2014-ford-c-max

If it hasn't been done (I doubt it), see if your dealer can perform CSP 15B04 - read it here. It seemed to clear up dead 12v battery problems for a lot of us years back. It does sound like you may be having overnight 12V battery drain issues. A good (or new!) battery can be drained beyond full discharge (below 10.5 volts) when the problem occurs. I once saw mine down around 4 volts! You can charge it back up and it may load test OK but keep doing it and the battery is progressively degraded. What happens when you try and start the car depends on how low it went. If it only went down to maybe 8 volts (?) it might still start with you unaware of what happened. Or you might have some errors. At some point the car won't start and has to be jumped. You might get a cheap voltmeter and plug it in the 12v jack in the back (it doesn't turn off). Check it often and see what is going on.

In my opinion, the compressor always sounds noisy from outside the car.

If it hasn't been done (I doubt it), see if your dealer can perform CSP 15B04 - read it here. It seemed to clear up dead 12v battery problems for a lot of us years back.

Here's my answer to oldbeyondmeasure's post about charge efficiency. I did not include charging efficiency - I haven't taken any measurements. 70% seems quite low but I did see an undocumented article saying efficiency could vary between 70 and 90 percent. Another article here references an EPA document that indicates the charge efficency for a Tesla Model Y at 88%. That would make my cost about 3.4 cents per mile. You should see if you can get lower electricity rates at night - so called time-of-use charges.

This topic is for discussion of charging efficiency, that is, the total energy needed to charge versus that used to run the car (energy out of the battery).