Leaderboard

7.6kwh is the full plug-in+hybrid capacity. In reality ~5.5kwh is the plug-in portion and this is what the capacity would be brand new. As a used vehicle, it very likely could be lower by now due to normal battery degradation and depending on how the previous owner drove it. The miles listed should not be relied on as it is not an accurate indicator of real battery capacity. The vehicle guesses this number based on a number of factors like recent driving habits, ambient temp, climate usage, etc.. If you want to determine the real battery capacity, do the following steps: 1) Fully charge the battery. 2) Drive the vehicle in EV mode. If in a colder climate currently try not to use heat. Anything that will force the ICE to be started will invalidate these numbers. Things that can do this are full WOT acceleration in EV Auto, high climate usage in low ambient temperatures, or using defrost (The vehicle will choose defrost in Auto mode on the climate control if it is under 32f outside, as an FYI). 3) Once the plug-in charge has been depleted and it drops into hybrid mode (ie: The battery display on the dash no longer shows the miles and switches to the 'flat' battery display), stop the vehicle somewhere safely and shut it off. The trip summary on the left screen will show the kwh used and that should be the current real capacity of the battery. Generally speaking anything over 4kwh is still good. 3+ is 'ok' but getting degraded. ==== Regarding your other notes: Regen braking is always active. Even if the plug-in charge is depleted and it is oeprating in hybrid mode. The hybrid mode still cycles the battery under normal operation as that is one of the biggest improvements in fuel economy. Regarding replacement packs, I couldn't tell you off the top of my head. I know there's a few companies who offer refurbed packs but don't have names. I can tell you that to the best of my knowledge I haven't seen anyone yet confirm they've pursued replacements that were not done under warranty (this is VERY rare in itself. Ford doesn't warranty any level of degradation, just outright failure which most owners have not run into).

To be clear, my 2013 never failed, but I traded it in at 66K miles. My lack of faith was bolstered by results of an early C-Max life test, service records attached, where 3 of 4 Hybrids, and 0 of 4 Energi's, had transmissions replaced at ~100K miles, in severe service. I can no longer find the data online, but can offer the attached for your perusal. For reference, the service records for many other hybrid/plug-in/electric vehicles in these tests went on for pages. There's very little C-Max service that's not replacing wear-out parts. And you may have the 4th hybrid, whose transmission will last. (Energi's have an electric oil pump.) IDL data 2013cmax HEV PHEV.zip

Very likely the battery is failing under high load and the car is falling back to hybrid mode as a safety. Probably have at least one or more cells that are seriously degraded and are falling below a given voltage threshold under load. No different than a dying 12v battery under engine starting conditions on a traditional ICE only vehicle. Pulling codes when this happens could help confirm this, but that is my educated guess what is happening. High EV load climbing a hill with the heater going is going to be a significant load on the battery. Do you follow the recommended battery management tasks many owners have already laid out and recommend? These vehicles unfortunately have poor management of the battery by default in 'Auto' mode and do require manual intervention to help maintain them and prolong their life. Here's a short abbreviated list of recommended tasks to prolong the battery life. It's not exhaustive and there have been a plethora of posts covering this not only here but on other sites that you can seek out: 1) Never drive in Auto/EV Now mode above ~50mph or so. Switch to EV Later. 2) Never use Auto/EV Now on the highway/freeway. Switch to EV Later. 3) In the winter if it is extremely cold and you use cabin heat, you may wish to start in EV Later and let the ICE do the bulk of the work to heat up the car. Once the coolant temp gets high enough that you see the climate use drop to 0, then you can drop back to Auto. You may even want to wait until the cabin reaches temp and the HVAC fan slows. The heaviest load on the battery from the climate system is trying to warm the coolant from low ambient temps. Once the ICE has done most of the work, just maintaining the coolant temp on battery is a low enough load to not be a huge issue. 4) In hotter weather especially if you live in a hotter climate like Arizona or South Florida, monitoring the battery temp is crucial. The battery is air cooled and even then it does a piss poor job at it. Even with the A/C going full blast, it makes little change in the battery temp. Once the battery temp gets above 90 or 100f, EV Later/hybrid mode should be used. The vehicle won't give you the battery temp by default, you'll need an aftermarket tool to view this either in the form of something like a ScanGauge or using a mobile app like Torque or ForScan with a cheap Bluetooth OBD dongle. As an addendum on the charging side: During hotter weather, you may want to set up charging to only occur overnight when the temps are cooler. The battery has ZERO cooling while charging. The fan you may hear is just for the the actual charging module and not the battery. Value Charging is often used to set the vehicle to start charging at set times. You can also find EVSEs with scheduling capabilities or use simple outlet timers (as long as they can support the amperage pulled by the vehicle).