Electric battery needs replacing at 100,000 miles??

[Sarah]

Hi,

 

I recently bought a Ford C-Max Energi

I had a yellow wrench signal come one, so decreased power though. When I turned the car off and back on it had gone away. I took it to the mechanic and they read the error code (P0dd6) and said one that indicates one of the batteries needs replacing but they couldn't tell me which one although they think it’s the electric one. Is there any chance this is a weird glitch that a software update might resolve or maybe the 12v battery needs to be replaced? Nothing has happened to the car and it isn't acting weird except that light coming on one  time. It also only has 102,000 miles on it which seems really odd for the battery to die that young. I'm a student without that much extra cash on hand. Any tips or advice would be greatly appreciated! Is there any way for me to find out if the electric battery actually needs to be replaced without paying a large fee to have a ford dealer look at it? And if it does and it's not some weird glitch, is there anyone who fixes ford electric batteries? I definitely can't afford a new one... Anyway this is all super stressful for me. 

Edited August 15, 2020 by Sarah

[plus 3 golfer]

P0DD6 - Hybrid/EV Battery Cell Balancing Circuit "K" Stuck Off.   Your High Voltage Battery consists of 84 individual lithium ion cells.  The 84 cells are grouped in 14 groups of 6 cells per group.  PDD6 indicates Group K was "stuck off" meaning that group of cells will not be balanced if it would be stuck off prospectively.  However, since in only happened once, I wouldn't be concerned and besides there's really nothing to do.  It may simply by a one-off anomaly and never happen again.  Below is an excerpt from the Ford 2017 OBD System Operations Manual for HEVs on cell balancing.

 

Cell Balancing:
Individual cells can deviate over the life of the high voltage battery. The purpose of cell balancing is to equalize the
individual cell charges. By balancing the cells the high voltage battery maintains top efficiency. The BECM
continuously monitors individual battery cell voltages and will perform balancing automatically only when required.
When balancing is performed BECM discharges individual cells with the highest voltage to match the remaining
cells.
 

Monitor execution:  At a power up before contactors are closed, and two consecutive power cycles.

[Sarah]

@Plus 3 Golfer Wow, thank you so much! That answer really called me down. If it does happen again, what would that mean/ what should I do?

[plus 3 golfer]

If the cells are never balanced in a group, the strongest cell(s) in the group will be overcharged and the weakest cells in the group will be undercharged.  Over charging cells lead to premature aging (faster loss of storage capacity).  Also, as the battery pack is being discharged, the weaker cells could be discharged below their minimum operating voltage which could lead to failure. 
 

The BECM monitors voltage variances among cells in the group and will set a DTC should the voltage exceed limits.  So, if cells never get balanced, my guess is that eventually a DTC would be set for voltage difference exceeded.  So, until one sees these DTCs, I doubt again there is anything to do. 

Edited August 15, 2020 by Plus 3 Golfer

[KW59715]

Hello all - I'm hoping you can advise, as I have a similar issue.

I had issues last winter with my 2017 Cmax Energi. It ran fine on the electric engine, but seemed to have trouble switching to the gas engine for passing, or when the electric charge ran out. It also chugged a bit when on the gas engine and I turned the key to shut off the car. It was worse in cold weather. I got the wrench light and took it to a mechanic who drove it around a bunch and couldn't get the light to come back on. So, I kept driving it, and noticed it still had a lag in getting the usual oomph when trying to pass, but otherwise charged and drove well. This winter, the probaly started early, when temps really weren't that cold (by Montana standards). The same issue with switching to the gas engine and chugging when turned off. The wrench light came on, then the engine light, and that stayed on. I took it to the dealership and they tell me I need a new high-voltage electric battery, to the tune of almost $8K. There is 108,000 miles on it, so I'm told it's out of warranty for the EV system. Any advice? Is it worth taking it somewhere for a second opinion (there aren't many mechanics here that work on EVs.)? I don't know if the car is even worth that. It seems the issue is switching to the gas engine, so could it be a different problem?

[JohnTrigger]

You need to find out what the check engine codes are, as it could be many problems.  Ask the dealer what they were or better yet take it to AutoZone or the like to have them read the codes.