[hacksics]

Sorry for posting PHEV problem here. But I believe this is related to High Voltage battery so it must be common to BEV or PHEV that BMW makes.

Recently I've lost electric range in my 2015-Late BMW X5 40e from average 20km to just 8km. When scanned time to time it shows cell module 1,2,3 and 6 faulty and sometime it shows only module 1 is faulty and strange enough sometimes no error!.

Therefore I believe it's correct to assume that probably not the cell modules are faulty but some electronics measuring the voltages. (SME or Cell Supervision Circuits).

In addition to this there is strange behavior when vehicle is parked after battery is around 40~50% remaining in on board computer, after few hours it rests to 0% :mad:

So to analyze what actually going on (if there's actual drop in voltages or internal battery drain) I got diagnostic reading immediately after vehicle stopped and when it resets to 0%. You wouldn't believe the results. Read below: (note: I've used ISTA-D latest version for diagnostics)

Immediately after 8km ride and when Onboard SoC is 37.5%

Actual SoC: 48.7%
Onboard SoC: 37.5%
Voltage: 357.96V
Individual Cell Block Voltages: 59.475V, 59.692V, 59.722V, 59.713V, 59.701V, 59.615V

​
After vehicle at rest for few hours

Actual SoC: 21.20%
Onboard SoC: 0%
Voltage: 358.82V
Individual Cell Block Voltages: 59.661V, 59.817V, 59.851V, 59.834V, 59.825V, 59.739V​

So I'm scratching my head off to solve this mystery (mind you that I'm out of warranty) to figure out what the actual problem is. Funny enough voltage increases by around 1V after vehicle is stopped (is that even possible? but based on individual cell block readings it seems legit though!), but SoC dropped by 27.5% if you consider the actual SoC.

So guys, have you experienced similar with your BMW BEVs or PHEVs and do you have any opinion on what's going on. I've already out of warranty so I don't want dealer to go back and forth with the car as it costs too much so any help/advice appreciated.