I have a US build 2022 "Defender SE Ingenium 3.0 liter 6-cylinder 395 HP Turbocharged Gas MHEV". I copied this image from the related P400 battery thread and I'm hoping someone can provide a bit more insight as to how this thing works. I can easily sense an energy harvest when lifting off the accelerator. However, never in the 2+ years of ownership has the vehicle engine stopped while on the move when braking below 3 mph. In fact, quite a few times, the engine will remain running even at a stop even though the auto stop/start is active. Is there something that has to be configured? Or worse, an indicator that I've had a problem with the MHEV system since I took delivery?

 

POPTOPP: what you describe is the behaviour of my P400 and that of a few others I have sampled. I am left wondering how often the system is even active as it wouldn't take much to deplete the very small 48V battery... If you listen carefully you can hear the electric supercharger when it is active, not very often in my case - I think most of my 48V battery is used up with the constant start/stop cycling (I have yet to try disabling start / stop to see if I get the super more often). It's plenty fast enough as is so not a priority. Start / stop will be over-ridden in cases where cabin temp needs addressed via heat or AC, or if state of charge is getting low enough not support continued start-stop cycling, etc. . .

 

I traded my 2019 Audi Q8 for a 2024 Defender SE (V8). The Audi had the MHEV and never really understood what it did, beyond the start/stop function. All the Audis with the MHEV, A6, A7, A8, Q7, Q8, RSQ8 have a belt starter generator(BSG) associated with the system. That BSG has been failing without warning, leaving driver's stranded. Audi extended the warranty on the BSG to 7 years/unlimited mileage. Seems like most of the failures occur around the 40,000 mile mark. Some have had a second failure after Audi replaced the BSG, indicating they do not have a permanent fix.

Mercedes uses a different system and I have not heard of theirs failing.

Not trying to be an alarmist. I am not a fan of MHEV.

 

l've driven other MHEV and they had
a display to tell you what was happening with the battery and power distribution.

Even the Suzuki lgnis MHEV (a small, cheap car) had a display showing MHEV battery status and whether it was charging or assisting.

My Defender D250MHEV has nothing. No indication of what's going on. Is it working? l
have no idea.

The stop/start works. So l assume the battery is okay. But apart from that l have no idea.

 

I was under the impression that the 48v battery was only used to spin up the turbo so there wasn't the typical lag with you depressing the pedaland the turbo engaging. It doesn't actually move the vehicle.

 

I was referring to the 2nd behavior described: "Driver presses brake pedal - as the vehicle speed drops below 3km/h, the engine stops on the move..." My auto stop/stop has never engaged before a complete stop.

 

Same here - mine does not shut off when the speed drops below 3km/h as that marketing material above indicates. The engine only shuts off when I'm at a complete stop, ie 0 mph/kmh. I would have noticed this !

 

Sorry I wasn't more clear/reassuring. I have never experienced an engine stop unless at a full stop (3km/h is between 1-2mph which is close enough to a full stop!)

 

That does make sense, thank you.