Lost all regen (again).

[15Peter20]

Second time this has happened. 75% SoC, 8 C ambient. Under such condictions I’ll normally have a ‘limited regen’ message but there will be about 25% from the start, building throughout my journey.

Tonight: zero regen for the whole journey and limited max power. Tried navigating to a SuC to warm the battery but nada.

Zero regen is pretty unnerving. The car just wants to keep rolling.

Both occurrences have been after I’ve been stationary in the car with the heating on for half an hour or so. I wonder if the heat pump is cooling the battery excessively or pushin a temp sensor into error.

Service booked.

 

[NorfolkMustard]

I was going to ask if you had a heat pump. Definitely a possible cause based on what I’ve seen.

It scavenges heat from the battery coolant if it’s not warm enough outside.

 

[15Peter20]

I was going to ask if you had a heat pump. Definitely a possible cause based on what I’ve seen.

It scavenges heat from the battery coolant if it’s not warm enough outside.

Indeed. I’ve watched a couple of ‘Bjorn goes camping in -20C’ YouTube videosand assume he would have noted if this was happening however.

Forgot to mention I tend to remotely turn climate on about 20 mins before I leave work which normally preheats the battery.

 

[15Peter20]

.....and 321, back in the room.

Slightly colder this evening, no preheat and yet regen was partially available from the beginning, increasing throughout the journey.

Either a remote fix or it is connected with the short ‘camp’ using the heat pump yesterday.

 

[Dangerous Fish]

Zero regen, as in exactly the same as if you put the car into neutral and coast?

 

[Jason71]

not something that was reported until recently so I am thinking this is may well be a 2021/heatpump "feature"

 

[SSonnentag]

Bjorn's recent video indicates that the heat pump is scavenging too much heat from the battery pack. This causes slow charging, reduced power, and in your case, reduced regen. I'm betting this will be addressed soon in a software update.

 

[15Peter20]

Happened again and seems to have properly broken now. 22 Celsius air temp and zero regen For the last 2 days.

It also doesn’t appear to be charging from my wall connector even though the display, smart meter and Teslafi show 7kW. Worrying about where the hell that 7kW is going (well, heat I guess).

It also limited max power until I pointed it at a SuC and let it precondition.

I’m guessing it’s a battery temperature sensor issue.

 

[Dangerous Fish]

Happened again and seems to have properly broken now. 22 Celsius air temp and zero regen For the last 2 days.

It also doesn’t appear to be charging from my wall connector even though the display, smart meter and Teslafi show 7kW. Worrying about where the hell that 7kW is going (well, heat I guess).

It also limited max power until I pointed it at a SuC and let it precondition.

I’m guessing it’s a battery temperature sensor issue.

Its not zero regen though is it? Have you compared it to being in N?

 

[15Peter20]

Its not zero regen though is it? Have you compared it to being in N?

Oh it’s zero alright, the car just coasts on lifts, no different to neutral. The entire left half of the power bar is dotted.

Edit to add: the behaviour is slightly different to the previous two times this happened. Both those times regen was severely limited and never approached a decent value. This time is has gone completely and doesn’t make any showing at all regardless of journey length, SoC, ambient temp.

 

[Dangerous Fish]

Oh it’s zero alright, the car just coasts on lifts, no different to neutral. The entire left half of the power bar is dotted.

Edit to add: the behaviour is slightly different to the previous two times this happened. Both those times regen was severely limited and never approached a decent value. This time is has gone completely and doesn’t make any showing at all regardless of journey length, SoC, ambient temp.

So you can shift from D to N to D again at say 10mph and there's absolutely no change at all? What SoC is this at?

 

[Cardo]

Sounds borked. I’d be getting that booked in.

 

[15Peter20]

So you can shift from D to N to D again at say 10mph and there's absolutely no change at all? What SoC is this at?

Yes, and it is impressive how little rolling resistance these things have! Makes it surprisingly difficult to drive. SoC has ranged from 90% down to 60%.

It is booked in for service. Trouble is that I can’t get a loaner for a fortnight so I either need to use it as-is until then, ie inefficient and without being able to AC charge meaning trips to the SuC, or do without a car which isn’t ideal.

With luck the SC can do a remote reset to keep me going until I can get a loaner.

 

[AndrewGR]

If you are lugged into your AC charger and you are definitely consuming 7kW, what does TeslaFi say is happening to the SoC? In my experience it reports the same SoC as the car displays. If you are consuming 7kW for any length of time without increasing the battery SoC, something will be getting very hot!

 

[15Peter20]

If you are lugged into your AC charger and you are definitely consuming 7kW, what does TeslaFi say is happening to the SoC? In my experience it reports the same SoC as the car displays. If you are consuming 7kW for any length of time without increasing the battery SoC, something will be getting very hot!

Teslafi shows 7kW input but, as you say, agrees with the car SoC and shows no net gain in charge. I left it unplugged last night as a precaution. Of course the weather has warmed up just as I’m trying to work out whether the interior feels warmer than normal!

edit: wow, lost 16% overnight. Sentry off. Teslafi showing huge amounts of battery heating.

Anyone know a quick way to look at the battery's measured temperature? I only have Teslafi.

 

[Jason71]

Yes, and it is impressive how little rolling resistance these things have! Makes it surprisingly difficult to drive. SoC has ranged from 90% down to 60%.

It is booked in for service. Trouble is that I can’t get a loaner for a fortnight so I either need to use it as-is until then, ie inefficient and without being able to AC charge meaning trips to the SuC, or do without a car which isn’t ideal.

With luck the SC can do a remote reset to keep me going until I can get a loaner.

you might not get regen on an ice but you do get engine braking so with no resistance at all I guess it would feel a bit wierd compared to anything we are used to driving

 

[kelvin 660]

By accident I went into neutral whilst driving. It was really odd as the car seemed to keep accelerating when I took my foot of the brake pedal... Very odd experience. I've never had anything like that in all my years of driving...

 

[15Peter20]

By accident I went into neutral whilst driving. It was really odd as the car seemed to keep accelerating when I took my foot of the brake pedal... Very odd experience. I've never had anything like that in all my years of driving...

Yeah, it's an odd sensation. I think it is because you expect one thing, especially based on ICE or normal regen experience, but perceive another.

Similarly, if you've ever used the Mercedes speed limiter function: you accelerate hard up to the target speed at which point the car stops accelerating in order to hold at the speed target. The sensation, however, is briefly that the car is actually decelerating.

I've done a lot of work with racing car gearshifting: if you automate an upshift the driver, without exception, complains that the shifts are harsh, even though the actual disruption is the same whether he commands the shift manually or it is automatic, it's just that he isn't requesting the shift himself which skews his perception of how things should feel.

 

[Dangerous Fish]

Yes, and it is impressive how little rolling resistance these things have! Makes it surprisingly difficult to drive. SoC has ranged from 90% down to 60%.

It is booked in for service. Trouble is that I can’t get a loaner for a fortnight so I either need to use it as-is until then, ie inefficient and without being able to AC charge meaning trips to the SuC, or do without a car which isn’t ideal.

With luck the SC can do a remote reset to keep me going until I can get a loaner.

Hmmm. OK well apologies it does sound like you have a hard fault there, particularly as you seem to have charging issues too. We do see a lot of comments from drivers who have limited regen for whatever reason and think it's zero. Once they take the 'neutral test' they see what no regen is really like!

With an ICE car there are a lot more frictional losses in the drivetrain and I doubt manufacturers make massive efforts to reduce that because they won't have such a big effect on the fuel economy figures (which they probably fudge in any case). With an EV it's so important to reduce the frictional losses wherever possible, so put one into N and it doesn't feel like it's slowing down at all to most people used to an ICE car in N.

There's no easy way to get temperatures AFAIK unless you put an OBD adapter and Scanmytesla in. You can get some temps in track mode but I don't think it will tell you what you need to know.

 

[15Peter20]

Hmmm. OK well apologies it does sound like you have a hard fault there, particularly as you seem to have charging issues too. We do see a lot of comments from drivers who have limited regen for whatever reason and think it's zero. Once they take the 'neutral test' they see what no regen is really like!

With an ICE car there are a lot more frictional losses in the drivetrain and I doubt manufacturers make massive efforts to reduce that because they won't have such a big effect on the fuel economy figures (which they probably fudge in any case). With an EV it's so important to reduce the frictional losses wherever possible, so put one into N and it doesn't feel like it's slowing down at all to most people used to an ICE car in N.

There's no easy way to get temperatures AFAIK unless you put an OBD adapter and Scanmytesla in. You can get some temps in track mode but I don't think it will tell you what you need to know.

Yeah, many thanks for your replies. From Teslafi I think it's clear that the battery thinks it is cold (no regen, constant battery heating), so I'm guessing a thermistor failure(s).

I'm booked in for a service now anyway, so hopefully it will get resolved. I'm just a bit concerned that any further driving could overheat the battery enough to reduce its life. Unless it's a heat pump fault and it is genuinely sucking the battery temperature down and dumping the excess heat to the outside.