Power loss uphill when below 50% battery

[Alistair S]

2023 ZS EV, about 14,000 kms. I live near Wellington, NZ and drive over some relatively steep, sustained hills to and from work. I've found when below 50% battery and driving up these hills, the power output will be capped at usually 30% (but sometimes some other number) after perhaps 5 seconds of good uphill acceleration.

These are 100 km/hr roads, and when this happens I'm doing 80 km by the time I get to the top. The other day it happend in an overtaking lane with a merge coming up and I barely made it on front of the car to the left. So this is I'd say dangerous as well as poor performance.

I might expect power to be capped at 10% battery or something but not 50%. Dealer has tried to tell me this is normal.. Surely not. Anyone have experience with this?

 

[Alb]

Did the dealer do a technical investigation?

 

[Alistair S]

Did the dealer do a technical investigation?

Honestly not sure - I only got to speak to a sales type guy who wasn't very helpful. Did say they would ask MG but not heard back about that.

Just hoping to get a few comments saying no this is definitely not correct behavior to take back to him.

 

[Alb]

It certainly doesn't sound correct (perhaps a motor overheat situation?)
If a proper investigation was done the fault logs would have been checked at the very least.

 

[Alistair S]

It certainly doesn't sound correct (perhaps a motor overheat situation?)
If a proper investigation was done the fault logs would have been checked at the very least.

Ok right - yeah I'll ask for those

 

[GaryMG4]

We had something similar with our Kia Niro EV recently, although we don't have any hills in Norfolk. The car would randomly go into turtle mode and limit the power. This, it turns out, was due to a known fault with the BMS loom. A poor connection meant the BMS was (incorrectly) registering a low voltage on a couple of cells so it limited the power. Because turtle mode at low cell voltage was a 'normal' event it didn't register a fault code so it took a little while for the dealer to see and then get Kia to authorise the fix, but all is ok now.
When it first happened I did a couple of full balance charges as it was a s/h car and I didn't know it's history, that might be worth trying.
Other than that a battery health check showing individual cell voltages might give a clue. At least you should be able to demonstrate to the dealer and something like car scanner will them a real time indication of lowest vs highest cell voltage when under load.