Had the same thing a couple of years back with same message, was the start stop battery that went flat, but often burns the alternator out when it happens (According to local garage).
When my stop start battery failed, Tayna did the stop start at half the price of ECP, I ended up replacing both batteries for about £170 and the alternator was about £250. It's probably double that now with inflation. I also bought a BMS module off ebay for £27 just in case.
I got the garage to swap the alternator as you have to jack the engine up to get it in and out and couldn't be arsed to do it, they charged 3 hours labour. I am fairly sure they never reset BMS and I had no issues, but in all fairness the original main battery still had over 12v and even a year later after sitting on my garage floor it still had charge so I probably didn't need to change it..
When my stop start battery failed, Tayna did the stop start at half the price of ECP, I ended up replacing both batteries for about £170 and the alternator was about £250. It's probably double that now with inflation. I also bought a BMS module off ebay for £27 just in case.
I got the garage to swap the alternator as you have to jack the engine up to get it in and out and couldn't be arsed to do it, they charged 3 hours labour. I am fairly sure they never reset BMS and I had no issues, but in all fairness the original main battery still had over 12v and even a year later after sitting on my garage floor it still had charge so I probably didn't need to change it..
