Thanks everyone. The car is a 2016 Leaf tekna with 55900 miles on the clock.
In the last 5 months I've had about 6 breakdowns - all to do with the startup braking problem whereby when you start the car the dashboard lights up like a christmas tree (yellow abs light, yellow brake warning light, red main warning light). If you put your foot on the brake, it goes virtually to the floor and you get abs pulsing sounds plus a horrible grinding noise. If you were to pull away and tried to stop the car it would take A LOT longer to stop and would require a lot more force applied to the brake. When the RAC man came to have a look he checked the voltage on the 12v and it was at only 12.27 volts. After leaving the car on for a bit and then resetting the car it seemed to rectify the problem. So I assumed the battery was not taking enough charge from the DC-DC convertor anymore and I needed a new battery.
I got a new battery(Varta lead acid) fitted but two days later I had the same braking problem. This time the problem occurred about 30 seconds to a 1 minute into the journey(scary! lucky i was on a quiet lane and not going fast) the dash lit up and I lost braking power. This time I had my pregnant partner in the car with me and shes lost all confidence in the car and rightly wont go in it anymore. The fact that the brakes failed after startup makes me wonder if this has got anything to do with the 12v at all and maybe its another design problem with the car. Possibly the firmware on the intelligent braking unit? I asked about this at the dealership and they said it didn't apply to my car despite this link (https://flipthefleet.org/2018/leaf-brakes-failures/
) suggesting that it affects models manufactured between March 2012 and Feb 2016 (mine was manufactured in Feb 2016).
So without any other options i'm considering upgrading to an optima yellowtop. Can i ask why would an AGM perform better than a lead acid in a Leaf in particular?. Do they retain a steady voltage despite a descreasing SOC % or is the benefit more to do with their low internal resistance and its ability to take charge better.
My other question would is .. does the leaf warn you when the 12v battery charge is low? The software that manages the charge of the 12v seems totally inadequate and can lead to this dangerous problem(?).
I'm currently working with someone from flipthefleet who is going to provide me a report on his findings about other leaf owners with the same problem. I'm hoping this report alongside my video of the issue will support my case to get a refund on the vehicle from the original dealership. Failing that then i'm taking it to the ombudsman.
Any help more help would be very welcome!
All the best, Mark