Hi
@JodyS21 .
I am running on the Jan 15th 21 BMS update, I think I must have been one of the first privately owned cars to receive it.
It was applied under MG Tech instructions, after the dealer who was carrying out the first service and drivers door wiring loom, rendered the car “Dead” !.
It was stuck on a ramp for three days.
Arh …… You remember it now !.
So, yeah - The car behaved strangely at first when I got it home, when plugging in, some times it would pull 7.5kw’s and then the next time it would only pull 3.5 kw’s ?.
The wall box was not the issue, it was the car acting strange.
This action continued for about 14 days regardless of what state of SOC the car was at prior to charging.
This made it extremely difficult to judge how long and how much the car was likely to receive on a timed overnight charge.
This is where the obsession with watching the energy meter started of course !.
It could actually tell me what the car was pulling and when.
I would watching this little black box almost on the hour, every hour !.
Making notes along the way, as I went.
Then after about 10 to 14 days, the car just started demanding the full 7.5kw’s when connecting to the wall box, every single time.
Which I am very grateful for, because try explaining this situation to a dealer to rectify !.
The observations of the cars charging behaviour and the effect on the energy meter became all consuming at the time.
So, like most people the car will demand roughly about 7.1 ish Kw’s when placed on charge.
It pulls this 7.1 ish kw’s until around the 97 - 98% SOC mark, then the car throttles back the draw by about 50% to about 3.5 kw’s.
Which does make sense to me.
I know a rapid charger is much different, but they start to throttle back the charge at about 80% SOC.
Reducing the high rate of load towards the end of the charging cycle, on a charger must be kinder of the HV battery.
Slamming a high load into a pack and then suddenly just stopping it at 100% SOC can not be good ?.
Back to my actual observations now.
Yeah ….. So at about the 98% SOC it reduces the pull down to 3.5kw’s.
Then at 100% it enters the balancing stage and the demand is throttled back even further.
Now we are only pulling around 500 Watts to start with, then this reduces ever more down to 350 watts and then to around 175 watts just before the balance completes and closes down the demand from the wall box.
Prior to the first service, I was running on the original factory software ( 456 volts ).
The car only had the Comfort 2 update but did not display any signs of receiving any of the affects of the “Buggy” software.
But my charging habits pre the problem in Jan 21 - would be that I would charge to a SOC that would suit our situation of journey demands.
I would only charge to 100% IF we had a long trip to make.
Therefore, I would regularly only charge to around 80% - trying to be kind to my battery.
It could be said that my battery was a little out of balance when the car was offered for service then ?.
The balancing process prior to the problems, would only take about 1 to 2 hours max, so I don’t think it was that far out of whack ?.
When I received the car back after the update, due to the charging problems that I mentioned earlier, the car was taking a stupid amount of time to charge and balance from my wall box.
Once the car was hooked up for over 12 hours !.
Over the last 4 - 5 months I have charged successfully ( thank the Lord ) but I still think it takes longer to complete a balance than when I was on the factory OEM software.
The last time I timed it, it was around 3 hours to balance.
Just for reference, the car is now 18 months old and we have covered 12.500 miles.
The car drives absolutely fine and due to the lift in restrictions in Wales, we have been able to make some longer trips that has stretched the range.
The GOM is reporting a pretty good actual rate of consumption.
But when making a longer journey, I do like to reset the accumulative trip before commencing the trip.
I am just more comfortable with it this way.