25/01/21: Just had latest BMS software. Observations...

[Mark Holmes]

You know when you get that feeling that something is just not right, but you can not put your finger directly on it !.
Gut feeling is the best way to describe it I guess.
The car drives as it did before, but the charging pattern feels out of wack somehow ????.

Tomorrow for me where I live it’s 4 degrees today, should be about 13 degrees tomorrow by all accounts if you have a similar increase in local temperature see how you get on tomorrow?

 

[Mark Holmes]

Tomorrow for me where I live it’s 4 degrees today, should be about 13 degrees tomorrow by all accounts if you have a similar increase in local temperature see how you get on tomorrow?

Just checked you should be about 10 degrees tomorrow, see what difference it makes..

 

[Cocijo]

You know when you get that feeling that something is just not right, but you can not put your finger directly on it !.
Gut feeling is the best way to describe it I guess.
The car drives as it did before, but the charging pattern feels out of wack somehow ????.

Did you track the charging behaviour before the update? Was it always pulling 7kw under the ideal conditions then?

 

[Chrisb]

I have the August BMS (455v) and it always pulls 6.6kw right up until the last couple of % no matter the weather/temperature.

 

[shikoku14]

I agree with Chris, mine is also on that same BMS and in my draughty garage (which is generally only a few degrees warmer than outside) the car never fails to pull 6.6kw from my Ohme cable until it hits the final few percent and then goes into balancing mode (for a fair few hours).

 

[Lovemyev]

Did you track the charging behaviour before the update? Was it always pulling 7kw under the ideal conditions then?

Yeah - I am pretty sure all was fine before the update, because if I just needed a small ( ish ) top up charge using the Off Peak rate, then I would set a delayed charge on my phone.
As an example, say the GOM was reading about 70 miles of range remaining and I wanted to take it to say .......... 120 miles (ish).
Then I would set the timer for 2 hours of charge.
2 hours at 7.0kw will give about 50 miles of range to the car.
Therefore the original 70 plus the added 2 hours at 25 miles per hour gives me my target of 120 miles of range.
If I was to do this now when only pulling only just less than 4.0 kw's for the same length of time, this would only give me a total range of 95 miles of range for the same length of time.
I have been charging a lot in this way for almost 12 months prior to the update and never had a problem.
Now I have an issue ( I am sure ).
To be honest, It was only my house energy meter that brought it to my attention at the weekend.
If there is very little running in the house and I commence a charge on the car, the meter swings right over to the red band and displays roughly about 7.1 kw are being pulled.
So this is the car charging without an doubt.
The display in the car confirms this because the estimated time that it should complete reflects this.
When I plug in and the energy meter displays only 4.0kw are being pulled, the car will again confirm this by showing a MUCH longer charge cycle and finish time.
The thing that has me really puzzled is why it if different over two days ????.

 

[Lovemyev]

I agree with Chris, mine is also on that same BMS and in my draughty garage (which is generally only a few degrees warmer than outside) the car never fails to pull 6.6kw from my Ohme cable until it hits the final few percent and then goes into balancing mode (for a fair few hours).

Thanks, both you and Chris agree that my understanding is correct, the car should pull 7.0kw from any point in the charge until it hits around 97%.
Then I believe ( and I have seen it on my energy meter ) that at this point, the car throttles back the demand from the wall box to about 3.6kw until it has completed the charge.
The the MG logo will convert from pulsing, to a steady glow as the car enters the balancing stage.
The energy meter is now only displaying a small demand of about 500 watts from the wall box to balance the cells.
If I do indeed have a problem and I do believe I have, given its behaviour.
How the hell to I start explaining this to my local dealer who buggered up the car when it went in for its first service !.
More concerning, how do they correct the problem !.
This could end up being a lengthy process and a job for the MG Tech team here !.

 

[Smendon]

As an aside, those who have had the new BMS update and have been rebalancing their cars multiple times, have you seen the voltage increase? If so, how many charges did it take for you to notice it? I’ve done 2 charges and the voltage in my car has stayed the same

 

[Lovemyev]

The dealer did the first one and I have conducted another two.
Voltage still at 449 volts with no increase.

 

[Jeps]

We have charged twice. The first one showed 446v the second 447v. I don't how it was before, I never checked up on that.

 

[Kithmo]

Thanks, both you and Chris agree that my understanding is correct, the car should pull 7.0kw from any point in the charge until it hits around 97%.
Then I believe ( and I have seen it on my energy meter ) that at this point, the car throttles back the demand from the wall box to about 3.6kw until it has completed the charge.
The the MG logo will convert from pulsing, to a steady glow as the car enters the balancing stage.
The energy meter is now only displaying a small demand of about 500 watts from the wall box to balance the cells.
If I do indeed have a problem and I do believe I have, given its behaviour.
How the hell to I start explaining this to my local dealer who buggered up the car when it went in for its first service !.
More concerning, how do they correct the problem !.
This could end up being a lengthy process and a job for the MG Tech team here !.

Are you sure it's not the charger that's throttling back the kW, based on what's switched on in the house, to protect the main fuse ?
I know the Pod Point has this built in as some others do.
Next time you notice it's only pulling 4kW, check what else you have switched on.

 

[JodyS21]

Are you sure it's not the charger that's throttling back the kW, based on what's switched on in the house, to protect the main fuse ?
I know the Pod Point has this built in as some others do.
Next time you notice it's only pulling 4kW, check what else you have switched on.

That is exactly what I was going to suggest.
This is kind of when you could do with the ability to switch the charger into totally dumb mode and let it just allow max charge as per whatever the car wants, that would then take the charger doing something clever out of the equation.

 

[rbpasapera]

Third full charge and balance after BMS update during this week and voltage is still at 450v. Balance took less than 30 min. Range with HVAC off, 206 mi E, 187 mi N, accumulated mileage at 4.9 mi/KWh. After resetting the milage GOM showed 179 mi E, 163 mi N.

 

[Smendon]

Third full charge and balance after BMS update during this week and voltage is still at 450v. Balance took less than 30 min. Range with HVAC off, 206 mi E, 187 mi N, accumulated mileage at 4.9 mi/KWh. After resetting the milage GOM showed 179 mi E, 163 mi N.

4.9m/kWh!? Do you constantly drive downhill!?! I hover between 2.9 and 3.0 m/kWh

 

[jamesie]

You don't live in Costa Rica! Warm climate works wonders!

 

[rbpasapera]

4.9m/kWh!? Do you constantly drive downhill!?! I hover between 2.9 and 3.0 m/kWh

It's totally different here in Costa Rica, average speed 50 mph and temp. 25°C, I always drive in Eco mode.

 

[Lovemyev]

That is exactly what I was going to suggest.
This is kind of when you could do with the ability to switch the charger into totally dumb mode and let it just allow max charge as per whatever the car wants, that would then take the charger doing something clever out of the equation.

Thanks for the suggestions.
But I check what the house is pulling via the energy monitor, before plugging in the car.
Therefore I have a base line to work from.
My wall box is a dumb unit, which has NO smart capability.
You plug it in and off it goes.
It has a WI-Fi relay inside that gives me control over delayed charging if I wish.
My brother has a 8 week old ZS EV with less that a thousand miles on the clock.
I may ask him to try his car on my wall box as proof of concept.

 

[Lovemyev]

Bit of an update, my Off - Peak rate has just started at 9.00pm.
So, I though I would just go and plug the car in again.
Guess what - It is now charging at the full 7.0 kw !!!!.
The car is now reporting that it will be 100% fully charged from 71% and 104 miles in 1 hour and 47 mins.
Which feels about right to me.
This SHOULD give me a fully charged range of about 150 miles (ish).
Let's just see.
So, how strange is this ?.
This afternoon it the car was only pulling 3.6 kw when plugged in - now it is pulling 7.0kw.
It's not just my house energy monitor displaying this discrepancy, the display in the car is reporting the same discrepancy.
I have no answers to explain this at all.

 

[Mike]

I had the BMS update done today. It was reporting 443V before I drove down to the dealer.
I drove at motorway speed limit each way then had a 20 mile trip across town. I have driven a total of 86 miles today and arrived home with 16%.

 

[WalkingBootWeather]

Just got home from a 400 mile round trip in a day with 4 rapid charges. Currently at 7% and 11 mile range remaining but I'll put it on charge (4th equalisation charge since Jan BMS update) and lets see where we are.

Car performed pretty well today. Regen does seem stronger and rapid now seems to taper at about 85%. Battery was pretty warm after such a long run and was getting decent speeds on 50kW chargers. (I often experienced sub 30kW speeds in the winter before the latest BMS update, but maybe the battery was cooler and SoC lower when I commenced charging?). Am getting just over 100 miles for 80% battery driving sensibly with heating on which is what I'd expect this time of year.