Quick discharge

[Davn]

Had a bit of an odd occurrence the other day, I left work with 45% charge and 84 mile range, during the journey I noticed that the charge was dropping dramatically and after 23 miles was at 12%! Forcing me to stop at a rapid charger. Anyone else had this type of sudden reduction, and no I wasn't in sport mode

 

[DanLH]

I've read this can happen if you've not balanced the cells in line with the guidance (every week-ish for the SE SR, every month for other variants). Seen stories of people being caught short when their range suddenly drops at lower SoC because they've been consistently charging only to 80% to preserve battery life.

I see you have an SE SR so might be a good habit to charge fully roughly every week to keep the cells balanced and the SoC and range should become more accurate.

(PS the colder weather won't be helping either)

 

[Davn]

This is something I do every week, I've had the car for 12 months never had it before

 

[Robf]

This is something I do every week, I've had the car for 12 months never had it before

Check you dont have battery heating turned on, if so, turn it off

 

[Davn]

Something I've never used I did think about using it this morning but the app wouldn't connect to the car, again!

 

[Robf]

Something I've never used I did think about using it this morning but the app wouldn't connect to the car, again!

Not that, intelligent battery heating, watch the below.

 

[Davn]

Yes that's what I was talking about but as I said I've never switched it on, but in the new version of the app you can switch it on remotely as with the cabin ac

 

[fnegroni]

Had a bit of an odd occurrence the other day, I left work with 45% charge and 84 mile range, during the journey I noticed that the charge was dropping dramatically and after 23 miles was at 12%! Forcing me to stop at a rapid charger. Anyone else had this type of sudden reduction, and no I wasn't in sport mode

Have you ever gone below 10% and then charged back up to 100% on a slow charger?

 

[fnegroni]

This is something I do every week, I've had the car for 12 months never had it before

I’d suggest let it run below 10% and then slow charge.
Depending on what caused the sudden drop in charge percentage you might see the number not changing for a while. Keep an eye on how many miles you have covered as well just in case.

It is odd but it can happen if something isn’t quite right.
Perhaps due to the battery pack being cold in some areas and warm in others. Which is why heating the battery when it’s below 0 degrees it’s a must with LFP batteries in my books.

 

[siteguru]

Yes that's what I was talking about but as I said I've never switched it on, but in the new version of the app you can switch it on remotely as with the cabin ac

You always could switch it on via the app. (It was hidden behind a Schedule option in the old app). However that is different to the "Intelligent" option in the car.

I once had this issue, over a year ago. (09-Dec-22 according to my spreadsheet). I left work with plenty of battery for the journey, dropped something off for a colleague in a nearby village, and then drove the 4-5 miles home. On arrival I was down to 6% according to the SoC ... however when I recharged (to 100%) the amount that went into the battery was more like the SoC had been 20% rather than 6%.

No idea what happened, and it happened once more (in Jan 2023). My only observation was that the GOM seemed suspect when the SoC dropped below 20% and temperatures were low. I've not noticed this happen again.

 

[Davn]

Have you ever gone below 10% and then charged back up to 100% on a slow charger?

No try never to go that low

 

[fnegroni]

No try never to go that low

You should once every 3 to 6 months as per user manual recommendation.

 

[Davn]

Don't think I ever will, I drive 80+ miles a day so have to have 40 odd % available to get home

 

[Martinonline]

With my Trophy I try to stay 20% to 80%, but having seen the post about the 10% to 100% requirement I had a go. After a long journey I got to 20% and then used cabin and battery heating to reduce further as I wanted the car to be on the drive when it got to 10%. (Range anxiety.)

At 14% and 25 miles indicated, my neighbour asked for a lift to take his punctured tyre to a particular garage. 8 miles later and at 12% and 19 miles on the GOM, I was back on the drive to reduce to 10%.

I charged to 80% as I'm not going on a long journey. I hope it did some good but the GOM is showing the same 80% range as before.

 

[Rolfe]

In September I took my car for a joyride to get under 10% and then charged all the way on the granny cable. It took about 26 hours. I should probably do it again soon.

 

[fnegroni]

In September I took my car for a joyride to get under 10% and then charged all the way on the granny cable. It took about 26 hours. I should probably do it again soon.

That’s what is recommended. I did it first time on my trip to Paris shortly after getting delivery of the car. once again in October and my next scheduled 5% to 100% charge is at the end of the month.
The only time I ever saw the percentage sudden drop off was indeed on the way to Paris. Never again since and I’ve been under 25% and done short charge sessions between 40 and 70% repeatedly in between.
I do tend to preheat the battery when the outside temperature is below 0C unless it’s parked in the underground car park at a balmy 17C

 

[MSvirus]

You always could switch it on via the app. (It was hidden behind a Schedule option in the old app). However that is different to the "Intelligent" option in the car.

I once had this issue, over a year ago. (09-Dec-22 according to my spreadsheet). I left work with plenty of battery for the journey, dropped something off for a colleague in a nearby village, and then drove the 4-5 miles home. On arrival I was down to 6% according to the SoC ... however when I recharged (to 100%) the amount that went into the battery was more like the SoC had been 20% rather than 6%.

No idea what happened, and it happened once more (in Jan 2023). My only observation was that the GOM seemed suspect when the SoC dropped below 20% and temperatures were low. I've not noticed this happen again.

I poked around the livedata from the car yesterday with an ELM327, and found three different SoC values, all showing different but reasonable values. I also found a "SoC-displayed" value.

 

[Davn]

I poked around the livedata from the car yesterday with an ELM327, and found three different SoC values, all showing different but reasonable values. I also found a "SoC-displayed" value.

I'm beginning to disbelieve anything that comes up on the display anymore

 

[Museruk]

In September I took my car for a joyride to get under 10% and then charged all the way on the granny cable. It took about 26 hours. I should probably do it again soon.

I would just like to query why so many people seem to believe that you need to use the Granny Charger (typ. 2kW only) in order to perform either the circa weekly or 2-week (depending on your typical mileage) charge to 100% including the balancing charge at the end of the charge?
Here is pg.173 of the manual (may have been updated now, since I downloaded this in July 2023):

Slow Charging

Note: Carrying out a full slow charge is the only way for the high voltage battery to reach the optimal equilibrium state (equalisation charge).

High voltage battery chargers are available with various power outputs. Chargers with outputs of up to 11kW are generally considered as slow chargers, larger than 11kW are considered as fast chargers and rapid chargers are available in AC or DC outputs. Generally the AC chargers are rated at 43kW and the DC chargers at 50kW plus.

Charging times are dependent on charger output.

To carry out an equalisation slow charge, it is recommended that the charger output does not exceed11kW.

Note: Chargers of up to 7kW power output are supplied via standard household single phase power. Any chargers that are rated above this, 11kW for example, will require a 3 phase power supply.

Further - in the Section on pg.295 of the manual under the title: "Precautions and Restricted Conditions for use of Battery" the last sentence in the first paragraph states:

"Every 3 months to half a year, a low-power (less than 10% or 1 grid) full charged is performed."

Apart from the fact that this is not exactly clear (I assume due to translation errors), I believe that this could be refering to charging at a 'low power' level of less than 10% of the cars maximum charge rate of 135kW i.e. < 13.5kW or '1-grid' which would be less than a single grid connection i.e. 30A or 7kW (assuming a 230V ac supply from the grid), to a full charge level of 100%.
Hence the definition earlier of low-power chargers being anything less than or equal to 11kW being suitable.
I will therefore persevere in trying to get clarification from MG on this - unless that is anyone else has already got a clearer answer already from MG on this topic?

 

[Rolfe]

I only have a granny charger, that's why! There is a public type 2 charger 400 yards away but there is a time limit of 55 minutes on it so it's no use for this job.

We did have this conversation earlier and I do know that if I had a wall box then that would also do the job. They should probably specify "AC" charging. (It did occur to me to ask a neighbour if I could borrow their wall box for a night, they did offer once, but I can manage with the granny lead.)