Second Hand MG ZS ev - Battery Degradation

[cjp40]

I'm in the process of looking for a second hand pre facelift MG ZS. Probably about 2 years old with 15 / 20k mileage. What should I be looking out for with regards to battery degradation. Any advice would be greatly appreciated

 

[N2STY]

I wouldn't worry to much just make sure it has full MG service history so the battery warranty is still active it will also still have AA\MG assist still covered as that renews each year with a new service

 

[Bluesparky]

we bought a 2 year old with 10k on the clock last year, battery was still giving us 160+ miles in the summer but as n2sty says, battery has a warranty so would worry about it.

 

[cjp40]

Thanks for your replies guys. I'm concerned about reduction of range if the battery degradation is too great. Most of my driving will be short, 20-30 miles return. I'll also be doing 5 / 6 journeys a year of about 100 - 120 each way to visit family. So you think I have nothing to worry about in the greater scheme of things

 

[jamesie]

Nov 2020 MG ZS EV Exclusive

At last service - mileage = 13,000 SOH = 95% and GOM showing range of 155 miles (Mode = normal).

Not great but to be expected according to the service manager. Still fine for my purposes but will probably hasten my trading it in for something else.

 

[JCFlippen]

Perhaps the thing to check would be that any updates for the BMS battery management system have been carried out. From various posts there seem to be many Gen1 cars that have slipped through the net. The updates improved range amonst other things.

 

[cjp40]

Perhaps the thing to check would be that any updates for the BMS battery management system have been carried out. From various posts there seem to be many Gen1 cars that have slipped through the net. The updates improved range amonst other things.

Is there a way to check if a car has had these updates, or would I have to trust the dealers honesty

 

[N2STY]

Is there a way to check if a car has had these updates, or would I have to trust the dealers honesty

I believe there are some telltale signs on the entertainment screen @Lovemyev may help on this

 

[Lovemyev]

My guess would be that the info unit will only display the firmware upgrade status of the head unit itself and not the software running system of the car I.e, BMS / BCM modules etc.

 

[N2STY]

My guess would be that the info unit will only display the firmware upgrade status of the head unit itself and not the software running system of the car I.e, BMS / BCM modules etc.

Was there not something with outside temp displayed on comfort 2 upgrade or something like that ok I seem to remember @BarryH had a lot of the updates

 

[JCFlippen]

My guess would be that the info unit will only display the firmware upgrade status of the head unit itself and not the software running system of the car I.e, BMS / BCM modules etc.

Just remembered, doesn’t the fully charged battery voltage give a clue that the BMS updates have been done on the Gen1? Must be info on forum somewhere - was it 456v original and down to lower figure after update?

 

[N2STY]

Just remembered, doesn’t the fully charged battery voltage give a clue that the BMS updates have been done on the Gen1? Must be info on forum somewhere - was it 456v original and down to lower figure after update?

Yes I think you're right it went down to 449v?
And being able to charge your car when unlocked?

 

[Gadget Geek]

I'm in the process of looking for a second hand pre facelift MG ZS. Probably about 2 years old with 15 / 20k mileage. What should I be looking out for with regards to battery degradation. Any advice would be greatly appreciated

One of the biggest effects on battery degredation is the number of rapid charges. If you buy from a dealership, ask them for a printout of the battery state of health, do they know what the previous owner used it for etc (a sales rep travelling hundreds of miles a day vs into town and back). If it's a private sale, ask them what they used the car for and invest in an OBD II dongle and plug it in, using eZS to see the SOH of the battery.

As an indication, my son just past his test and bought a 2014 LEAF. I went with him with a checklist on my tablet, an OBD dongle and LEAF Spy on my phone. The SOH of the battery was 83.9%, which for a 9 year old LEAF was pretty good. Needless to say, he's now the proud owner of a used LEAF.

 

[Lovemyev]

One of the biggest effects on battery degredation is the number of rapid charges. If you buy from a dealership, ask them for a printout of the battery state of health, do they know what the previous owner used it for etc (a sales rep travelling hundreds of miles a day vs into town and back). If it's a private sale, ask them what they used the car for and invest in an OBD II dongle and plug it in, using eZS to see the SOH of the battery.

As an indication, my son just past his test and bought a 2014 LEAF. I went with him with a checklist on my tablet, an OBD dongle and LEAF Spy on my phone. The SOH of the battery was 83.9%, which for a 9 year old LEAF was pretty good. Needless to say, he's now the proud owner of a used LEAF.

Agreed ?.
Although not a 100% certainty, if the car ( ZS EV ) is only a couple of years old and has not covered a lot of miles, then in a low user case it is unlikely to have subjected to a lot of rapid charging cycles.
High mileage cars would make me a little more concerned I think.
A lot of low usage owners tend to use the Granny lead to charge their cars also, which is a quest wort asking if you are buying privately.
None of these things alone give to certainty of course, but when added up together they help build up a picture of the way the car has been treated / looked after.

 

[jamesie]

Some low mileage cars may still have been charged using DC rapids as there were a fair number of free chargers 2+ years ago (specially in Scotland).

I think that's why my 20 plate ZS EV is 95% SOH! I just couldn't resist my local free rapid charger!!

 

[p1xelman]

The situation can be quite complicated if you're buying a car that may have been off the road for a while (because of lockdowns or just sitting on a dealer forecourt). A year ago we cancelled an order for a pre-registered vehicle with delivery mileage because the dealer couldn't say the battery had been checked regularly & charged appropriately.

The ZS EV mk1 manual says "If the vehicle is not going to be used, parked, or stored for a long time it is necessary to charge the vehicle at least once every 3 months. During this time, the High Voltage battery state of charge should not be allowed to drop below 50%."

It goes on to say "If the battery is in a low state of charge and the instrument pack displays '—' this indicates that the range is below 10 miles (15km), in this case the vehicle MUST NOT be left in a stored state for more than 7 days without being charged to above 50%."

It also recommended using the vehicle at least once a month. witht a 9-hour slow charge every month "to extend the service life of high-voltage battery pack" ie to equalise the batteries.

The batteries are probably not as sensitive as it might appear but charge cycles etc may well be logged by the vehicle management systems so in the event of a warranty claim MG may be able to tell if the vehicle has been off the road for weeks, with the charge going below 50% and/or below 10% for more than 7 days.

 

[Gadget Geek]

It's always worth getting an independent check of a used vehicle (AA/RAC) to access the logs and see how the car has been used/stored.

 

[N2STY]

At least on a 2 year car you still have 5 years on battery warranty
Will you be a winner and get a battery replacement on like year 6

 

[Lovemyev]

Some low mileage cars may still have been charged using DC rapids as there were a fair number of free chargers 2+ years ago (specially in Scotland).

I think that's why my 20 plate ZS EV is 95% SOH! I just couldn't resist my local free rapid charger!!

I see your point !.
Sometimes things that appear free at first, end up costing you more in the long run it would appear !.
Or as the saying goes :- “You don’t get out, for now’t”.

 

[cjp40]

The situation can be quite complicated if you're buying a car that may have been off the road for a while (because of lockdowns or just sitting on a dealer forecourt). A year ago we cancelled an order for a pre-registered vehicle with delivery mileage because the dealer couldn't say the battery had been checked regularly & charged appropriately.

The ZS EV mk1 manual says "If the vehicle is not going to be used, parked, or stored for a long time it is necessary to charge the vehicle at least once every 3 months. During this time, the High Voltage battery state of charge should not be allowed to drop below 50%."

It goes on to say "If the battery is in a low state of charge and the instrument pack displays '—' this indicates that the range is below 10 miles (15km), in this case the vehicle MUST NOT be left in a stored state for more than 7 days without being charged to above 50%."

It also recommended using the vehicle at least once a month. witht a 9-hour slow charge every month "to extend the service life of high-voltage battery pack" ie to equalise the batteries.

The batteries are probably not as sensitive as it might appear but charge cycles etc may well be logged by the vehicle management systems so in the event of a warranty claim MG may be able to tell if the vehicle has been off the road for weeks, with the charge going below 50% and/or below 10% for more than 7 days.

The car I'm looking at hasn't been taxed since Sept 22. This would suggest that it's been on dealer forecourt for 6 months. Should I just walk away ?