Sudden loss of range from 25% SoC in ZS Excite

[RayC333]

Drove a 72 plate MG ZS Exite yesterday. Started with about a 40% charge, gauge showed down to 25% after about 40 miles. In the next ten - fifteen miles, heading for the nearest service station on the M4, a low battery warning came up followed minutes later by a flashing low battery warning, then a warning to pull over to a safe spot. Drive stopped completely and I coasted to the nearest refuge area (total of 56.4 miles).
I've driven a number of EV's, including a previous MG ZS EV and have never experienced such a dramatic drop off of battery power. Very scary with lorries taking evasive action around me; so easily could have been a serious accident.

 

[fred12345]

Drove a 72 plate MG ZS Exite yesterday. Started with about a 40% charge, gauge showed down to 25% after about 40 miles. In the next ten - fifteen miles, heading for the nearest service station on the M4, a low battery warning came up followed minutes later by a flashing low battery warning, then a warning to pull over to a safe spot. Drive stopped completely and I coasted to the nearest refuge area (total of 56.4 miles).
I've driven a number of EV's, including a previous MG ZS EV and have never experienced such a dramatic drop off of battery power. Very scary with lorries taking evasive action around me; so easily could have been a serious accident.

must have been very Exite-ing ... joking aside, as soon as the battery reaches about 35% and I'm on motorways or A-road, time to stop at the nearest charging point; I was going for a 80-ish miles round trip last night, 65 mph, rainy freezing night ... just about reached fast chargers when I was on about 20% left ... that percentage melts before your eyes so fast ... (and stupidly failed to use the opportunity to test Tesla charger, bunch of them, right next to me, all free at 3:00AM)

on the other hand, I was driving in circles around the block for about 30 min trying to get the battery down from 20% to 10% so that I could do a full slow charge ... aircon blowing, sport mode, up the hill fast, 1 reg ... and still took forever

 

[Jomarkh]

must have been very Exite-ing ... joking aside, as soon as the battery reaches about 35% and I'm on motorways or A-road, time to stop at the nearest charging point; I was going for a 80-ish miles round trip last night, 65 mph, rainy freezing night ... just about reached fast chargers when I was on about 20% left ... that percentage melts before your eyes so fast ... (and stupidly failed to use the opportunity to test Tesla charger, bunch of them, right next to me, all free at 3:00AM)

on the other hand, I was driving in circles around the block for about 30 min trying to get the battery down from 20% to 10% so that I could do a full slow charge ... aircon blowing, sport mode, up the hill fast, 1 reg ... and still took forever

Hi, where are Tesla chargers free at 3am?
I thought it was just the MG4 that needed a 10% - 100% charge now and again.

 

[fred12345]

Hi, where are Tesla chargers free at 3am?
I thought it was just the MG4 that needed a 10% - 100% charge now and again.

Misunderstanding, apologies ... My bad, not free as in nothing to pay but not occupied....
About 10-100%, it's in the instructions manual says:
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).

 

[Rolfe]

Drove a 72 plate MG ZS Exite yesterday. Started with about a 40% charge, gauge showed down to 25% after about 40 miles. In the next ten - fifteen miles, heading for the nearest service station on the M4, a low battery warning came up followed minutes later by a flashing low battery warning, then a warning to pull over to a safe spot. Drive stopped completely and I coasted to the nearest refuge area (total of 56.4 miles).
I've driven a number of EV's, including a previous MG ZS EV and have never experienced such a dramatic drop off of battery power. Very scary with lorries taking evasive action around me; so easily could have been a serious accident.

When you say you drove the car, it wasn't yours then? You don't know how the battery had been managed?

That sudden drop after 25% is something I have never experienced. My MG4 never misses a beat, the range goes down exactly as you'd expect from the way you're driving it - I had it down to 7% on Saturday and there were no nasty surprises at all. But I have heard of this happening to other cars, especially the Kia eNiro. And, interestingly, someone reviewing my own car, the MG4 SE SR, claimed it happened to him.

My theory, shoot me down if you like, is that this behaviour is caused by the battery not being balanced as per the instructions in the manual, and maybe in particular by the car never being given the long charge from <10% to 100% and balance on AC, which it needs to see the bottom of the discharge curve and keep the GOM accurate.

I'm splitting this off to a new thread, because it isn't on topic for this thread, which is about battery degradation.

 

[Pimbers]

No one pointing out that a 72-plate ZS Excite doesn't exist in the UK (OP is apparently in Bristol)?

 

[Ruislip Resident]

No one pointing out that a 72-plate ZS Excite doesn't exist in the UK (OP is apparently in Bristol)?

I did clock it was a random new novice member with a battery issue I had not read about before.

 

[Rolfe]

No one pointing out that a 72-plate ZS Excite doesn't exist in the UK (OP is apparently in Bristol)?

Well, that would be because I didn't know that. Although I was slightly surprised that the "Excite" model name was used because it's not used for the MG4 in Britain.

@fred12345 seemed to indicate that something similar had happened to him though, although the car didn't give up on him. Is the ZS prone to losing range fast near the bottom of its curve?

I've been very reassured by my MG4 in similar circumstances. On Saturday, as I said, I had to go to Aberdeen, which is about 140 miles and near the edge of my winter range. It's still pretty cold in Scotland. I was confident of making it, although I left time in hand in case I had to drop my speed to conserve range near the end.

But there was a complication. The car was serviced the previous day and came back with a factory reset on the GOM. 199 miles range apparently. In your dreams. I knew I couldn't trust that. So I set Android Auto for my destination and watched both that and the GOM count down as I drove. Inevitably the GOM range decreased a lot faster than the AA distance did, but by half way I seemed to have 14 miles in hand which I thought was about right.

However the last part of the route was a bit hilly and the margin eroded a bit more until I had only five miles in hand. Still not worried because I was quite close to Aberdeen by then and obviously the last bit was downhill. At 12 miles the car asked me if it should turn on energy saving mode and I said yes, but I didn't notice any difference in the way it drove. Never saw a turtle. I ran into the MFG charging station on the North Esplanade on seven miles of range, feeling as if the car still had full power.

The car has been like that every time I've driven it low. It's very reassuring. Is the ZS different?

I'd be interested to hear more about the OP's experience. How come you were driving a car called "Excite" in Britain? Did you get a low charge warning and the opportunity to turn on energy saving mode? Did the turtle come up? How long did the car go after losing power before you were "coasting"? (Does an EV actually coast?) Whose car was it?

And do they have "refuge areas" on the M4? That's a term I've only encountered on the continent. Did it have chargers and were you able to "coast" on to one, or did you have to call a rescue service?

Inquiring minds would like to know.

 

[Pimbers]

The car has been like that every time I've driven it low. It's very reassuring. Is the ZS different?

Based on my experience of running out of charge on the A30 in Cornwall last summer (Gridserve broken, 5% SoC, 7 miles uphill to the next charger...) it does just stop, in my case showing 1%. Naturally it gives low charge warnings but one would expect some kind of bottom buffer.

Furthermore, I do think 100%-50% goes further than 50%-0%. This was something noted in the Korean cars, as the SoC display is based on Ah rather than Wh, meaning as the voltage decreases the available charge per % reduces.

 

[Rolfe]

Yes, that last is something I have read about in a number of places. I think it applies to most EVs, although I have heard Tesla owners reporting that their scale is linear. It doesn't seem to me to be a very noticeable effect.

I'm not sure how long the ZS has been out, but I'm reading about better bottom buffers in modern cars. The MG4 seems to have it.

 

[Bodgerx]

If I was admin, I would delete this thread completely.

The details are off, the OP has posted just this message to the forum and has not answered follow up questions.

It smells badly of another attempt to spread EV FUD.

 

[Rolfe]

The suspicion has been raised.

Given that the OP has not returned to the thread to explain further, and serious questions have been raised about the accuracy of the original account, I'm locking this thread. If the OP would like to discuss the incident further in good faith, he is invited to contact a moderator to have the thread unlocked.