Speak EV - Electric Car Forums banner

1 - 20 of 29 Posts

·
Registered
Joined
·
143 Posts
Discussion Starter #1
Apologies for raising this topic again. I started another thread as the last one descended into a discussion of people's bikes!

Steadily working my way through the 300+ pages of manual, I came across the Battery Maintenance instructions on pages 290-293. I strongly suggest that anyone planning on not using their car for a prolonged period, whether due to COVID or any other cause, should read those pages, as they cut across advice circulating on this forum and elsewhere. MG are quite explicit that not following their instructions will invalidate the battery warranty.

Reading the manual must take precedence over my interpretation but in essence:
  • if you're storing the vehicle for a month or more, disconnect the 12V battery -ve terminal. It doesn't say whether this affetcs the keyless entry, so unless you know different, be sure you know how to enter the car with a key before doing this!
  • a vehicle stored for a prolonged period must be charged at least once every 3 months. The manual doesn't specify to what level, but elsewhere states that a full equalisation charge of the HV battery is recommended at least once a month. The implication therefore is presumably that the three monthly charge should be an equalisation charge.
  • At no point in prolonged storage should the HV battery level be allowed to drop below 50%
You can see why this cuts across "keep it at 20/30 to 60/80%" type recommendations.

That's it folks. Form your own opinion, but they are the people underwriting the battery warranty!
 

·
Registered
Joined
·
276 Posts
You should not leave it at 100% SOC for extended periods of time, and you certainly should not keep charging it to 100% to equalise the batteries while in storage.

The equalisation is to do with multiple charging of the battery, which would happen in normal use.

Can accept the don't let it fall below 50% rule and disconnecting the 12V battery.
 

·
Registered
Joined
·
3,763 Posts
Actually the disconnect 12v battery terminal is probably the first time we have heard any sensible input into this line of discussion.

Then again, if EV manufacturers specified Lead Acid AGM (some do) for the 12v service, you could probably change the one month to 6 months due to the very low self discharge.
 

·
Registered
Joined
·
143 Posts
Discussion Starter #4
I understand the issue over high levels of charge, but battery best practice isn't the only matter in play. There's the question of the warranty terms, and what MG are expecting to happen.

I've no idea whether the BMS records the charging history of the battery. I know I would do so if I was designing a multi-thousand pound battery that my company was on the hook for a seven year warranty over. It helps you understand battery performance, diagnose genuine battery problems and helps refuse claims relating to mistreated batteries.

It would have been good if the manual had been more explicit. Hey ho! :oops: I have raised a ticket with MG to see what they say.

Barring personal tragedy, or the government confining us all completely to barracks, I'm not expecting to lay the car up for that sort of period, but it would be good to know.
 

·
Registered
Joined
·
213 Posts
Switching the car on to the ready state initiates the DC to DC inverter/converter which charges the 12v services lead Acid Battery from the High Voltage Drive-Train Battery. If the 12v battery discharge too low then it is unable to power up the car's systems and even with a high State Of Charge (SOC) the car's systems can not boot up including the DC to DC inverter/converter. Turning the Car on to the "Ready" state once every few weeks will kick start the charge top-up process of the 12v battery.

Regard the SOC of the main HV Battery lithium cells in the battery are best stored for long periods at or about 50%. Unfortunately, the MG ZS (European) car only displays the percentage at the start of a charge or during a charge if the "lock" button on key-fob is pressed. However, if you know your car when full (temperature dependant) would show say 140 to 150 miles for the 44.5kWh (available) if you show 70 to 90 miles range when the Battery button is pressed I would say it is about right to store like that for some months.
 

·
Registered
Joined
·
3,231 Posts
Took the ZS for an essentials run yesterday. 4 bars on the charge indicator and the GOM was showing over 100 miles on eco. Loving the warmer weather!
Did a very similar run out for food the other day.
It was a nice warm day, sky roof tipped back ( first time this year ).
I don’t think the GOM moved at all !.
It would have been nice to carry on driving, but all too soon it was over and we where back on the drive.
 

·
Registered
Joined
·
213 Posts
sky roof tipped back
Tilt the roof and kill the power to the HVAC then cancel the default recirculation and the "Sky Roof will create a reasonable air-flow through the car and just see the difference it makes to the range estimate. I have 144 miles in Eco showing like that but turn the HVAC on and select Sport-mode and it dropped to 118 miles.
 

·
Registered
Joined
·
143 Posts
Discussion Starter #9
I had a reply from MG about long term storage requirements. Actually I had it a while ago and forgot to update this thread. My bad.

This will be like tossing meat into a lion's cage, but here goes. I am merely passing it on. 😎
  1. The car should be driven as often as possible (well, yes, but not now, certainly not in Wales...:(:cry::cry:)
  2. It should then be charged, ideally using the granny charger.
  3. Do not be too worried about charging to 100%
  4. If the car is not being driven at all then follow the advice in the manual, and charge the car if the charge level reaches 60%. (I took that to mean that they really don't want you to let it go below 50% in long term storage.)
  5. That charge should be a top-up, ideally with either granny charger or at the very least, an AC charger.
I'm assuming that 60% means the fifth bar on the battery meter, but hopefully, I'll never have to find out. Just for information, in the current lockdown, I have observed no loss of charge at all during storage, in either the HV or 12V battery. I think the longest it has gone without moving is just over two weeks.
 

·
Registered
Joined
·
4,095 Posts
Was that written by the importer's trainee customer service apprentice or someone that knows what they are taking about?
 

·
Registered
Joined
·
143 Posts
Discussion Starter #11
Well, the email came from customer service, obviously, but the advice had come to them from MG's after-sales technical support..

The only part that is "new" in the sense of not being in the manual is to recharge at 60%, i.e. not to let it hit fifty percent at all, rather than simply not go below it. The manual is very sanguine about full charges. And the charging methodology advice is all there as well.

It is basically just a restatement of what is in the manual

I told you it would be like throwing meat in... :)
 

·
Registered
Joined
·
213 Posts
charge the car if the charge level reaches 60%. (I took that to mean that they really don't want you to let it go below 50% in long term storage.
Lithium ion battery cell chemistry if not used and stored ie the car is parked up for a substantial time should be at half charge state so that the Cathode and Anode are protected. In practice, since HV battery will slowly discharge, charging to 60 % SOC would be ideal so thereby allowing for self-discharge to 50% or just below over time. Depending on how the low voltage 12v electronics are managed the HV Battery may periodically be used to power the DC-DC Converter to top up the 12v battery. Tesla's for instance do this quite often and the HV will loose about 1% per day. MG ZS I believe doesn't fire up the DC-DC Converter automatically when stored and it is activated only when car in READY state. Potential therefore the 12volt battery can run down. You could consider connecting a solar top-up charger if car parked for very long periods, although since the UK models don't have the App and live connection, which is found on Asian model, battery drain should be less significant.
 

·
Registered
MG EZS 2020
Joined
·
4,177 Posts
I don’t think the GOM moved at all !.
I had reason to make a run to the farm shop in April. I was pleasantly pleased by the m/kWh I got!
IMG_20200426_140124.jpg
 

·
Registered
MG EZS 2020
Joined
·
4,177 Posts
This from Dr. Euen McTurk

A SOC calculator for determining the amount of charge to keep your battery healthy during LockDown:

 

·
Registered
MG EZS 2020
Joined
·
4,177 Posts
I have 144 miles in Eco showing like that but turn the HVAC on and select Sport-mode and it dropped to 118 miles.
I thought I had something wrong with my GOM. I've only ever seen 138 or 140 miles after a full charge (rain or shine). I thought 'max' range was 163? Is what you're seeing fairly standard?

Zoe always showed max range according to the conditions at the time. I've seen 185 miles on the Zoe's GOM in high summer and 138 in the depths of winter.
 

·
Registered
Joined
·
213 Posts
I thought I had something wrong with my GOM. I've only ever seen 138 or 140 miles after a full charge (rain or shine). I thought 'max' range was 163? Is what you're seeing fairly standard?

Zoe always showed max range according to the conditions at the time. I've seen 185 miles on the Zoe's GOM in high summer and 138 in the depths of winter.
Max I've seen is 167 miles after balancing charge. But battery is warm and any battery cell after a charge will be slightly high on voltage and then settles and this can slightly skew the results. But do the calculation your self 5.5 miles/kWh x 44.5 kWh useable = 244 miles so go to the shops more often 😁
 

·
Registered
Joined
·
1,798 Posts
Got 144 (D3/HVAC on) / 176 (E3/HVAC off) yesterday. I think ambient temperature makes the biggest difference as my overall avg is still only 3.2mpkWh with a fair bit of motorway miles.
 

·
Registered
Joined
·
65 Posts
I've seen 175 on mine. I averaged 3.4mpkWh over the winter and its crept up to 3.5 now. I was averaging 1000 miles a month until the begining of February when my mother passed away. That slowed me down for a while while I dealt with all the paperwork. Now we are in lockdown I've just been doing a click and collect shop every week. The nearest supermarket that does it is 12 miles away and doesn't always have slots available so I have been as far as 25miles to get to one. At least it keeps the 12v topped up and the rust off the brakes.
 

·
Registered
Joined
·
283 Posts
I have had 174 (Eco Mode) after rapid charging to 80% and a slow charge top up and balance at home. Generally it indicates 154 in Normal on start up after such a charge.

The last five months the accumulated figure has stayed at 3.3. Recently the dealer added the latest updates (4 separate updates he told me). He also rerouted the front driver electric cable as per the recall (old routing exposed the cable to rain running inside the door and over the cable so re-routing it is to avoid any shorting). This involved disconnecting the battery and the accumulated range figure was reset (or he reset it himself).

Since then I am getting slightly better figures per trip - 3.5 to 3.9, updates(?) or more probably warmer weather. Hilly area, Normal Mode, town driving, 50-60mph on an A road. The accumulated figure is now 4.0 kW/mile. It appears that the accumulated figure does not update very often.

Anyone else have thoughts on this?
 
1 - 20 of 29 Posts
Top