MG5 EV Poor Range

[Petriix]

What do you make, Petriix, of the advice in the manual to do the balance charge once a month? Must admit, it was never something I did with the Leaf I had before, but in the MG community it seems to be de rigeur. I've just done it a second time, but a full charge at the moment is lasting me the best part of the month, whereas with the Leaf I'd just charge a bit here and a bit there, as and when...

It's pretty essential to balance the cells, otherwise the consequences of letting it go out of balance can be severe on the overall capacity and, ultimately, the range of the car. But I wouldn't charge to 100% more than necessary for three reasons...

1. As mentioned above, full battery means no regen which makes any journey less efficient.
2. A fair amount of additional energy is wasted to squeeze the last bit of power into the batteries (charging losses increase as the voltage nears its peak); and the balancing itself uses a fair amount of energy without actually adding to the amount stored in the battery. 95% SOC to full and balanced took 7kWh of energy.
3. Battery degradation is highest when it's left sitting at higher (or very low) states of charge so keeping it close to 50% when not being used much is ideal. It also leaves me plenty of headroom for charging with surplus solar as and when the sun shines. Apparently trickle charging little and often is good for battery health.

 

[Petriix]

What exactly is this Balance Charge, and how do you do it?

It's happens automatically every time you charge to full. Once the overall battery voltage is up to around 405V, the BMS begins balancing the voltage of the individual cells within each battery module. It takes a couple of hours to complete the process.

 

[jonathanhoey]

From time to time you’re supposed to leave your MG EV on AC charge for a few extra hours after it gets to 100%, rather than disconnecting it straight away. It draws a small amount of power - nothing like the usual amount it would draw for actual charging - and uses it to make sure all the thousands of individual cells that comprise the HV battery pack are in sync with one another. Particularly if you often use DC rapid chargers, the cells can end up out of whack with one another, which manifests as early degradation.

I’m used to this after three years in an i3. BMW explicitly advises always keeping the i3 on charge. None of this “stop at 80% to protect the batteries” business that you hear people talking about.

Indicated 100% isn’t true 100% anyway. Likewise, indicated 0% isn’t true 0%. There’s a buffer of capacity at either end to protect from any harmful effects of overcharging or overdischarging. Hence (from memory) the MG5 has a total capacity of 52kWh but a useable capacity of 48kWh (those might not be the exact numbers but it’s close).

 

[greentangerine]

Just plug it in every night and let it sort it; that's why there is a BMS after all.

 

[Frank]

Just plug it in every night and let it sort it; that's why there is a BMS after all

 

[Frank]

Just plug it in every night and let it sort it; that's why there is a BMS after all.

Exactly, that is what I have being doing for the last 18 months and I have NEVER had any of the battery problems (both main HV battery and 12v battery).

Frank

 

[Valiant5]

Thanks, Petriix, for your reply earlier.

The difficulty is being on a full charge, but then having a battery close to 100 per cent for a few days because I'm doing only 40 miles a week at the moment. It won't be a problem once we can start going further afield.

 

[Ranger]

Just plug it in every night and let it sort it; that's why there is a BMS after all.

May have to put a little more thought into it if you have a timed charge set up as it may not allow the car to complete the balance, I tend to 4hr charge my car on a Tuesday and have set zappi to 8hrs from 00:30h Wednesday to take what it needs and balance. I'm not currently doing great miles though, I've done less than 700miles since new years when I got the car.

 

[Petriix]

Exactly, that is what I have being doing for the last 18 months and I have NEVER had any of the battery problems (both main HV battery and 12v battery).

Frank

It's fine to charge to full every day. The BMS and top buffer will protect the battery from most of the degradation. You'll probably lose slightly more capacity over 5 years than someone who keeps their SOC at around 50% most of the time, but you may not care about that. It's not going to cause a serious issue.

You will, as explained above, waste a bit more energy because of the additional charging losses from balancing and the higher proportion of driving when regen is limited.

For those of us who like to take extra care of our expensive cars, and want to maximise our efficiency, there are some gains to be made by keeping the battery at around 50% SOC.

 

[Petriix]

[double post removed]

 

[Frank]

What exactly is this Balance Charge, and how do you do it?

Guys and Gals,

I have been on this forum basically since the beginning and Now have over 18 months experience of EVs. I have driven a few on test drives and the conclusion is they are ALL VERY similar. The only difference is (always driven by cost) usually just battery size, heat pump instead of a basic resistor heater and probably the thing that most people would like, an app on your phone that can remotely control the heating, charging etc etc.

The common denominator is of course the battery. Now currently the batteries are Lithium -Ion. I have read many articles about said batteries and their degradation. Conclusion is that everything about this is theory and speculation with no main output other than, yes your battery WILL degrade over time alone, no matter what one does, however they all agree RAPID charging is not good for your battery.

This forum has turned into a FUD (yes, Scottish guys we know what it means in your (my) neck of the woods) about your battery health and what one should do about it. This has been caused by the faulty BMS software finacle, I think. Anyway face the facts your battery WILL degrade no matter what you do. My advice is stop bloody worrying about it, let your BMS (correct one) deal with ALL the batteries needs, including equalization. Now how do you do that, use your home charger, plug it in every night and like my experience you shouldn't have any problems with the batteries, both 12v and HV.

Let's talk about battery degradation. Even if your battery degraded by 50% (and this should ONLY happen after many, many thousands of miles (and based on data from many older high mileage EVs) the car is still viable unlike an ICE cars of the same mileage which is probably at the end of its life. Example, if you have an EV with 50% degradation and you're either out of warranty or can't afford to repair it then you still have a car that is useable , the ONLY difference is that you have a correspondingly reduced range (dependant on your range available when new), MG ZS EV, 50% reduction could still easily drive 50 - 70 miles on a full charge. Not good for long trips but still brilliant for Urban use.

So please stop worrying about what state of charge your car is maintained at, just use your Home Charger as it should be. Enjoy the convenience a home charger brings and before I get trolled (is that the right expression, I am of the older age group) for those without a Home Charger, I personally advise anyone not to buy an EV without one as the public infrastructure is not good enough yet.

Best wishes.

Frank

PS It looks very likely that within 2-3 years Lithium-Ion batteries will be replaced by Solid State Batteries,different ball game altogether.

PPS Note , driving characteristics don't change on an EV with a degraded battery only the range is reduced, it will still be smooth, quiet and quick.

 

[Petriix]

Guys and Gals,

I have been on this forum basically since the beginning and Now have over 18 months experience of EVs. I have driven a few on test drives and the conclusion is they are ALL VERY similar. The only difference is (always driven by cost) usually just battery size, heat pump instead of a basic resistor heater and probably the thing that most people would like, an app on your phone that can remotely control the heating, charging etc etc.

The common denominator is of course the battery. Now currently the batteries are Lithium -Ion. I have read many articles about said batteries and their degradation. Conclusion is that everything about this is theory and speculation with no main output other than, yes your battery WILL degrade over time alone, no matter what one does, however they all agree RAPID charging is not good for your battery.

This forum has turned into a FUD (yes, Scottish guys we know what it means in your (my) neck of the woods) about your battery health and what one should do about it. This has been caused by the faulty BMS software finacle, I think. Anyway face the facts your battery WILL degrade no matter what you do. My advice is stop bloody worrying about it, let your BMS (correct one) deal with ALL the batteries needs, including equalization. Now how do you do that, use your home charger, plug it in every night and like my experience you shouldn't have any problems with the batteries, both 12v and HV.

Let's talk about battery degradation. Even if your battery degraded by 50% (and this should ONLY happen after many, many thousands of miles (and based on data from many older high mileage EVs) the car is still viable unlike an ICE cars of the same mileage which is probably at the end of its life. Example, if you have an EV with 50% degradation and you're either out of warranty or can't afford to repair it then you still have a car that is useable , the ONLY difference is that you have a correspondingly reduced range (dependant on your range available when new), MG ZS EV, 50% reduction could still easily drive 50 - 70 miles on a full charge. Not good for long trips but still brilliant for Urban use.

So please stop worrying about what state of charge your car is maintained at, just use your Home Charger as it should be. Enjoy the convenience a home charger brings and before I get trolled (is that the right expression, I am of the older age group) for those without a Home Charger, I personally advise anyone not to buy an EV without one as the public infrastructure is not good enough yet.

Best wishes.

Frank

PS It looks very likely that within 2-3 years Lithium-Ion batteries will be replaced by Solid State Batteries,different ball game altogether.

PPS Note , driving characteristics don't change on an EV with a degraded battery only the range is reduced, it will still be smooth, quiet and quick.

You're right that the evidence about battery degradation at different states of charge is not entirely conclusive, but I've delved reasonably deeply into the studies and base my position on the balance of evidence which points to better long-term health when predominantly used in the middle range of the voltage. There is certainly nothing to be lost by doing so and a reasonable wealth of evidence to support the suggestion of a small benefit, which will add up over time.

You've completely ignored my points about efficiency which are objectively true in whatever way you look at them so, regardless of the health of the battery, there are other reasons for avoiding having a fully charged battery. If you've decided to manage your battery a certain way, that's absolutely fine. I have no problem with that, but I'm not sure why you feel the need to actively advise people to do the same against better advice.

Fine if you want to say "I can't be bothered with all that, I'll take my chances for the convenience of just plugging in and forgetting about it"; but less fine if you say "It's best just to charge to full every night" because the fundamentals of chemistry and physics disagree with you. It might not be worth it for you, and it's certainly hard to measure the outcome, but it's still good advice to only charge to full once per month or when needed for a longer journey.

 

[Kithmo]

What do you make, Petriix, of the advice in the manual to do the balance charge once a month? Must admit, it was never something I did with the Leaf I had before, but in the MG community it seems to be de rigeur. I've just done it a second time, but a full charge at the moment is lasting me the best part of the month, whereas with the Leaf I'd just charge a bit here and a bit there, as and when...

I don't see anything in the manual about having to balance charge "once a month" it just says do it when the 'Please Charge for BMS Balance' warning comes up ?

 

[RossN]

To balance the battery you have to fully charge to 100% ?

 

[Kithmo]

To balance the battery you have to fully charge to 100% ?

Yes, but on the 5 I don't know how you would know its finished balancing, unless you're at home and your smart meter monitor tells you.

 

[Petriix]

I don't see anything in the manual about having to balance charge "once a month" it just says do it when the 'Please Charge for BMS Balance' warning comes up ?

On page 235 under maintenance: High Voltage Battery Pack...

Where possible it is recommended that you carry out a slow charging (equalisation charging) every month to extend the service life of high-voltage battery pack. The battery management system will monitor the status of the high- voltage battery pack; after monitoring for a period of time, if an equalising charge has not been carried out for some time the message centre in the instrument pack will display ‘Please Charge for BMS Balance’. At this time you must carry out an equalising charge. For operation mode, please refer to ‘Equalisation Charging’ in ‘Starting & Driving’ section.

 

[Petriix]

Yes, but on the 5 I don't know how you would know its finished balancing, unless you're at home and your smart meter monitor tells you.

My Zappi displays the current power flowing to the car and shows "Charge Complete" when the balancing is done.

 

[EWD]

Yes, but on the 5 I don't know how you would know its finished balancing, unless you're at home and your smart meter monitor tells you.

Power up the car and look at the power flow screen. I recommend you turn off the AC etc as this uses lots of power.

You'll see how much power is flowing in. Before I reached 100%, I had a reading of about -11 Amps (I only have access to an on-street 5kW lamppost charger).

Once mine reached 100% and it started balancing, it fluctuated between 1 and 5-ish Amps.

When balancing had finished it went to zero or even a small positive number.

 

[BillyWhizz]

I have only had my EV a few days I will be using it just like I did in my ICE car drive till I need to fill it

 

[Scorpion]

I have only had my EV a few days I will be using it just like I did in my ICE car drive till I need to fill it

I tried that from new and ended up on the hard shoulder of the M1 with 34 miles range and 18% battery left after the HV battery shut down from what i understand to have been an unbalanced battery someone on this forum said "you a charge an EV because you can not because you have too" and I think that's the biggest eye opener I've learnt. I do still run it down to around 50% but I'm still weary of what happened before, that said I am getting 90-100 miles out of 50% of the battery now on mixed driving