Battery balancing

[Cliff Mitchell]

I've had my MG for nearly three months now and have travelled about 3500 kms. I have never charged it to 100%, and I have only ever charged it using 15amps input from my charger. A simple question, do I wait until it tells me to do a battery balance, or do I charge it to 100% and try and make it go into balance mode? I would be interested in your advice.

 

[micky]

I've had my MG for nearly three months now and have travelled about 3500 kms. I have never charged it to 100%, and I have only ever charged it using 15amps input from my charger. A simple question, do I wait until it tells me to do a battery balance, or do I charge it to 100% and try and make it go into balance mode? I would be interested in your advice.

hi cliff i am sure i have seen it somewhere where it says once a month to balance but that could be if only using 50kw chargers ,but to do it once a month wont do any harm and it keeps the cells well balanced.do you no what bms (battery management system) you might be on,

 

[Lovemyev]

Hi Cliff.
I would agree with @micky .
If you are only doing “Part Charging” due to your low usage pattern, then I would be tempted to carry out a full charge and balance about once a month, just to help keep the cells balanced.
But if you decide to take this option, try and time it that you use the car within a couple of days after you fully charged and balance.
It is not seen as good practice to fully charge and then leave the battery bursting at the seams for days on end.
This is not a good practice either.
Be kind to your battery .

 

[Cocijo]

Why have you never charged to 100%?

 

[Cliff Mitchell]

Why have you never charged to 100%?

Based on a number of discussion points on this forum, it was recommended not to charge the car to 100% except when there was a need for full charge (long trip etc). Most suggestions recommended a charge up to 80 to 90% - also suggesting not to allow the vehicle to discharge too low.

hi cliff i am sure i have seen it somewhere where it says once a month to balance but that could be if only using 50kw chargers ,but to do it once a month wont do any harm and it keeps the cells well balanced.do you no what bms (battery management system) you might be on,

No, I have no idea what BMS the vehicle is running. It was purchased in April 2021 and it seems to be running very well. At 90% charge in N mode the car displays 232km's range - in E mode it displays much more. Over the full 3500 kilometers it is running at 14.9 kilowatts per hundred kilometers. Using the 15amp charger the battery charges at 20 kilometers per hour - which makes it easy to complete the required charge to around 90%.

 

[Cliff Mitchell]

Hi Cliff.
I would agree with @micky .
If you are only doing “Part Charging” due to your low usage pattern, then I would be tempted to carry out a full charge and balance about once a month, just to help keep the cells balanced.
But if you decide to take this option, try and time it that you use the car within a couple of days after you fully charged and balance.
It is not seen as good practice to fully charge and then leave the battery bursting at the seams for days on end.
This is not a good practice either.
Be kind to your battery .

Thankyou for the advice. Because I have never been there before, if I charge to 100% will the vehicle tell me it is balancing? The next question is, if it doesn't need balancing, will it just stop?

 

[Goofy]

Hi Cliff, I had the unfortunate luck of getting the corrupt software update released in Nov/Dec, which has meant that ever since getting the new update to correct the bad update I’ve had to balance my battery when recharging. I only use the granny charger & the balancing occurs after the car reaches 100% charge. You’ll know it’s balancing when the charge light in the MG badge is on constantly & not displaying as it does when charging. When the light goes off & on. Keep an eye on your full charge voltage, it should be 449v when switched on, but without anything else that might be drawing current.

 

[mj224]

When I charge on my 7Kw home charger, I let it continue to balance, mainly because I don't want to get out of bed to switch the charger off...

 

[Cocijo]

Based on a number of discussion points on this forum, it was recommended not to charge the car to 100% except when there was a need for full charge (long trip etc). Most suggestions recommended a charge up to 80 to 90% - also suggesting not to allow the vehicle to discharge too low.

No, I have no idea what BMS the vehicle is running. It was purchased in April 2021 and it seems to be running very well. At 90% charge in N mode the car displays 232km's range - in E mode it displays much more. Over the full 3500 kilometers it is running at 14.9 kilowatts per hundred kilometers. Using the 15amp charger the battery charges at 20 kilometers per hour - which makes it easy to complete the required charge to around 90%.

Based on a number of discussion points on this forum, it was recommended not to charge the car to 100% except when there was a need for full charge (long trip etc). Most suggestions recommended a charge up to 80 to 90% - also suggesting not to allow the vehicle to discharge too low.

No, I have no idea what BMS the vehicle is running. It was purchased in April 2021 and it seems to be running very well. At 90% charge in N mode the car displays 232km's range - in E mode it displays much more. Over the full 3500 kilometers it is running at 14.9 kilowatts per hundred kilometers. Using the 15amp charger the battery charges at 20 kilometers per hour - which makes it easy to complete the required charge to around 90%.

I was just interested that after 3500kms you did not have occasion at least once to need a full charge

 

[rbpasapera]

I always charge mine to 100% because the battery has an upper buffer that protects the battery, 100% on the display is 93-ish% real battery percentage.

 

[Vince31]

Thankyou for the advice. Because I have never been there before, if I charge to 100% will the vehicle tell me it is balancing? The next question is, if it doesn't need balancing, will it just stop?

Every time you charge to 100% the charger (home charger or granny, not a Rapid) will automatically go into Balancing mode. When the car starts balancing then the MG logo on the charging flap stops pulsing slowly like when its charging, and stays on steady. The balance procedure can take a number of hours so you need to leave it on charge until it stops (no timed charging) otherwise the balance will not complete. When the balancing is finished the MG logo goes out completely. Its important to balance, more important than to not charge to 100% once in a while.

 

[Deleted member 2439]

With my Zappi 7kW charger, the charge rate will slow right down to 300watts, which I assume is the balancin happening. It will then stop completely with the Zappi itself and it’s associated apps showing that it’s stopped. All nice & easy & nothing to worry about

 

[Lovemyev]

With my Zappi 7kW charger, the charge rate will slow right down to 300watts, which I assume is the balancin happening.

You are correct.
Generally 32 Amp wall boxes will provide just over 7.0kw's from the get go.
The MG badge in the grill of the ZS EV will be pulsing in and out slowly, to indicate that the car is charging.
When the SOC reaches around 97% the car will throttle down the charge supplied to 3.5 kw's.
The MG logo is still slowly pulsing in and out.
When the car reaches the 100% SOC mark, the charge received will be reduced right down to 500 Watts.
This is when the "Balance" process has commenced.
Now the MG logo in the grill badge is now displaying a soft ( but constant ) glow, no pulsing.
When the car has finished balancing the HV pack, it will automatically shut down the wall box and return it to its "Standby" state.

 

[Cliff Mitchell]

You are correct.
Generally 32 Amp wall boxes will provide just over 7.0kw's from the get go.
The MG badge in the grill of the ZS EV will be pulsing in and out slowly, to indicate that the car is charging.
When the SOC reaches around 97% the car will throttle down the charge supplied to 3.5 kw's.
The MG logo is still slowly pulsing in and out.
When the car reaches the 100% SOC mark, the charge received will be reduced right down to 500 Watts.
This is when the "Balance" process has commenced.
Now the MG logo in the grill badge is now displaying a soft ( but constant ) glow, no pulsing.
When the car has finished balancing the HV pack, it will automatically shut down the wall box and return it to its "Standby" state.

Thankyou for the information - I finally went through the charge and balance process last night. Everything you said was very good. The process took 12 hours 40 minutes, using my charger on 15 Amps. From 59 kilometers to 100% (273 kilometers) it required 33.5 kilowatts with the final voltage of 451 volts. On my charger the balance was using a registered 190 to 200 watts. The soft glow was on while balancing and it turned itself off when complete.

Thankyou for the guidance, I will give the car the opportunity to balance every month or so as suggested.

 

[Deleted member 2439]

Thankyou for the information - I finally went through the charge and balance process last night. Everything you said was very good. The process took 12 hours 40 minutes, using my charger on 15 Amps. From 59 kilometers to 100% (273 kilometers) it required 33.5 kilowatts with the final voltage of 451 volts. On my charger the balance was using a registered 190 to 200 watts. The soft glow was on while balancing and it turned itself off when complete.

Thankyou for the guidance, I will give the car the opportunity to balance every month or so as suggested.

That will be 33.5kWh then, it’s the total energy delivered to the car. kW and kWh are often mistakingly mixed up, so I hope you don’t mind being corrected on this point. One is power, the other is energy, a quick google should resolve things for you. I’m not singling you out here - lots of people make the same mistake and as an Electrical Engineer I feel obliged to correct the wrong. Cheers - Rob

 

[Cliff Mitchell]

That will be 33.5kWh then, it’s the total energy delivered to the car. kW and kWh are often mistakingly mixed up, so I hope you don’t mind being corrected on this point. One is power, the other is energy, a quick google should resolve things for you. I’m not singling you out here - lots of people make the same mistake and as an Electrical Engineer I feel obliged to correct the wrong. Cheers - Rob

Feel free to correct all things EV. You are perfectly correct it is kWh's - things to do with the car are measured in kWh's - importantly they are the things I pay for.

As an Electrical Engineer you may be able to tell me, someone who knows nothing about electricity. When you turn on the air conditioning or the fan, the vehicle loses 25 or so kilometers of distance, yet when I turn on the seat heating, I lose nothing! I suppose there is a simple answer, but as indicated above, I'm easily confused.

 

[mystreet]

Feel free to correct all things EV. You are perfectly correct it is kWh's - things to do with the car are measured in kWh's - importantly they are the things I pay for.

As an Electrical Engineer you may be able to tell me, someone who knows nothing about electricity. When you turn on the air conditioning or the fan, the vehicle loses 25 or so kilometers of distance, yet when I turn on the seat heating, I lose nothing! I suppose there is a simple answer, but as indicated above, I'm easily confused.

Easy answer, seats use the 'normal' 12v battery, air con uses the big battery

 

[Cocijo]

The predicted range drops by about 15miles if only the fan is used (on cold with no aircon or heating). Does the fan also use the HV battery?

 

[Deleted member 2439]

Feel free to correct all things EV. You are perfectly correct it is kWh's - things to do with the car are measured in kWh's - importantly they are the things I pay for.

As an Electrical Engineer you may be able to tell me, someone who knows nothing about electricity. When you turn on the air conditioning or the fan, the vehicle loses 25 or so kilometers of distance, yet when I turn on the seat heating, I lose nothing! I suppose there is a simple answer, but as indicated above, I'm easily confused.

The aircon uses a lot of power. In an ICE car if you switch the a/c on whilst it’s ticking over you can see the revs drop for a fraction of a second until the ECU compensates by injecting more fuel to bring the revs back up again. Use of a/c will use fuel - it’s the same with an EV. Our summers aren’t as extreme as yours so the impact of using a/c is lower - but still there.

We got our ZS EV just before Christmas and had to use the heater a lot, both to warm the car and defrost the cabin. Our range was down to between 110 and 120 miles!

Although the seat heaters run off 12volts, as has been mentioned, they don’t actually draw that much power - and also they are fitted with thermostats to stop overheating the occupant of the seat - which means they switch on and off once at temperature. I’d suggest that the seat heaters only draw 5 to 10 amps, so in the scheme of things are only a fraction of the power of the a/c or main heater.

What we have all got used to is petrol and diesel fuel having very high energy densities, which means that a litre or kilogram of the stuff holds a lot of energy. There’s a great Aussie motoring guy who’s worth a look on YouTube, his name is John Cadogen and I think goes by the name Autoexpert.Au. He’s quite opinionated- but very funny and has done some very good videos on all aspects of cars from a technical perspective, including EVs. He’s particularly critical of the government!

Cheers

 

[JodyS21]

Thankyou for the information - I finally went through the charge and balance process last night. Everything you said was very good. The process took 12 hours 40 minutes, using my charger on 15 Amps. From 59 kilometers to 100% (273 kilometers) it required 33.5 kilowatts with the final voltage of 451 volts. On my charger the balance was using a registered 190 to 200 watts. The soft glow was on while balancing and it turned itself off when complete.

Thankyou for the guidance, I will give the car the opportunity to balance every month or so as suggested.

Be careful, it may not have actually completed the balancing process.... The car will only balance for (we think) 10 hours maximum at a time.
If you have not ever balanced, it may take longer than the 10 hours to actually finish the balance.

I would suggest to be on the safe side, that after doing a few miles in it, you put it on AC charge again and let it go through the balance process again.
I have a little cctv camera in the front window that I can use to see when mine starts the balance and it completes, it's the only way I actually know what it is up to!
(I fully AC charge 3-4 times a week, so mine never needs to balancing for much more than a couple of hours anyway)