Voltage & Battery balance

[Wendycar127]

Morning,
So I've been ready through these threads to educate myself, still new to this game.
I'm reading a lot about balancing the battery and not too clear on how/when/why you do this the more I read the more confused I am.
Also interested to know what the voltage should read when fully charged to see if there is any deteriation (or what level should be a cause for concern)

 

[ChrisR]

Morning,
So I've been ready through these threads to educate myself, still new to this game.
I'm reading a lot about balancing the battery and not too clear on how/when/why you do this the more I read the more confused I am.
Also interested to know what the voltage should read when fully charged to see if there is any deteriation (or what level should be a cause for concern)

I'll have a go.

How: charge the car with granny charger or 7kW charger until the light on the badge is completely out. It pulsates while charging, is on full when reached 100% and off when balanced. The balancing time will vary depending on how unbalanced the battery is - might be 1 hour or much longer if hasn't been done for ages.

When: recommended once a month. May need more often if you do mostly rapid charging or less if you don't do many miles. Apparently a warning will come up on the dash reminding you if it leave it too long though I've never seen this.

Why: the battery is made up of many (60 maybe, not sure) smaller cells and these need to all have the same charge for battery health.

Voltage at full charge should be 449 or 450 volts.

 

[teepee]

The car will tell you via the binacle if it needs to be balanced but the handbook, I think, recommends doing it monthly. Just leave the car plugged in, get to 100% full and the lights on MG stay on permanently. Keep car plugged in until lights on badge go off - then it's balanced. Voltage should read about 449 when full.

 

[Cosmic Resident]

I can answer the balancing part for you.

The traction battery, although referred to and presented as one big battery, is actually made up of lots of individual little batteries, known as cells.

Each cell has a nominal voltage of 3.7V (higher when fully charged) so you need a lot of them connected together (in series) to get the 400v or so (not the exact value for the MG, but in the ballpark) that the car requires.. Let’s call that a series pack.

Then, because each cell has only a limited capacity, you need multiple series packs connected side-by-side to make a pack with enough capacity to go in the car.

So you end up with an awful lot of individual cells, which need looking after.

Balancing is necessary to make sure each individual cell has the same terminal voltage as the rest of the cells in the pack.If it does not, it is out of balance and will not perform in the same way, giving out less energy and accepting less energy when charging. This can result in the cell going further and further out of balance therefore a balancing operation is required to bring it back up to the same voltage level as the rest of the cells in the pack.

Balancing can only be done when using the cars on-board charger, and consequently can only be done on AC, not rapid DC chargers which by-pass the on-board charger.

 

[Wendycar127]

Thank you all for your replies. Going to try this today if i connect to a 22kw (which I was told only deliveres 7kw ) and I've got 30 miles left how long do you think it may take to get to full charge. I might attempt this today at work if from 9-4 is long enough

 

[Deleted member 7171]

Thank you all for your replies. Going to try this today if i connect to a 22kw (which I was told only deliveres 7kw ) and I've got 30 miles left how long do you think it may take to get to full charge. I might attempt this today at work if from 9-4 is long enough

If you want to know more about batteries check this YouTube channel out...

https://youtube.com/c/PlugLifeTelevision

 

[JCFlippen]

Thank you all for your replies. Going to try this today if i connect to a 22kw (which I was told only deliveres 7kw ) and I've got 30 miles left how long do you think it may take to get to full charge. I might attempt this today at work if from 9-4 is long enough

Charging will be at 4-6 miles per hour.

 

[JodyS21]

Thank you all for your replies. Going to try this today if i connect to a 22kw (which I was told only deliveres 7kw ) and I've got 30 miles left how long do you think it may take to get to full charge. I might attempt this today at work if from 9-4 is long enough

You can figure this out pretty easily.
The car has officially a 44.5kWh battery, if you're using a 7kW charger, 44.5/7=6.35 hours to fully charge from empty.
If you've got 30 miles left then you can guess that's about at about 20% charge currently, so you need to add 80% to fill up - so about 5 hours.
(This isn't precise for various factors but I'm keeping it simple enough).

FYI, the important factor is that you must use an AC charger to balance.
An AC charger just uses the round plug (the top bung only is removed).
If a charger is using the combined plug (both bungs are removed) then it is a DC charger.

 

[Lovemyev]

A very simple and rough guide is this.
For every hour you are connected to a 7kw A/C wall box, you are going to add about 25 miles of range to the car.
Just make a mental note of your remaining range on the GOM before leaving the car, then figure in roughly 25 miles of extra range added for every hour you spend on charge.
Handy if you only want to charge to a certain level / percentage of the capacity of the battery.
So, if you remaining range was at 25 miles before you placed the car on charge and you wanted to charge to range of 100 miles, then you need to charge for a total of 3 hours.
It’s not absolutely spot on, but it will get you close enough to what you want, rather than charging the battery to full every single time.
I have Wi-Fi relay inside of my dumb Rolec wall box.
From the App on my phone, I am able to set a delayed / timed charge to commence and take advantage of cheaper off peak rates.
This facility has been extremely useful over the last two years.
As we know, the original ZS EV does not have any built in feature, that will allow this.
It can be achieved if you have a smart wall box of course, but when the ZSEV was first released, it had no provision to delay charge.

 

[Coulomb]

if i connect to a 22kw (which I was told only delivers 7kw )

That's because for a 22 kW "charger" to deliver 22 kW, it has to do so using three phases. Think of a phase as a separate source of 230 V AC. Our cars only have one on-board charger; others have 1, 2, or 3. Cars that have 3 on-board chargers can take advantage of the available 22 kW by loading each 7 kW phase (source) fully. Since we only have the one 6.6 kW charger, we only load one 230 V AC source, so we only get 6.6 kW (often rounded to 7 kW) of charge power.

 

[Wendycar127]

Voltage after full charge and balance is 443 range is 131 does this sound ok for this time of year in Scotland.

 

[Lovemyev]

Voltage after full charge and balance is 443 range is 131 does this sound ok for this time of year in Scotland.

Bit confused about these figures ?.
I will tell you what mine reports this morning.
Both trips reset to zero.
448 volts on the pack with a predicted range of 154 miles in normal mode.
Yes - I am on the latest BMS and my car is almost two years old and has covered 16,500 miles.
Hope this helps !.

 

[Wendycar127]

Sorry reading is 443 voltage and predicted range is 131 on eco. My car has the upgrade is 2 years old in march has done 8500 miles and I've had it a week

 

[Lovemyev]

Are you sure your car is on the latest BMS update ?.
That voltage and range looks low to me ?.

 

[Wendycar127]

I specifically ask before I purchased it. Is there anyway I can confirm for myself?

 

[Wendycar127]

Ive just went out and checked again the miles have went up.

 

[Lovemyev]

Ive just went out and checked again the miles have went up.
View attachment 6010View attachment 6011

Do you have ALL electrical items tuned off ?.
And have you reset BOTH of the mileage recorder trips back to normal first ?.
After you have fully charged and balanced, when you enter the car, leave your foot OFF the foot brake.
Now press the start button once, wait about 10 seconds, the press the start button again.
You may get a yellow HV battery warning on the dash panel, but don’t worry.
Now score through your screens and check your voltage and predicted range.
Your car has not covered many miles, so you SHOULD be seeing between 161 - 163 ( best case ) miles of range and between 448 - 450 volts ( best case ).
This will be in the default NORMAL mode and Regen level 3.
443 volts with EVERYTHING turned off is a bit low and MAY suggest a buggy software problem.
Unless you have a dongle you n not check your BMS software version.
The dealer can check by plugging in their computer.
Has the car had the Comfort2 update done ?.
Has all the bongs gone away ?.
Maybe that is the software update they are refers too ????.
I would try out the steps above, then recheck your figures again.
A relative has a ZS EV that has covered very similar mileage and is about 18 months old.
He is seeing 163 and 449 volts.

 

[Wendycar127]

@Lovemyev thank you I will double check using your detailed steps. The bongs you refer to in terms of the comfort 2 update what are they how would i know if this had been done. I appreciate your help.

 

[Lovemyev]

@Lovemyev thank you I will double check using your detailed steps. The bongs you refer to in terms of the comfort 2 update what are they how would i know if this had been done. I appreciate your help.

One simple check, do you have the outside temperature showing in the dash panel and the predicted range shown on he dash panel without pulling back on the battery toddle switch next to the KERS button.
If you have both of these, you have the comfort 2 update.
Depending when it was applied and who applied it will have some bearing on if you do indeed have the buggy software.

 

[Wendycar127]

One simple check, do you have the outside temperature showing in the dash panel and the predicted range shown on he dash panel without pulling back on the battery toddle switch next to the KERS button.
If you have both of these, you have the comfort 2 update.
Depending when it was applied and who applied it will have some bearing on if you do indeed have the buggy software.

@Lovemyev yeah I can see this on my dash. As you mentioned this might be the update that was done. Not sure when it was done but it was Frasers in Falkirk Scotland who are an MG dealer.