BMS- Battery balancing etc

[BruceT]

I'm sorry, I know this has been asked before, I was reading it, now I can't find it. My battery says this.......

As you can see 98 miles, the fuel level gauge thingy is reading 5 bars out of 8. should my voltage be showing 411v? Seems really low, I mean I wouldn't want to put my fingers in there, but you know what I'm saying.

The thread I was reading before was talking about 450v when full. the car is behaving quite nicely, no problems with range. I don't often look at this screen.

If anybody can give me some advice, or just tell me to stop worrying, please do. If you need me to get more info I can do that too.

Thanks all.

 

[Kithmo]

TBH, I have no idea what the battery voltage should be at different levels of charge and don't need to know, as long as it's 456V (or 450V if you have the new BMS) when it's fully charged it's fine.
If you have 5 bars of charge with 98 miles remaining that sounds about right.
(98/5)x8=157 (approx) when full.

 

[Gomev]

TBH, I have no idea what the battery voltage should be at different levels of charge and don't need to know, as long as it's 456V (or 450V if you have the new BMS) when it's fully charged it's fine.
If you have 5 bars of charge with 98 miles remaining that sounds about right.
(98/5)x8=157 (approx) when full.

Remember @Kithmo all bars are not equal. 5 bars represents about 65/67% SOC so 98 miles looks a little low, but could be down to weather or driving style etc. etc..
@BruceT the only way to quickly tell is to fully charge (and balance if you can) and then look at the volts with nothing switched on, eg heating etc.. As mentioned above should be either 455/456v or 449/450v.
Let us know when you have done that.

 

[Kithmo]

Remember @Kithmo all bars are not equal. 5 bars represents about 65/67% SOC so 98 miles looks a little low, but could be down to weather or driving style etc. etc..
@BruceT the only way to quickly tell is to fully charge (and balance if you can) and then look at the volts with nothing switched on, eg heating etc.. As mentioned above should be either 455/456v or 449/450v.
Let us know when you have done that.

Hence the "approx", it could be on the lower end of the 5th bar.

Here's what I have written down from earlier posts:
8 : 91-100%
7 : 80-91%
6 : 69-80%
5 : 58-69%
4 : 47-58%
3 : 36-47%
2 : 25-36%
1 : <25% (HV battery light comes on)

So, based on 163 miles WLTP when full, the 5th bar is representing anything from 94.5 miles (58%) to 112.5 miles (69%), 98 miles being within that range.
Looks ok to me.

 

[BruceT]

Remember @Kithmo all bars are not equal. 5 bars represents about 65/67% SOC so 98 miles looks a little low, but could be down to weather or driving style etc. etc..
@BruceT the only way to quickly tell is to fully charge (and balance if you can) and then look at the volts with nothing switched on, eg heating etc.. As mentioned above should be either 455/456v or 449/450v.
Let us know when you have done that.

Hi guys, thanks for the ideas, I wasn't actually worried about the 98 miles, my last little drive was at night, in the rain heater on, so 98 miles would be ok.

I plugged it in last night, at home, and left it to charge until it cut off it only 12Kwh.

Screen today.....

So I think all good?

 

[Kithmo]

Looks ok to me, 157 miles range this time of year, the 448V indicates that you have the new BMS.

 

[JodyS21]

Hi guys, thanks for the ideas, I wasn't actually worried about the 98 miles, my last little drive was at night, in the rain heater on, so 98 miles would be ok.

I plugged it in last night, at home, and left it to charge until it cut off it only 12Kwh.

Screen today..... View attachment 5617

So I think all good?

448V is ok. New BMS as Kithmo said.
We always say, reset your trips, then the range GOM shown (157 in your example) will be relative to WLTP & comparable.

 

[Gomev]

Hi guys, thanks for the ideas, I wasn't actually worried about the 98 miles, my last little drive was at night, in the rain heater on, so 98 miles would be ok.

I plugged it in last night, at home, and left it to charge until it cut off it only 12Kwh.

Screen today..... View attachment 5617

So I think all good?

Looks good, let it balance after it finishes charging (if you didn't this tis time) and it may get to 449v 163 miles.

 

[BruceT]

Looks good, let it balance after it finishes charging (if you didn't this tis time) and it may get to 449v 163 miles.

AFTER it finishes?

 

[Bluejeros]

Hi there, Just a quick question? I use my Wallbox to charge my car which is now 6 weeks old, On the little screen it says charge completed 165 miles. However when I start the car this mileage estimate drops to around 148 miles, why? I checked the voltage and after charge it is 449v

 

[Lovemyev]

Hi there, Just a quick question? I use my Wallbox to charge my car which is now 6 weeks old, On the little screen it says charge completed 165 miles. However when I start the car this mileage estimate drops to around 148 miles, why? I checked the voltage and after charge it is 449v

Likely you have something still tuned on from the previous trip ?.
Check if you the HVAC still turned on, bet you have !.

 

[biffo]

Hi there, Just a quick question? I use my Wallbox to charge my car which is now 6 weeks old, On the little screen it says charge completed 165 miles. However when I start the car this mileage estimate drops to around 148 miles, why? I checked the voltage and after charge it is 449v

Pretty sure the estimated range uses the trip computer miles per kWh value - try resetting the and see what range is displayed?

 

[EVTECH]

A quick bit of advice, use slow chargers most of the time for balancing the cells. If you use DC chargers too often it will throw the cell balance miles out and will give range issues and can take weeks to get cells balanced again.

 

[JodyS21]

A quick bit of advice, use slow chargers most of the time for balancing the cells. If you use DC chargers too often it will throw the cell balance miles out and will give range issues and can take weeks to get cells balanced again.

I'm not sure that is correct.
Yes rapid chargers aren't great for the battery compared to AC chargers, but it's not that bad and I've never heard anyone on the forum here ever say it has caused their imbalance to become so bad that it's taken weeks of AC charging to rebalance them.
Only the bad BMS software has ever been reported to cause such imbalance issues.

 

[EVTECH]

I'm not sure that is correct.
Yes rapid chargers aren't great for the battery compared to AC chargers, but it's not that bad and I've never heard anyone on the forum here ever say it has caused their imbalance to become so bad that it's taken weeks of AC charging to rebalance them.
Only the bad BMS software has ever been reported to cause such imbalance issues.

Sorry to disagree with you but I’ve worked on various brands of EV for over 15 years and can assure you that I am correct. I do know what I’m talking about, still working on mostly electric vehicles today see these issues cropping up more nowadays as some people use dc charging more than ac because it’s quicker.

 

[JodyS21]

Sorry to disagree with you but I’ve worked on various brands of EV for over 15 years and can assure you that I am correct. I do know what I’m talking about, still working on mostly electric vehicles today see these issues cropping up more nowadays as some people use dc charging more than ac because it’s quicker.

I'm not saying you're wrong, but it's never been a reported issue on this forum with the MG.

I have no idea about other EVs, but the MG tells you to do an AC charge/rebalance once the imbalance caused by DC charging reaches a set threshold. It is not that uncommon for folk on here using mainly DC charging to see this warning, but none have ever reported that it has needed several AC charge/balances to get it rebalanced.
Could it be that the batteries / electronics are better nowadays that it doesn't become such an issue as it used to?

 

[Kithmo]

Battery technology has changed a lot in the last 15 years.