Battery Cell Imbalance - difference

[JodyS21]

I thought I'd do a bit of a poll, as it's asked a fair bit.
What is an ok cell imbalance amount - and balance time needed.

You would only be able to know the actual Min & Max cell voltage, if you have the OBD2 gadget & app, or OVMS.
E.g. Max cell voltage 4.168 / Min cell voltage 4.151 (total 449.75v) = 0.017v imbalance.

(0.013Volts difference between min & max seems to be about as good as people usually report).

Please share yours
E.g.
Max cell V - Min cell V - Imbalance V - Total V - How long yours takes to complete a balance.

 

[Tango130]

11mV, looks like a very short balance or not at all, but in the past I've had a ~5hour balance(expected as BMS software 0603610R28)

Previous long balance:

 

[JodyS21]

11mV, looks like a very short balance or not at all, but in the past I've had a ~5hour balance(expected as BMS software 0603610R28)
Previous long balance:

I like the graphs you get from your charger.
Hopefully the omhe when I get it, can log this info.

I'm not surprised, 11mV is very good, maybe below the threshold to even do a balance.

 

[MG ZS EV WEST YORKSHIRE]

I thought I'd do a bit of a poll, as it's asked a fair bit.
What is an ok cell imbalance amount - and balance time needed.

You would only be able to know the actual Min & Max cell voltage, if you have the OBD2 gadget & app, or OVMS.
E.g. Max cell voltage 4.168 / Min cell voltage 4.151 (total 449.75v) = 0.017v imbalance.

(0.013Volts difference between min & max seems to be about as good as people usually report).

Please share yours
E.g.
Max cell V - Min cell V - Imbalance V - Total V - How long yours takes to complete a balance.

Here is an example. I put in 32kw on my home charger and my balance took around 5 hours. My voltage is 449v but at 100% full on car app reports 93%. SoH is 99.67% after 8500 miles

 

[Gomev]

Here's mine, getting there.
Vltage 448.75
Max 4.172
Min 4.120
SoC 93.4

 

[JodyS21]

Here's mine, getting there.
Vltage 448.75
Max 4.172
Min 4.120
SoC 93.4

A 52mV (0.052) imbalance is not particularly balanced, does it try for the full 10 hours to balance?

 

[JodyS21]

Here is an example. I put in 32kw on my home charger and my balance took around 5 hours. My voltage is 449v but at 100% full on car app reports 93%. SoH is 99.67% after 8500 miles

Did you get your imbalance voltage - max / min cell volts?

 

[Gomev]

A 52mV (0.052) imbalance is not particularly balanced, does it try for the full 10 hours to balance?

It goes for quite a while and is improving.

Comparing previous and current readings from OBD2.
was and now figures
Vltage 448.25 --> 448.75
Max 4.171 --> 4.172
Min 4.107 --> 4.120
SoC 93.4 --> 93.4

 

[JodyS21]

It goes for quite a while and is improving.

Comparing previous and current readings from OBD2.
was and now figures
Vltage 448.25 --> 448.75
Max 4.171 --> 4.172
Min 4.107 --> 4.120
SoC 93.4 --> 93.4

It's slowly getting there then.
Your figures show what I suspected, the SoC is based on the Max cell Volt and not on the total Voltage.

 

[Mike]

Last time I checked mine was 21mV.

 

[Gomev]

Next charge done, now

Vltage 448.25 --> 448.75 --> 449.25
Max 4.171 ------> 4.172 ---> 4.173
Min 4.107 -----> 4.120 ----> 4.128
Diff 0.64 Diff 0.52 Diff 0.45
SoC 93.4 --> 93.4 --> 93.5

 

[JodyS21]

Next charge done, now

Vltage 448.25 --> 448.75 --> 449.25
Max 4.171 ------> 4.172 ---> 4.173
Min 4.107 -----> 4.120 ----> 4.128
Diff 0.64 Diff 0.52 Diff 0.45
SoC 93.4 --> 93.4 --> 93.5

@Gomev How long does your balance go on for until it ends?
I was thinking the other day, Miles I think it was said it will only balance for a maximum of 10 hours, but I don't know if anyone has actually looked properly to see if it really does cut off the balance at the 10 hour mark.

 

[Gomev]

@Gomev How long does your balance go on for until it ends?
I was thinking the other day, Miles I think it was said it will only balance for a maximum of 10 hours, but I don't know if anyone has actually looked properly to see if it really does cut off the balance at the 10 hour mark.

@JodyS21 - I really couldn't tell, I go out and check occasionally.
I have had trouble with the car stopping charging for no apparent reason.
Last charge was from 83%. Went out to check and it had stopped charging. Re-started it and it was at 93%. This is not the first time since the BMS update, previous charge took several start stops before it got to 100%

 

[JodyS21]

@JodyS21 - I really couldn't tell, I go out and check occasionally.
I have had trouble with the car stopping charging for no apparent reason.
Last charge was from 83%. Went out to check and it had stopped charging. Re-started it and it was at 93%. This is not the first time since the BMS update, previous charge took several start stops before it got to 100%

That's a bit weird it stopping the charge, not heard of anyone having that issue before.
Are you just using the granny charger, or a "smart" charger that could be acting very unsmartly!?

 

[AbuG]

@JodyS21 - I really couldn't tell, I go out and check occasionally.
I have had trouble with the car stopping charging for no apparent reason.
Last charge was from 83%. Went out to check and it had stopped charging. Re-started it and it was at 93%. This is not the first time since the BMS update, previous charge took several start stops before it got to 100%

Might be a problem their could be the car or the charging point.

 

[Gomev]

That's a bit weird it stopping the charge, not heard of anyone having that issue before.
Are you just using the granny charger, or a "smart" charger that could be acting very unsmartly!?

It's a Rolec smart charger being used in dumb mode as don't have an off-peak rate.

 

[JodyS21]

It's a Rolec smart charger being used in dumb mode as don't have an off-peak rate.

Very odd.
Maybe you should try the granny cable, that would allow you to know if it's the car or the Rolec that is causing the issue.