[CasperStorm]

Absolutely no problem interrupting a balancing cycle to drive your car.

Pre-ballsup the balance cycle was 30-60 minutes on the end of the charge.

 

[Carty]

Pre-ballsup the balance cycle was 30-60 minutes on the end of the charge.

Yeah - This is what I use to find prior to the so called fix from the latest update.
The car commenced it's charge / balance cycle at 11.30am this morning and at 8.30pm it is STILL balancing the pack !.
Bare in mind, it was only charging from a 92% SOC charge in the battery to start with.
This is not right or practical for ANY normal type of usage pattern for any EV, how the hell are suppose to find the time to charge / balance.
There are only 24 hours in a day and the charging is likely to take 12 plus hours of charging / balancing in this time.
Needless to say the cost implications of having the car on charge for this length of time also.
This is far from the result that owners had been expecting.
Pulling the car off charge in order to use it just means a bigger reduction in range and a more lengthy procedure over again.

 

[CasperStorm]

Yeah - This is what I use to find prior to the so called fix from the latest update.
The car commenced it's charge / balance cycle at 11.30am this morning and at 8.30pm it is STILL balancing the pack !.
Bare in mind, it was only charging from a 92% SOC charge in the battery to start with.
This is not right or practical for ANY normal type of usage pattern for any EV, how the hell are suppose to find the time to charge / balance.
There are only 24 hours in a day and the charging is likely to take 12 plus hours of charging / balancing in this time.
Needless to say the cost implications of having the car on charge for this length of time also.
This is far from the result that owners had been expecting.
Pulling the car off charge in order to use it just means a bigger reduction in range and a more lengthy procedure over again.

I suspect the reason it is taking so long to fail to balance the cells is precisely that: it isn't balancing them at all.

So, I also suspect breaking the current balance cycle will likely do bugger all to reduce the range any more than leaving it to "balance" would.

Roll on next week - "fix" due Tuesday morning.

 

[Jim R]

Charge overnight has given 438v so an increase of 1v .

Reference the number of Watts added. How do I do that? I have a Rolec charger but the app cannot connect. Also I don't have a smart meter.

 

[CasperStorm]

Charge overnight has given 438v so an increase of 1v .

Reference the number of Watts added. How do I do that? I have a Rolec charger but the app cannot connect. Also I don't have a smart meter.

Neither do I - for kWh added I will use a local public AC unit that displays it.

 

[Jim R]

First full balanced charge where my voltage on completion has gone down. 437v compared to 439v. 10 hours to charge and balance. Starting to get concerned now.

 

[CasperStorm]

Updated BMS software yesterday.

Straight to my reliable public AC charger - took 23.895kWh to go from 22%->100% (car still trying to balance when I returned 6h 45m later though drawing about 0.3kW)

That equates to a gross figure of 0->100% of 30.63kWh. All last year I would be seeing 44.5-45.5kWh (so 40.5-41.5 roughly usable once AC->DC loss taken into account)

= 68% nominal capacity at present.

However..... plugged in at home overnight and voltage 440V after finishing balancing. Last few home balancing charges have been 438 or 439V so that looks positive. It has been said that 50 hours of balance charge is worth an extra volt or so.

Looks like it may well be the "long game". Will update these figures as I get them.

 

[Jim R]

So I was tempted to start a separate thread. At present maybe the last thing the forum needs on this topic.

About three weeks in now and I feel I am seeing very slow improvement. What I want to see is factual written down improvement.

Having read this article on the owners club page and comments that is could take between 30 -50 balances to get back to hopefully original capacity, I have stared to keep a tracker, noting the miles per kWh between charge, mileage completed since last charge, percentage battery capacity at start of charge, if balance was fully completed, outside temperature, and voltage after completion with HVAC off. I then calculate the battery capacity based off the miles completed between charges, the miles per kWh and the percentage of battery as charge is started and the assumption the capacity is 100% after charge is completed. Does this sound reasonable? Should I measure anything else?

I don't have OVMS and don't have a smart meter.

 

[davesul]

So I was tempted to start a separate thread. At present maybe the last thing the forum needs on this topic.

About three weeks in now and I feel I am seeing very slow improvement. What I want to see is factual written down improvement.

Having read this article on the owners club page and comments that is could take between 30 -50 balances to get back to hopefully original capacity, I have stared to keep a tracker, noting the miles per kWh between charge, mileage completed since last charge, percentage battery capacity at start of charge, if balance was fully completed, outside temperature, and voltage after completion with HVAC off. I then calculate the battery capacity based off the miles completed between charges, the miles per kWh and the percentage of battery as charge is started and the assumption the capacity is 100% after charge is completed. Does this sound reasonable? Should I measure anything else?

I don't have OVMS and don't have a smart meter.

You haven't mentioned how many balancing cycles you've achieved so far.
Looks to me that the miles/kWh value is rather sensitive to driving conditions and heating so using it as a basis to estimate battery capacity is rather dubious.

From various user reports it looks to me that aiming for 450 volts when fully charged should be the first aim and then, AFTER that has been achieved, try assessing the achievable range from miles/ kWh values.

According Miles Roberts in this thread - post #71 - the charging/ balancing process can be achieved in the top 7% of the HV battery capacity, ie the top 3 kWh of stored energy.

So this suggests to me the method at home would be : after charging to "full", then running the heater for perhaps half to one hour to achieve 3kWh discharge and then start another charging / balancing process. And so on, recording HV battery volts everytime, as you're probably doing.
Maybe this is your cycling method anyway?

 

[damo2929]

My battery is to 444v now after 1k miles with taking it to 10miles regularly. Am not sure the ohme charger is good for balancing it seams to cut off and give the silly kw usage figures etc. The car seams to be recovering better on the work dumb public 7kw chargers.

 

[Jim R]

You haven't mentioned how many balancing cycles you've achieved so far.

Will be four weeks this week since my update. Charge approx every second night. Not all balanced. So I would guess I have had ten plus fully balanced charges. Another reason for logging the charges.

According Miles Roberts in this thread - post #71 - the charging/ balancing process can be achieved in the top 7% of the HV battery capacity, ie the top 3 kWh of stored energy.

I have seen different opinions on this. Conversely I run the battery right down before charging. The option I have been taking. That side @Miles Roberts is, I believe, at a Dealer so more ITK . Will give that a go.

 

[davesul]

Will be four weeks this week since my update. Charge approx every second night. Not all balanced. So I would guess I have had ten plus fully balanced charges. Another reason for logging the charges.



I have seen different opinions on this. Conversely I run the battery right down before charging. The option I have been taking. That side @Miles Roberts is, I believe, at a Dealer so more ITK . Will give that a go.

Miles has been a member of these forums for a good few years and is Innovation Development Manager for Chorley Group
In that role I understand he has closer information flow with the UK technical authority at MG UK, compared with most other posters to these forums...

 

[CasperStorm]

"How to measure approximate battery capacity?"

The car mpkWh reading appears not to include regen energy so isn't accurate enough.

I would suggest find a 7/22kW AC public charger that shows how many kWh it has dispensed.

Run the car pretty low (maybe <25%) - plug in and charge it to almost full.

Read the kWh dispensed, divide by the portion of battery refilled (to give a 0-100% equivalent).

It should be around 45.5kWh (~40.5kWh usable with 90% charge efficiency). At 438V I was getting 31kWh.

I rarely use DC rapids but I guess you could do similar with 100% of a good battery taking about 42.5kWh (assuming 95-96% efficiency)

 

[MikeProcter]

My battery is to 444v now after 1k miles with taking it to 10miles regularly. Am not sure the ohme charger is good for balancing it seams to cut off and give the silly kw usage figures etc. The car seams to be recovering better on the work dumb public 7kw chargers.

Switch the Ohme charger to max charging. For the time being I have deleted all schedules and just using it as a dumb charger, but it records my kWh usage. That way it will keep charging and perform an equalisation charge. This is what I’ve been doing since the latest update.

 

[damo2929]

Well got my car to 445v over the last couple of days and have actually been able to get to work and back so my battery is to the point where its able to do 120 mile trips on single charge now, with 15 miles left on the gong. Its taken 20 charge cycles to get to this point.

 

[Carty]

Well got my car to 445v over the last couple of days and have actually been able to get to work and back so my battery is to the point where its able to do 120 mile trips on single charge now, with 15 miles left on the gong. Its taken 20 charge cycles to get to this point.

It is great news ti hear that you now seeing that your car is returning the very similar range that you had “Pre - Buggy” software.
The voltage on the pack is now approaching the “New” target figure of 448 - 450 volts.
If you are able to use your car and then charge / balance on a fairly regular basis, then 20 charges do not take that long to rack up.
However, under the current situation of C19 this process of returning your HV battery to full state if health, could take a lot of owners ages to complete !.
Thanks for the update, at least it offers owners some confidence in the Jan 15th 2021 BMS update.
The fix is relatively quick, but returning the SOH of the battery to normal could take a lot longer under the current lockdown rules.

 

[Jim R]

Little update on mine.

Circa 20 charges in now. Last two have hit 445v. Charging every day now so hope to see further improvements this week.

 

[CasperStorm]

Mine now 448V. Still to do a "see how many kWh I can stuff in it" test.

 

[Jim R]

Ahead of me. Curious to see what you achieve.

What is the theoretical maximum?

 

[CasperStorm]

Ahead of me. Curious to see what you achieve.

What is the theoretical maximum?

All last year I would get c.45.5 kWh 0-100% from AC charging.

Given around 10% conversion losses that suggests c.40.5-41 kWh usable.