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The nissan brochure says 9 bars out of 12. Would that mean each bar is 8.3%? If so, warranty only kicks in when battery is below 75%. If my battery degrade continues would hit would hit 72.4% in 8 years so would need warranty.

8-YEAR / 100,000 MILE WARRANTY FOR NISSAN LEAF LITHIUM-ION BATTERY.

NISSAN LEAF LITHIUM-ION BATTERY WARRANTY ALSO PROTECTS AGAINST CAPACITY LOSS BELOW 9 BARS OF CAPACITY (OUT OF 12) AS SHOWN ON THE LEAF’S CAPACITY GAUGE.
"Below 9 bars" ? 9 bars is 66% to 72%, this means battery warranty wouldn't be covered until the battery degraded below 66%.... :(
 

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Nissan LEAF 30-kWh Battery Degrades More Rapidly Than 24-kWh Pack - amazing that battery technology goes backwards at Nissan! :eek:

“At two years of age, the mean rate of decline of SoH of 30 kWh Leafs was 9.9% per annum (95% uncertainty interval of 8.7% to 11.1%; n = 82). This was around three times the rate of decline of 24 kWh Leafs which at two years averaged 3.1% per annum (95% uncertainty interval of 2.9% to 3.3%; n = 201).”

View attachment 135688
Do a bit more research and you'll find the same source (flip the fleet) who first documented and reported this issue later reported that Nissan addressed a firmware issue in the BMS which caused it to report lower than true SoH:


And this has been independently verified to be a valid fix and not just a fudge job to make the degradation look less than it really is.

The Leaf 30 battery is no worse than a Gen 2 24kWh battery for degradation after the firmware update.

That's not to say that either of them is "good" though, all Leaf batteries degrade a lot faster than they should and compared to other makes.
 

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View attachment 135679

Here is my SOH. Car was new in May 18. There was a 1.8% drop in March 19 over 8 days.
Lithium Ion batteries don't lose capacity in abrupt incremental amounts like your graph. So your battery did not really drop 1.8% over 8 days. What you are seeing is the estimate of the SoH by the BMS.

Only long term trends over years are meaningful, and this is particularly the case with the Leaf BMS which is unusually inaccurate at estimating true SoH.
 

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Because my car sat on someones drive doing not a great deal for the first 2 years of its life it has developed a low cell.

at the moment I'm charging it from below 50% SOC to 100% 6 times a week as this seems to be sorting this issue out.

I have been doing this for 2 weeks now and the imbalance has dropped from 92mV to when I purchased the car @ 2 years old to 76mV this seems to be improving by between 1 - 2 mV per charge cycle by top balancing every day.

At this rate I'm hoping that in about 8 weeks that it will have sorted itself out.
76 mV is a large error in balance and due to the very tiny balance resistors in the Leaf it will take a long time for this to be balanced. I think it will take a lot more than 8 weeks. A 50mV error near full charge is equivalent to about 5% of the entire Ah capacity of the cells. I believe the bleed resistors only draw 10mA...

If speeding up balancing time (in weeks) is your goal you're best to charge the car as slowly as possible (eg a granny charger) as this prolongs the amount of time in each charge session where balancing can be performed.
 

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Hi Simon

Thanks for the info, from the 3rd September to 7th October the imbalance in my battery has dropped from 93mV to 73mV.

for the last 2 weeks I have been charging to 100% every night (from mid 40’s SOC) following Donald’s advice when I asked the question on how best to deal with this.

Given that it’s rebalanced 20mV in 4 weeks (only 2 of which I have been top balancing daily) is it likely to continue in a linear fashion?

If this were the case it would mean that it would rebalance by another 40mV over the next 8 weeks.

So it may take 12 weeks on that basis to completely rebalance the pack, at which point I could return to charging to 80% and full balance every 2 weeks hopefully.

I don’t really have the time to charge back to 100% daily using a granny cable, I don’t think it would be done in time for when I need to use the car again in the morning, but if I did how much do you think this would speed the process up?
 

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Are you currently charging at 3.3kW or 6.6kW ? Are you running it down to mid 40% from a single days driving or are you driving a couple of days to do that ?
 

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Discussion Starter #47
"Below 9 bars" ? 9 bars is 66% to 72%, this means battery warranty wouldn't be covered until the battery degraded below 66%.... :(
Yes, this is not good. I'm pretty sure I've read with the 24/30 leaf that when it gets to 9 bars you get an automatic replacement, but I've now seen in a number of places the term 'less than 9' which may indicate that it is really 8 bars. Nissan should really say 8 bars as this would be much clearer :(
 

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Discussion Starter #48
Do a bit more research and you'll find the same source (flip the fleet) who first documented and reported this issue later reported that Nissan addressed a firmware issue in the BMS which caused it to report lower than true SoH:


And this has been independently verified to be a valid fix and not just a fudge job to make the degradation look less than it really is.

The Leaf 30 battery is no worse than a Gen 2 24kWh battery for degradation after the firmware update.

That's not to say that either of them is "good" though, all Leaf batteries degrade a lot faster than they should and compared to other makes.
Yes, I did see another article saying that leaf 30 degradation had been exaggerated. I can't find any leaf 40 battery analysis. It has been out a few years now and you would think there would be some research out there. Guess I can keep googling...
 

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Discussion Starter #49
Lithium Ion batteries don't lose capacity in abrupt incremental amounts like your graph. So your battery did not really drop 1.8% over 8 days. What you are seeing is the estimate of the SoH by the BMS.

Only long term trends over years are meaningful, and this is particularly the case with the Leaf BMS which is unusually inaccurate at estimating true SoH.
Thanks for clarifying. I still don't understand if my degradation is average. I think mine is on the lower side. I have had the car from new and know all the history. I don't think it has had any worse treatment that any other leaf - I don't have offroad parking so tend to drive on the more conservative side as I can't top up overnight at home.

I'll keep on measuring SOH, who knows it might go up! :LOL:
 

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Hi my leaf 40 is two years old (sep 2018) 12500 miles only short trips two long trips which needed 6 rapid charges SOH 90.15. It seems to be like the out dated navigation nissan hopes it will go away.

Sent from my SM-N975F using Tapatalk
 

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Are you currently charging at 3.3kW or 6.6kW ? Are you running it down to mid 40% from a single days driving or are you driving a couple of days to do that ?
I’m charging at 6.6kW yes down to 40-45% from a single days driving 6 times a week.
 

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An Excel chart! I track my charge history in Excel along with costs etc.

Someday I might make it something easier to ingest and aggregate, like Grafana...


Sent from my iPhone usi
An Excel chart! I track my charge history in Excel along with costs etc.

Someday I might make it something easier to ingest and aggregate, like Grafana...


Sent from my iPhone using Tapatalk
I like an Excel spreadsheet. But where do you get the SOH%?
(I almost don't want to know actually; paying too much attention to it might be unhelpful/unhealthy)
 

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Discussion Starter #54
Hi my leaf 40 is two years old (sep 2018) 12500 miles only short trips two long trips which needed 6 rapid charges SOH 90.15. It seems to be like the out dated navigation nissan hopes it will go away.

Sent from my SM-N975F using Tapatalk
That is the lowest SOH I've heard of. Do you have any historical values- I might start pulling a data set together.
 

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That is the lowest SOH I've heard of. Do you have any historical values- I might start pulling a data set together.
Not realy got any data its my wife's car just shopping and occasionally work run never more than 25miles a day (apart from 2x150 mile trips last January) its very rarely charged up to 100% normally kept between 25% and 80%. I got leaf spy after reading this thread. Not too much of a shock considering nissans overall response to other faults found by users. There is one thing that differs from normal charging and that is we have a zappi charger and a small pv system as well as battery storage. So during the bright days the car is plugged in in eco mode so mostly drawing 1.4kw charge this is a little erratic so charger stops and starts a few times hence the 863 L1/L2 charges, reading leaf spys PDF this figure is not a true reading. I will say that our next ev will not be a nissan not because of the car which i think is great but because of the customer service from top to bottom its rubbish If there is anything else I can add please ask.
Regards Len

Sent from my SM-N975F using Tapatalk
 

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If speeding up balancing time (in weeks) is your goal you're best to charge the car as slowly as possible (eg a granny charger) as this prolongs the amount of time in each charge session where balancing can be performed.
So I’ve tried charging slowly from 35% - 100% SOC this weekend as I wasn’t using the car.

At the end of the charge cycle the battery had rebalanced by 1mV which is exactly the same result as when I charge at 6.6kW.

I believe the rebalancing happens in the last 2% of the charge when the battery top balances.

My charger has a digital readout on it and during this last 2% it drops to around 5A over the last hour and stops / starts charging 3 times as it top balances.

Because I charge 6 times a week I think I will be able to rebalance my battery in 8-10 weeks.

what I have wondered is if could use for example use 3% of my charge and then top off 3 times in 1 day and see if I can achieve 3mV of progress in a single day by doing this.

I understand this is not great for the battery but it would be a way or rebalancing far more rapidly.

Any thoughts?
 

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Discussion Starter #57
Well everyone, Christmas has come a day early. I've now been checking my SOH more regularly (taking screenshots of my leaf spy app). SOH was 91.59% on 3dec and has only gone and risen to 91.8% today!
 

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Hi I’ve double checked today between 7th October and today I have lost 1.1% SOH and covered 3778 miles.

My battery imbalance has dropped from 73mV to 25mV in 82 charging cycles so average balancing per cycle has worked out at just over 0.5mV.

138973
So that’s 1.1% in just under 12 weeks at that rate I’ll be loosing 4.76% per year.

It will be interesting to see if my loss slows when I’m no longer charging to 100% every day when my battery has re balanced.
 

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My 40 kWh Leaf from 01/2019 has a SoH of 91,2 %. Unfortunately the first owner did 250 quick charges in 18 months.
140721
 
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