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Discussion Starter #1
Hi all

My brother has a gen 2 leaf tekna with 18000 miles on the clock. He has owned it since it was a year old and 6000 miles.
He does little miles per week, generlly charging of a granny charger as it has lower current draw to enable him to top up off his solar production.
I did recommend to him a few months ago to start charging fully thro the summer whislt he is producing good solar power to get the cells to balance, as previously he would end the charge early.

I own a E-NV200 and always charge to full, use mine every day travelling about 50 miles per day.

A few eeks ago he noticed an odity. going from his house to mine, over a mountain, he lost loads of SOC going up and and gained a load coming down. When i go to his house, generally i loose 25% going up same mountain, and regain 3% coming down, its about a 10 mile mountain trip top to bottom.

That was odd compared to mine, I plugged in my leafspy and it shows 1 cell 60mv lower than the rest, CELL 49.

The odd thing was that the BMS was actively working, showing draining on all cells including cell 49, and cell 50 was taking energy, the cell next to the rogue one.

I would have thought that all cells would have been draining into the weak one.

Anyhow, i`ll upload the leafsy pic for you to see, and any thoughts / suggestions would be greatly appreciated.

Thanks.

Anthony.
132841
 

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Hi it looks like you could have a weak cell there , you will get a better picture if you drop the state of charge to as low as you can get it and then have a look at the cells again, this should give you a better idea of any cell problems.
Good luck
 

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The key is whether you have any battery warranty left. Exactly how old is the car?
 

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Discussion Starter #5
Thanks for the replies.

Its a 2014 plate, registered jan 1st 2014 so out of the 5 year warranty.
After doing alot of reading today, on here and mynissanleaf forum, im going to do a manual balance procedure for a few hours / days to try to manually force balance to try to help out the low out of balance or rogue cell.

I havent heard of a CVLI test, if the manual balancing doesnt work, then maybe a trip to the dealer in inevitable.

We cold always remove the battery ourselves and manually balance the low cell, i have the skills and equipment to do it, have made a battery store for the house using 1/2 a leaf pack and a ZEVA bms.
It just alot of work / hassle to open the pack and manually balance, then only to find having to drop out the pack again to replace the cell.
If we have to open it, we will probably replace the cell anyway, or at least do a capacity test on it.

Anything else we could try thats easy?

Thanks.
 

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You clearly have a lot of knowledge and abilities.
Personally I'd try discharging the car to see if the cell is worse at the bottom end or consistently bad. If the former it needs changing, if the latter balancing might help.
At this point I'd consider getting a pack swap to a 30 or 40 and break the existing pack for spares. Splitting and resealing a pack is a lot of work at not inconsiderable risk.
 

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He’s recharging it every 14 miles, that’s really bad for the battery.
 

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Discussion Starter #8
Hi Edd,

He isnt recharging every 14 miles. the way he has operated the car, as he does low miles, is charge the pack when he needs to use the car, which isnt very often, always relatively short journeys.
He mostly never charges to full, mostly ends the charge when the solar drops off, then he unplugs.
Ive now told him for the next few weeks charge to full, and then force charge after that to initiate a rebalance, maybe do that 3 or 4 times after its ended on full.

then we shall read the dta on leaspy again to see if the 62mv gap has closed.
If not, then we will have a decision to make when his range loss starts effecting his journeys.

Thanks.

He’s recharging it every 14 miles, that’s really bad for the battery.
 

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Discussion Starter #9
ive yet to see a 40kwh pack up for sale, bet they are pricey.

My e-nv200 is on 70k miles. just lost its first bar, id love a 40kwh pack in that, and defo would consider it if one was to fall into my lap for reasonable money.

Anthony.

At this point I'd consider getting a pack swap to a 30 or 40 and break the existing pack for spares. Splitting and resealing a pack is a lot of work at not inconsiderable risk.
 

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The 40kWh packs for LEAFs come up at the bigger breakers quite regularly, but I've never seen one for the e-NV200.
The alternative is Muxsan.
Talking of whom, he recently successfully rebalanced a single out of balance cell but with no description of how so it's unclear whether he split the pack. The claimed three hours implies not and that he's working his magic via the BMS.
 

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Discussion Starter #11
Wow, if Muxsan is doing that, then thats a breakthro, wonder if it can be done via his interface tool.

Tiem to catch up with the muxsan youtube page again i think.

If i came across a 40kwh pack, id have a go squeezing it into the current 24kwh box. It may fit with abit of jiggery pokery lol... id love to get my hands on one tho, but not for stupid money.

Even better would be a model 3 complete battery and find a way to sling it under the van, now that would be a project.




The 40kWh packs for LEAFs come up at the bigger breakers quite regularly, but I've never seen one for the e-NV200.
The alternative is Muxsan.
Talking of whom, he recently successfully rebalanced a single out of balance cell but with no description of how so it's unclear whether he split the pack. The claimed three hours implies not and that he's working his magic via the BMS.
 

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If i came across a 40kwh pack, id have a go squeezing it into the current 24kwh box. It may fit with abit of jiggery pokery lol... id love to get my hands on one tho, but not for stupid money.
If you go the "brute force" route you can fit 40kWh LEAF cells into your 24 kWh eNV200 case, but I wouldn't recommend it as a safe thing to do.
 

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Muxsan also offer full pack replacement from 24kWh to 62kWh. 62kWh costing €12500 battery supplied

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Ev's Enhanced state
"manually re-balancing these 30kWh packs has become one of the few reasons that we still have to open a Leaf battery pack these days."
So I doubt Muxsan will have a way to do this via software, you have to target individual cells to bring their charge level upto within a few mV of the rest of the cells, you need a pretty accurate charge controller to do that with.
 

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Ev's Enhanced state
"manually re-balancing these 30kWh packs has become one of the few reasons that we still have to open a Leaf battery pack these days."
So I doubt Muxsan will have a way to do this via software, you have to target individual cells to bring their charge level upto within a few mV of the rest of the cells, you need a pretty accurate charge controller to do that with.
I'm pretty sure they manually balanced the cell

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I'm pretty sure they manually balanced the cell

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Asking Emile is the best way to find out. The job only taking 3 hours can only mean costed time (not including charging time) and is incredibly quick to just drop, open, reseal and reinstall let alone anything else. Not all of the cells are easy to reach due to the way that they are stacked so I'm impressed whatever way they did it.
 

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Asking Emile is the best way to find out. The job only taking 3 hours can only mean costed time (not including charging time) and is incredibly quick to just drop, open, reseal and reinstall let alone anything else. Not all of the cells are easy to reach due to the way that they are stacked so I'm impressed whatever way they did it.
Their tweet (screenshot attached to previous post) says they used crocodile clips

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If it only costs 350 Euro's (plus travel) that's excellent value.
I wonder how/why a single cell gets so far out of line?
 

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Discussion Starter #19
You would have hoped the bms wold keep all cells pretty balanced.

The good news for us with this battery is the cell is low on the bottom and top of the charge cycle, meaning its a balance issue not a weak cell hopefully)

We will try the manual balance option by plugging in a few times after every full charge to force balance for a few weeks.
As you say, 350 euros is a fair price to maually balance, maybe a weekend in amserdam at the same time, win win...

If it only costs 350 Euro's (plus travel) that's excellent value.
I wonder how/why a single cell gets so far out of line?
 

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BTW I have seen a 40kWh pack on sale in UK for 7.5k if anyone is interested

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