18650 battery range extander and main battery remake ( DIY please help )

hi I am from asia,
LEAF car year is 2012 last


i make project (DIY) range extender for my leaf car, using 18650 li-ion batteries. but i faced some problem with LEAF car. is that problem is leaf there car remaining Range (km/Miles) over (3 side strips on range remaining dash) time voltage is (from leaf spy) "365V" one li-ion cell voltage is 3.8V ( 365/96 = 3.8) .

the after we can drive for charging, but i drive car end of turtle "mode" ( car is totally battery lost) that time i check with my leaf spy app the car voltage, after car stop voltage is "355V" one li-ion cell voltage is 3.7V ... now have a problem, 18650 cell nominal voltage is 3.7V .. the low voltage is 3.1V or 3.2V. have a power of cell 4.2 v to 3.2V i can use that battery cell to 3.2V low volt but LEAF HV battery cutoff the main battery one cell voltage is 3.7V .. that my question is how configuration nissan LEAF main battery low voltage cutoff move down from program. If the program how to change with any diagnosis tool or any program tool ?? pleas help guys its most important to me for DIY project



thanks!!!

Others with real expertise at this will follow, but it is my understanding that you cannot change the programming of the Leaf LBC/BMS. You are facing other serious issues, but if you cannot match voltage profiles, you will not be able to connect the range extender as you intended. I think it is possible to work around this limitation, but again I suggest you wait for the experts to post here.

I'm no expert either, but these articles discuss some details about the AESC cells in the LEAF packs and some of your assumptions seem to be incorrect:

https://qnovo.com/inside-the-battery-of-a-nissan-leaf/

https://www.nissan-global.com/EN/TECHNOLOGY/OVERVIEW/li_ion_ev.html

... It uses a different material for the cathode called lithium-manganese-oxide with nickel oxide (LiMn2O4 with LiNiO2) that is inherently safer than the lithium-cobalt-oxide cathode material used in mobile devices and the Tesla pack. The cell’s voltage chart shows a maximum cell voltage of 4.2V. Rated nominally at 3.75V ...

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On 2011/2012 LEAFs, it looks like the nominal cell voltage is 3.75V whereas on 2013+ 24kWh packs, it's 3.65V

You might also want to check out this YouTube channel:

https://www.youtube.com/user/PowerElectronicsBlog/videos

So how could someone do this? Can you get another controller? And a bms that will work?

Jatgm1 said:

So how could someone do this? Can you get another controller? And a bms that will work?

Click to expand...

At that point you might as well gut the car.
Either utilize the (readily available) CAN-bridge tools to replace/upgrade the Nissan battery pack...or abandon the Leaf platform all together and do a "conversion" (like the old days).

Converting the leaf to what? Something that can use 18650 cells?

I find it hard to believe theirs no way to just make the controller ignore the battery warnings.

So I haven't seen any updates, but is there a way to change the bms to ignore the low battery warning? Just force it to work? Ignore turtle mode? Is the bms and Motor controller one unit? Or are they separate? Like can you just make an Arduino provide information saying it's charged constantly even if it's not and just use a separate bms system that has Bluetooth connectivity so I can get the battery status on a phone? And just completely turn the drive battery off when it's low enough?

Or add extra cells to raise the voltage so it's not under the voltage limit? Idk.

If the cell voltage goes too low the batteries will be ruined (as in DEAD) or potentially catch on fire. It's like asking if you can just remove the tachometer from an ICE so you don't have to worry about that pesky redline reading. You could, but it's just not a good idea.

I don't understand the obsession with 18650 cells that require numerous parallel connections and active cooling, but the voltage per cell of the LEAF battery is not significantly different. Full charge is approximately 4.2 volts per cell and the LBC (lithium battery controller or BMS) allows discharge to below 3.2 volts per cell on the 62 kWh pack in my 2019. The minimum voltage was about 307 volts (or 3.2 volts per cell) on my 2011, but the 2015 24 kWh and 2019 62 kWh packs will go lower if the cells are well balanced.