# Gen 3 Nissan leaf cells. BMS options?



## tortuga (Sep 11, 2017)

Greetings all
Does anyone on here have experience with Gen 3 Nissan leaf cells?
I have recently acquired some for revitalizing my (4 wheeled) Zap pickup (its been sitting for 4 years).
They seem to come in 3P9S modules (32.85V) and 3P4S (14.6V) Nominal modules.

I am considering re-configuring them to a simple 35S pack,
then using the stock CHWP-12008 charger, with some minor reprogramming.
That would be:
147V Maximum
127.75V Nominal
105V Minimum

Charging to 144V would be approximately 4.11V cell.
Total pack weight 271 Lbs about 400lbs lighter that the old (long dead) AGM's
I have little experience in EV sizing but experience as an electrician, so your input and thoughts are appreciated. 
From what I can tell of the motor in this Zap its: 

Battery Full charge Volts​144​*Nominal Volts: (DC)*​120​Continuous rating kW​19​Continuous rating hp​25.2​​​Peak output (kW)​68.3​Peak output (hp)​85​Average speed MPH​35​Peak amps:​569.17​Continuous Amps:​158​
Thanks in advance.


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## PocoJoe (Feb 18, 2021)

Hello Tortuga, I’m in a similar place. I am awaiting delivery of 8 of the 3P4S modules. They will be the traction pack for a long sitting VW Pickup that was set up for 120v flooded lead acid pack of 20 6v US125 batteries. My motor is a 8 inch Advanced DC, and controller a Curtis 1221. See Joe Miller's 1981 Rabbit Pickup White Rabbit for what I have to start with.

I am considering leaving the cells in their present packaging because I understand them to be compressed. My uninformed alternative would be to take the modules apart, and form 3 strings of 32 cells, with independent chargers and contacters. This would be more modular, and my range needs are limited to maybe 20 miles on city streets. I’d probably see if I could operate on one string, and keep the vehicle weight down. One string will probably weigh in at about 100#, and I can see a cart that I could use to slide it into the bed and lock it down. It will be interesting to see how the car drives when not dragging 1300# of lead and acid.

It’s fun to think about for now, but in a few days a major investment in batteries will show up, and the desire to get started will build.

I think our starting points are similar. Do you have any insights into the need to keep these cells compressed?

Good luck with your build!

Joe


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## PocoJoe (Feb 18, 2021)

I have found a reference that indicates cells within each pack are laser welded, suggesting reconfiguring the packs will be difficult if not impossible. Can you confirm this? Is this why other threads reference ultrasonic and spot welding? These babies are born to burn. Not sure I want to contemplate a home brew spot welder.

Thanks for reading

Joe


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## tortuga (Sep 11, 2017)

PocoJoe said:


> I have found a reference that indicates cells within each pack are laser welded, suggesting reconfiguring the packs will be difficult if not impossible. Can you confirm this? Is this why other threads reference ultrasonic and spot welding? These babies are born to burn. Not sure I want to contemplate a home brew spot welder.
> 
> Thanks for reading
> 
> Joe


Thanks so whats the best plan for using these Gen3 ? Separate BMS/charger for each module that is also centrally controlled.
The upshot of that is then if there is an issue you can drop in replace another gen3 module.


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## brian_ (Feb 7, 2017)

tortuga said:


> Does anyone on here have experience with Gen 3 Nissan leaf cells?


The only example of anyone using the Leaf+ 62 kWh battery that I can think of is Rockcrawler and his race 4Runner:

Differences in dimension between 24kwh and 62kwh Nissan Leaf battery modules
Toyota 4Runner 4x4 Race truck Leaf conversion
Those discussions provide illustrations and dimensions of the modules... left intact.



tortuga said:


> They seem to come in 3P9S modules (32.85V) and 3P4S (14.6V) Nominal modules.


This appears to refer to the modules of the 62 kWh battery found in the Leaf+. They actually come in three module sizes:

9S3P (four per pack)
4S3P (eight per pack)
7S3P (four per pack)



tortuga said:


> I am considering re-configuring them to a simple 35S pack...


Unfortunately...


PocoJoe said:


> I have found a reference that indicates cells within each pack are laser welded, suggesting reconfiguring the packs will be difficult if not impossible. Can you confirm this? Is this why other threads reference ultrasonic and spot welding?


Yes, like every other module consisting of a stack of pouch cells, the cell tabs are (ultrasonically) welded into the stock electrical configuration. They can be separated and reconfigured, but it is difficult.

Since the 62 kWh battery of the Leaf+ which is made up of these modules seems to use essentially the same cells as the 40 kWh battery of recent base Leaf models (just 50% more of them), it would be easier to work with the 40 kWh battery, leaving the module pairs intact.

40 kWh Leaf battery: 196 cells as 96S2P in 48 modules of 2S2P each, modules mechanically bonded in pairs weighing 8.7 kg per pair
62 kWh Leaf battery: 288 cells as 96S3P in 16 modules, 4 x 7S3P + 8 x 4S3P + 4 x 9S3P
The only problem with unmodified modules from the 40 kWh battery, which are the same as earlier Leaf modules other than their capacity, is that you would still have a 2P configuration, or a multiple of that in parallel.

A 36S2P battery assembled from them would be 18 modules (9 pairs), or about 79 kg (172 lb) for 15 kWh
A 36S4P battery assembled from them would be 36 modules (18 pairs), or about 157 kg (345 lb) for 30 kWh
I realize that the original question was about the BMS; I don't have any suggestion for that.


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## tortuga (Sep 11, 2017)

Thanks Brian in the months since I made this post I have acquired 
two 4S2P (14.6V) and three 9S3P (33V) leaf packs for a good deal.
So yeah I guess I have to treat them as 5 different batteries.
Or find someone whom can reweld them.
Or sell them.


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## brian_ (Feb 7, 2017)

tortuga said:


> Thanks Brian in the months since I made this post I have acquired
> two 4S2P (14.6V) and three 9S3P (33V) leaf packs for a good deal.
> So yeah I guess I have to treat them as 5 different batteries.
> Or find someone whom can reweld them.
> Or sell them.


Or you can just connect them in series, for 35S3P. Since you want (need for it to fit) less battery (weight and bulk), so you need less than 3P... then yes, getting different modules might make sense.

The alternative to re-welding tabs, and the approach taken by most people who reconfigure modules like this, is to break apart the original welds (without destroying the tabs), then drill holes in them and bolt them together instead of welding. No fancy tools or skills required.  Here's an example: Modified Bolt Pack for Tesla Cobra EV Race Car

Also, for clarity, combinations of cells like these which are not intended to be broken down further are normally called "modules"; a "pack" is normally a set of modules in an enclosure. Most EVs have a single pack with several (4 to more than 30) modules. The combination of all of the packs in the vehicle is called the "battery". Those are not the only valid uses of these terms, but they are the normal terminology so they're the most readily understood.


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## tortuga (Sep 11, 2017)

Gotcha, I'd rather not sell it, so perhaps Ill try to disassemble one of the smaller 3P2S 'modules' and see if I can get all 8 cells apart and tap some threaded hols in them. If so I can make my simple 35S pack and re-use my charger.


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## brian_ (Feb 7, 2017)

tortuga said:


> Gotcha, I'd rather not sell it, so perhaps Ill try to disassemble one of the smaller 3P2S 'modules' and see if I can get all 8 cells apart and tap some threaded hols in them. If so I can make my simple 35S pack and re-use my charger.


You won't be able to tap holes in the cell tabs - they're thin sheets. You can punch holes, make matching holes in some copper strips, and bolt through them.


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## tortuga (Sep 11, 2017)

PocoJoe said:


> ..
> I am considering leaving the cells in their present packaging because I understand them to be compressed. My uninformed alternative would be to take the modules apart, and form 3 strings of 32 cells, with independent chargers and contacters. This would be more modular, and my range needs are limited to maybe 20 miles on city streets. I’d probably see if I could operate on one string, and keep the vehicle weight down. ..


Hey Joe hows your build going? Did you get your truck on the road?


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## PocoJoe (Feb 18, 2021)

Hi Everyone,

I am making progress on my build. At the moment, I have the (six) correction eight Nissan Leaf Gen 3 3P4S modules strung in series, and mounted in a frame ready to drop into place.









I have wired up the J1772 interface with a relay to cut out the AC, and interface of the Traction battery charger and Accessory Battery charger.









I elected to go with a small intelligent 12 volt charger for the FLA 12 volt deep discharge accessory battery so that it would not boil. 

Next steps are to interface the Orion2 to the Stealth EV, and discover the joys of CANBUS control.

The Battery box is already in the bed of the truck, and my wife is wondering how long the hoist I have constructed spanning the gap between the house and the garage is going to be there - it is built to drop the battery pack into the truck when all the programming and wiring is complete.

I am using a resistive heater to simulate the load of the motor and learn how the charge cycle goes.

Joe


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## tortuga (Sep 11, 2017)

PocoJoe said:


> Hi Everyone,
> 
> I am making progress on my build. At the moment, I have the six Nissan Leaf Gen 3 3P4S modules strung in series, and mounted in a frame ready to drop into place.
> 
> ...


Thanks for the update, you have made more progress than me.
So you have had this ev since 2002?
So your just keeping the 3P4S modules unmodified?
If you sting 6 together you'll only have about 88 volts nominal right?
Were you not doing 8 for 117 Volts?
How does the 'Sealth EV' charger balance all the cells?
Can you post some more info on the charger?

Thanks!
--Turtle


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## PocoJoe (Feb 18, 2021)

Hi Tortuga!

Hi - yes, big mistake in typing without thinking - there are 8 leaf modules for a nominal 120 v pack, not six as I said. DOH!

I decided to keep the 3P4S modules in original compressed packaging. This allows for better air flow and there was no trying to learn how to weld wires onto something that likes to burn.

The charger comes from StealthEV. Stealth EV 3.3KW 108V Aircooled Charger+1KW DC/DC Converter - it is the 108 volt unit. 

I also bought the Orion2 from Stealth.

I found that Ewert Energy Systems were extremely responsive to my questions and I rented the BMS cable validation tool from them as there was ambiguous labeling on two of the cables where 6 and 9 could be flipped. 

While there is a $300 discount on the charger, there is a $300 consulting fee to Stealth EV for product suitability review, so it comes out as a wash. It was good to have someone who has done this before review my plans and confirm that I was ordering the correct charger and BMS for my needs. I personally think it was money well spent.

Elsewhere on the board in some other posting by me are details regarding the manufacturer of the charger in China. StealthEV is the sole source in the US for this integrated charger and 12v inverter. It is a nice package but the documentation is EXTREMELY thin. I did learn that the CAN Bus protocol is documented and the manufacturer supplied me with the listing, should you need it. The manufacturer was quite responsive.

Still no "smoke test" but I have to get this thing on the road - It is on the insurance and is again licensed and titled. It was last driven in February of 2006. At that point it wasn't able to make a 14 mile round trip to work, even with opportunity charging at work. The next step was to build a "Lee Hart battery balancer" - an extremely clever BMS that would actively balance a string of lead acid batteries. I hated the monthly chore of watering all those cells and put off building the charger. 

Fast forward a year, and I was visiting Stanford and found myself wandering around the garage of a startup on El Camino Real Tesla Motors dealership coming to Menlo Park - 

It was the Tesla dealership and I think that there was one car in the showroom and three being worked on in the shop when I was there. One Roadster was open to the floorboards and getting worked on. The folks in the garage let me watch, answered a bunch of questions, and I knew at that point I couldn't go back to flooded lead acid batteries and my "lead sled".

I'm glad that I have held on to the Rabbit all this time, as it will be fun to get it back on the road with a J1772 interface!

Joe


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