[G00se]

Hi All,

I'm doing an EV conversion of a Land Rover and looking to use a Nissan Leaf battery pack complete, with the OEM BMS.

Quick question about my approach - I'm using the pack as is, but I need to rearrange the modules so they fit in the space available.

Can I do this and keep the BMS wires to the same modules? I'll be changing the order of modules, but not the overall configuration of the pack.

Any guidance would be appreciated.

 

[matthew.stead]

@G00se I did this with my BMW 2002 conversion. I split the wide 24 pack with extensions soldered into the BMS wiring and I "folded" the 12 packs so they were 2 wide & 6 high. Using this method I was largely able to reuse the bus bars and BMS wiring.

The split 24 (2 stacks 12 high ea) went into the boot & the other 2 x 12 were then put behind the driver & passenger seat.

I hope this helps a little. I have another post with lots of photos. I was also able to use the holes in the cells so that they became the fixing points. I used high tensile threaded rod (M8) through the batteries.

 

[G00se]

I want to change the sequence or order of the modules in the left hand and right hand stack.

I'm assuming if I just keep the BMS wires on the same modules, I'll be OK?

 

[Electric Land Cruiser]

You can't change the "sequence" of the cells, they must all be wired to the BMS in the same order they are connected in series. Otherwise you'll break the BMS or cook some cells.

My plan is to label every single of the 96 cells 1-96 and also the busbar connections. In the rear of the leaf pack there are 24 modules in one long stack about 32x10x8 inches. I plan to keep that stack complete and build a 2nd identical stack from the other 24 modules and connect them all as original.

Each stack should fit in my engine bay in a protective box like two hot dogs on top of each other.

 

[G00se]

You can't change the "sequence" of the cells, they must all be wired to the BMS in the same order they are connected in series.

Right, so long as I have the same BMS cables to the same modules, I should be fine?

I'm going to keep the modules wired up in series, as per the original Leaf pack. But I don't see exactly how to keep the same order of modules if I make them into one stack?

What am I missing?

 

[Electric Land Cruiser]

Right, so long as I have the same BMS cables to the same modules, I should be fine?

I'm going to keep the modules wired up in series, as per the original Leaf pack. But I don't see exactly how to keep the same order of modules if I make them into one stack?

What am I missing?

All 48 modules in the LEAF pack are wired in series as is. They are just organized into 5 separate banks of modules. Every single module is in series, however. You can re-arrange the modules in literally any configuration you want, but the modules must match the BMS taps 1-96 (2 cells per module). You can mix and match the modules if you wanted for whatever reason but the balance tabs and the position in the string must remain the same. Hope that makes sense. The low voltage BMS wires can be extended with no issue. You can use a multi-meter to figure out which cell is most negative and which is most positive of each bank.

 

[G00se]

All 48 modules in the LEAF pack are wired in series as is. They are just organized into 5 separate banks of modules. Every single module is in series, however. You can re-arrange the modules in literally any configuration you want, but the modules must match the BMS taps 1-96 (2 cells per module). You can mix and match the modules if you wanted for whatever reason but the balance tabs and the position in the string must remain the same. Hope that makes sense. The low voltage BMS wires can be extended with no issue. You can use a multi-meter to figure out which cell is most negative and which is most positive of each bank.

Thanks. That was my assumption.

Wanted to double check before I blew something up.

 

[matthew.stead]

Photo of "folded" stack. No BMS connections changed. The bolts were removed and replaced with M8 when re-stacked. One busbar was removed & replaced with a shorter one. Various plastic cover sections were cut and removed.

 

[gillisk]

@matthew.stead This is great information. I'm leaning toward the Nissan Leaf modules for a Porsche 996 Tesla Model 3 Swap due to their form factor. You can be pretty creative in how you package them. It doesn't look like you are doing cooling of any sort for the pack. I know it didn't come with any cooling, but I was just curious if you have considered any sort of cooling system for your Nissan Leaf modules. Thanks!

 

[Cor]

Right, so long as I have the same BMS cables to the same modules, I should be fine?

I'm going to keep the modules wired up in series, as per the original Leaf pack. But I don't see exactly how to keep the same order of modules if I make them into one stack?

What am I missing?

As long as you keep both the BMS connections to the same modules and wire the power wires to the same modules, then everything will continue to work.
When you split a stack of modules, simple replace the short copper bus bar with a heavy copper insulated wire with lugs to go under the M6 bolts of the replaced bus bar.
If you bring stacks together with their connection points facing (where there used to be a wire connecting the two stacks) then you can re-introduce a bus bar.
Do make sure you keep the same order electrically (in wiring) even if yo ucompletely re-shuffle them mechanically.
For my electric truck (US Electricar S10) I converted one of the two "quart" packs from 2+2+4+4 into 3x4high by "folding" a 2-stack on top of the other 2-stack (and cut off one position of the base mounting plate) and converted the remaining quart and the half pack into 4 stacks of 9 high, because that was the most economical filling of the existing battery box. So, I split the stack of 24 modules in 9+9+6 and re-arranged the 2+2+4+4 into the remaining 3+9. I split the bus bars and the "sensing" wiring for the BMS, keeping all sections wired in the same order and am using the original Leaf BMS with 12V continuous power for balancing and switched power for the CAN bus, which is connected to an ELM327 for reading with LeafSpy in "BMS only" mode.

For the order in the voltage of the pack, just follow the big orange wires and when you stand with the black dual contactor block closest to you (pack connectors towards you) then the wiring goes from the contactors to the left quarter pack, immediately behind the stiffening bar, this is the negative most contact; then from the contact nearest the relay block on the left quarter pack jumping across to the right quarter pack; then from the contact immediately behind the stiffening bar on the right quarter pack to the service disconnect (which includes a fuse) and which is the mid pack voltage and from there to the right contact on the halfpack; then from the left contact on the halfpack back to the relay block, this is the positive most contact at about 380V higher than the negative contact. Each quarter pack delivers about 95V (12 times 4+4V) and the 24 stack halfpack delivers about 190V. Hope this helps.

 

[matthew.stead]

@matthew.stead This is great information. I'm leaning toward the Nissan Leaf modules for a Porsche 996 Tesla Model 3 Swap due to their form factor. You can be pretty creative in how you package them. It doesn't look like you are doing cooling of any sort for the pack. I know it didn't come with any cooling, but I was just curious if you have considered any sort of cooling system for your Nissan Leaf modules. Thanks!

They don't come with cooling - so I have not provided it!!

 

[scubascooby]

This is really good info.

I hope (one day) to get my Subaru converted and a Leaf system is my current favourite. The battery would have to be split between engine bay, fuel tank and under boot floor.