[daltonguitar]

Hi everyone, I recently purchased 8 LG Chem Modules for my EV Conversion and I'm looking into a possible BMS to use. I am planning on configuring the modules 2s4p (in cell terms 32s4p) for a voltage of around 128V. For context I am using an ADC fb1-4001a 120V Motor and a Kelly controller kdh14650b.

I am looking for a cost effective system that can be expanded upon in the future. I was looking into a ZEVA BMS but I believe I would need 11 of their 12-cell modules to get all the batteries included. I went to EV West and they suggested I purchase a Dilithium Design BMS. They said I'd need just 1 master module, 1 satellite module and the thermistors for my setup. I'm not quite too sure how that would work since that would only allow up to 48 cells and i have 128. I am a bit lost at the moment I was hoping someone here could guide me towards the right decision in buying and wiring a BMS properly.

Appreciate any help. Thanks

 

[frodus]

Zeva is pretty flexible. I don't think you can use Orion for that, since you'd need 1 central BMS per parallel group, and you have 4. You still need 11/12 modules from Zeva, but they're far cheaper and it supports parallel groups.

I'd go for distributed for these, since you're paralleling modules and you should not connect the cell taps to each other (current will flow across during charge/discharge).

I looked into buying these and the Zeva checked all of the boxes, they're easy to deal with and the modules themselves are fairly cheap and you only need one master + 12 modules + LCD. I've used one before on a 24s Go Kart and it works great.

 

[john61ct]

Don't know their layout, but be aware many designs use each input to monitor each lowest-level parallel group of cells, considering monitoring each cell individually to be overkill.

 

[daltonguitar]

Thank you for the comments. So if I have the choice to monitor each cell individually or each parallel group of 4 cells with the same voltage I would rather do the later just for money sake. Once I have enough funds I can change to an individual level.

In the meantime, I made a schematic of how I believe the BMS and batteries need to be wired. It is attached to this post. Let me know your thoughts or if I messed up anything.
Thanks for all the help

 

[frodus]

No, you need one set of 3 BMS modules for each parallel group. You cannot parallel the packs at the cell level, not without significant work and large gauge wires connecting all cells together in paralle. These LG modules are difficult and cells are not meant to be put in parallel.

You will need to monitor and balance as if you have 4 separate packs, each pack requiring 3 BMS slave boards. Total 1 master and 12 slave boards.

 

[GregShay]

No, you need one set of 3 BMS modules for each parallel group. You cannot parallel the packs at the cell level, not without significant work and large gauge wires connecting all cells together in paralle. These LG modules are difficult and cells are not meant to be put in parallel.

You will need to monitor and balance as if you have 4 separate packs, each pack requiring 3 BMS slave boards. Total 1 master and 12 slave boards.

@frodus
How do you mean you cannot parallel the LG Chem modules at the cell level? Inside the Nissan Leaf metal cans, are LG Chem modules paralleled: 2s2p.

The one trick is to make sure cells to be connected in parallel are at the same charge voltage level before you connect them together, to avoid high currents as they equalize.
Greg

 

[daltonguitar]

Thanks for all the input guys. So I have decided to go with the ZEVA BMS that frodus recommended I go with.

For anyone else who is working with these modules heres something that might be of use. Apparently EV West has PCB boards that allow for paralleling with a fuse on the LG modules, and they sell them for $39 each. You could also parallel them in the harness if you wanted but I thought I'd put that out there in case you're in the market.

When it came to cost, monitoring every cell with ZEVA turned out to be around the same price as parallel monitoring with a Dilithium BMS with the PCB boards. I also ordered the CAN hall sensor interface, 1200A max and the EVMS Monitor V3. Figured I might as well want to see what the hell everythings doing in the system in case any problems emerge.


Appreciate all the comments

 

[NikMish]

Subscribed

 

[baxy]

For anyone else who is working with these modules heres something that might be of use. Apparently EV West has PCB boards that allow for paralleling with a fuse on the LG modules, and they sell them for $39 each. You could also parallel them in the harness if you wanted but I thought I'd put that out there in case you're in the market.

link?

Sent from my SM-G975F using Tapatalk

 

[daltonguitar]

They're not on the EV West website yet but if you email any of them or call them they'll tell you about it. Went in and saw them in person they're really cool and just attach to the standard LG Wiring harness. Also, considering how cheap they are I am going to try them on my build just to see how it will work. Ill keep you updated.

 

[leman2112]

Got the same pack! Thanks for making this thread. Thunderstruck ev sells the OEM bms connection s for these cells. In case anyone was interested.