Rate my 30S12P battery design

[Joona]

I'm currently designing a battery pack for my 2009 Yamaha YZ250F electric conversion and would appreciate some feedback before I begin building it.

The pack will have a 3-layer construction, the photo only shows one layer of the design. I'm planning to use EVE 50PL cells, which I purchased for €2.80 per cell including DDP shipping to Finland.

The bus plates will be made from 1mm thick copper.

The drivetrain consists of a 3Shul GBX80 motor paired with a Hyper Leo controller. For battery management, I'll be using ANT BMS 420A continuous and 1050A peak version.

Before I start assembling the pack, I'd like to know if anyone can spot any potential issues or weaknesses in the design.

 

[freesty]

Nothing wrong with that. Good job from me. Maybe one idea, what I've seen in oem builds. How about to add some screws to hold the layers together.
How do you gone weld this 1mm copper?

 

[lnanek]

Looks like a tight fit. If you sacrificed some capacity you might be able to box it up, put it on rails, and pull it out sideways to save the bike if it catches fire. Also to charge safely off the bike.

 

[Joona]

Looks like a tight fit. If you sacrificed some capacity you might be able to box it up, put it on rails, and pull it out sideways to save the bike if it catches fire. Also to charge safely off the bike.

Thanks for the reply. That's a great suggestion. I may end up doing something like that, since I'd much rather lose only the battery pack than lose the entire bike in the event of something catastrophic.

I think I can implement it without sacrificing any capacity, since I've already left some room for a battery enclosure.

 

[Joona]

Nothing wrong with that. Good job from me. Maybe one idea, what I've seen in oem builds. How about to add some screws to hold the layers together.
How do you gone weld this 1mm copper?

Thanks for the reply. Having something mechanically holding the layers together is probably a good idea. My original plan was to have the battery enclosed in a case, with plates on each side compressing the layers together, but adding some screws to hold the layers certainly wouldn't hurt.

I'm ordering the bus plates from Huizhou WLJ Technology Co. in China. The plates have nickel tabs where they connect to the cells, so I won't need to weld the 1 mm copper directly to the cell terminals.

To connect the layers, I'm currently thinking of soldering braided copper wire between them, similar to what Blacksheep Engineering did in his battery build video:

I'm also interested in hearing if anyone has better suggestions for connecting the layers!

 

[BlueSwordM]

I'm currently designing a battery pack for my 2009 Yamaha YZ250F electric conversion and would appreciate some feedback before I begin building it.

The pack will have a 3-layer construction, the photo only shows one layer of the design. I'm planning to use EVE 50PL cells, which I purchased for €2.80 per cell including DDP shipping to Finland.

The bus plates will be made from 1mm thick copper.

The drivetrain consists of a 3Shul GBX80 motor paired with a Hyper Leo controller. For battery management, I'll be using ANT BMS 420A continuous and 1050A peak version.

Before I start assembling the pack, I'd like to know if anyone can spot any potential issues or weaknesses in the design.

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Seems nice, do you plan on doing any battery potting?

Would be quite useful for keeping battery health all equal and in tip top shape.

 

[Joona]

Seems nice, do you plan on doing any battery potting?

Would be quite useful for keeping battery health all equal and in tip top shape.

Thanks for the insight, I hadn’t really considered that. I was thinking that having something to transfer heat from the cells to the aluminum side panels would be beneficial. Do you know of any materials that are lightweight, electrically insulating, and thermally conductive?

 

[AnthonyC]

Thanks for the reply. That's a great suggestion. I may end up doing something like that, since I'd much rather lose only the battery pack than lose the entire bike in the event of something catastrophic.

Reliability might be an issue, with the battery as a single-BMS lump rather than modules. If manually assembled cells have a one-in-100,000 chance of failure during the bike's life, that's worse than one in 300 for the battery as a whole. You'll want to release fastenings securing way more than the pack's 30kg (against vibration), undo connections capable of 100s of amps and slide the pack out, while 3.5kWh (half full) does its thing within the space of a few minutes. I don't see it myself.