Battery protection add-on board

I’ve been considering ways to prevent deep discharge on my Reform’s cells in the future after letting nearly all of mine get too low. The obvious solution is to buy the protected battery boards in the store, but shipping to the US is pretty expensive, and I wanted to see if there was a DIY solution.

I considered modifying the existing battery boards or starting with a copper clad board and making my own protected board from the schematics, but I realized that the cells could also be protected by disconnecting the whole battery board rather than just individual cells. This opens the door to an add-on board that connects to the battery board’s 5-pin output and sits between the battery board and the motherboard.

I did some research on battery protection chips and it looks like the Texas Instruments BQ7790509PW is a promising option. Each chip supports monitoring up to 5 cells and can be connected with others to handle larger battery packs, so two of these could handle all of the cells in the Reform.

Has anyone else looked into doing this?

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Shipping to the US is pretty expensive… I would also love to be updated about something like this. I was thinking about the possibility of adding something between the battery boards and motherboard, but I am not (yet) knowledgeable or skilled enough to attempt it on my own…