LiBSU - Redesigning the "Battery Support Unit" to Support Lithium

I'm designing LiBSU to be battery agnostic. It'll have several serial buses (USB, isoSPI, SPI, UART, CAN, etc), and will support pretty much any lithium battery with an onboard BMS (or a breakout BMS node that I will also offer, for the DIY crew).

My initial focus is Gen3 Prius (including Prius V), but Gen2 Prius is very similar mechanically from my product's PoV.

This will depend on the battery you use:
First offering is a complete drop-in unit that uses OEM Toyota cells, including Toyota's onboard lithium BMS.
Mechanically it will fit in the Gen2/3/V Prius and all similar.

Later offering is a blade-like daisy-chained isoSPI solution using what I call a '4xBlade' (because it's four OEM blades wide). There will be a single '2xBlade' for those cars whose OEM blade count isn't wholly divisible by four. 4xBlade considerably reduces cost, because a properly designed BMS has a fixed price per node (i.e. there's very little price difference between QTY4 & QTY8 cells... the cost is in the node, not the cell count). Mechanically it will fit in any Toyota vehicle that uses blades.

Not for the above products, but again LiBSU is battery agnostic (just like LiBCM).

I'm doing Gen3 Prius first, followed by Gen2.
I'm working on showing a working prototype soon.

 

FYI: Here's a color-coded preview of the Gen3's serial protocol:


...it's a little more complicated than the Honda Insight's BATTSCI frames, but still not too difficult to figure out if you know what you're doing. Fun problem to reverse engineer. For reference, the Honda system packs all this data into 16x fewer bytes (24 vs. 384). Not saying Toyota's method is bad... just very verbose.

I'm still trying to figure out what a couple bytes do, but the other QTY382 are fully deciphered. I believe one of the two unknown bytes is actually an error in Toyota's official serial data stream (0x37B10 is always identical to 0x37B11). For now I intend to just duplicate the as-found behavior, although for academic purposes I'd like to figure that out eventually.

Overall I think Toyota made some odd design decisions on the BSU. I prefer Honda's system of having separate battery and motor control computers (BCM & MCM, respectively). Toyota does things differently, which means the BSU ends up passing a bunch of pack-specific information to the main computer. It's less modular, but obviously it works.