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

Discussion in 'Gen 3 Prius Technical Discussion' started by mudder, Jun 7, 2024.

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  1. mudder

    mudder Active Member

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    Thanks. It's taken a while for me to get to this project, but now it's full steam ahead. Spent the day penciling in LiBSU's blank hardware canvas.

    I've added you to the beta waiting list (no ETA). If you turn PM notifications on in your priuschat user settings, you'll get an email whenever I have beta LiBSU units.

    This guy sees the forest through the trees: LiBSU will work just fine with sodium if it does ever take over. I'm not convinced, as solid state lithium will absolutely trounce sodium cells – as well as all lithium cells – whenever they release sometime in the (perpetual) "next five years".

    Bingo. LiBSU doesn't care which cell chemistry it's monitoring; it'll do them all just the same.

    In this particular case, I suspect it's the other way around: we'll eventually be replacing NexPower's sodium packs with lithium and LiBSU. Congrats on the first year, I guess.

    Right now there's ~2500 GWh of installed lithium capacity worldwide, versus 40 GWh for sodium. By 2030 lithium is expected to grow to 8000 GWh, versus 100 GWh for sodium. In other words, lithium's installed capacity will increase more rapidly than sodium's in the next five years.

    In general, I don't see sodium taking over the automotive market. Sodium's energy density is just too low, and that's not a solvable problem at the fundamental level; sodium ions store less energy in both volume and weight. And of course there's always the promise of solid state lithium on the horizon... which will absolutely dominate the automotive market if they're ever commercialized economically ("five years out" for the past fifteen years and counting).

    In short, sodium isn't a lithium killer by any means. The energy density alone isn't even the same ballgame. Sodium without a BMS is less safe than lithium with a BMS. And of course it's worth repeating the fact that LiBSU will work with sodium cells, too.

    This is a false comparison. Show me sodium sweeping over the EV/hybrid automotive market. Sodium is a stationary storage solution at best.

    I don't get why Team Jack continues to think that knowledge is hostile.

    Are you referring to the one where there's (still!) no BMS and also for a while there was no HVDC fuse or service disconnect? Lol.
     
    #41 mudder, Oct 28, 2025 at 12:02 AM
  2. Ivoh95

    Ivoh95 New Member

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    @mudder

    Not to get ahead of your development efforts, but im curious if you've gotten a chance to start mapping out the factory nimh limits via data spoofing?

    Main question im curious about: is voltage/current data spoofing viable? EG if you report 200v to the car, but the actual pack is 230v, does that trigger faults? Those are the main vectors i see for manipulating SOC. I believe the factory system only calculates SOC via coulomb counting and SOC drift at high/low voltage thresholds? Or maybe you have some other trick planned?

    There are definitelyncriteria to "encourage" only EV operation, but in the end the 30ish HP from battery alone isn't enough for safe driving, so the ICE should never be disabled from starting. There are ranges of SOC that result in different operation modes. In my experience SOC over 70% is pretty aggressive to prefer battery power. It will stay in "battery preferred" mode until the SOC drops below 65ish. Ive never been able to get the SOC above 80%, i think thats the maximum value it will drift to. 60% is the neutral point. 40% triggers slow charging to 50%. under 30% is aggressive charging with limiting discharge.

    Would also be awesome to see plots of how the factory Discharge/Charge limit vary with battery parameters, i suppose you could sweep the serial data to the car and observe the effect on DCL/CCL as well as SOC for each battery parameter. Unfortunately I have not been able to find SOC or DCL/CCL on the canbus as streaming data, they need to be requested from the ECU which isn't the fastest.

    I suppose it might be useful to sweep the same parameters on the cell doner vehicle type as well, as i wonder what the factory DCL/CCL is for the Ford cells below freezing. Ensuring cell safety without sacrificing too much performance in demanding conditions such as long regen when below freezing (think returning from a ski day in the mountains) is definitely a balancing act. It seems you've already done quite a bit of work for this on the Linsight project.

    I believe the inverter will operate up to 235V (openinvertor wiki), so that allows up to 56s packs if the cells are taken to 4.2V. 48-56s is probably the best range to use, and 48s is very common.

    Forgive me if any of these are already answered or commented, Great work!
     
    #42 Ivoh95, Oct 28, 2025 at 6:57 AM
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