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

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.

 

Sounds like you understand the development process. Yes, your question is premature, but we will need to figure it all out eventually. For now, I've only just verified that YES, I can completely disable regen and/or assist as needed to keep the pack safe. I'll wait for functional RevA prototype hardware before I continue exploring these details. The car is parked until I get RevA PCB.

I haven't tested your exact example, but the car does allow at least some voltage spoofing. I tested with a +16 volt delta without issue. I haven't researched the Prius' inline HVDCDC converter enough to know if too much voltage spoofing will blow it up. However, I read that that is a common issue with the Gen3 Prius... so at some point I'll need to research the safe voltage spoofing limits.

Yes, and it does both continuously during a drive cycle. Under load it favors coulomb counting, but at rest it will slowly recalibrate based on Voc->SoC LUT.

The G1 Honda Insight is more controllable in this regard because:
-I've had time to fully explore the OEM system's response to the various stimuli (which will happen with the Prius in due time), and;
-Insight's BCM computer generates SoC internally, hence LiBCM (which replaces BCM) can always just tell the OEM system the SoC.

There are other variables besides voltage and coulomb counting. For example, we can send fake current sensor data and manipulate pack temperature. These are just hand wavy concepts right now. The key point is that I know we can manipulate the system as needed to keep the pack in a safe operating area.

Thanks for the background. I'll explore this much later in the development cycle. For now I need to convert my PoC to a functional prototype.

Good data to capture eventually.

Reminder: I don't intend to ship LiBSU with 47Ah Samsung SDI modules (i.e. 'Ford cells') anytime soon. However, I do have the manufacturer's full specification sheet for these modules, which lists assist/regen limits at numerous temperatures.

Yes, we will need to limit regen/assist below freezing. Temp spoofing is the prime candidate, but again those are future details to figure out. For now the focus is prototype hardware. We'll do the firmware minutiae later.

I would never run a lithium cell at 4.2 volts... much too high for such a demanding application. Right now I'm using 60S, and wouldn't go below 56S in a production system. Note that I've run the car at 245 VDC without issue, so seems like the Gen3 limit is slightly higher (or the battery voltage dropped between when I charged to 245 VDC versus when I turned the key on).

No need to offer forgiveness; I'm always grateful when others offer their experience/feedback. You are taking the time to potentially turn unknown unknowns into known unknowns. While many of these questions are unanswerable at this moment, we'll need to figure them out eventually.

 

Are you referring to NexPower V1, V2, V2.5, V3, or V3GT, or whatever new version they're announcing next month? Just wondering.

Please reread my previous reply to your previous misguided statement.

So you're saying NexPower already redesigned their product to add supervisory control? Wow, I guess I missed that. Link please. You're comparing an automobile to a horse and carriage.

...

I'm probably already done responding to your uninformed talking points.
Keep shooting your shot I guess, but please understand that I might stop responding.
Eventually I'll let the product do the talking on my behalf.