New (ish) LTO option suitable for eskate = Microvast 10Ah 20C pouches?

These guys: Microvast 10Ah 20C LTO Prismatic Cells | SRIKO Batteries | Online store for electronics | Online battery store

I’ve talked these up on facebook, nobody seems to share my optimism that these would make a great FLIGHT pack for a board.

Apparently Microvast has been around for a couple years, has been quietly making these and several larger versions for EV OEMs.

Within the FAA and carrier rules, it seems possible to carry 2x 160Wh packs + 2x 100Wh packs provided the 160Ah packs power something into which they’re installed. I’ve no problem making a boombox or flood light etc who’s sole purpose is transporting a battery pack.

These are NOT very dense vs NMC or even LFP, but are good enough to satisfy my goal of a ~15mi board that can be charged in ~15min. They’re also gloriously cheap, and available from Illinois (via sriko batteries), not just directly from China. $10ea even in small quantity.

I’d like to make/carry 2x 5S packs and 2x 4S packs, which I’ll assemble into an 18S1P 43Vnom, 50.4Vmax (same charging voltage as 12S NMC) pack. They weigh 300g ea, so 5400g = about 12lbs.

I’d be packing 432Wh on paper ~ 367Wh useable cycle life, so should net 12-15mi at ~27-30W.

My hobby budget is shot for the season, I can’t afford to tinker with these until I’ve sold some golf cart / mower / solar packs… I’m hoping someone else will give these a shot.

As for charging, even a single 900W (Lacroix or similar) charger would take only 22min to push 367Wh. I intend to push harder than that.

Anybody else excited to play with these, give 'em a try for eskate?

1 Like

Just get some spim08hp pouches. They do have similar voltage limits as liion cells. Easy and cheap to get a proper bms for.

Andy87, BTDT… My very first DIY pack was a 10S1P in an Apache case I used with my Evolve Bamboo GTX for 2+ seasons. It still works great, I loan it out to 10S folks for group skates.

Those SPIM08HP cells are the best deal on the planet, but also not very dense (still better than these LTO due to higher voltage) and not really meant for brutal charging, just brutal discharging.

I’ve never fed regen current only into the SPIM08HP, always used it in parallel with the internal pack (connected directly to the ESC input, not the charging input) so really do not know how they would absorb that or charging current beyond 10A, which is the max I’ve tried. I really want to be able to charge at 20A+ to make such a small pack worthwhile for skating 30-50mi in a day (without spending 2hrs++ charging)

As for BMS’s, I don’t really feel one is needed with these cells… The BMS handles low-voltage shutdown, they are hugely tolerant of over-charging, which would really only be an issue with regen braking on a full pack. (The charger is set to Vmax, so no danger of pack over-voltage. I still plan to use a fast balancer, which should mitigate cell over-voltage.) I live in a flat state, am not worried. The balancer I use is capable of transferring 5A between cells/groups so should be able to keep up with even a feisty charger.

IF somebody wants a proper BMS with an LTO pack, JBD makes a newish line that can be used with ANY of the 3 main chemistries, is configurable via end-user software, not just with a proprietary cable by them (to artificially differentiate different cell counts, chemistries.) They are well-priced too, not really any more than the single-chemistry model for a similar cell count.

So yeah, I’m with ya on the SPIM08HP being a great value if you don’t care about weight, but they don’t offer the rapid charging capability that LTO brings to the party.

I’m not just after “last mile” transport to a hotel from the airport, I want to travel TO SKATE, want this travel pack + rapid charger to be an enabler, not a sorry substitute for a big proper pack.

Idk, data sheet for the SPIM08HP says 120A max charge current for the 8Ah cell.
Seems reasonable high enough, no?

The microvast data sheet says 6C max charge, so in our case that would be :face_with_monocle: 60A :man_shrugging:

But yeah you are right the SPIM08HP are not very energy dense. 26,4 Ah/kg vs. 33,3 Ah/kg.

2 Likes

The link is already broken, only a day and a half later.

Maybe they don’t want to sell to DIY folks?

Wow, must have been hacked. I buy BMSs from him all the time, have for a couple years. He filled my last order lickety-split just a few weeks ago.

Huh, I’ve never seen a data sheet I trust for either the SPIM08HP or these, thought the limit was 2C for any Lipo, which would only be 16A. Yeah, 120A charging current would be fine :slight_smile: I do see that batteryhookup describes the 2P module as “240A max charging current”, so 120A per cell. The respective power densities are 98.7Wh/kg for SPIM08HP and only 76.7Wh/kg for the LTO pouches. If max charging current and energy density are both LESS for the LTO pouches, no point in using them instead. The LTO pouches are rated for 20C only for a 10sec burst, 10C continuous… These are nearly matched by the SPIM08HP. I guess I’ll stick with them for the flight pack since I’ve already got a pile of 'em. Thanks for talking me down.

I’m laying this LTO idea to rest. Finally there are decent 18650 size LTO cells that handle heavy current, but at the same time we have more choices for high-power NMC 18650s and 21700s. I’ve decided to game the system to enable flying with a proper battery pack in modular form instead of this short-range + quick-charge scheme. I’ll post that saga, which should result in a strategy others can easily follow.