RagingGrandpa

Pack fires intensify until they stop... if you can recognize the problem (odor, smoke, and first sparks) early, before it gets intense, you often have a practical opportunity to act.

"What can you do if an EUC fire starts in your upstairs apartment or hotel room (while you're there)?" Disclaimer: I am not a fire expert. The following is my opinion. My ideas, in order of preference, are: Move the EUC to an outdoor patio (if there is one). Shut the patio door to prevent burning debris from re-entering the interior. Moving a burning EUC is difficult. Thick leather gloves (fire gloves) help. You could also wrap the burning EUC in a carpet rug (or door mat, or fire blanket, etc) and drag it. You could even push it onto the rug using a broom, chair, etc to

There are some nice demonstrations of sand used to suppress battery fires online. It helps but isn't great... Similar ideas using water have been proposed... but it's quite a contraption to create, store, and maintain

For Abrams, the "pack module" is the entire side-assembly pictured above. 27100 24s 3p 1332wh. It looks like they built it using two sealed boxes of 12s3p each. Lovely. (You should not replace just one 12s 'box' though; the entire 1332wh assembly of two boxes becomes one 24s "pack") Like this: It will be balanced

Supposedly, Gotway is reducing its BMS charging current limit settings. My 800wh 84V modules from 2019 would accept about 10A each (unsafe for charging; tested only briefly). This provides short-circuit protection at the charging port. Below claims the new 900wh 100V modules will now permit only 3A each. It would suck to not be able to use our popular 900w chargers on 1800wh wheels like Hero and RS There were occasional reports of overheated and charred BMS charge-stop FETs in some RS and MSP though... perhaps this is the response.

@Rick2021 : you want CC-CV charging. "Constant-current, then constant-voltage" Some intro materials are found below: https://www.grepow.com/blog/what-are-the-3-stages-of-lithium-battery-charging/ (ignore "precharge" because your battery voltage should never be so low to need it) https://www.youtube.com/watch?v=taNI-7x5BoY https://www.youtube.com/watch?v=FaEX_2Ubc7A And, most consumers do not need to understand it. Instead, they meet their needs by purchasing a charger specifically designed for their device. Who makes your 40V battery pack? What is it used for?

Mine (2019 firmware) is pretty close to GPS: https://euc.world/tour/601700166344160 Discover the "80% beep speed" safely by lifting up the EUC and balancing it carefully, with L1+L2 beeps and tiltback disabled... More info here: https://forum.electricunicycle.org/topic/4258-gotway-alarm-beep/ Ride the MTen >20mph at your own peril

Be sure to see the notes in the catalog below: https://forum.electricunicycle.org/topic/19972-18x3-street-tire-catalog-msupers-sherman-etc/

New additions

Seems like a kluge to me... the cable bundle has to pass thru small openings in the shell, so there's not enough room for a nice inline connector (MT60, etc). So we're stuck with cheap crimp terminals and nuts that can rattle loose. Seems like a miss here... the large bullet (Gotway) or screw-post (Sherman) connectors could handle larger bursts of current before desoldering themselves. Future revisions get better connectors, perhaps? And what's going on with these GX16-5 pinouts? 2 pins for battery current and 3 pins for other things? Many secrets remain

https://forum.electricunicycle.org/topic/20470-understanding-the-real-world-considerations-and-implications-of-speed-vs-torque-models/?tab=comments#comment-341032

For posterity...

No! It's only 0.16 times more energy dense. ("5x energy" referred to single-cell capacity vs 2170, a physically smaller cell.) https://forum.electricunicycle.org/topic/20078-tesla-4680-batteries/?tab=comments#comment-335491 100wh/kg. No thanks. We have 250wh/kg today. (It's best suited for stationary power applications where mass doesn't matter so much...) Different strokes for different folks

Great example! It drives home the point that for the same output power, and the same number of cells, the pack's dissipation is practically independent of cell configuration. And higher pack voltages (with the corresponding higher-Kt motor) let the control board run cooler. (All presuming that motors are sized to match the pack voltage: 3 physically different motors are implied in the 3 example configurations above. Which seems appropriate, since 126V S20 is expected to have a lower-Kv motor than 84V S18.) Yes! Sherman speed with RS:T torque! Yes!

Backe is Back! And, we have a teardown!