After the collapse of my first lightning powered murder machine, I’ve embraced the fact that Houston streets are basically an apocalyptic wasteland that require an all-terrain build. The goal here is to build a capable off-road mtb that I can both use in a minimum-weight configuration for launching off hills/curbs/ramps as well as on longer group rides. I’ve chosen most of these parts either for light weight (deck, drive, hubs) or because they’re interesting to play with (NESE, Davega).
There is a large grassy hill in the middle of a field a few blocks from my house that’s been tempting me for 2 years now…
To that end, I’d love feedback on where I’ve gone wrong with this modular jump build, before it’s complete.
The only novel aspect of this build is using two NESE battery packs. 1x 12s2p P42A ‘jump pack’ that is permanently installed and 1x 12s3p P42A ‘range pack’ that is added or subtracted as necessary.
At some point in the planning stage, I was convinced this was not the worst idea. Although I’m having second thoughts. Reference threads:
- Here’s what can happen when you parallel (mix) different cells in a pack
- Adding another lipo pack in parallel?
- weak battery pack parallel to a bigger pack?
- Battery Discussion - Can we mix cell brands?
- Can run 2 Battery Packs with BMS in parallel
- 10s4p + 10s2p making 10s6p. Possible?
- Charge and Ride
- Evolve GTX 2nd battery in parallel
The plan is to use 60 fresh P42A cells in NESE modules, and wire the two 12s packs in parallel to the ESC. No BMS onboard - Daly 12S BMS will be mounted to the 6A YZPower charger and the two packs will be charged individually. No charge port - everything will use XT90s connectors - must disconnect pack from ESC to charge, but that’s easy with the Nanuk case.
(Obviously, packs will only be plugged in together when both are charged to 100% on the same charger. The range pack would not be added on the fly)
Pack config like this, with ESC permanently mounted under the range pack, bolted to an aluminum enclosure floor plate, which is then mounted to the deck. Each pack has its own balance harness:
(still printing NESE modules)
Alternative pack options I’m considering:
- Qty 2 x 12s3p NESE packs - would required a bigger enclosure or 3D printing a custom enclosure. This solves the current draw imbalance issue. Not that I need 12s6p but I wouldn’t hate it. ‘Jump mode’ would be heavier than planned
- Salvage the unused 10s4p P42A (1 year old, ~15 cycles) pack I had in my now dead 1st build - could reconfigure into a 12s2p pack by chopping some connections (probably?). This pack will have higher internal resistance, so may actually be better balanced with the new 12s3p NESE? Unclear here. I’m no electronics rocket wizard.
- Sell all the new P42A cells and NESE hardware. Wait for sales on gently used 12s2/12s3/12s4/12s5 welded packs. Buy two full packs, swap as needed, don’t try to parallel them.
- Use second pack as charge-and-ride. I don’t know much about this - more research necessary.
|DECK||Haero||2021 Bro 96 Mountainboard Deck||Stiff Flex [$325]||2,300||$326.00||$0.00|
|TRUCKS||MBS||Matrix II||16.3" width, 6061-T6 Alum, qty 2 [$200] 12mm hanger axle, 1.9lb ea, used||1,800||$135.00||$0.00|
|BINDINGS||MBS||F5s||1 pair (540g pair), used||540||$74.95||$0.00|
|BINDINGS||MBS||F5 heel straps, used||1 pair||40||$40.00||$0.00|
|DRIVE||Moon||AT Moon Drive Batch 6||POM spur wheel Gear (1140g), 4.7 ratio (47:10)||1,140||$360.00||$41.00|
|WHEEL HUBS||MBS||FiveStar - white||Material: Nylon, Fits 8" & 9" Tires, used||567||$40.00||$0.00|
|WHEEL BEARINGS||MBS||Bearings||12mm I.D. X 28mm O.D.||?||$19.95|
|WHEEL SPACERS||Boardnamics||12.2mm ID x 22.2mm L||?||$14.00||$0.00|
|TIRES & TUBES - road 6"||Clever||6x2 (150x50) tires + tubes||set of 4||?||$44.25||$13.52|
|TIRES & TUBES - knobby 8"||AliE||200x50 (8")||tire + tube||?||$49.68||$11.23|
|MOTORS||Flipsky||6374 Brushless DC Outrunner Motors, 190kV||Battle hardened, 3500W, 85A max, 8Nm - already have||1,960||$0.00||$0.00|
|ESC||BKB||Xenith V1 (already have)||80a cont||274||$0.00||$0.00|
|ESC (OPTION)||MakerX||Go-FOC DV6||Go-FOC DV6||365||$225.25||$13|
|REMOTE||Hoyt St||Nylon Puck, Black||used||N/A||$100.00||$0.00|
|BATTERY A||NESE Modules||11 sets||12s2 + 12s3 packs, 10 bus bars||1,422||$98.29||$15.69|
|BATTERY B||Molicel||P42A||21700 cells (ordered qty 65, used 60)||3,960||$321.10||$10.92|
|POWER HARNESS||Turnigy 12awg silicone||-||XT90s, parallel harness||?||?||?|
|BALANCE HARNESS||?||qty 2||22awg, 13-pin JST (daly: 26g ea)||52||?||?|
|BMS||Daly 12S||ebay dickyho||N/A||$15.00||$7.73|
|ENCLOSURE||Nanuk||905||empty / no foam, Interior: 9.4 × 7.4 × 5.5”||1,396||$48.95||$4.04|
|TELEMETRY SPACER||-||Rubber sealing/wiring pad||TPU printed||?||$0.00||$0.00|
|BRAKE LIGHTS||XLITE||100||smart brake light, 38g ea||76||$25.64||$2.12|
|LIGHT MOUNT||Mount to Moon drives||custom PETG||qty 2||50||0||0|
Credit to Tarboxx for the super dope artwork. Local area graffiti artist