I’ve ordered everything, plan to build this in the coming weeks to finally enable FLYING to interesting skate spots. This is the culmination of 5+ years of reading, re-reading the FAA and IATA rules, reading about others’ experience, and trying/failing several other ways to make a legal single pack (tiny LTO + quick charge, monster NiMH.)
Batteries 99Wh or less are a GO, do not require airline approval. (100-160Wh pack DO require airline approval, invoke a whole new set of limitation.) Devices that serve primarily as chargers/powerbanks/power supplies for something else are considered spare batteries, and the only limits I’ve found are FIFTEEN and TWENTY on the quantity of spares, depending on where you read.
So, I’m building 12 individual 1S8P 18650 packs using modular polycarbonate boxes + cheapie bidirectional USB-C boost/buck boards just to give them some function when not part of the larger pack. I already have at least 100 30Q cells, which will yield 24Ah, 1036Wh. 3300-3450mah cells delivering at least 10A continuous would be a better choice, yield closer to 1.2kWh, but I’ll use what I have here. 8P of 15A 30Q cells should deliver plenty of current for any board… 120A on paper. (I’ve never drawn more than 70A from a 12S pack.)
There’s nothing fancy going on here, just a pre-made box that happens to fit nicely x12 into the tool bags I’ve used for top-mount packs for years. I plan to stack them 4 across the deck, 3 along the deck, should occupy 101H x 255L x 196W w/o the BMS. I plan to use all 8 bus strips inside each, may get fancy & cut/punch copper sheet to replace the included bus strips if they prove weak. Each box will be finished with 2x 5.5mm sockets on the Neg side, each fed by 2x 16GA wires (35A each, 70A per bullet) and thick M3 ring terminals, and 2x 5.5mm bullets on the Pos side to enable easy series connection. (I’ll use sockets on the last Positive pack for main output to match the bullets on my mountainboard harness.) I’m using a JBD BMS to manage the whole pack, will terminate the balance harness with 2mm bullets for easy connection to each sub-pack. Again, the balance connection will be made with a 3mm ring terminal on a short pigtail w/ the matching 2mm socket.
When I fly, I’ll have a dozen ~1lb 101x49x85mm boxes to stash in my carry-on and on my person, each of which are transparent, showing nothing but labeled legit cells, nothing loose inside, protected I/O via USB Type-C, demonstrable function. Since they are 1S, all cells are aligned the same, no potential for internal shorts at the screws atop or on the bottom. I’m Kapton taping the charging PCB to prevent shorts too. All 5.5mm and 2mm bullets will be tucked inside the covers… no external wires.
To assemble the pack, I remove all the covers, (2 screws each,) flop all wires outside, connect the 2x parallel 5.5mm bullets between each sub-pack, connect the 13x 2mm bullets for balancing, replace the covers, cram it into the bag, go skate.
There IS a way to connect these using the included bus strips, but I want quick/easy assembly/disassembly, will add the bullets to enable. This whole thing could be done w/o any bullets if you’re willing to fool around with a nut driver to assemble… I’d do so for a non-flying version, but for that, why bother with modular at all?
Here’s what started this madness: https://www.amazon.com/gp/product/B0BZL8ZVCL/
