Size your battery pack, cells and BMS

Type a configuration like 20s6p, choose your motor and controller, and see the power you can really draw. Add more packs to combine them and get matching cell and BMS recommendations.

1. Drive system

Spintend hub motors and Ubox controllers. The motor is the load; the controller sets the battery current limit. Both decide how much the battery is asked to deliver.

Motor Motor

Controller Controller

Number of motors 2 for a dual-motor scooter. Number of controllers A Dual Ubox is one controller with two channels. Consumption for range estimate Custom consumption, Wh/km

2. Battery packs

Each pack has its own cell and layout. Extra packs are combined into one bank using the wiring you choose.

Packs wired

3. What you can draw

Power is limited by whichever is weakest: the cells, the controller's battery current limit or the motor. The sag figure uses the cells' internal resistance.

Per pack

Pack	Cell	Config	Voltage nom / full / empty	Capacity	Max continuous	Peak	Draw from this pack continuous / peak	Load on cells

4. Recommended cells

Ranked for the selected pack's series/parallel layout against the current your drive system will pull from it.

For pack Priority Format

All cells compared

Cell	Format	Per cell	Pack in this layout	Headroom	Min. parallel groups	Verdict

5. Recommended BMS

One BMS per pack. It must match the series count and chemistry, and its continuous discharge rating should exceed what the controller can pull from that pack, with margin.

Notes and assumptions

Component figures are typical datasheet or community values rounded for planning. Verify the exact part before ordering; the custom options let you enter your own numbers.
Pack internal resistance is estimated as cell resistance × series ÷ parallel and ignores nickel strips, connectors and wiring, which add resistance and sag.
Continuous draw is what the controller can sustain into the motor; peak is a short burst. A pack is comfortable when its cells run at or below about 80 % of their continuous rating.
BMS ratings are continuous discharge with 25 % margin over the expected pack draw. Contactor-type BMS units need a separately sized contactor and shunt.
Parallel packs must have the same series count and chemistry. Current splits between them in inverse proportion to their internal resistance.