Guides — which e-bike battery case fits your pack
The questions that come up before anyone talks to a supplier — answered with the numbers from our own range rather than with a sales page.
Start here — how pack configurations work
If you are still working out what your pack actually is, read these four first. They are the same arithmetic the selector uses.
What does 13S5P mean?
The two numbers do different jobs: one sets the voltage, one sets the capacity, and only one of them decides which case fits.
How many cells in 13S5P?
The full series-by-parallel cell count chart from 10S to 20S, with the case each configuration needs.
48 V — how many cells is that?
Voltage to series count: why 48 V means 13S, and what the S number changes about the housing.
21700 vs 18650 in the same case
The same interior holds 20–32% fewer 21700 cells. Computed across every series we mould, not asserted.
Then choose a case
The fitting questions: what fits, what to measure, and what to ask a supplier for.
How to read a case drawing
L, L2, L3, tolerances and the section view — what each figure on a mould drawing tells you.
How far will a pack take you?
Watt-hours per configuration, and the range each one gives at three assist levels.
How to measure your bike frame
The five measurements that decide whether a housing fits, taken off your own bike.
How many cells fit in a Hailong case?
Hailong cases hold 52–117 cells on 18650 or 30–80 on 21700. Why the listed figure is usually the 18650 one.
Why your 13S5P pack will not fit
It is the BMS, not the cells. Four interior dimensions to ask for, and the cheap fix.
What internal dimensions to ask for
The four numbers that decide whether an empty housing fits your pack, and how to read a supplier's reply.
13S4P vs 13S5P vs 13S6P
52, 65 and 78 cells — and where the jump from 4P to 5P starts ruling cases out.
Common questions
Send us the pack and we will confirm the fit
Cell type, series and parallel count is usually enough. If the answer is that none of our moulds fit, we will say so rather than sell you the nearest thing.