20S3P battery case — 60 cells, 72 V
A 20S3P pack is 60 cells: 20 groups in series, 3 in parallel in each group. This page lists the 21700 housings that actually take it, in the order of how much room they leave for the BMS and the wiring.
Short answer: 12 of our 110 housings take a 20S3P on 21700. 10 of those leave at least six cells of room — which is the practical minimum once a 20S BMS and the wiring are in.
The pack, in numbers
| Cells | 60 |
| Nominal voltage | 20 × 3.6 V = 72 V |
| Charge voltage | 20 × 4.2 V = 84.0 V |
| Capacity (typical) | 3 × 5.0 Ah = 15.0 Ah |
| Energy (typical) | 1080 Wh |
Capacity assumes 5.0 Ah per 21700 cell. Your cells will differ — the cell count and the voltage are exact, the capacity is a working figure.
Housings that take it
| Model | 21700 ceiling | Room left |
|---|---|---|
| ALX127 · Downtube | 65 | 5 |
| ALX163B · Downtube | 65 | 5 |
| ALX149A · Hailong | 70 | 10 |
| ALX166B · Rear Rack | 78 | 18 |
| ALX100 · Downtube | 80 | 20 |
| ALX110B · Integrated | 80 | 20 |
| ALX149B · Hailong | 80 | 20 |
| ALX061 · Silver Fish | 91 | 31 |
| ALX063 · Silver Fish | 91 | 31 |
| ALX139 · Downtube | 100 | 40 |
| ALX136D · Silver Fish | 160 | 100 |
| ALX178 · Downtube | 160 | 100 |
Why room left matters more than the ceiling. A housing listed at 60 cells holds your pack exactly and nothing else — no BMS, no nickel, no cable exit. In practice a 20S pack needs roughly six cells of space beyond the cells themselves, because a 20S BMS is longer than the 10S board these moulds were designed around. That is the single most common reason a build that “fits” does not close. There is a longer explanation in why your 13S5P pack will not fit.
Work out your own configuration
The pack calculator does this for any series and parallel count, and the case selector takes a plain cell count if you already know it.
What 1080 Wh actually gets you
The figure above is energy, not distance. A 20S3P pack on 21700 works out to about 1080 Wh, which is roughly 90–135 km on low assist and 34–49 km at full assist for a 75 kg rider on mixed terrain. How far a pack will take you explains what moves that figure, and how the same configuration on the other cell format compares.
Common questions
How many cells is a 20S3P pack?
What voltage is 20S?
Which battery case takes a 20S3P pack on 21700?
Can I use a 20S3P pack in a case listed at fewer cells?
Send us the pack and we will confirm the fit
Cell format, series and parallel count is usually enough to answer the same day. If the answer is that none of our moulds fit, we will say so.