How many cells fit in a Hailong case?
Short answer: between 52 and 117 cells on 18650, or 30 to 80 on 21700 — and the number that matters is the smaller one if you are building on 21700.
Short answer: between 52 and 117 cells on 18650, or 30 to 80 on 21700 — and the number that matters is the smaller one if you are building on 21700.
"Hailong" is a mounting standard, not one product. Every factory that moulds a Hailong-pattern case makes a different interior, so the only honest answer carries a range. Here is what the range actually looks like in ours:
| Cell format | Smallest Hailong we mould | Largest Hailong we mould |
|---|---|---|
| 18650 | 52 cells | 117 cells |
| 21700 | 30 cells | 80 cells |
Two things trip people up, and neither is the cell count.
The "18650 or 21700 compatible" line means less than it looks like. A listing that says a case takes 91 cells is quoting the 18650 figure, because that is the larger and more impressive number. The same mould holds roughly 70 on 21700, because a 21700 is wider. If you are building on 21700, the 18650 number is not about your build.
The ceiling is not a target. A pack built to the absolute maximum has no room for a BMS, and the BMS is the part that usually decides whether the case closes. Read the next guide if your pack "does not fit" while the cell count clearly says it should.
To go from "a Hailong case holds 52–117" to "this model holds my 13S5P", put your configuration into the case selector — it lists the specific models that take it, with the opening length for each.
Common questions
How many cells fit in a Hailong case?
Is a Hailong case 18650 or 21700?
Why does the listing say 91 cells but my pack of 80 will not fit?
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.