13S4P vs 13S5P vs 13S6P: how many cells, and which case?
Short answer: 13S4P is 52 cells, 13S5P is 65, 13S6P is 78. The S count sets the voltage, the P count sets the capacity — so the case question is really a question about the P number.
Short answer: 13S4P is 52 cells, 13S5P is 65, 13S6P is 78. The S count sets the voltage, the P count sets the capacity — so the case question is really a question about the P number.
48 V nominal is 13 cells in series. That part is fixed for almost every 48 V build. What you choose is the parallel count, and that is what decides which housings will take your pack.
| Configuration | Cells | Typical use |
|---|---|---|
| 13S3P | 39 | Compact 48 V builds, folders |
| 13S4P | 52 | The most common 48 V pack; fits most downtube moulds |
| 13S5P | 65 | Longer range; above the ceiling of the smaller moulds |
| 13S6P | 78 | Needs a mid-size or larger housing |
| 13S8P | 104 | Large downtube and rack moulds only |
The jump from 13S4P to 13S5P is where cases start running out. 52 cells is a size most downtube moulds accommodate. 65 is above several of them, and it is also the point where the BMS problem gets worse, because more parallel groups means more current and often a larger board. Builders who plan for 13S5P and then discover they need a different format usually picked 13S4P first and grew it.
On 21700 the same configuration needs a bigger housing. A 13S5P on 21700 is still 65 cells, but each cell is wider, so the mould that takes 65 on 18650 may only take 52 on 21700. Check the 21700 number, not the 18650 one, if that is what you are building with.
What this means when you are choosing a case. Work out your P count first, then look for housings that take it in your chosen cell format. The case selector does exactly that — enter the configuration and it lists the models that hold it, with the opening length for each one.
Common questions
How many cells is 13S5P?
How many cells is 13S4P and 13S6P?
Does a 13S5P pack need a bigger case than a 13S4P?
Why does the same case hold fewer cells on 21700?
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.