Here’s a spreadsheet I’ve come up with
All data below comes straight from the battery datasheets, via manufacturer:
- Capacity (stdrd)
- Capacity (stdrd)
- Current (max cont)
- Current (rec)
- Cycles @ Max
- Cycles @ rec
- Voltage Range
All data below comes from my calculations:
- Wh/cm^3 (max current)
- Wh/cm^3 (rec current)
- A/Wh/cm^3 max
- A/Wh/cm^3 rec
I’ll explain a few things that the data may not fully explain.
Capacity:
First of all, the “Capacity (stdrd)” spec is not really useful for us when we are exceeding this on our packs. What you should instead use to calculate capacity is the “Capacity @max” rating, as this is the true capacity of the cell when you are pulling the maximum amount of amps.
In this case, the 30Q is really only a 2.975 Ah cell when pulling 15A from it. This is actually quite good, indicating low internal resistance.
Cells like the 48G cell are poor performers when it comes to high current draw, since they drop from the 4.8Ah spec down to 3.84 Ah under a 9.6A load. However, this cell would shine when used in a high P count pack where current isn’t the bottleneck.
The 30T, 40T, 50E, 30Q, 25R, VTC4, VTC5, and VTC6 all have a good capability to deliver amps without significant capacity drop relative to their starting capacity spec.
Current:
This is the manufacturers current specification. Here you can see some real differentiation between what is meant to be a high power cell and what is not. The 25R was never meant to be high power, it simply managed to function as one with reduced performance and without damaging the cell beyond repair. This is likely why the 30Q is heavily used instead of the 25R nowadays.
Wh/cm^3:
This is the watt hour density of the cell when used to its current maximum limit.
You can clearly see that there is not much overlap between the high current and recommended current cells. Ones that perform well in one category don’t in the other.
So from this data you can conclude that the 50E, 30Q, and 25R are good cells to use when you expect to reach their maximum current capability. You can also conclude that the 48G, 50E, M50, HG2, MU1, and 35E cells would all be very good performers when in a high P count pack. They simply will add much more capacity relative to their competitors.
A/Wh/cm^3:
This is an interesting spec. I decided to add this as a way to differentiate which cells are good performers in the current category relative to their power density. This spec is also a good indication of the heat dissipation ability of the cell. Cells that perform well at the high current spec are able to output significant amounts of amps while running at similar temperatures as their competitors.
As you can see, the 30T, 40T, VTC4, and VTC5 are all good cells to use in low P count packs where you may be pulling excessive current from each cell.
These cells also perform well when in higher P count packs, along with the 30Q and the HG2.
Lifetime
This spec on’y really matters to those who want their pack to last as long as possible. The 50E, VTC4, and MU1 will all last a long time when using them at high current.
At lower current, the 48G, M50, and VTC4 will all last a long time.
Unfortunate, the 30T and 40T under perform at high current. However I expect them to last a long time at low current. If someone has this spec, please let me know!
Here’s my final input, all of which is my OPINION:
The long range commuter goes to the MJ1. This cell simply can’t be beat when it comes to power density and lower speeds. It has a lower current output, meaning you can’t accelerate fast or climb steep hills, but it will take you FAR when in a high cell count pack.
The lightweight pack goes to the 30Q. It simply has a great power density at low and high current draw.
The speed demon goes to the 30T. This cell can output serious amps and will almost never be the bottleneck for most boards.
The pack to last goes to the VTC4. This cell, simply put, has a great lifetime. Stay within its recommended limit of 10A and it will easily last you 1000 discharges till you hit 80% capacity.
Special nomination goes to the 50E. This cell just has such a good capacity for a cell that can deliver 10A. I was more surprised to see it have a cycle life of 500 to 80% for a 5A discharge. This cell is on par with the MJ1 in regards to the “long range commuter” choice.
In conclusion:
I don’t think the 30Q is the end all, beat all, cell. It certainly has some very good specs, however I see many other cells outshining it in certain specific applications. Similarly, the 40T isn’t a “larger, better” 30Q. It has some very different characteristics and downfalls that really differentiate them. Choose your cell wisely and you can get a pack that’s truly tailored to your own needs.
