Comparisons, with the figures and their conditions
Five decisions that come up repeatedly: two formats, two grades of the same family, and two chemistries. Each page opens with the answer, then shows the table it came from.
Most comparison pages are written to rank, not to be used. They list specs without the conditions attached to them, which is how a 60 A cell ends up specified into a pack that can only cool it to 30 A.
These five pages are written the other way round. Each one starts with the conclusion, then gives the table behind it, then explains where the conclusion stops being true. Where a figure is not published in the source we hold, the table says so — a missing value is more useful than an invented one.
21700 vs 4680
21700 vs 4680: what the larger format changes
What changes between a 21700 and a 4680 cell, where the larger format wins, and why 21700 is still the format you can source and second-source.
Read the comparison →P45B vs P50B
Molicel P45B vs P50B: two 21700 power cells compared
P45B and P50B compared on capacity, continuous discharge, charge rate and mass — with the figures taken from the manufacturer data sheets held on file.
Read the comparison →50E vs 50S
Samsung 50E vs 50S: same format, different duty
The 50E and 50S share a format and a capacity class but not a duty. How the energy and power variants differ, and which packs each one suits.
Read the comparison →High capacity vs High drain
High capacity vs high drain: choosing the right grade
Energy cells and power cells are built differently in the same can. How to tell which one a pack needs, and what the wrong choice costs.
Read the comparison →LFP vs NMC
NMC vs LFP for energy storage
LFP and NMC differ in voltage, density, cycle life and thermal behaviour. Where each wins in stationary storage, and what this catalogue stocks.
Read the comparison →How to read these
Three questions worth asking of any comparison
Is the current figure conditional? A continuous discharge rating only holds while the cell stays inside the manufacturer temperature cut-off. If a table does not say what that condition is, the number is not comparable with one that does.
Is the capacity typical or minimum? Designing runtime against a typical figure means designing against a value the manufacturer does not guarantee. For a worst-case calculation, use minimum.
Is the part actually obtainable? A comparison between two cells where only one can be sourced in volume is an academic exercise. Availability is a specification.