Battery compatibility requires more than matching a connector. Chemistry, cell count, voltage, dimensions, connector polarity and the vehicle electronics must all be appropriate.
NiMH
Nickel-metal hydride packs are robust and familiar in many beginner systems. They are heavier for a given energy level than LiPo.
LiPo
Lithium-polymer packs offer high energy and discharge capability but require compatible charging, correct cell settings, appropriate storage and careful physical handling.
Cell count
A “2S” LiPo contains two cells in series; “3S” contains three. Higher voltage can increase performance but must never be used unless the vehicle electronics are rated for it.
The compatibility database therefore stores voltage, chemistry and connector information separately.