Nimh

Nickel-metal-hydride is the chemistry that AEGs were originally designed around. It's slower to discharge than LiPo — meaning slightly less trigger response and a marginally lower rate-of-fire ceiling — but it tolerates everything LiPo doesn't. Overcharge it slightly: no problem. Forget about it for six months: it'll still work. Deep-discharge it on a long game day: it recovers. There are very few ways to actually damage a NiMH pack short of physical impact or extreme heat, which makes it the right pick for new players still learning battery care.

Two voltage standards see most use. 8.4V is the legacy AEG default — every stock rifle from the early 2000s onward was specced for 8.4V NiMH, and the chemistry remains a safe drop-in for any AEG without MOSFET upgrades. 9.6V is a moderate uplift — slightly faster motor spin-up, a few extra RPS at the cost of marginally faster gearbox wear. Either is safe for an unmodified AEG.

Where NiMH wins decisively over LiPo: charging simplicity (most NiMH chargers are dumb plug-in units that don't need balance leads or storage modes), travel safety (no LiPo fire-bag requirements, no discharged-cell shipping restrictions), and forgiveness with players who genuinely forget the rifle exists between games. Where it loses: power density, weight, and self-discharge rate (a stored NiMH loses noticeable charge every month even when not used). Pair with a simple NiMH-capable charger — most chargers labelled as multi-chemistry handle both NiMH and LiPo, though dedicated NiMH-only chargers are cheaper if you don't run LiPos.