Flash Recycle Time Battery Pack

Flash Recycle Time & External Battery Packs

Recycle time is how long the flash takes to refill its main capacitor after firing. Fresh AAs inside the unit usually give you t_full ≈ 5–10 s at full power. Drop to a fractional setting and the time scales more or less with the fraction of energy you spent, which makes t = t_full · fração a decent first guess. Plug in an external high‑voltage battery pack and the capacitor gets fed at far higher current, pulling that ceiling down to 2–4 s and keeping the heat away from your AAs.

Common packs include the Quantum Turbo series and the Godox PB960 / PB960S, both built for Speedlights, alongside Profoto B1/B10 and Godox AD200/AD600 that run on proprietary Li‑Ion bricks. Inside a Speedlight, alkaline AAs sag quickly under load, low‑self‑discharge NiMH cells like the Eneloop Pro 2500 mAh are the studio workhorse, and Li‑Po converters give you the fastest recycles of the lot. One thing to keep separate is recycle time versus flash duration. T0.1 and T0.5, which typically run from 1/300s to 1/20000s, describe how long the pulse of light itself lasts, and that is what freezes motion.

Applications

Wedding and event photographers lean on packs to stay with the action during entrances and the dance floor. At indoor arenas, sports shooters use them to hold 2–3 fps with TTL fill. Studio and product work favours packs too, mostly to dodge the thermal cutoff that kicks in to protect a Speedlight after a long string of full‑power pops.

FAQ

Does a battery pack increase flash power? No. The capacitor and the tube are the same parts they always were, so peak output doesn’t budge. All the pack does is shorten the refill cycle.

Will I cook the flash by recycling that fast? Given enough time, yes. Most Speedlights trip a thermal cutoff after something like 15–20 full‑power pops fired back to back, and a pack just gets you to that point quicker, so build in some cool‑down windows.

Why are Eneloops preferred over alkalines? NiMH cells keep their nominal voltage even under heavy load. Alkalines droop instead, and as they run down your recycle time can stretch from 5 s out to 12 s.