Short answer: one 1100mAh 90B-3 gives the GR III about 200–300 frames on the street and 40–60 minutes of continuous video. What decides runtime is not the capacity printed on the label — it is screen brightness, stabilisation, wireless, and how long the camera sits switched on.
Runtime by shoot type
| Shoot | One cell lasts | Main drain |
|---|---|---|
| Street (on for 10–20s, off between) | 200–300 frames / 3–4 h | EVF, boot cycle |
| Travel (frequent review) | 164–245 frames / 2.5–3.5 h | Review, brightness, Wi-Fi |
| Wedding / event (always on) | 164–245 frames / 2–3 h | IBIS, bursts, AF-C |
| 4K continuous | 40–60 min | Encoder, heat, screen |
| 1080p continuous | 70–100 min | Encoder, screen |
In our use the GR III lands at 200–300 frames on the street, a little lower at events, and 40–60 minutes of continuous recording — less with an external monitor, active stabilisation or high ambient temperature. These are working ranges, not manufacturer ratings.
Five settings that buy back power
- Fix screen brightness at mid — auto brightness pins to maximum outdoors.
- Turn off high frame rate display; focusing feels almost identical.
- Disable Wi-Fi and Bluetooth auto-connect; leaving Wi-Fi on is the fastest drain.
- Set power save to one minute; the body wakes in a fraction of a second.
- Switch stabilisation off on a tripod or above 1/500s.
Charging beats buying
Most “battery problems” are scheduling problems. With a PD power bank of 30W or more, any gap in the day becomes a charging window on bodies that accept USB power.
| Method | Speed | When |
|---|---|---|
| In-body USB, PD 30W | about 2–3 hours to full | Lunch, car, hotel |
| In-body USB, plain 5V | six hours or more | Not worth it |
| Dedicated dual charger | two cells in about 2 hours | Overnight, batch |
| Dummy battery + power bank | unlimited while plugged in | Static setups, livestreams, interviews |
The economical setup is two cells, one dual charger and a 65W power bank: rotate during the day, top up in gaps, charge both overnight. It costs far less than four batteries and weighs less too.
FAQ
Can one GR III battery last a full day?
Light street shooting, yes. A full travel day or an event, no. Plan on two cells minimum and three to four when no moment can be missed — a swap takes ten seconds.
Does charging while shooting slow the camera down?
No performance penalty, but you need PD 30W or higher to run the body and charge at once. On a plain 5V charger the percentage still falls, just more slowly.
How should I store batteries I am not using?
Keep them at 50–60 percent and top up every three to six months. Full or flat storage ages the cell faster and shows up as obvious capacity loss after two years.
What to buy
If you simply need a spare, a single 90B-3 (1100mAh) is the cheapest way to fix it — the right format for this body at a fraction of the OEM price.
Shooting events regularly? Two cells plus a dual charger pay for themselves. The full 90B-3 range puts single cells, kits and chargers on one page, so you can pick by how you travel.
Still own a TG-7? It takes the same cell, so the TG-7 battery page applies to you too — accessories swap in both directions. The GR III ships with a DB-110 cell; the 90B-3 is listed here on the same form factor, so check the compartment label before fitting.