The short answer most people land on is start with two: one in the grip, one in the bag. A better method is to work out how many packs your camera eats in a day. Official CIPA figures usually sit between 500 and 700 frames, and real use commonly lands around 60% to 80% of that, less for video and burst work. A rating that looks like a full day can be half a day on location. Working backwards from that: one spare covers everyday shooting, while weddings, travel days and long recording sessions usually want three total.
First, the math: how many packs is a day
Capacity sets the ceiling. Body draw sets what you actually get. The YO NP-FZ100 compatible battery is rated 2280mAh / 7.2V / about 16.4Wh, matching the original NP-FZ100 spec, and the TNP-FZ100 in the same family is 2400mAh / about 17.3Wh. Runtime is capacity divided by draw, so the same pack behaves differently in an A7S III than in an A1.
- Stills, intermittent shooting: closest to the CIPA figure. Take 60–80% of that 500–700 range and most bodies use one to two packs a day.
- Burst and live view heavy: screen and processor run constantly, draw climbs, and two packs a day is a safer plan.
- Video: long 4K takes are hard on a pack. One cell often does not reach two hours, so three or more is the comfortable number.
- Cold conditions: capacity drops noticeably below freezing, and around -10°C you may see roughly half of room-temperature runtime. Plan on 1.5–2x your usual count. Details in cold-weather runtime tips.
Recommended count by scenario
| Scenario | Total packs | Notes |
|---|---|---|
| Weekend snapshots, a few times a month | 2 | One in the body, one spare, enough for a full day |
| Street and portrait sessions | 2–3 | Live view use means you may swap twice in a half day |
| Weddings and event coverage | 3–4 | You cannot stop. Carry one more rather than hunting for an outlet |
| Travel, sunrise and sunset locations | 3 | Cold plus limited charging; pair with a power bank |
| Video and long-form vlogging | 3+ or external power | A dummy battery with an adapter is steadier — match voltage and connector |
What one pack versus two costs
A single YO NP-FZ100 is around $17.89, and the two-battery kit with charger is around $36.74, which works out to roughly $18 per pack and includes a charger. A charger on its own adds about $5 to the cost of a bare cell. If you were going to buy a charger anyway, the kit usually beats two separate purchases — the kit-versus-single breakdown goes through the numbers. If you already have a charger that works, adding one battery is perfectly reasonable. Do not buy the kit just because it exists.
When you really need a third
- No reliable top-up window: outdoor locations, weddings, long transfers where a wall socket may not appear.
- The body is a video workhorse: FX3, ZV-E1, A7S III and similar run long takes, and one pack gives you limited recording time.
- Two bodies in play: two cameras drain two packs at once, so scale your spares per body.
- Winter or high altitude: once capacity is derated, a count that was comfortable becomes tight.
- Batteries over two years old: after 300–500 cycles, capacity is commonly around 80%, and older packs run visibly shorter than fresh ones.
Details worth getting right with multiple packs
Number your packs and rotate them, so one does not sit at full charge for months while another gets deep-cycled every weekend. When flying, spare lithium batteries go in carry-on only, never checked. A 16.4Wh pack is well under the 100Wh threshold, terminals should be protected against short circuits, and some airlines cap how many you may carry per person — commonly around 20. Confirm with your carrier before you go.
Carry another battery, or carry a power bank?
They solve different problems. A spare battery means you swap and keep shooting. A power bank means you stop and recharge. On location or at a wedding there is rarely a window to stop, which is where a second and third pack earn their keep. At a fixed position or back at the hotel, charging from a bank or wall charger is cheaper per joule. If your body accepts USB power, a dummy battery setup is worth a look if you need continuous power.
Two things get overlooked. Carrying and storage: several packs need short-circuit protection and quick access, which travel and location battery carry setups covers. Rotation: without numbering and a rota, one pack gets deep-cycled while another sits idle, and the wear rates diverge fast. Numbering and rotating packs spreads the wear evenly across them.
FAQ
Is one spare enough?
For everyday stills, usually yes. If you shoot video regularly or work in the cold, we suggest going to three total.
Buy two at once, or try one first?
With a new body or your first compatible pack, buy one, confirm recognition and runtime, then top up. If the model is already confirmed and the shoot cannot stop, go straight to the two-battery kit.
Will extras go bad sitting in the bag?
Not if you store them properly. For long breaks, hold roughly 40–60% charge in a cool, dry place around 15–25°C and top up every three months. See long-term camera battery storage.
Planning by scenario beats shopping by price. Two packs covers most days: the YO NP-FZ100 compatible battery is around $17.89 each, or around $36.74 for the two-battery kit with charger. The higher-capacity TNP-FZ100 at 2400mAh pairs well with it. Studios, rental houses and resellers ordering 100 units or more should use the wholesale inquiry page for volume pricing.