The Sony A9 and A9 II are built for sports, wildlife and news, and both run on the NP-FZ100 (2280mAh, 7.2V, roughly 16.4Wh). In normal shooting they typically deliver somewhere around 300 to 500 frames. Step into 20fps-class burst work and the pace changes noticeably: the sensor reads at full speed, the buffer keeps writing, AF and stabilisation run flat out, and one cell can hit empty in an hour or two. Working rule for a burst day: bring at least four cells, or fit a vertical grip. Here is the reasoning.
Why bursts cost so much
Four things happen at once during a burst:
- Full-speed sensor readout: the stacked sensor keeps streaming data at its maximum rate;
- AF and tracking running non-stop: real-time tracking cannot pause mid-burst, so the processor stays loaded;
- Buffer and write pressure: the flood of files has to reach the card, and the body keeps running hard until the buffer clears;
- Shutter and stabilisation cycling: mechanical or electronic shutter running at high frequency, with stabilisation compensating alongside it.
That also explains why frames shot do not convert linearly into charge remaining. Two hundred frames in a burst often costs more than four hundred shot at an easy pace.
It also explains the rhythm most sports shooters adopt. Rather than trying to stretch a pack, they treat the battery like film — load it, shoot it to a known count, swap it, and let the spent one cool before it goes back into rotation. Once you have a rough figure for how many bursts one cell survives on your body, planning a whole fixture becomes simple arithmetic.
Practical run time brackets
| Usage | A9 (approx.) | A9 II (approx.) | Notes |
|---|---|---|---|
| Normal shooting via viewfinder | 350–480 frames | 360–500 frames | CIPA around 480–650 / 500–690 |
| Rear screen shooting | 300–420 frames | 310–450 frames | Screen brightness matters a lot |
| Dense bursts at match pace | Well below normal | Well below normal | Step the count up one notch |
| With network transfer | Lower still | Lower still | FTP and wireless transfer are hidden draws |
Treat these as brackets. Body firmware, lens choice, temperature and card speed all shift the result. Sports shooters usually do something simpler: note how many batteries a fixture consumed, and plan the next one from that.
Planning a burst day
A9 and A9 II owners tend to be people who cannot go dark mid-assignment, so planning differs from casual shooting:
- Single match or performance: start with four cells and top up on a dual-slot charger at half-time;
- Full-day wildlife: four to six cells, ideally with car or power-bank charging;
- News and unpredictable jobs: two loaded in body and grip, two in the bag, ready to slot in;
- Tethered transfer workflows: transfer draw is significant, so add another cell or move to external power.
On cost: four cells at $17.89 comes to about $72 before you add a charger, while two 2+1 kits at $36.74 each come to $73.48 and include four batteries plus two chargers. The kits are the tidier buy and let you charge two bodies’ worth simultaneously. Prefer more margin per cell? The 2400mAh option at roughly 17.3Wh runs $19.66 each, or $39.92 for two with a charger.
Grips and external power
A vertical grip is the classic answer for the A9 series. It holds two NP-FZ100s, doubling capacity, steadying vertical frames and removing the mid-sequence battery change. Two cautions: keep the grip and body contacts clean and check the insertion direction before loading, and try to pair cells of similar health, since a large mismatch confuses the readout.
For long stretches on a fixed position — a finish-line remote or a robo-pan setup — a dummy battery wired to an AC adapter will run indefinitely. Just confirm the voltage and connector match the body.
Saving power without giving up burst rate
- Set auto power-off to a short interval so waiting time costs less;
- Keep screen brightness just high enough and use the viewfinder rather than the rear LCD;
- Turn off Wi-Fi, Bluetooth and FTP when you are not transferring — transfer draw is considerable;
- Avoid sitting with the shutter half-pressed during lulls;
- In cold weather keep spares warm in an inside pocket; capacity drops below freezing and may be roughly halved near −10°C (14°F).
FAQ
Do the A9 and A9 II use the same battery?
Yes, both take the NP-FZ100, shared with the A7 III, A7R series, A1, A6600, FX3 and others.
Does a third-party cell affect burst speed?
Not in normal use. Burst rate is governed by the buffer, card write speed and body settings. If the buffer feels slow to clear after a run, look at the card first.
How should I store unused cells after a job?
Around 40 to 60 percent charge, somewhere cool and dry near 15–25°C (59–77°F), topped up every three months. Neither full nor empty suits long-term storage.
Will a worn battery slow my bursts?
Battery health affects run time, not frame rate. Once a batch is two years or so old, shorter run time is normal ageing — roughly 80 percent capacity remains after 300 to 500 cycles — so replace by batch.
Enough power for the A9 series
Base stock: the YO NP-FZ100, 2280mAh at roughly 16.4Wh, $17.89 each, $22.93 with a charger and $36.74 for two plus a charger — two kits is the sensible load-out for a burst day. More margin per cell: the TNP-FZ100, 2400mAh at roughly 17.3Wh, $19.66 each and $39.92 for the two-battery kit. Sports agencies, rental houses and resellers can quote bulk runs through the wholesale enquiry page, from 100 units up. Care and warning questions are handled in the NP-FZ100 FAQ, and other bodies’ ranges in the battery life database.