Short answer: the G7X III, G9X II, and SX740 all take NB-13L packs, rated by Canon at 1250mAh / 4.5Wh / 3.6V. Their power profiles differ considerably: the G7X III is a one-inch sensor with 4K, the SX740 is a 40x superzoom with 4K, and the G9X II is gentler but has a screen that dominates the front of the body. For stills, a single pack typically manages two to three hundred shots; start recording 4K and runtime drops much faster than expected, which is the direct reason most people end up buying a second pack.
The NB-13L II is a replacement built on that foundation, with improvements in cell consistency and cycle life rather than in the capacity number. The rest of this article covers three questions: which body is thirstiest, what actually changed, and when to replace a pack.
One: power profiles of the three bodies
| Model | Power characteristics | Approximate stills per pack | Suggested spares |
|---|---|---|---|
| G7X III | One-inch sensor, 4K video, articulating screen; warms up quickly | About 200-300 | At least one spare |
| G9X II | Small body with a screen that fills most of the back; noticeable standby draw | About 250-350 | One spare is prudent |
| SX740 | Tele zoom motor is thirsty, 4K recording draws heavily | About 200-300, lower with frequent zooming | Two spares for travel |
These figures are range estimates, not lab data. Many things move them: screen brightness, flash use, how often you zoom, how long the camera idles, ambient temperature. The same pack can differ by more than three tenths between outdoors in winter and indoors.
The SX740 deserves a separate note. Its tele end needs the motor to drive the lens group continuously, and many people habitually sweep between tele and wide while hunting for composition, a habit whose cost is routinely underestimated. For concerts or sports, where you hold a half-press on a moving subject for long stretches, the pack drains much faster than when shooting landscapes.
Two: what the NB-13L II changes, and what it does not
What it does not change is the capacity class. Canon rates the original at 1250mAh / 4.5Wh / 3.6V, and the second-generation product is close to that; there is no “doubling”. If you see an NB-13L rated at over two thousand milliamp-hours, question the rating convention before celebrating.
What it does change is cell consistency and cycle life. Consistency means a narrower spread of capacity and internal resistance within a batch, which in the camera shows up as a more linear charge reading, closer behavior between packs, and no sudden jump from two bars to shutdown at low charge. Cycle life means capacity falls more slowly across repeated charging, so remaining capacity after a year looks a little better than earlier products.
Neither improvement appears on a spec sheet, so neither can be judged from numbers. Their value only emerges over long use: consistency affects whether you dare treat the last bar as a reserve, and cycle life affects how soon you buy another pack.
For ordinary users the practical meaning is simpler: one pack can be relied on for two or three years without a sudden halving of runtime forcing a replacement. These products usually sit in the budget bracket, clearly below the price of a single OEM pack, which makes them a consumable you can comfortably keep two of. Other models in the same series are listed in the NB-13L II category.
Three: five signals that it is time to replace
A pack rarely fails suddenly. It degrades slowly to a point where you finally notice. Check these five in order:
- Runtime halves: it used to last a full day, now it is done by noon. The most obvious signal.
- Charges faster and discharges faster: with higher internal resistance, charging reaches cut-off early and less energy actually goes in.
- Jumping charge readings: three bars to one in a step, or two bars again after a power cycle.
- Poor contact once fitted: a slight shake cuts power, usually from a slightly deformed case reducing contact pressure.
- A swollen case: it spins like a top on a flat table, or fits noticeably tighter in the compartment. At that point it is no longer a runtime issue but a safety one.
If any two of the first three appear, start planning a replacement. For the fourth, rule out dirty contacts first — wipe the pack and the compartment contacts with a cotton swab and a little anhydrous alcohol, let them dry, and retry; very often “poor contact” is just oxidation. The fifth has no room for negotiation: stop using it immediately.
Four: three things to confirm before buying
First, confirm the model is NB-13L, not NB-6L or NB-11L, which look similar but differ in size. Across these small Canon generations the packs look alike, and buying the wrong one is common.
Second, confirm your camera is on the compatible list: G7X, G7X II, G7X III, G9X, G9X II, SX730, SX740. Do not assume a body outside the list works because it “looks the same”.
Third, confirm how you will charge. The OEM charger for the NB-13L is the LC-30 dock, so if you plan to keep using a dock, check how a third-party pack fits it; if you plan to use a third-party charger, choose one built for 3.6V single-cell lithium packs. The NB-13L category covers this in more detail.
FAQ
Will a second-generation pack trigger a non-OEM warning on the G7X III?
These Canon bodies are less prone to third-party battery warnings than Fujifilm models, but not entirely free of them. Some bodies show an odd charge reading or a brief notice on first insertion and return to normal after a restart, with no effect on shooting.
How long can one pack record video?
The 4.5Wh capacity rules out long recordings. Continuous 4K typically lasts only a short single clip and is limited by body heat, so in practice you hit the thermal wall first. For video-heavy work, carry two or more packs and shoot in segments.
Can a first-generation G9X use a second-generation pack?
Yes. The G9X and G9X II share the NB-13L spec, so packs are interchangeable. The older body is itself aged, so a fresh pack often produces an obvious jump in runtime — that reflects the old pack’s degradation rather than anything exceptional about the new one.
How should I store a pack I will not use for months?
Keep it at four to six tenths of charge, remove it from the body, and store it somewhere dry and cool. Long storage at full charge or fully empty accelerates aging. Top it up every few months.