Direct answer: a swollen NP-FZ100 is done. Don’t use it, and don’t charge it. Swelling means gas has formed inside the cell and the internal structure is no longer stable. Further charging or discharging risks more expansion, leaking, or thermal runaway. The correct response is to stop using it, insulate the terminals, store it alone, and hand it over to a battery or hazardous waste collection point. The price of one pack is far below the cost of one incident, and this isn’t a place for optimism.
How to tell whether it’s swollen
Mild swelling isn’t always obvious to the eye. These checks will confirm it:
- The spin test. Set the pack on a flat table or a piece of glass and give it a gentle push. If it spins or rocks freely, the underside is no longer flat.
- Look at the seam. Is the case seam opened up, or do the sides bulge so the middle sits higher than the edges?
- How it fits. Noticeably tight going into the compartment, sticking on the way out, or a battery door that won’t close properly.
- How it feels. A hollow or slightly springy feel under light finger pressure, instead of the solid feel of a healthy pack.
- Companion symptoms. Sudden capacity loss, clear heat while charging, or the level jumping — all possible signs of internal trouble.
Any one of these is enough. Treat it as swollen and don’t wait for it to get more obvious.
Why packs swell
| Cause | What happens | Preventable |
|---|---|---|
| Overcharging or failed charge control | Long overcharge, or a charger that doesn’t match the spec | Yes |
| Short circuit | Terminals touching metal, or an internal micro-short | Yes |
| High temperature | A car in summer sun, or long storage beside a radiator | Yes |
| Stored at full charge | Full charge plus heat accelerates gas formation | Yes |
| Deep over-discharge | Left unused without top-ups, cells take damage | Yes |
| Normal aging | Wear sets in after roughly 300–500 cycles | Only slowed |
| Physical damage | Drops, crushing, puncture | Yes |
Almost every cause traces back to use and storage habits. Even a dropped pack that looks fine deserves an observation period before you trust it on paid work.
What to do once you find one
- Step 1: stop using it. No camera, no charging, and don’t try to drain it.
- Step 2: remove it. If it’s stuck in the compartment, don’t pry or force it — rock gently or use tape to pull, without squeezing the cell.
- Step 3: insulate the terminals. Tape over the contacts, or use the original packaging or a cap, so they can’t meet keys or coins.
- Step 4: store it alone. Dry, cool and away from anything flammable. Don’t stack it with other packs.
- Step 5: never puncture, crush or burn it. All of these can start a fire. Don’t put it in general trash either.
- Step 6: take it to a collection point. Hazardous waste facilities, electronics markets and retailer battery drop-offs, following local rules.
- Step 7: check the rest of the batch. Inspect other packs from the same set and the same charger, and retire them together if needed.
If a pack is smoking, clearly hot or smelling, move people and flammables away, keep the area ventilated and follow local emergency guidance.
Preventing the next one
- Use a charger that matches the spec on voltage and interface. Cheap chargers without protection circuitry carry more risk.
- Avoid sitting at full charge. If you’re not shooting for a few days, bring packs down to 40–60% rather than leaving them on the charger.
- Control temperature. Store around 15–25°C. No packs in a sunlit car, none beside a heater.
- Avoid over-discharge. Top up every three months in storage — see charging cycles and storage basics.
- Prevent shorts. Terminal covers or individual slots; no loose packs sharing space with metal objects.
- Don’t drop or crush them. Keep batteries in their own pouch, not under heavy gear at the bottom of a bag.
- Inspect routinely. A glance at each pack before and after a shoot catches problems early.
More on third-party pack safety in are aftermarket camera batteries safe; if the pack also shows recognition errors, the recognition troubleshooting steps applies.
FAQ
Can I keep using a slightly swollen pack for a while?
We wouldn’t. Swelling is irreversible and progresses unpredictably — especially not on a job that matters.
Can I fly with a swollen battery?
No. Lithium cells in an abnormal condition aren’t permitted on aircraft, in the cabin or in checked bags. Dispose of it through a collection point instead.
Can I release the gas and carry on?
No. Puncturing or squeezing to vent gas destroys the internal structure and can cause a short and a fire. It’s a dangerous maneuver — never try it.
How do I tell swelling apart from a normal curved case?
A healthy pack sits flat and doesn’t rock on a tabletop. The spin test answers it in a second; if it rocks, treat it as swollen.
Replace what you retire and match stock to your shooting volume: our NP-FZ100 compatible battery is rated 2280mAh / 7.2V / roughly 16.4Wh, around $17.89 per pack, around $22.93 with one charger and around $36.74 for two batteries plus charger, with the TNP-FZ100 (2400mAh, roughly 17.3Wh) at about $19.66 / $24.70 / $39.92 — pair either with a charger built to the same spec. Studios and rental houses cycling out aging packs on a schedule should use wholesale inquiry — orders above 100 units are quoted by batch.