Open up a third-party NP-FZ100 and there are only four things worth looking at: the cells, the protection board, the communication circuit and the shell. Across the price band that matches our NP-FZ100 at around $17.89 per cell, our lab testing generally finds structure and protection circuitry to be reasonably complete. Where samples separate is cell consistency and solder quality. On usable capacity against the label, the range we typically observe runs from about 90% of the rated figure up to close to the full number, with the occasional sample below that.
One caveat up front: what follows is structure and build quality, not precise per-unit numbers, and no single visual detail should be used to judge whether a cell is good.
Before opening anything: safety and method
- Don’t do this at home: a lithium pouch or can that is deformed or shorted can heat up and ignite. Read the structure below as public reference and service-level information.
- Discharge first if you must open one: a full cell carries far more energy into a short.
- Never puncture, bend or burn a cell: a swollen one stops being used and goes to a recycling point.
- Opening voids the warranty: everything below comes from samples prepared specifically for this purpose.
Swelling and other safety questions are covered in are third-party camera batteries safe and in our guide to handling a swollen NP-FZ100.
Part one: the cells
The NP-FZ100 is rated 2280mAh / 7.2V / around 16.4Wh. That nominal 7.2V points to the usual two-cells-in-series (2S) layout: two 3.6V nominal cells stacked. In practice you see two formats:
| Format | Characteristics | What to look at |
|---|---|---|
| Two cylindrical cells, aluminum or steel can | Easier to match, lends itself to standardized packs | A dedicated holder, and solder joints that look full |
| Pouch (polymer) cell | Adapts to the shape, uses shell space well | Cushioning around it, and no creases at the edges |
A few indirect indicators we lean on in our own testing:
- Usable capacity against the label: under fixed conditions we generally see somewhere in the 90%–100% band.
- Spread between samples of the same model: the tighter the numbers across several samples run under identical conditions, the better the consistency control.
- Voltage settling after a full charge: a small drop over time is normal; a fast slide usually means higher self-discharge.
- Capacity retention after cycling: hard to measure short-term. Judge it by feel after a few months of real use.
To check whether the cell in your hand is honestly rated, see how to spot inflated capacity ratings.
Part two: the protection board (PCM)
The protection board is the small circuit inside the pack that keeps abnormal conditions contained. The parts worth recognizing:
- Protection IC and MOSFETs: handle overcharge, over-discharge, overcurrent and short circuit.
- Fuse or resettable protection device: the last physical line of defense under fault current.
- NTC thermistor: feeds temperature back to the charger or body, which is what cold and overheat protection hang on.
- Balancing resistors: passive balancing between the two series cells, slowing the drift in voltage between them.
In our experience, mid-priced samples usually include all of the above. Differences show up in component selection, solder quality and whether any insulating separation is present. Packs with no separator, holding cells in place with tape alone, tend to survive drops less well. Worth saying plainly: a protection board reduces risk, it does not remove it, so any claim of zero risk is not credible.
Part three: the communication circuit, or “chip”
To show a percentage on screen, the body has to talk to the cell. On the battery side there is usually a small MCU or a dedicated fuel gauge returning voltage, current and temperature in the format the body expects.
- With a communication circuit: the body shows a percentage, and the reading is generally usable.
- Some Sony bodies warn that remaining charge may not display accurately: a routine message with compatible cells. Power is unaffected and shooting continues.
- “Cannot recognize this battery”: that is a fault. Clean the contacts, try another charger, then go to the seller.
- Jumpy gauge readings: usually a fuel-gauge calibration issue, often settled by one full charge-and-discharge cycle.
The mechanics of gauge reporting are explained in our chipped versus non-chipped comparison, and error handling is in our unrecognized battery fix.
Part four: shell and structure
- Material: flame-retardant PC/ABS is typical; the surface should be free of burrs and sink marks.
- Internal fixing: cells should sit in a holder or on cushions, with no rattle when you shake the pack.
- Contacts: even plating, no obvious wear after a few dozen insertions.
- Catch and dimensions: it should go in smoothly without play. Too tight wears the compartment, too loose risks intermittent contact.
- Seam finish: ultrasonically welded seams are usually tidier, and also the part you should never pry at.
Appearance and actual consistency do not line up one to one. Cleaner build suggests controlled process, but cell quality still needs measured data to confirm.
Turning structure into a buying checklist
- Clear model, capacity, voltage, Wh and responsible party: the baseline for traceability.
- Specific protection functions named: overcharge, over-discharge, overcurrent, short circuit — written out, not implied.
- Warranty term and how to reach someone: worth more than any build description; see the NP-FZ100 warranty page.
- Buy several from one batch: easier to manage and easier to compare.
- Pick capacity by need: the practical difference between 2280mAh and 2400mAh is analyzed in 2280mAh versus 2400mAh.
FAQ
Does opening a cell ruin it?
Yes. Once the shell is pried apart, sealing and cell fixing are compromised. Even glued back together, it should not go back into a camera, and it should not fly.
Can I judge quality from the cell brand printed inside?
Only as a hint. One maker’s cells come in different grades and batches, and end performance depends on pack consistency and protection design.
Why do some third-party cells fade noticeably after a while?
Usually limited cycle life in the cells themselves, compounded by deep discharges and hot charging. Holding around 80% capacity after 300–500 cycles is a normal range.
Do our teardown observations apply to every third-party cell?
They do not. Cell sourcing and process vary a lot between suppliers. What is here is a general structural read; any specific model still has to be judged on its labeling and warranty.
Our NP-FZ100 compatible battery is rated 2280mAh / 7.2V / around 16.4Wh, at around $17.89 per cell, around $22.93 for one cell with a charger and around $36.74 for two cells with a charger. For more capacity, the TNP-FZ100 (2400mAh / around 17.3Wh) runs around $39.92 for the two-cell kit. Studios, reviewers and purchasing teams wanting to compare samples side by side can use the wholesale inquiry page for volume pricing and same-batch samples.