I Tested the K&F Concept Osmo Action Battery Charger Set: 3 Batteries and a Slim Charging Case

If you shoot with a DJI Osmo Action camera, you already know the drill. These little cameras burn through a battery fast, and the moment you are out in the cold or filming something long, the one cell in the camera is not enough. A single spare straight from DJI is not cheap either, which is exactly the gap the K&F Concept Osmo Action Battery Charger Set is built to fill.

At its core this is a third-party battery and charger set: three 2100mAh, 3.87V replacement batteries plus an all-in-one USB-C charging case that holds and charges all of them. The case doubles as storage, with two SD card slots built into the top, and the whole bundle sells for $49.99. That is close to the price of one official DJI spare, so the value pitch is obvious before you even open the box.

I ran this kit with an Osmo Action camera, cycling the batteries through real shooting sessions and timing them against the stock DJI battery. I paid attention to the two things that matter most with an action camera battery: whether the runtime holds up, and whether the charging case is actually useful or just a plastic afterthought. Here is where it earns its place in your bag, and where it falls short.

What I Liked About the K&F Concept Osmo Action Battery Charger Set

Most of what works here comes down to one idea: you get three charged batteries ready to swap instead of babysitting a single cell. A few things stood out once this became the battery charger living in my camera bag.

Three 2100mAh Batteries for the Price of One DJI Spare

The headline is the math. You get three 2100mAh replacement batteries plus a charging case for $49.99, which is roughly what a single official DJI Osmo Action spare costs on its own.

Each battery is rated at 3.87V and 8.17Wh, and all three are identical. For anyone who has priced out buying two or three DJI cells, this 3-pack is the kind of value that makes the third-party route hard to ignore.

Runtime That Holds Right in Line With the Stock DJI Battery

My biggest worry with any third-party camera battery is inflated capacity claims, so this is where I focused my testing. In real use, each K&F cell delivered right around what the stock DJI battery does, and if anything it edged out the original by a hair.

The product panel quotes about 120 minutes in 4K 60fps recording mode, which matched my experience closely enough. The point is not that one battery lasts dramatically longer, but that you have three of them, so when one dies mid-shoot you swap in the next and you are rolling again in seconds.

One Battery Pack That Works Across the Whole Osmo Action Lineup

These cells are not locked to one body. The same batteries feed the DJI Osmo Action 6, Osmo Action 5 Pro, Osmo Action 4, and Osmo Action 3, plus the DJI Osmo 360, since all of them share the BCX-204 battery form factor.

That cross-compatibility is genuinely useful if you run more than one DJI camera, whether it is helmet-mounted or worn as a body camera. If you shoot an Osmo Action 5 Pro and an Osmo 360, one set of spares covers your whole kit instead of two separate battery stacks, and the same Osmo 360 batteries drop straight into the older bodies.

A Slim 3-in-1 Charging Case With Two SD Card Slots

The case is a 3-in-1: it charges the batteries, stores them behind a magnetic lid, and has two slots built in for SD cards. It powers off any 5V USB source through the included USB-C cable, the same kind you charge a smartphone with, so a wall adapter, power bank, laptop, or car charger all work.

It is slim enough to toss into a bag without thinking about it, and the magnetic lid clamps down cleanly. Keeping the batteries and SD cards in one place is a small touch, but it is the kind of organization that saves you digging through pockets on location.

Per-Slot LED Indicators and Built-In Safety Protection

Each slot has its own LED indicator: it glows red while a battery is charging and turns green once that cell is topped off. It is basic, but it does keep you from guessing which battery is ready to go.

The product description lists protection against overcharge, overheating, and short circuits, and the kit is backed by a one-year warranty. Nothing exotic there, but it is the baseline safety you want from a rechargeable battery charger you leave plugged in.

What Needs Improvement

The batteries are the star, and the case does its job, but a handful of caveats keep this kit from being a no-questions pick. None are dealbreakers, but you should know them going in.

No Battery Gauge at a Glance When the Case Is Unplugged

This is the one that comes up most in customer reviews, and I agree with it. The LED indicators only tell you anything while the case is plugged in and charging; unplug it and there is no way to see how much charge each cell is holding.

DJI’s own case shows battery levels the moment you open it, and you lose that here. In the field you end up either topping everything off before you leave or just trusting that a green light from this morning still means a full battery. That same guesswork around battery level shows up with other field gear, like the PSIER Bone Conduction Headphones you load before a swim and then trust to last the whole session.

The Charging Case Feels Like Basic Plastic, Not DJI-Grade

The case is plain plastic and does not feel as solid as DJI’s official case. It never felt fragile to me, and I would not worry about a short drop, but it reads as a basic charging station rather than a rugged piece of kit.

If you already own the DJI Osmo Action Multifunctional Battery Case, you are buying this set for the three batteries, not to replace that case. One Amazon reviewer made the same call and was glad they kept the DJI case as their main one.

Charging Is Not Truly Simultaneous Across All Three Slots

K&F markets the case as charging three batteries at once, but in practice it cycles through them, charging one or two at a time rather than blasting all three at full speed. It still tops everything off, it just takes longer than the marketing implies.

This is also not the fast charging you get from DJI’s 30W USB-C Power Delivery setup; the case runs off a basic 5V input. If you need a true fast charger that refills three cells quickly, plan around that or look at a higher-wattage kit. Osmo Action owners who film their own runs and rides often round out that kit with open-ear audio, like the Raycon Fitness Open Ear Earbuds that keep them aware of traffic while recording.

A USB-A to USB-C Cable That Can Be Hit or Miss

The included cable is USB-A to USB-C rather than the USB-C to USB-C most people now carry, which feels dated. At least one buyer received a cable that would not charge at all and had to swap in their own.

It is a minor gripe since spare USB cables are everywhere, but it is a strange corner to cut on an otherwise complete kit. There is also no option to use the case as a power bank to charge the camera directly, so do not buy it expecting that. For charging gear that bundles a better cord, the Rokform Magnetic Wireless Charger with Stand ships with a braided USB-C to USB-C cable instead of the dated USB-A one here. Proprietary charging is a common friction point across camera kits, something I ran into with the Mic Air puck in my Insta360 Luna Ultra unboxing.

How the K&F Osmo Action Battery Charger Compares

The DJI Osmo Action accessory aisle is crowded with batteries and chargers, so it helps to see what you trade away and gain. At heart this is a battery charger for DJI Osmo Action cameras, a charger compatible with DJI Osmo gear across several generations, rather than a universal cell. One note first: these batteries are made for the Osmo Action line and the Osmo 360, not the Osmo Pocket cameras or DJI drones, so check your model against the BCX-204 form factor before buying.

vs the DJI Osmo Action Multifunctional Battery Case

DJI’s own case is the premium benchmark. It shows battery levels the instant you open it, integrates cleanly with the camera’s firmware, and feels more solid than the K&F case.

The catch is that DJI sells that case without the spare batteries this kit bundles in. If you want the better case and the three batteries, you pay for both; the K&F set gives you a working charging solution for action camera shooters plus the cells for close to the cost of the DJI case alone.

vs OEM DJI Extreme Battery Plus Spares

A single DJI Osmo Action Extreme Battery Plus runs roughly $45 to $49, lands at 1950mAh, and is rated for a wider -20°C to 45°C range with tighter firmware integration. Independent testing also credits OEM cells with more charge cycles before they fade and better cold-weather retention.

That is the honest trade: the K&F batteries advertise a higher 2100mAh number and perform right around OEM runtime in moderate conditions, but their long-term and deep-cold durability is less proven. For one DJI spare, you get three K&F replacement batteries, which is the whole reason to consider them.

vs llano, SmallRig and Other Third-Party Kits

Other third-party makers attack the same problem differently. The llano three-pack pairs 1950mAh cells with a 30W Power Delivery case that adds a numeric LED display and a genuine fast charger, while SmallRig sells a lightweight 3-slot charger on its own without batteries.

Those options win on charging speed or a clearer readout, but they either cost more or leave you sourcing cells separately. If your priority is the most batteries per dollar in one box, the K&F Concept kit is the simpler buy; if you want faster, smarter charging, the llano-style kits are worth the step up.

Final Verdict

The K&F Concept Osmo Action Battery Charger Set does one thing and does it well: it hands you three batteries that perform in line with DJI’s own, plus a slim case to charge and store them, for about the price of a single official spare. For an Osmo Action shooter who films long sessions, that is a lot of extra recording time for not much money.

I am giving it a 4.3 out of 5.

It earns that score for the three-battery value, runtime that matches the stock DJI cell, broad compatibility across the Osmo Action lineup and Osmo 360, the two SD card slots, and sensible safety protection. It loses a little because the case is plain plastic, there is no battery gauge when it is unplugged, charging is not truly simultaneous, and the bundled USB-A cable feels dated.

Bottom line: If you own a DJI Osmo Action camera and you are tired of one battery cutting your shoot short, this kit is an easy recommendation and a smart value for travel, hikes, and all-day filming. If you specifically want a premium case with an at-a-glance battery readout or true fast charging, keep your DJI case and buy spare cells to match it instead.