If you're cheap like me, you don't want to pay the high-price for an OEM Sony NP-FW50 battery. The price isn't terrible if you only need 1 extra battery. Unfortunately, one of the problems with the Sony A7 is the short battery life.
You can get third party NP-FW50 batteries for much less than an OEM Sony battery.
This begs the question, is there a difference in quality? To find out I purchased and tested the capacity of batteries from RAVPower, Neewer, Powerextra, Wasabi Power, and the cheapest I could find on eBay.
Wasabi Power and PowerExtra overstate the capacity of their NP-FW50 batteries. Opening them up shows cells with 880mAh and 900mAh ratings, not the labeled 1300mAh and 1500mAh.
RAVPower and Neewer sell quality batteries. Opening them up did not reveal any information about the cells used. However, capacity testing showed that they were close to the 1100mAh listed on their labels. Keep in mind that an OEM Sony NP-FW50 is rated at 1020mAh.
I also purchased the cheapest unbranded batteries I could find on eBay. What should come as a surprise to no one, they're garbage.
What's Inside a Camera Battery?
RAVPower and Neewer likely came from the same factory. The tested capacity, weight, and case are all the same. They can even be purchased with the same charger.
Opening the RAVPower and Neewer batteries did not reveal any information on the cells used. Internally, the battery protection boards appear to be the same. I would not be surprised if they were made at the same factory.
The Best Third-Party NP-FW50 Battery Is…
RAVPower or Neewer are the best batteries. While they don't meet their labeled capacity, they are close. What they do have is higher tested capacities than the labeled 1020mAh of a genuine Sony battery.
Differences in price mean you can get 4 RAVPower or Neewer batteries for the price of 1 Sony battery.
|Brand||Weight||Tested Capacity||Labeled Capacity||Voltage|
|Wasabi Power A||43.34g||916mAh||1300mAh||8.35V|
|Wasabi Power B||43.65g||892mAh||1300mAh||8.30V|
|Cheapest eBay A||42.77g||884mAh||1500mAh||8.38V|
|Cheapest eBay B||36.80g||453mAh||1500mAh||8.18V|
- Test Capacity is an average of 5 discharge cycles at a 500mAh draw rate.
- The Voltage reading was taken 4 hours after batteries were fully charged in the Neewer charger.
TEC-06 Battery Capacity Tester
The TEC-06 is a USB powered battery capacity tester. A test load can be placed on a battery. The measured capacity is displayed on the screen when the battery is fully drained.
Energy stored in the battery is turned in to heat. The heat sink and fan are there to dissipate that heat.
- Batteries were charged with the Neewer USB charger.
- 6 volts was used as the cutoff voltage.
- A 500mA load was placed on the batteries.
- Nickle strips were soldered to wires to connect to the batteries.
- The TEC-06 has firmware V6.06.
Two Li-Ion cells are wired in series to make the batteries. I do not have a data sheet for any of the batteries. I picked the most common cut off voltage, 3V, for Li-Ion cells with a nominal voltage of 3.7V.
Cells in a series have their voltages added together. 3.7V + 3.7V = 7.4V.
When the cell reaches 3V, it is considered fully drained. Discharging the cell past 3V can shorten the life of the cell. The cells are in series, so 6V was used as the cutoff for the batteries.
My Sony A7 gets about 2 hours of life out of a battery. A 500mA load was used because it would drain the cells in approximately 2 hours.
500mA x 2 hours = 1000mAh
Testing Self Discharge
Batteries will slowly discharge over time. This is an issue with high drain rechargeable Ni-MH batteries. There was almost no change in charge of the FW-NP50 batteries over the course of a week. Self-discharge is not a problem you have to worry about.
Here is the process I used to test the batteries:
- All batteries with fully charged on the Neewer charger.
- Batteries sat for ~4 hours before the initial voltage was taken with the TEC-06.
- A week later the battery voltages were checked again with the TEC-06.
At the end of the week, all of the batteries read 0.02V lower. This is a negligible amount. You would not notice the difference in charge from a battery that sat for a week. All of the batteries started as showing a 100% charge in my Sony A7.
Neewer & RAVPower USB Battery Charger
The Neewer batteries I purchased from Amazon came with a USB charger. It looks identical to the charger that is bundled with RAVPower batteries.
A micro USB cable is required and not included. Charging requires 5V 2.1A USB power. USB chargers that powerful are not common. Most chargers will be 1A or less. Using a less powerful charger will still work, but charging will take longer than it would with a more powerful charger.
After seeing that it worked, I took it apart. There's not much inside. The case is either glued or plastic welded together. I would not recommend disassembling the charger.
If you need a USB NP-FW50 charger, this one charges batteries. I am going to continue to use it. If you want an adapter that plugs into an outlet, get a DigiPower TC-U450.
Sony Cameras That Use NP-FW50 Batteries
These are all the models of cameras that use NP-FW50 batteries.