Regrettably the Nikon charger MH-25 , unlike the cameras has not evolved beyond a very basic design. There remains the solitary blinking/solid lamp to indicate charging and completion. The charger housing, in my opinion is a retrograde step as the battery is partially enclosed which does not aid cooling. The battery is insecurely located whereas it used to clip firmly & securely to the charger and being an open design offered more air circulation.
I was surprised to discover it’s Nikons only offering as a charger for the EN-EL15 battery. The lack of a dual bay and or USB powered offerings are somewhat shortsighted. With a USB charger power conversion is carried out elsewhere (computer etc) whereas the Nikon charger has to convert the power within the body of its charger which in turn contributes heat.
The NiteCore UNK1 improves almost all of this and features:
1. Compact & light with short fold away USB cable
2. Excellent charging intelligence which adopts charge type from constant current to constant voltage accordingly
3. A good clear display for monitoring charge progress – current, capacity & temperature. Also Good/Normal/Poor to indicate the battery ‘health’
4. Powered by USB therefore completely independent of 110/240V AC supply.
5. The battery is held securely in the charger
6. It has two connection faceplates, one for EN-EL15 batteries with the reverse for EN-EL14s
The maximum charging current of 1000mA is slightly less than the Nikons 1200mA charge rate. A lower charge rate is slightly beneficial as it helps prevent heat build up.
The charger also claims to be able to revive a ‘sleeping’ battery. More information on the Li-on protection circuitry here (external link).
In use, the UNK1 will charge upto a maximum rate of 1000 mA if your USB port or adaptor does not provide that current, it will charge at a lower rate. For example: my early iPhone 3 USB charger charged at an initial rate of 680mA whereas the later 6s type at 560mA which reduced once it switched to constant voltage towards charge completion.
A longer charge at a lower rate reduces temperature during charge and aids battery longevity.
A ‘blobometer’ displays charged capacity in 20% bars
Trivial acceptable points:
1. The USB cable is short but fits away very neatly, its a travel charger not your every day one. It’s easily overcome using a USB cable extender.
2. To appeal to a wider audience, It charges two types of battery: EN-EL14 (for D3100 & D5100 onwards) & EL15’s (D600, D750, D800 D7000 etc) . I would prefer a version that could charge 2 x EN-EL15s if even at half the single 1000mA/hr rate.
3. The slightly lower maximum 1000mA charge rate may be seen as a negative by some requiring rapid charge times. But a lower charge current is beneficial for your batteries longevity.
So its a 9.5 from me.
We have a RavPower 22,000 mA/hr powerbank so I’d expect to get about full 9-10 charges allowing around 10% for losses.
NiteCore – A larger dual bay charger powered by a USB plug in lead for two of the same type of batteries with switchable charge rate & same monitoring & control would be a perfect desktop replacement for the outdated Nikon one.
These are my own findings and I have no connection with NiteCore