Does that discharger stop at 50%?
It has 2 position switch ....
Pos 1 stops at 15.2V which is ideal storage voltage point.
Pos 2 is a full discharge to 3V per cell - which I do not advise to use
Here's the write up :
"
Description:
This is a smart discharger, specially created to help you correctly store, maintain and carry your Phantom 3 Standard/Professional/Advanced batteries.
Features:
1. Discharge Power For DJI Phantom 3 Battery
Full-discharging mode:the battery can be fully discharged,before carrying it on an airline flight or proceed with some deep charge-discharge cycles to increase the optimal performance of your new battery or stored battery which has a “passivation” problem.
Auto-discharging Mode: the battery will automatically discharged to its nominal voltage(15.2V) prior to storing or transporting it.
2,Mobile Power Bank
It was designed with USB port, can out put 5V power from DJI 3 battery to charge USB your devices such as USB LED light,Bluetooth Speakers, Mp3/4, GoPro Cameras, and Smart phones.
3,Lighting
An USB 10W light bulb coming with the package,it is used to consume the power when discharging battery, and can be used as emergency lighting working with the DJI battery.
Specifications:
Dimensions: 8.15x3.02x1.25cm/3.2x1.49x0.49 inches
Item Weight: 22g / 0.78ounce
Packing Include:
1 * Battery discharger
1 * 10W USB Bulb"
Unquote...
For the $5 ... I think its a good item to have ... mine certainly does a good job.
Nigel