Product size (L x W x H): 8 x 8 x 5 cm / 3.14 x 3.14 x 1.97 inches
Inside the rubber is some shrink wrap around the cells.
The protection circuit looks like it checks all cells, but it do not have balancing.
There is no strain relief on the cable.
Connection cable is slightly above 0.5meter.
The protection circuit, one chip and two dual transistors.
Capacity varies with load and due to cable/connector resistance (Both pack and my test cable) the over discharge protection kicks in at different voltage (At the battery it will be 6 volt all the time).
I wonder why the 5A trace has as little capacity as it does. The Panasonic NCR18650B cell can handle 5A.
Conclusion
I like the rubber packing and the supplied pouch, this makes it fairly easy to mount on a bicycle and gives some protection for bumps.
The pack can deliver the rated current, but not more than that. The missing strain relief is rather bad.
I’m also wondering what happened at 5A measurement. With 2S2P setup there should be only 2.5A per cell. Peace of cake for the Panny cells. Maybe there is problem in the protection module and/or cabling, see below.
What interests me is what are resistances of cabling and connectors. We are always wondering what can expect from the conector of that type and what voltage drop it cause. Can you somehow measure the resistance of the whole path from battery pack to the “light” (ie. first part of cable, female + male conn. the other part of cable all together up to 1 meter long). OK we know what resistance of 20AWG should be, but we don’t know for the connector.
Edit: I’ve assumed it has 20AWG cable (like Kaidomain sample), but in reality it is 22AWG. Nevertheless, the main point of interest is 5.5x2.1mm connector .
You can fairly easy calculate the resistance. The overdischarge protection will always trip at the same voltage, what I measure includes the resistance of the cable and connectors.
I.e. when current is 0.2A the trippoint is 6 volt, and at 3A it is 5.6 volt, that is about 0.4 volt for a 2.8A change or 0.14 ohm, but I cannot tell if the transistor resistance is included in that value.
