Hi,
The MOSFET they use is not a Logic Level MOSFET.
So you are not switching the MOSFET ON enough for the current and voltage combination of your 14.4V battery.
Model number: HCMODU0083
Weight: 10g
Size: 33.5 x 25.5mm
Max load (drain) current: <5A
Output load voltage :0-24V
Input Voltage: 3.3V, 5V
This is a common stuff up, as they quote 3.3v to 5V input, is not true.
If I was you I would complain that the module is not to spec and what they are going to do about it.
Tom... 