AEG / RIDGID 18v Battery voltage drop at BMS

Thread Starter


Joined Nov 23, 2019
Gday all,
Looking for some assistance to fault find a 18v RIDGID / AEG chinese knockoff battery.
New 4.0Ah battery pack, charges fine, drops out under low load, and capacity seems diminished.
After full charge battery voltage at Positive and negative terminal at BMS output terminals is 20.58v dropping to 18.21v after a couple of hours.
battery voltage at pack still reads 20.58v however.
there looks to be a voltage drop from the pack through the BMS.
Wiring connections look substandard and wiring underated for the task.
Looking for some advice as to possible faults in the circuitry before I dissassemble.
photos attached.

Thanks in advance20191121_152858[1].jpg20191121_152941[1].jpg20191121_152923[1].jpg20191121_152934[1].jpg20191121_152825[1].jpg20191121_152839[1].jpg20191121_152909[1].jpg20191121_152858[1].jpg


Joined Jun 22, 2012
Measure between the battery terminals B+, B1, to B4, and B-, to see where the voltage drop is, the batteries are in series with fets to connect them together.