Hi all,

I'm using  a 3 cell battery made with NCR18650B cells with PCB protection on my tricopter. My tricopter only draws 3A to hover (~40-50 watts) so I believe these batteries can handle the discharge current required without exploding. 

The issue I'm having is that when I measure the battery voltage disconnected it is 11.7V.  When I connect the battery in mission planner it only reads 10.4V  When I power the tricopter the voltage drops instantly to about 9V and hovers for maybe 20 seconds and then the power completely cuts out.  The last reading from the telemetry is about 8V and 3.4A.

The first cell in the battery is dead but cell 2 and 3 are fine.

Is it the PCB protection? Does anyone know why the voltage is dropping so low even though there is not much current being drawn.

Any advice would be much appreciated.


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  • Moderator

    Also, 18650b cells have a lower voltage under load than LiPo cells, I run 4S to get a (high) 3S voltage under load.

  • SOLVED: Ripped the PCB protection off and is working well now. Battery is not getting too hot either.

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