Two parallel p-channel mosfets with under voltage detector ~3.2v for single or parallel batteries.

Tin exposed traces.

Wire with 24 and 14 or 16 gauge wire.

Off board, wire battery negative contact to 510 negative ring, 14 or 16 gauge wire.

Parts: https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=8e6b935a24

Want to use the board with 2 batteries in series? Well you can. The 14.3K (R2) resistor will need to be replaced with one of a different value.

Use this voltage divider calculator: http://www.raltron.com/cust/tools/voltage_divider.asp

Enter the following

• Input voltage: The appropriate under voltage value (example 6.4v should be good for 2S)
• R1: 100000 ohms
• R2: leave blank
• Output voltage: 0.4v (this is a reference voltage for the voltage detector)

Click compute and you’ll get the R2 value. Go to Mouser and search for surface mount resistors, select one close to R2, case code in 0805.

Want to use 3-4 batteries in series? Do the same as above. Also, the mosfets MUST be replaced with 2 of the following instead: http://www.mouser.com/ProductDetail/Vishay-Semiconductors/SI7633DP-T1-GE3/?qs=LWWr1WFOkdG4pdeq2lDwHw%3D%3D

Due to voltage limitations of components, DO NOT exceed 4S.