Configuration Calculator

This page will help you pick part values for your battery board.

This calculator is a goal-seeker. If you don’t like the answers, change the goals. :)

If the charge time is 10 hours or more, the calculator assumes you’re making a trickle-only charging board. It leaves out R1, assumes that there is one fewer diode drop along the charging path, and doesn’t calculate Vsen divider resistor values.

Some of the rules the calculator follows are:

1. Only E-24 values (5%) are used for resistors.
2. Calculated R1 and R2 values give current levels below the target value.
3. The calculated divider resistors are picked to be within the Vsen pin’s sensitivity range.
4. The maximum divider current is kept well below typical NiMH self-discharge rate.
5. The divider current is well above the Vsen pin’s bias current.

	Number of cells:
	Cell capacity:	mAh
	Charge time:	hours
	Regulator type:	Standard (NPN)  LDO
	Backup fast-charge termination method:	Time-based  Temperature-based (not implemented yet)
	Answers: