Designing a Battery Charger
Nominal output voltage: 
Step 1:  Setting the Float Voltage
Open circuit float voltage:  V
Float voltage trim range:  V
Step 2:  Setting the Charge Current

Output current trim range: A
Desired float voltage: V    Desired output current: A   
Trim resistor value: K ohm
Trim resistor value: K ohm

B: Battery
V
R1: Sets zener bias current
ohm
R2: Sets charge current
K ohm
Ru Rd: Sets float voltage
K ohm