3 serially connected 12 V. 12 Ah. batteries are used
1 Amps. current limit between SMPS and 7 amps. diod
48 V. hub motor control + SMPS charger schematic with serial current limiter (+12 V. for driving gate is taken from the connection of first two batteries). Note that no diode is placed palalel to motor as it acts as a varicap shunting the pulse and also there is no need for it as the reverse induction currents are shorted by the internal diode of the FET.
My lift used to carry the bicycle to 4.th floor balcony
Picbasic code for PWM
FIRST CALIBRATION: Start charging with a voltmeter connected to battery poles reads 43.2V (which may take 2-3 hours even in maximum SMPS voltage setting). Set voltage to back to 43.2 if it exceeds. When the voltage becomes stable charge for 5 hours more. FOLLOWING CHARGES: Do not change the first calibration settings. Charge for 8 hours without the need of voltage measurement. When used; charge before the battery voltage drops below 36 V (===Battery empty)