125A starting rectifier

It is a simple and useful starting rectifier inspired and based on ZTR-120 starting rectifier.

Assumptions:

• voltages 12 and 24V
• protection:
  • overvoltage (to prevent overcharging)
  • undervoltage (connecting the accumulator with a different voltage)
  • overcurrent (short circuit protection)
  • polarization of the terminals (reverse connecting the terminals)

Construction:
The device consists of:

1. supply block – transformer + rectifier bridge
2. control blocks – board of relays and power supply, control module based on microcontroller Atmega88, the multifunction indicator (processed microvoltmeter with a switch and dividers on miltiturn potentiometers)
3. power contactors (relay of truck starter)
4. measuring shunt (own design made of stainless steel wire)
5. control panel (switch and simultaneously voltage switch, range switch, „start” and „manual” switch, controls)

Operation:
When the rectifier is connected to the mains and charging voltage is selected, the display shows „Connect the accumulator”. Connect alligator clamps to the accumulator clamp, the controller checks the connection and if everything is okay, switches the power contactor, corresponding to the voltage. If irregularities are found (lack of too low voltage, too high voltage, lack or too high charging current), the rectifier is turned off and the appropriate message is displayed.

By default, automatic charging runs (the charging lasts for approximately 10 hours, charging periods alternating with periods of degassing are activated after exceeding the corresponding voltage), you can switch it to manual charging mode or start by the appropriate button.

You can view parameters of charging on the display and multifunction indicator. Switching ranges on the indicator can be done using the rotary switch (V – range up to 28V, A – 28A and 110A).

Schematics:



Pictures:






Link to original thread (useful attachment) - Prostownik rozruchowy 125 A