Active SLA Battery Desulfator / Charger with MCU Battery Status Monitoring

[Mechatrommer]

this is my 40V 5A Lead Acid battery Desulfator / Charger with 1.25 - 30V SMPS PSU. Features are:

1) MCU (atTiny13A) controlled pulse between 500 - 2500 Hz user adjustable
2) adjustable pulse duty cycle 1 - 80%
3) can desulfate/charge 6, 12, 24V lead acid batteries
4) Pulse/desulfate/charge every 10 seconds, rest 1 second and check battery status. If battery is full ( equal or more than 6.75, 13.5, 27V), stop pulse and beep twice every 5 seconds.
5) If battery not connected, stop desulfation/charge process.
6) If user set duty cycle to less than 30%, the unit will go into unconditional trickle charge (no battery voltage level monitor)
7) Internal Mosfet (power element) Damage or input overvoltage check by continuous warning beep.
8} 2 SMPS output since i have more room on the PCB

some idea and inspiration came from this thread... https://www.eevblog.com/forum/oshw/desulfate-regenerate-lead-acid-batts-a-new-diy-guide-overnight/msg1253994/#msg1253994 with mcu control, error can also be checked (and beep accordingly):

Attached are the schematics and the build process. As of this post, this unit has been working 24/7 for the past 4 weeks repairing my old batteries.. FWIW...
Best regards...