4 string charging and discharging +12V UPS

I bought N Shante c1ks before, and most of them failed. Either the host failed or the lead-acid battery aged. After that, I rarely encountered power outages, so I didn’t configure them again.

However, the NAS recently encountered a power failure and the 12V power supply failed. For the safety of the NAS, a UPS is still needed. Based on the fact that the NAS is powered by 12v, as is the router, so the construction is as follows

The main power supply is still 12v, and then LTC4412 ideal diode is used for power path management. The charging part uses CN3306 to boost the voltage, and the discharging part uses kic1210, 40V input, and 10A output with its own heat sink.

The output part of the power monitoring uses an INA226, and the input voltage and battery voltage are roughly detected by the ADC pin of the ESP32.

When the power is cut off and restored, esp32 sends email prompts. Of course, if you need more, you can write it yourself, but there is no automatic shutdown.

The charging part uses CN3306 boosted multi-string lithium battery charging with MPPT, modified based on https://oshwhub.com/583703056a/dian-chi-zu-ban_copy

There is a small bug at the moment. The LTC4412 turns on the MOS at the input for some reason. It’s no problem with Schottky. I don’t know if it’s related to the position of the SENS pin. Later versions will try to use jumpers to detect the front and back of the MOS.