I did some testing with my Renogy Wanderer 10 and a pinout diagram I found here.
It looks like pins 5 and 6 carry some subset of voltage depending on the battery voltage. From my test (powering the Wanderer 10 using a 12V wall wart power supply), the RS232 only supplies 100mA of current at about 10.5V. I was using an ESP32 with a LM2596 buck converter. At some point in the ESP32 boot process, the system pulls more than 100mA, browns out the RS232 power supply, and crashes the loop().
All that to say, the power provided by the RS232 wasn't enough for me to make use of. Higher battery voltages or different charge controllers may yield different results.
I did some testing with my Renogy Wanderer 10 and a pinout diagram I found here.
It looks like pins 5 and 6 carry some subset of voltage depending on the battery voltage. From my test (powering the Wanderer 10 using a 12V wall wart power supply), the RS232 only supplies 100mA of current at about 10.5V. I was using an ESP32 with a LM2596 buck converter. At some point in the ESP32 boot process, the system pulls more than 100mA, browns out the RS232 power supply, and crashes the loop().
All that to say, the power provided by the RS232 wasn't enough for me to make use of. Higher battery voltages or different charge controllers may yield different results.