Chosen Solution
I have a Macbook Air Early 2015 A1466 (EMC 2925) 661-02391 in the shop that randomly goes to sleep while using the Macbook. I have tried all the basics such as updating macOS. changing and disabling sleep settings, inserted another drive into the logic board, this resulted in the Macbook booting with the same issue. I also tried SMC Reset and NVRAM/PRAM Reset to no avail. The Macbook also goes to sleep in safe mode and recovery mode, the Macbook can stay awake for up to 30 minutes then decides to go to sleep and also will go straight back to sleep when woken up. I have already guessed it’s likely a logic board issue and started to some minor probing with the multimeter in diode mode. After testing Pins 3/4 on the LCD connector I noted a diode reading of .468 which would indicate a bad U7701/LP8550 IC according to the following post: inverter board for a1466? I am cautious to do anything like replacing the IC as I cannot see how a backlight IC would cause the Macbook to go to sleep. So before I go ahead and change the chip U7701, just off the diode readings alone, I thought I would ask you, fine people, for some advice on how to proceed. I am quite new to board diagnostics but have a basic understanding, Just tell me where to stick the probes and I can relay any readings :)
So I would not normally answer my own question, but after replacing the main logic board the problems Persisted. So out of pure chance, I decided to disconnect the MagSafe charger board from the main logic board and now I have no more issues. So new Magsafe board has been ordered and will fully resolve these issues. Again Thanks @danj for the help in troubleshooting, I have some very happy customers who have also opted to keep the new battery as the old one is still slowly dying :)
Still need to do a bit more diagnostics here. Your battery is still running well. But we need to see if you have a short. Can you stop using your system and unplug it for a good 12 hours? What we want to see if the battery runs down (it won’t be much) note the Battery charge cap did it decrease a bit?
