That’s an interesting behaviour.
You are correct, the PMIC is rated at 17V max. We have tested the Electron to operate at 17V as well. Due to the size constraints of the PCB, there isn’t enough thermal dissipation available. This is the reason we have capped the max input voltage to 12V so that the operation is guaranteed to run cooler. You can definitely run it above that voltage but you may run into overheating. Having said that, the PMIC has an inbuilt thermal shut-off, so it won’t destroy the Electron.
What is the ampere rating and max discharge rate of the 12V lithium battery pack? The Electron will consume transient peak currents of up to 1900mA @3.8V
Regards,
Mohit