During my activation of DM/BW-078, the setup went smoothly until I switched on the KX3. Then I saw a message on the dispaly, saying something like: 'above 15 V‘. The words took a second to sink in, then I immediately hit the buttons and switched the KX3 off.
By mistake, I connected a fully charged 4S Li-Ion battery to the KX3. The voltage reducer, which is mandatory when using this kind of battery, was missing. I knew it had to happen one day! The KX3 supply voltage was approx. 16.3 volts.
When my blood pressure returned to normal, I plugged in the voltage reducer and turned the KX3 back on. Fortunately, there was no damage whatsoever. Thanks, Elecraft for the rugged design!
This mistake was possible because all my DC connectors are of the same type.
New task: change the 4S battery connector to a different type.
Answer to above question: The KX3 can tolerate up to 16.3 volts but I won’t try it again