Paul K0ZYV asks, “What is the maximum safe input voltage to µBITx?”
Paul has lithium ion batteries that provide up to 4.2 volt when fully charged, and he hoped to put four in a pack which could max out at 16.8 volts providing about 2300 maH to power the µBITx.
The consensus seems to be around 15v is the maximum voltage that should be applied to the µBITx.
The reason is that the audio amplifier absolute voltage limit is 15V. All the other components can handle the 15V voltage. This assumes of course that the 5V regulator on the raduino has a heatsink and better still has a series resistor to limit power dissipation.
Regulating the voltage when using Lithium Ion Batteries
VE7WQ uses a $1.45 Boost Buck DC adjustable step up down Converter XL6009 Module with a 4 cell 18650 Li-ion Rechargeable Battery pack. This has the following characteristics:
Wide input voltage 5V ~ 32V;
Wide Output Voltage 1.25V ~ 35V
Built- 4A MOSFET switches, efficiency up to 94%.