Sinclair UK1400 power supply (rubber key version), it gives 13,5V
unloaded Charging current starts with appr. 500mA and is appr.
<100mA when voltage is appr. 12V
I have used 3x 3,7V 1020mA lithium phonecell battery's
Charging time: 4h
Usability time: 1h,18m
You can't have spectrum running while charging, there is not enough
voltage, It's not healty to leave a lithium to charge for too long
time it will fail Maybe a kitchen timer 4h connected to supply unit
would be a good idea!!!