Inverter / UPS
Power
Turns DC (battery/solar) into AC mains power. A UPS is an inverter with a charger and a fast transfer switch. Waveform quality is the split: pure sine runs everything; modified sine annoys motors and some electronics.
What it looks like
Inverter / UPS
A typical power — exact shape, colour and markings vary between manufacturers.
Types & variants
Key specs
Continuous power
WReal deliverable watts — not the marketing 'peak'.
Surge power
WShort overload capacity for motor/compressor starts (needs ~3× running).
Waveform
Pure sine vs modified sine — THD % tells the truth.
Efficiency / idle draw
% / WIdle consumption drains batteries even with no load.
Markings
Ratings plate: DC input voltage (12/24/48 V), AC output, continuous/surge watts, waveform type.
Standard values
12 V 300–1000 W hobby inverters; 600–1500 VA home UPSes.
How to choose
Sum your real loads +30%, check surge covers motor starts, and buy pure sine for anything with a motor, transformer or sensitive electronics. Size battery bank for runtime — the inverter is only half the system.
Pinout & package
Heavy DC terminals (short, thick cables — 12 V at 1000 W is 80+ A!), AC outlets, chassis earth stud.
Example circuits
- 12 V battery + 500 W pure sine inverter as camp power
- UPS keeping a router + NAS alive
- Grid-tie inverter exporting solar
Common failures
Blown output stage from overload/surge, cooked electrolytics from heat, low-voltage alarms from undersized DC cabling (voltage drop), UPS batteries dead after 2–3 years.
How to test
Measure output with a true-RMS meter (~230/120 V); modified sine reads oddly on cheap meters. Test UPS transfer by pulling its plug under a safe load. Check idle current draw against spec.
Substitutes
Bigger cousins interchange if DC voltage, waveform and wattage match. For small electronics, a DC-DC converter to the device's voltage beats DC→AC→DC round-tripping.