Power inverter

01

Size continuous power at your temperature and peak loads

Victron's Phoenix Inverter Smart datasheet rates its 1600 VA model at 1,300 W continuous at 25 °C, 1,200 W at 40 °C and 800 W at 65 °C, with 3,000 W peak; the 3000 VA model gives 2,400, 2,200 and 1,700 W with 6,000 W peak, and the 5000 VA model 4,000, 3,700 and 2,800 W with 10,000 W peak, measured on non-linear loads with a 3:1 crest factor. Output is 230 VAC ±2% at 50 or 60 Hz ±0.1%. It says the full-bridge plus toroidal transformer topology gives high start-up power for loads such as LED drivers, halogen lamps and power tools. [1]

The smaller Phoenix VE.Direct range runs from 250 VA (200 W at 25 °C, 175 W at 40 °C, 400 W peak) to 1600 VA (1,450 W and 1,200 W, 2,200 W peak), with 230 or 120 VAC ±3% output. [2]

Editorial calculation: the 1600 VA Smart model's 1,300 W at 25 °C is about 81% of its VA rating, and its 800 W at 65 °C is about 38% lower again, so a hot engine bay or cabinet can cut usable power sharply; its 3,000 W peak is about 2.3 times its 25 °C continuous rating. [1]

A North American model shows the data a Victron sheet leaves out. Samlex's PST-2000 data sheet (12 V and 24 V versions, 120 V AC) gives a pure sine output with total harmonic distortion below 3%, 120 V AC ±3% at 60 Hz ±1%, 2,000 W continuous and 3,500 W surge for under one second (both at power factor 1), and 85% peak efficiency at full load. DC input current at no load is below 1.0 A (12 V) or 0.8 A (24 V); maximum input current is 240 A or 120 A, with internal fuses of 6 × 40 A or 6 × 20 A. It alarms at 10.7 V or 21.4 V, shuts down at 10 V or 20 V and at 16.5 V or 33 V, operates at 0–40 °C, is ETL-listed to ANSI/UL 458 and FCC Part 15 Class B, has GFCI outlets, and weighs 7.1 kg. [3]

Model names do not always equal continuous watts. Xantrex's PROwatt SW true sine wave range for truck, RV and marine use lists: [4]

Give the supplier the continuous load in watts and the largest start-up surges, ambient temperature at the installation, battery voltage and chemistry, output voltage and frequency, idle-time profile (for ECO mode), transfer switch or charger needs, remote control and monitoring, enclosure and mounting, standards and markings for the market (for example vehicle EMC), and quantity.

02

Check battery input, efficiency, idle draw and protections

The Phoenix Inverter Smart accepts 9.3–17 V on 12 V models, 18.6–34 V on 24 V and 37.2–68 V on 48 V, with a load-dependent dynamic low-voltage cut-off and configurable alarms and restart levels. Maximum efficiency is 92–96% depending on model and voltage; idle consumption is 8–20 W, falling to 0.6–3.2 W in ECO mode, where the inverter sleeps below a set load and checks every 2.5 seconds. Protections cover output short circuit, overload, battery voltage too high or too low, over-temperature, 230 VAC on the inverter output and excessive input ripple; it operates from −40 to +65 °C with fan cooling, is IP21 in a steel case, and lists EN 60335-1 safety, EN 55014 and IEC 61000-6 EMC and ECE R10 automotive approval. [1]

Editorial calculation: at 1,300 W and 92% efficiency a 12 V inverter draws about 118 A from the battery, while a 24 V 3000 VA unit at 2,400 W and 94% draws about 106 A — for roughly twice the power at twice the battery voltage, the current stays about the same. An 8 W idle draw over 24 hours uses about 192 Wh, against about 14 Wh at 0.6 W in ECO mode. [1]

Editorial calculation: the Samlex 12 V model's under-1.0 A no-load draw is up to about 12 W, or roughly 0.29 kWh a day if left on (12 W × 24 h); at full load its 85% efficiency means about 196 A from a 12 V battery for 2,000 W (2,000 ÷ 0.85 ÷ 12). [3]

Xantrex gives the PROwatt SW models a 10.5–15.5 V DC input range, 104–127 V AC output at 60 ± 0.5 Hz, 90% optimum efficiency, 0–40 °C operation, dual GFCI outlets, a 5 V / 500 mA USB port and a two-year warranty, and lists UL 458 with marine supplement, CSA 107.1 and FCC Part 15 Class A. [4] Editorial calculation: each model's continuous rating is 90% of the number in its name (540 of 600, 900 of 1,000, 1,800 of 2,000 W); at 1,800 W and 90% efficiency the 2000 model draws about 167 A at 12 V and about 190 A at its 10.5 V lower limit, inside the 250 A fuse Xantrex recommends. [4]

03

Compare what suppliers offer

Suppliers linked to this page list power inverters; each card links to the page reviewed.

Listings include car and modified-sine-wave inverters, inverter/chargers, hybrid and energy-storage inverters, inductive-load inverters and mining power inverters; ask each for continuous watts versus temperature, peak power and duration, waveform and THD, efficiency and idle draw, protections and approvals.

04

Trace the inverter construction

This is a functional reference built from the sources cited; it is not one maker's specification.

05

Fill the specification fields with values for your system

A power inverter quotation needs values for your system. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

06

Send the loads, battery and site together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Loads: [continuous W; surge W and duration]
Battery: [voltage; chemistry; capacity]
Output: [voltage; frequency; waveform]
Site: [ambient temperature; ventilation; enclosure]
Features: [ECO mode; transfer switch; charger; monitoring]
Compliance: [safety; EMC; vehicle approval]
Quantity: [units]

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