Soft Start Calculator
The number that decides whether a power station can run your air conditioner is not the running watts — it is the startup surge (locked-rotor amps). A soft-start kit cuts that peak by a documented 50–70%. Pick your unit and see what becomes possible.
Starts it as-is
Surge rating covers the published startup peak.
- EcoFlow DELTA 31,800W · surge 3,600W
- EcoFlow DELTA 3 Plus1,800W · surge 3,600W
- EcoFlow DELTA 3 Max2,400W · surge 4,800W
- EcoFlow DELTA 3 Max Plus3,000W · surge 6,000W
- EcoFlow DELTA Pro 34,000W · surge 8,000W
- Jackery Explorer 1000 v21,500W · surge 3,000W
- Jackery Explorer 2000 Plus3,000W · surge 6,000W
- Bluetti AC1801,800W · surge 2,700W
- Bluetti AC200L2,400W · surge 7,200W
- Anker SOLIX F15001,800W · surge 2,400W
- Anker SOLIX F38006,000W · surge 9,000W
- Generac GB10001,600W · surge 3,200W
- Generac GB20001,600W · surge 3,200W
Starts it WITH a soft-start kit
Checked against the conservative end (50% reduction) — never oversold.
- Bluetti AC701,000W · surge 1,500W
Soft-start figures assume a 3-phase compressor soft starter (e.g. Micro-Air EasyStart) installed on the outdoor unit; reduction ranges are the manufacturer-documented 50–70%. Inverter-driven compressors don't need one — they already ramp. Verify your unit's actual LRA on the nameplate or spec sheet before buying.
Startup surge, with and without a soft-start kit
| Unit | Running | Startup (published) | With soft start | Stations as-is | Stations w/ kit |
|---|---|---|---|---|---|
| Window AC (8,000 BTU) | 550 W | 1,650 W | 495–825 W | 13 | 14 |
| Window AC (12,000 BTU) | 800 W | 2,400 W | 720–1,200 W | 13 | 14 |
| Central AC (2-ton, 24,000 BTU) | 1,930 W | 8,740 W | 2,622–4,370 W | 1 | 2 |
| Central AC (3-ton, 36,000 BTU) | 3,460 W | 17,710 W | 5,313–8,855 W | 0 | 1 |
| Central AC (4-ton, 48,000 BTU) | 4,880 W | 25,070 W | 7,521–12,535 W | 0 | 0 |
| Ductless Mini-Split (12,000 BTU heat pump) | 1,400 W | 2,240 W | 672–1,120 W | 12 | 12 |
| RV Rooftop AC (13,500 BTU) | 1,800 W | 7,800 W | 2,340–3,900 W | 2 | 6 |
Frequently asked questions
What does a soft start kit do for an air conditioner?
It replaces the brutal locked-rotor start with a phased ramp: the compressor motor is walked up to speed over about a second instead of being slammed at full voltage. The documented effect is a 50–70% reduction in the startup current peak (Micro-Air publishes a measured example of 81.4A LRA starting at 26.2A). For backup power this is often the difference between a station tripping offline and running fine.
Can a portable power station run a central AC?
As-published, almost never: a 2-ton condenser starts at roughly 8,700W (38A LRA at 230V), which is beyond consumer stations. With a soft-start kit the start peak falls to roughly 4,400W or less, which several 240V split-phase stations can cover — check the tool above for current matches.
Does an inverter AC need a soft starter?
No. Inverter-driven compressors (modern mini-splits, inverter window units, most ENERGY STAR Most-Efficient models) already ramp from zero speed and have no locked-rotor spike. A soft-start kit only helps conventional single-speed compressors.
How much does a soft start kit cost, and is it worth it?
Popular units (Micro-Air EasyStart Flex, Hyper Viper class) run roughly $125–$330. If it converts "no station can start my AC" into "a $1,500 station can", it is the cheapest capacity you will ever buy. It also reduces mechanical stress on every normal start.
Surge data from manufacturer spec sheets (Goodman SS-GSX14 LRA, Dometic Brisk II LRA) and ENERGY STAR datasets; soft-start reduction from Micro-Air's published measurements (EasyStart product data). See our methodology for how every number on this site is sourced.