What size inverter for an air cooler?
An air cooler with two fans, four lights and the TV, the usual summer set in North India.
- Typical appliance watts, change them in the calculator
- Indian inverter sizes
- Tubular or lithium
The load
Typical ratings. Check the plate on your own appliances; a BLDC fan uses about 30 W instead of 75 W.
| Appliance | How many | Watts each | Total |
|---|---|---|---|
| Air cooler motor | 1 | 200 W | 200 W |
| Ceiling fan | 2 | 75 W | 150 W |
| LED bulb | 4 | 9 W | 36 W |
| Television | 1 | 80 W | 80 W |
| Running load | 466 W |
Battery for the backup you want
Tubular: 12 V batteries, the usual choice. Longer backup moves you to a 24 V inverter with two batteries. Lithium: LiFePO4 modules.
| Backup | Tubular battery | Inverter for that | Lithium |
|---|---|---|---|
| 2 hours | 1 × 150 Ah tubular | 750 VA, 12 V | 2 × 12.8 V 100 Ah lithium |
| 4 hours | 1 × 230 Ah tubular | 750 VA, 12 V | 3 × 12.8 V 100 Ah lithium |
| 6 hours | 2 × 165 Ah tubular | 1500 VA, 24 V | 4 × 12.8 V 100 Ah lithium |
| 8 hours | 2 × 220 Ah tubular | 1500 VA, 24 V | 3 × 25.6 V 100 Ah lithium |
What it adds to your bill
| Power cuts a day | Recharging | Standby | Adds to your bill |
|---|---|---|---|
| 1 h | 21.8 units | 4.3 units | 26.2 units a month |
| 2 h | 43.7 units | 4.3 units | 48 units a month |
| 4 h | 87.4 units | 4.3 units | 91.7 units a month |
Inverters in our list that fit
From the makers’ stated ratings, smallest first. Brands are not ranked.
| Model | Rating | Battery | Wave |
|---|---|---|---|
| V-Guard Nextgen 850 | 750 VA / 600 W | 12 V | Modified (pseudo) sine wave |
| Livguard LGS1000i | 800 VA | 12 V | Pure sine wave |
| Microtek Super Power 900 (Pure Sine Wave) | 800 VA / 640 W | 12 V | Pure sine wave |
| Microtek Super Power 900 Advanced Digital | 800 VA / 672 W | 12 V | Not stated |
| Exide STAR 12V 850VA | 850 VA | 12 V | Pure sine wave |
| Exide GQP 12V 850VA | 850 VA | 12 V | Pure sine wave |
| Amaron HB950A | 880 VA | 12 V | Pure sine wave |
| Livguard LGS1100i | 900 VA | 12 V | Pure sine wave |
| Livguard LG1100 | 900 VA | 12 V | Square wave |
| Luminous Zelio+ 1100 | 900 VA / 756 W | 12 V | Pure sine wave |
| Luminous Eco Volt Neo 1050 | 900 VA / 756 W | 12 V | Pure sine wave |
| V-Guard Nextgen 1100 | 900 VA / 720 W | 12 V | Modified (pseudo) sine wave |
Questions
How is the inverter size worked out?
Running watts × 1.25 for a safety margin ÷ 0.8, the power factor Indian brands rate their inverters at. Then we pick the next standard size. Motors such as a fridge or pump also need starting surge, which we check against the inverter’s rating.
Why do the hours change the battery but not the inverter?
The inverter sets how much can run at once; the battery sets for how long. Longer backup needs more Ah, and past what one 12 V battery can give, a 24 V inverter with two batteries.
Will this raise my electricity bill?
Yes, a little. The battery is recharged from the grid after every cut, with some loss, and the inverter draws standby power all day. Each page shows the units a month; the calculator prices them at your state’s slabs.