Home / Appliances / BLDC Ceiling Fan
A BLDC Ceiling Fan draws about 30W, so a 150Ah 12V tubular battery runs one of them for roughly 21 hours on its own. That comes from 630Wh usable energy divided by 30W. A BLDC fan does the same job on roughly 40% of the power of an induction fan.
A BLDC fan does the same job on roughly 40% of the power of an induction fan. The 30W figure used across this page is a typical mid-range Indian retail unit — check the nameplate on yours and put the real number into the calculator, because a 10W difference on an appliance you run for six hours is 60Wh out of a budget of only a few hundred.
Category: Cooling. People search for this as bldc fan, energy efficient fan, 5 star fan — all the same question, and all answered by the same arithmetic.
Usable energy is Ah x 12V x 0.7 efficiency x 0.5 depth of discharge. Divide that by the appliance draw and you have the runtime with nothing else connected.
| Battery | Usable energy | Runtime with one unit | Runtime with two |
|---|---|---|---|
| 100Ah | 420Wh | 14 hours | 7 hours |
| 120Ah | 504Wh | 16 hours 48 minutes | 8 hours 24 minutes |
| 135Ah | 567Wh | 18 hours 54 minutes | 9 hours 27 minutes |
| 150Ah | 630Wh | 21 hours | 10 hours 30 minutes |
| 165Ah | 693Wh | 23 hours 6 minutes | 11 hours 33 minutes |
| 180Ah | 756Wh | 25 hours 12 minutes | 12 hours 36 minutes |
| 200Ah | 840Wh | 28 hours | 14 hours |
| 220Ah | 924Wh | 30 hours 48 minutes | 15 hours 24 minutes |
| 250Ah | 1050Wh | 35 hours | 17 hours 30 minutes |
Nothing stops you connecting more units — the limit is runtime, not the inverter, until you hit the surge ceiling below.
| Quantity | Continuous draw | Runtime | Band |
|---|---|---|---|
| 1 | 30W | 21 hours | Low load |
| 2 | 60W | 10 hours 30 minutes | Low load |
| 3 | 90W | 7 hours | Low load |
| 4 | 120W | 5 hours 15 minutes | Low load |
| 5 | 150W | 4 hours 12 minutes | Moderate |
| 6 | 180W | 3 hours 30 minutes | Moderate |
Very few appliances run flat out for a full hour. A fridge compressor cycles, a mixer runs in bursts, a pump fills a tank and stops. Battery Buddy asks for minutes run per hour and multiplies the wattage by that fraction — which is why its answers are usually longer, and more honest, than a calculator that assumes continuous draw.
| Minutes run per hour | Average hourly draw | Runtime on a 150Ah battery |
|---|---|---|
| 15 min | 7.5W | 84 hours |
| 30 min | 15W | 42 hours |
| 40 min | 20W | 31 hours 30 minutes |
| 45 min | 22.5W | 28 hours |
| 60 min | 30W | 21 hours |
This is a surge-sensitive appliance. Battery Buddy applies a 1.5x start-up multiplier to a BLDC Ceiling Fan, so one unit spikes to about 45W for a second or two at switch-on. Your inverter has to survive everything else already running plus that spike — not just the average load.
Peak demand = total continuous load + the single largest start-up surge. The sizing advisor runs that check automatically for whatever mix you enter.
These are complete household and shop profiles we model, each with its own worked page.
| Profile | Average draw | Backup on a 150Ah battery |
|---|---|---|
| 3 BLDC fans + 6 LED bulbs | 144W | 4 hours 23 minutes |
About 30W while running. A BLDC fan does the same job on roughly 40% of the power of an induction fan. Always confirm against the nameplate rating on your own unit before sizing a battery around it.
Roughly 21 hours with nothing else connected: 630Wh usable divided by 30W. Add anything else to the inverter and that time drops proportionally.
Battery Buddy applies a 1.5x multiplier, so a single unit peaks near 45W at switch-on before settling to 30W. That spike, not the running load, is what trips undersized inverters.
Yes — one unit runs about 14 hours on a 100Ah 12V battery at 70% efficiency. Whether that is enough depends on how long your outages actually last and what else shares the inverter.
The figures assume 70% system efficiency. An older battery, low electrolyte, corroded terminals or thin cabling all reduce the effective factor. Measure yours with the efficiency estimator and re-run the numbers — it takes one discharge test.
Battery Buddy is free, needs no sign-up, sells no batteries and shows every formula it uses. It is built by Flocci Technologies, an India-first AI-native software studio behind 30+ apps that share one Flocci identity.