Home / Backup time / 220Ah with 2 fans, 4 lights, TV, WiFi
A 220Ah 12V tubular battery runs 2 fans + 4 lights + TV + WiFi router for about 3 hours 45 minutes. That load averages 246W, and the battery holds 924Wh usable once you apply 70% inverter efficiency and the 50% depth of discharge lead-acid batteries are limited to. 924Wh / 246W = 3.8 hours.
The family living-room load: cooling, lighting, television and internet together. Duty cycle matters here: Battery Buddy multiplies each appliance by the minutes it actually runs in an hour, so a fridge that cycles 40 minutes an hour is counted at two-thirds of its nameplate wattage instead of full blast.
| Appliance | Watts each | Qty | Minutes per hour | Average draw |
|---|---|---|---|---|
| Ceiling Fan | 70W | 2 | 60 min | 140W |
| LED Bulb | 9W | 4 | 60 min | 36W |
| LED TV (32-inch) | 60W | 1 | 60 min | 60W |
| WiFi Router | 10W | 1 | 60 min | 10W |
| Total average hourly load | 246W |
On paper a 220Ah 12V battery stores 220 x 12 = 2640Wh. You never get that. Lead-acid tubular plates are rated for roughly 50% depth of discharge, and the inverter loses more converting DC to AC, so the honest figure is 220 x 12 x 0.7 x 0.5 = 924Wh.
Heavy tubular used where outages run past 6 hours. If you have already measured your own system with the efficiency estimator, put your real factor into the calculator — that single number moves the answer more than any other input.
At 3 hours 45 minutes this is a Moderate Load setup — it clears the 2-hour danger line but stays under 5 hours, so a long monsoon outage will need you to shed something.
Runtime and capacity are two different questions. With every appliance on at once this profile draws 246W continuous, which sizes to (246W / 0.8) x 1.25 on average draw and lands on a standard 600VA inverter.
The start-up surge test is the one most calculators skip. Ceiling Fan spikes to about 210W for a second or two when its motor kicks in, so peak demand is 246W continuous + 210W surge = 456W. Against a 600VA inverter that is 24% headroom — it holds.
Battery age, electrolyte level, cable thickness and terminal corrosion all show up as one thing: a lower effective efficiency. Here is the same battery and the same load across the realistic range.
| System efficiency | Usable energy | Estimated backup |
|---|---|---|
| 55% | 726Wh | 2 hours 57 minutes |
| 60% | 792Wh | 3 hours 13 minutes |
| 65% | 858Wh | 3 hours 29 minutes |
| 70% (default) | 924Wh | 3 hours 45 minutes |
| 75% | 990Wh | 4 hours 1 minutes |
| 80% | 1056Wh | 4 hours 18 minutes |
Run the two-hour test on the efficiency estimator to replace this guess with your own measured factor.
If you are still choosing a battery, this is the whole shelf against exactly this load.
| Battery | Usable energy | Estimated backup | Band |
|---|---|---|---|
| 100Ah | 420Wh | 1 hour 42 minutes | High load |
| 120Ah | 504Wh | 2 hours 3 minutes | Moderate |
| 135Ah | 567Wh | 2 hours 18 minutes | Moderate |
| 150Ah | 630Wh | 2 hours 34 minutes | Moderate |
| 165Ah | 693Wh | 2 hours 49 minutes | Moderate |
| 180Ah | 756Wh | 3 hours 4 minutes | Moderate |
| 200Ah | 840Wh | 3 hours 25 minutes | Moderate |
| 220Ah (this page) | 924Wh | 3 hours 45 minutes | Moderate |
| 250Ah | 1050Wh | 4 hours 16 minutes | Moderate |
And this is the same 220Ah battery against every other load profile we model.
| Load profile | Average draw | Estimated backup |
|---|---|---|
| 2 ceiling fans + 3 LED bulbs | 167W | 5 hours 32 minutes |
| 1 ceiling fan + 2 LED bulbs | 88W | 10 hours 30 minutes |
| 3 ceiling fans + 5 LED bulbs | 255W | 3 hours 37 minutes |
| 2 fans + 4 lights + TV + WiFi router (this page) | 246W | 3 hours 45 minutes |
| Refrigerator + 2 fans + 4 LED bulbs | 276W | 3 hours 21 minutes |
| Laptop + WiFi router + 1 fan + 2 lights | 163W | 5 hours 40 minutes |
| 2 fans + 6 lights + TV + refrigerator + WiFi | 404W | 2 hours 17 minutes |
| Air cooler + 2 LED bulbs | 198W | 4 hours 40 minutes |
| 4 tube lights + 2 fans + billing computer | 420W | 2 hours 12 minutes |
| 1 fan + 2 lights + 2 mobile chargers | 98W | 9 hours 26 minutes |
| TV + set-top box + 2 fans + 3 lights | 242W | 3 hours 49 minutes |
| 3 BLDC fans + 6 LED bulbs | 144W | 6 hours 25 minutes |
About 3 hours 45 minutes. The load averages 246W and the battery delivers 924Wh usable at 70% efficiency and 50% depth of discharge, so 924 / 246 = 3.8 hours.
Because 70% is an assumption, not your measurement. A battery two or three years old, a low electrolyte level, thin cabling or a charger that never completes a cycle in short grid windows all pull the effective factor down. At 55% the same setup gives 2 hours 57 minutes. Measure yours with the efficiency estimator.
A standard 600VA inverter. The sizing rule is (average load / power factor 0.8) x 1.25 safety margin, which on 246W gives 384VA and rounds up to the nearest retail tier.
No. Lead-acid tubular batteries are rated for roughly 50% depth of discharge — draining past half state of charge sulphates the plates and shortens life sharply. That is why 220Ah x 12V = 2640Wh nominal becomes 924Wh usable.
Cut the load, not the comfort. Replacing induction ceiling fans with 30W BLDC fans and any remaining CFLs with 9W LEDs typically removes 40-45W per fan and 6W per bulb. On this profile that is the difference between 3 hours 45 minutes and materially more, at a fraction of the cost of a second battery.
No. Battery Buddy is a free, brand-neutral calculator from Flocci Technologies. It shows the formula for every number so you can check it against any dealer's quote, and it needs no sign-up.
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.