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228W average load - 6 hour target - 12V system

What size inverter and battery does a work-from-home professional need?

For a work-from-home professional running 228W average load for 6 hours, Battery Buddy sizes a 600VA inverter and a 220Ah battery bank at 12V — Single 220Ah 12V battery. The energy target is 1368Wh, which needs 326Ah at 70% efficiency and 50% depth of discharge. Charge it at 22-27A.

The load this premises actually carries

Two laptops, the router and a fan — enough to hold a video call through a full outage. Each appliance is counted at the minutes it genuinely runs in an hour, not at full nameplate wattage for sixty minutes — that duty-cycle step is what separates a sizing you can trust from a dealer's round number.

Average hourly load, appliance by appliance
ApplianceWatts eachQtyMinutes per hourAverage draw
Laptop65W260 min130W
WiFi Router10W160 min10W
Ceiling Fan70W160 min70W
LED Bulb9W260 min18W
Total average hourly load228W

Why 600VA and not something bigger

Inverters are sold in VA, not watts. Battery Buddy converts with the standard power factor of 0.8 and adds a 25% safety margin: (228W / 0.8) x 1.25 = 356VA, which rounds up to the 600VA tier actually sold in Indian retail.

Oversizing is not free. A larger inverter idles at a higher no-load draw, costs more, and tempts you to add load the battery cannot support. Size the inverter to the load, then size the battery to the outage.

Why the system runs at 12V

Common for small loads and basic home backup. Usually a single 12V battery. Battery Buddy escalates system voltage automatically once average load passes 400W (to 24V), 800W (to 48V) and 2000W (to 96V). At 228W this profile sits at 12V.

Higher DC voltage carries the same power at lower current, which means less heat in the cabling and a safer install. The cost is that batteries must be added in matched series sets — Single 220Ah 12V battery.

Battery bank and charging

Target energy is 228W x 6 hours = 1368Wh. Dividing by 12V x 0.7 efficiency x 0.5 depth of discharge gives 326Ah, and the nearest standard bank is 220Ah — rated for a sustained load of 280-375W.

Charge it at 22-27A, the C/10 to C/8 guideline. Under-charging leaves a lead-acid bank permanently short of full and is one of the most common reasons backup quietly halves over two years.

Note: at this bank size the honest achievable runtime on this load is about 4 hours 3 minutes, short of the 6-hour target. Either add a parallel string, move to the next voltage tier, or accept a shorter window and plan what you switch off.

The overload check nobody runs

With everything on, continuous draw is 228W. The Laptop spikes to about 156W at start-up, so peak demand is 384W. A 600VA inverter holds that with 36% headroom.

Backup target versus battery cost

Every extra hour of backup is bought with amp-hours. This is the trade-off for exactly this load.

What each backup target costs you in battery
Backup targetEnergy neededBank Ah requiredNearest retail bank
2 hours456Wh109Ah150Ah at 12V
3 hours684Wh163Ah180Ah at 12V
4 hours912Wh217Ah220Ah at 12V
5 hours1140Wh271Ah220Ah at 12V
6 hours1368Wh326Ah220Ah at 12V
8 hours1824Wh434Ah220Ah at 12V

Frequently asked questions

What size inverter is needed for a work-from-home professional?

A 600VA inverter for a 228W average load. That comes from (228 / 0.8) x 1.25 = 356VA, rounded up to the nearest standard retail size.

What battery capacity does a work-from-home professional need for 6 hours of backup?

About 326Ah at 12V, which maps to a standard 220Ah bank — Single 220Ah 12V battery. The energy target is 1368Wh at 70% efficiency and 50% depth of discharge.

Should this run on 12V or a higher system voltage?

12V. Common for small loads and basic home backup. Usually a single 12V battery. The threshold Battery Buddy uses is 400W average load for 24V, 800W for 48V and 2000W for 96V.

What charging current should the inverter provide?

22-27A, following the C/10 to C/8 guideline for a 220Ah lead-acid bank. Too little current never completes a cycle in short grid windows; too much cooks the electrolyte.

Will the inverter trip when a motor starts?

Peak demand here is 384W — 228W continuous plus the 156W start-up surge of the Laptop. A 600VA inverter clears it.

Is this a brand recommendation?

No. Battery Buddy is brand-neutral and free — it returns a VA rating, an Ah figure, a system voltage and a charger current, and shows the formula behind each. Take those four numbers to any dealer and compare quotes on equal terms.

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.