The question is usually framed as which to buy. The more useful framing is what each one actually is.
A generator is an engine that makes electricity for as long as you feed it. Its constraint is fuel, and its costs are noise, exhaust, maintenance and a genuine carbon-monoxide hazard.
A battery is a fixed quantity of stored energy. Its constraint is capacity, and it has essentially none of those costs.
Side by side
| Petrol generator | Battery power station | Notes | |
|---|---|---|---|
| Runtime | Indefinite with fuel | Fixed by capacity | The core difference |
| Refuelling | Minutes | Hours, or a sunny day | |
| Indoor use | Never | Safe | CO kills |
| Noise | 60–75 dBA typical | Near silent | |
| Maintenance | Oil, filters, fuel stabiliser | None | |
| Cold starting | Can be difficult | Discharges fine | Batteries will not charge when frozen |
| Emissions | Exhaust | None | |
| Upfront cost | Lower per watt | Higher | |
| Cost over 10 years | Fuel + servicing | Effectively nothing | |
| Powers 240 V | Commonly | Rarely | Only the Delta Pro 3 here does |
| Fuel storage | Required | None | Petrol degrades in months |
- Petrol generator
- Indefinite with fuel
- Battery power station
- Fixed by capacity
- Notes
- The core difference
- Petrol generator
- Minutes
- Battery power station
- Hours, or a sunny day
- Notes
- Petrol generator
- Never
- Battery power station
- Safe
- Notes
- CO kills
- Petrol generator
- 60–75 dBA typical
- Battery power station
- Near silent
- Notes
- Petrol generator
- Oil, filters, fuel stabiliser
- Battery power station
- None
- Notes
- Petrol generator
- Can be difficult
- Battery power station
- Discharges fine
- Notes
- Batteries will not charge when frozen
- Petrol generator
- Exhaust
- Battery power station
- None
- Notes
- Petrol generator
- Lower per watt
- Battery power station
- Higher
- Notes
- Petrol generator
- Fuel + servicing
- Battery power station
- Effectively nothing
- Notes
- Petrol generator
- Commonly
- Battery power station
- Rarely
- Notes
- Only the Delta Pro 3 here does
- Petrol generator
- Required
- Battery power station
- None
- Notes
- Petrol degrades in months
Where a generator is the right answer
Outages lasting days. This is decisive. The largest battery on this site delivers about 72 hours of refrigeration alone.[1] A generator with fuel runs for a week. If you live somewhere hurricanes or ice storms take the grid out for five days, a battery alone is not the answer.
Large 240 V loads. Well pumps, electric ranges, central air conditioning. Only one measured unit on this site provides 240 V at all, and it will not run central air for a useful period.[2]
Lowest cost per watt today. A generator producing 5,000 W costs far less than a battery storing 5 kWh.
Where a battery is the right answer
Outages lasting hours. Which is most of them. A 2 kWh unit covers a day and a half of refrigeration silently, with nothing to start and no fuel to have gone stale.[3]
Anything indoors. Apartments, medical equipment, a CPAP beside the bed. A generator is simply not an option here.
No warning. A battery on UPS duty switches over in 10–30 ms — the fridge does not notice and a computer does not reboot.[4] A generator needs someone to go outside and start it.
Neighbours, and sleep. A generator at 60–75 dBA is a conversation you will have with the people next door at 2 a.m. Nobody independent has measured these units' noise, but every manufacturer figure is well below a generator and the mechanism — a small fan against an engine — is not in dispute.
No maintenance. A generator that has sat for two years with stale fuel in the carburettor frequently will not start. That is the most common way backup generators fail: not during use, but at the moment they are needed.
The honest recommendation: often both
For most households facing multi-day outages, the sensible arrangement is a battery for the first day and a generator for the rest.
The battery handles the common case silently and automatically — the four-hour cut where nobody even goes outside. The generator handles the rare multi-day event, and can recharge the battery during the day so the battery covers the night with the engine switched off.
Several units here accept generator input directly for exactly this reason.
What each actually costs over ten years
An illustrative comparison for a household with roughly four outage days a year:
| Generator | Battery | |
|---|---|---|
| Purchase | ~$800 | ~$1,200 |
| Fuel, 10 years | ~$400 | $0 |
| Servicing, 10 years | ~$500 | $0 |
| Replacement in period | Possible | No — rated 4,000+ cycles |
| Approximate total | ~$1,700 | ~$1,200 |
The figures are illustrative rather than sourced, and they will move with your fuel prices and usage. The structural point is robust: a generator's purchase price is the start of its cost and a battery's is close to all of it.
Solar changes the argument
The one thing a generator cannot do is refuel itself.
A battery with panels recovers energy every day the sun is up — 550 to 1,050 watt-hours a day from two 100 W panels on our figures, and more from a real array.[5] Over a five-day outage that turns a fixed 2 kWh into something closer to 5 or 6 kWh delivered.
That does not match a generator's output, but it substantially narrows the runtime gap that is the generator's main advantage — and it does it with no fuel, no noise and no exhaust. See solar recharge in practice for realistic numbers.
FAQ
Is a battery or a generator better for home backup?
A battery for outages of hours, which is most of them — silent, safe indoors, automatic, no maintenance. A generator for outages of days, or for large 240 V loads. Many households are best served by a battery for the common case and a generator for the rare one.
Can I run a generator in my garage?
No. Never, even with the door open. Generators produce carbon monoxide, which is colourless, odourless and lethal, and garage use is a recurring cause of fatal poisonings during outages. Generators run outdoors, well away from windows, doors and air intakes.
How long will a battery last in an outage compared to a generator?
A battery is finite: about 17 hours of refrigeration from a 1 kWh unit, or roughly 72 hours from a 4 kWh one. A generator runs as long as you have fuel. Solar panels narrow that gap considerably but do not close it.
Can I charge a power station with a generator?
Yes, and it is the best way to use both. Run the generator for a few hours in daylight to recharge the battery and cover heavy loads, then switch it off and run off the battery overnight. Several units here accept generator input directly.
Which is cheaper overall?
Over ten years the battery usually wins, because a generator's purchase price is only the beginning — fuel, oil, filters and servicing continue for its whole life, and stale fuel is the most common reason a backup generator fails to start when needed.
For measured runtimes by unit see running a fridge through an outage, or the best power stations for home backup.
Sources
- OutdoorGearLab. EcoFlow Delta Pro 3 Review. Independent lab test · accessed 5 September 2026
- EcoFlow. DELTA Pro 3 Portable Power Station — specifications. Manufacturer spec · accessed 5 September 2026
- StorageReview. Bluetti Elite 200 V2 Review. Independent lab test · accessed 5 September 2026
- StorageReview. Bluetti AC70 and AC2A Portable Power Station Review. Independent lab test · accessed 5 September 2026
- OutdoorGearLab. Jackery SolarSaga 100 W panel — measured output. Independent lab test · accessed 5 September 2026