Can a 2000-watt generator run a circular saw?

Sometimes, but it depends on the saw’s startup surge and how hard the tool is working. A smaller generator may run a circular saw under light conditions, but thicker cuts or added loads can push it past its limit.

Can a portable generator run a table saw?

Yes, but table saws usually need more headroom than smaller tools. Startup surge, heavier cutting, and running multiple loads at once can quickly expose an undersized generator.

Do power tools need startup watts?

Yes. Many power tools with motors need extra wattage when they first start. That startup surge is often why a generator that looks adequate on paper still struggles in real use.

Can I run power tools and a refrigerator at the same time?

Sometimes, but you need to add both the running watts and startup surge together. This is exactly why a load calculator matters before buying or connecting a generator.

Is an inverter generator enough for DIY tools?

For lighter DIY use, battery chargers, and some smaller tools, yes. For heavier saws, air compressors, or multiple simultaneous loads, a larger conventional or higher-output generator is often the better fit.

Why is my generator running but not powering my house?

This usually means your generator is not connected to your electrical panel. Running extension cords only powers individual appliances, not your home circuits. A proper setup requires an inlet box and interlock or transfer switch.

Do I need to turn off the main breaker when using a generator?

Yes. The main breaker must be turned off before turning on your generator breaker. This prevents backfeeding electricity into the grid, which is dangerous and illegal in most areas.

Battery Run Time Calculator

Estimate how long your battery will last based on voltage, amp-hours, load in watts, inverter efficiency, and depth of discharge. This is one of the fastest ways to estimate backup battery runtime during a power outage.

12V / 24V / 48V Lead-acid or LiFePO4 Runtime in hours + minutes Usable watt-hours shown

Enter Your Battery and Load

Battery Voltage

Most small backup batteries are 12V. Larger systems may be 24V or 48V.

Battery Capacity (Amp-Hours)

Example: 100Ah battery.

Load (Watts)

Enter the device or combined load you want to power.

Inverter Efficiency

Use 90% as a realistic starting point for many inverter setups.

Depth of Discharge

LiFePO4 often uses higher discharge. Lead-acid is commonly limited to around 50%.

Battery Type Preset

Presets auto-adjust inverter efficiency and depth of discharge.

Quick Load Examples

 Battery watt-hours = Volts × Amp-hours
 Usable watt-hours = Battery watt-hours × Inverter efficiency × Depth of discharge
 Estimated runtime = Usable watt-hours ÷ Load watts

This calculator gives an estimate. Real-world runtime can be lower due to startup surges, inverter losses, battery age, temperature, discharge curve, and manufacturer limits.

Your Estimated Runtime

Estimated Runtime

8h 38m

8.64 hours total runtime

Usable Energy

864 Wh

Total battery energy: 1200 Wh before losses and discharge limits

Setup Summary

12V × 100Ah ÷ 100W

Using 90% inverter efficiency and 80% depth of discharge

What This Runtime Really Means

Good for short backup use

This runtime is usually enough for brief outages or light essential loads, but may not be enough for overnight use or repeated outages without recharging.

Common Battery Runtime Examples

Battery	Load	Rough Runtime
12V 100Ah	100W	~8 to 9 hours
12V 100Ah	600W	~1.4 hours
12V 200Ah	100W	~17 hours
24V 100Ah	300W	~5.8 hours

Important Notes

Square footage does not determine battery runtime. Your actual load does.
Motor-driven devices like refrigerators and pumps often have startup surges.
Lead-acid batteries should usually not be drained as deeply as LiFePO4.
For outage planning, always leave yourself margin instead of sizing too tightly.
If you need to run major household loads, a generator or larger battery system may make more sense.

Battery vs Generator Runtime Reality

Batteries store a fixed amount of energy. Once that energy is used, the system must be recharged before it can provide power again.

Generators work differently. As long as you have fuel, you can continue running them for extended periods.

Batteries: Quiet, clean, but limited runtime
Generators: Longer runtime, refuelable, better for extended outages

If your runtime estimate is shorter than expected, you may need a larger battery system — or consider a generator for longer outages.

Planning a Bigger Backup Power Setup?

Compare generators, battery backup options, and home backup gear to find the right fit for your outage plan.

Compare Backup Power Options