Free
Mobile power calculator: battery vs generator
This free mobile power calculator sizes battery power units for a construction site or event, and compares fuel use with a diesel generator alone, a hybrid or a site supply.
Calculator
Size your mobile power
Your results
Estimates to guide planning, not a design.
–battery units
–fuel saved vs a generator alone
–kWh used per day
–kWh usable battery energy needed
–kW battery output needed
–generator hours per day
Fuel over the project
| Option | Litres | Fuel cost |
|---|
Assumptions and disclaimer. Results are planning estimates, not a design. Example figures, including fuel use per kWh and diesel price, are illustrative: use your generator's fuel curve and current prices. Battery energy includes a 20% margin; battery output includes 10% headroom, but motors and other inrush loads can need more, so check start-up currents. The hybrid assumes the generator runs during working hours at about 80% load and the battery covers the rest, with 10% battery losses. Off-site recharging assumes units are swapped each day. The comparison covers fuel only, not hire, transport, maintenance or emissions rules.
How to use it
Getting reliable results
Get the inputs right
Log real loads on a similar site if you can
Separate working-hours loads from overnight loads
Check start-up currents for motors and pumps
Use your generator's actual fuel curve
Reading the results
Units are sized for both energy and output
The hybrid runs the generator only when it is efficient
Fuel savings exclude hire and transport costs
Amber messages show where to look harder
Questions
Frequently asked questions
How do you size a battery for a construction site?
Work out the peak power and the daily energy from working-hours and overnight loads, then choose units that cover both with a margin, and plan how they will be recharged.
Is a battery cheaper to run than a diesel generator?
Often on fuel, because a generator sized for the peak burns more fuel per kWh at light load. Compare hire, transport and fuel together for your site.
What is a hybrid mobile power system?
A battery paired with a smaller generator that runs at an efficient load to recharge it, while the battery handles light and overnight loads quietly.
Can battery units run cranes or welders?
Large motors and welders draw high start-up currents. Check the unit's output and surge rating against the load, or use a hybrid.
How are battery units recharged on site?
From a site or temporary grid supply, from a generator in a hybrid, or by swapping units with ones recharged elsewhere.
Is the result a design?
No. It is a planning estimate. Logged loads, start-up currents and supplier specifications are needed for a design.
Further reading
Mobile power insights
Insight
Mobile BESS explained
What it does and what drives its cost.
Learn more
Insight
Battery power units vs diesel generators
Where each one wins on site.
Learn more
Insight
Temporary power supply
Options for construction sites and events.
Learn more
Insight
Battery power for events
Sizing and planning.
Learn more
Talk to us about mobile power
Send us your results and we will tell you plainly which mix of batteries, generators and grid supply fits your site.