Two problems, not one
Almost every oversized food truck generator comes from adding these together when they never happen at the same time.
The overnight problem. Refrigeration and freezing, from close to open. Modest continuous draw — a couple of hundred watts averaged — for twelve to sixteen hours. This is an energy problem.
The service problem. Cooking, hot holding, coffee, lighting and the till, for four to eight hours. Large, spiky draw. This is a power problem.
A battery is good at the first and bad at the second. A generator is good at the second and a wasteful, noisy way to solve the first. A lot of successful operations own both.
Where the watts actually go
| Equipment | Running watts | Notes |
|---|
| Commercial refrigerator | 300-800 W while the compressor runs | Cycles; large starting surge |
|---|
| Chest freezer | 150-400 W cycling | Holds temperature well when closed |
|---|
| Electric griddle or fryer | 1,800-5,000 W | Continuous, resistive — the load that sets the generator |
|---|
| Espresso machine | 1,200-2,400 W in bursts | Heavy cycling; hard on small machines |
|---|
| Hot holding cabinet | 800-1,500 W | Continuous during service |
|---|
| Exhaust hood fan | 200-600 W | Runs whenever cooking does |
|---|
| LED lighting, POS, card reader | Under 200 W together | Trivial, and the last thing you should lose |
|---|
Ranges are typical for light commercial equipment. Your own plates are authoritative — reading a nameplate properly explains what the numbers promise and what they do not.
The pattern is clear: anything that makes heat electrically dominates everything else. Which leads directly to the most useful decision on this page.
Cook with propane, not electricity
Almost every successful mobile operation cooks on propane and uses electricity only for refrigeration, lighting, water and the till.
The reason is arithmetic. A propane griddle costs you a cylinder. An electric one costs you three to five kilowatts continuously, which roughly doubles the generator you need, the fuel you burn and the noise you make.
If you are specifying a build, this is the decision with the largest downstream effect on your power system. The propane generator page covers the case for running the generator on the same fuel.
Rules that will decide this for you
Unlike every other scenario on this site, the constraints here are mostly other people's.
- Event and market rules. Many festivals, farmers markets and stadium lots cap generator noise or ban generators entirely, sometimes in favor of supplied power at a fee. Ask before you book.
- Health department requirements. Refrigeration must hold temperature continuously, which means an outage is a compliance problem as well as an inventory one. A logging thermometer is cheap evidence.
- Fire code on fuel storage. Quantities of gasoline and propane carried on a vehicle are regulated, and the limits are lower than people assume.
- Carbon monoxide. A generator on a truck sits close to a serving window and to the people working inside. The CO safety page matters more here than almost anywhere, and a CO alarm inside the truck is not optional.
The overnight arithmetic
Using a refrigerator and freezer averaging 300W combined, across sixteen hours from close to open.
| Battery | Hours at 300 W |
|---|
| 2,048 Wh | About 5.8 hours |
|---|
| 3,024 Wh | About 8.6 hours |
|---|
| 4,096 Wh | About 11.6 hours |
|---|
| 4,096 Wh plus one expansion | Comfortably overnight |
|---|
Calculated as capacity x 0.85 / 300 W. Real draw depends on ambient temperature and how often doors open — a parked truck in summer is the worst case.
The failure that costs the most
Not the generator, which you will notice. It is refrigeration failing overnight, unattended, in a parked truck — discovered at open, with a full inventory to throw away and a shift already booked.
Two cheap defenses. A wireless temperature alarm that pushes to a phone, and a second, independent power path for the refrigerator so a single failure does not take it out. The battery-plus-generator pairing above gives you that naturally.
The short version
- Cook with propane. It halves the power system.
- Size the generator for service, the battery for overnight. They are different problems.
- Check event rules before you book. Noise limits and bans are common and increasing.
- Alarm the refrigeration. The expensive failure is the one nobody is there to see.
