Autonomy on the road: how to calculate the charging station needs for a multi-day car trip
The expert selecting a charging station for an overnight trip starts with the device’s daily power consumption in watt-hours, and checks the wattage as the second step. Watts answer the question of what can be done simultaneously, while watt-hours determine whether the energy reserve will last until the next charging opportunity. On a trip without guaranteed access to electricity overnight, the second figure is decisive.
Daily Consumption: The Starting Point for Choosing a Station
At home, the difference between these values isn’t noticeable: the grid recharges the battery every night, and it’s sufficient as long as the device turns on. On a trip, energy becomes a resource with strictly limited capacity, so calculations are based on the length of the journey in days.
The wattage of each device is multiplied by the number of hours it operates on a typical day.
The obtained values are summed and a margin for conversion losses is added: some energy is lost in the inverter and charging circuits.
The figures are taken from the device’s specifications sheet or its power supply, as estimating battery capacity in such calculations results in errors of several dozen percent.
Here’s what it looks like for a family traveling for a few days with an automotive refrigerator, a laptop for navigation and work tasks, phones, and a camera:
:
Device
Power consumption
Hours of operation per day
Daily energy usage
Car compressor refrigerator
about 45 W when the compressor is running
~10 (compressor turns on in cycles)
~450 W·h
Laptop
60 W
5
300 W·h
Two smartphones
20 W
3
60 W·h
Camera with charger
30 W
2
60 W·h
The amount is around 870 watts per day, and this is a verified figure from which it makes sense to move on to the specific model’s specifications. The Fossibot F3600 Pro claims a base capacity of 3840 watt-hours and a sustained power output of 3600 watts; the full list of specifications can be found at
motostuff.com.ua/products/fossibot-f3600-pro-zaryadnaya-stantsiya,
and it’s convenient to compare your own figures with these before setting out. It’s not possible to guarantee an exact number of days of autonomy based on such calculations: heat in the trunk, cold nights, and conversion losses all reduce the actual result, so it’s wise to consider the calculated figure as an upper limit.
Multi-day trip: where the base capacity runs out
For weekend trips where the vehicle can provide charging en route, the battery capacity is sufficient for almost any set of equipment. An endurance of several days changes the entire scenario: the question shifts from “is it enough?” to “how many days will it last?” and the answer depends on whether it’s possible to increase the capacity. The F3600 Pro allows its capacity to be expanded with two additional battery modules, raising it to 11520 Wh from the base 3840 Wh. In practical terms, with these modules, the total energy capacity reaches 11520 Wh without the need to purchase a separate power station, and the decision to add modules must be made before departure—there’s no way to acquire them once on the road.
Sustained power operates on a different level—it is limited to one minute. It’s not advisable to plan for loads of up to 3600 watts: compressors, pumps, and high-power chargers have starting currents that are many times higher than their rated values, so a short-term surge needs somewhere to go. The peak value, which only lasts for a fraction of a second, is unsuitable for planning; sustained power, with a deliberate safety margin, remains the key figure.
It’s easier to compare equipment for a specific route even before setting out. MotoStuff’s website gathers selected models from reputable manufacturers and helps with selection without getting lost among hundreds of brands.
Cables and connectors: where calculations usually go awry
The shape of the connector does not indicate anything about whether the device will receive the necessary power: port types and power protocols vary, and the same USB-C port is designed for different output levels across different devices. The F3600 Pro’s output options include AC outlets, USB-C, USB-A, car outlet, XT60, and DC5521 — each suited for its specific class of equipment. The practical check involves listing all the devices in the route and noting next to each item the port type required, the appropriate cable, and the connection priority in cases where simultaneous power supply is limited. Forgetting a converter at home invalidates any capacity calculations.
The vehicle outlet deserves special attention. It is designed for power supply and charging through the standard onboard circuit, meaning moderate currents, whereas starting the engine requires entirely different currents and relies on separate starter devices. A portable power station does not serve this purpose, so planning a trip with the assumption that “I can start it using this if the battery dies” is a mistake that will manifest at the most inconvenient moment.
For the F3600 Pro, check the connectors, allowable input power, and charging options
in
The official model specifications,
and
do not choose cables based solely on port shape. This helps assemble a suitable kit for the trip according to the device’s actual specifications.
Calculating costs and checking ports addresses the energy issue, but a station on the go has another aspect—it needs to be transported somewhere. Space in the trunk, securing it against movement on rough roads, and interior temperature in summer or extreme cold affect the actual performance of the storage capacity just as much as arithmetic calculations, and this issue is resolved in the same way: ahead of time, with a tape measure and a list in hand, while the trunk is still empty.