Your trip
Describe a real day
Record the season, location, people travelling and the time you want to spend without charging. Make a second sheet for a demanding day if your use varies.
Campervan electrical planning
Plan your campervan electrics, one day at a time.
Start with what you need to power and when you use it. This manual worksheet turns that list into daily energy use, with the unknowns still visible. Then plan storage, charging and individual circuits.
Checked 11 October 2026 · 12 V DC planning · your manual wins
Start with evidence
Write down the life your van needs to support.
Your equipment
Collect numbers you can trace
Use a manual, a label or an appropriate meter. Record which one, the operating mode and any uncertainty. A maximum input rating is not necessarily typical consumption.
Your schedule
Count actual operating time
Add short uses together and convert minutes to hours. For cycling equipment, record compressor-on time or measured energy over a representative period. Include standby devices.
Your measurement
Name where the number comes from
Mark each value as appliance-side or battery-side. A battery monitor shows net flow: charging during the measurement can hide part of the load. Record charging separately.
Your daily-energy worksheet
Copy the table. Fill it with your own equipment.
Select and copy this table into a document or spreadsheet, then duplicate rows as needed. You can also print this page and fill it by hand. These cells are a blank template; they do not calculate or save entries.
For a steady draw, quantity × watts per item × operating hours = Wh. If you already have measured Wh for a whole day, use that energy directly; do not multiply it by hours again. Keep AC appliance energy separate until you know the corresponding battery draw.
On a small screen, scroll the table sideways to see every column.
| Appliance & quantity | DC / AC supply | Consumption & measurement point | Hours / day | Cycling / occasional use | Source & uncertainty | Daily Wh & accounting side |
|---|---|---|---|---|---|---|
| ________________ | ________ | ________________ | ________ | ________________ | ________________ | ________ |
| ________________ | ________ | ________________ | ________ | ________________ | ________________ | ________ |
| ________________ | ________ | ________________ | ________ | ________________ | ________________ | ________ |
| ________________ | ________ | ________________ | ________ | ________________ | ________________ | ________ |
| ________________ | ________ | ________________ | ________ | ________________ | ________________ | ________ |
Battery-side subtotal
______ Wh/day · include each load once
Still unknown
______ · leave unresolved consumption visible
Time without charging
______ days · describe the expected conditions
Charging opportunities
Driving ______ · shore ______ · solar conditions ______
Count inverter consumption once.
An AC appliance's Wh leaves out the inverter's own consumption. If you measure the inverter's DC input with the appliance running, that reading already includes conversion losses and operating overhead. Do not add the AC Wh or another loss factor to it. Record extra time with the inverter on but unloaded separately. If you only know AC Wh, leave the battery-side amount unresolved until you have suitable measurement or manufacturer data for that operating point.
Worked example
One invented day: 586 Wh at the battery.
Every number below is an invented planning assumption, not a measurement or a recommended appliance rating. Replace the values with your own evidence.
For this example, the DC watts represent each branch's draw at the battery supply, including any losses along that branch. The laptop's AC draw is shown for comparison; only the inverter's DC input enters the battery subtotal. No charging is subtracted.
| Appliance | Quantity & assumed draw | Operating time | Daily energy | Assumption to verify |
|---|---|---|---|---|
| LED lights | 4 × 3 W, DC battery-side | 4 h each | 48 Wh | All four at this draw for the stated time. |
| Ventilation fan | 1 × 15 W, DC battery-side | 6 h | 90 Wh | One assumed speed; other settings need their own figures. |
| Water pump | 1 × 48 W, DC battery-side | 15 min = 0.25 h | 12 Wh | Total on-time across all short uses. |
| Compressor fridge | 1 × 40 W while running, DC battery-side | 8 compressor-on hours in 24 h | 320 Wh | Assume no off-cycle draw here. Actual cycling and standby remain to be checked. |
| Laptop at AC outlet | 1 × 45 W, AC appliance-side | 2 h | 90 Wh AC; excluded from battery subtotal | Same laptop session as the next row, not another load. |
| Inverter powering laptop | 1 × 55 W, DC battery-side | 2 h | 110 Wh | Assumed total input while the laptop is running; includes conversion and operating overhead. |
| Inverter left on, unloaded | 1 × 6 W, DC battery-side | 1 additional hour | 6 Wh | Only idle time outside the two loaded hours; off for the rest of the day. |
| Battery-side subtotal | 48 + 90 + 12 + 320 + 110 + 6 = 586 Wh/day | |||
The inverter uses 110 Wh to deliver the assumed 90 Wh AC during that session: 20 Wh is the difference, already included in 110 Wh. Its separate idle hour adds 6 Wh. This does not establish a general inverter efficiency.
This is a subtotal for the listed equipment only. Heating controls, device charging, alarms or other loads are still unknown until listed. Fridge runtime also changes with conditions. Measure a representative day and revisit the worksheet instead of adding an unexplained percentage.
A separate power check
What might run at the same time?
Daily Wh does not size an inverter, a battery/BMS current limit, a cable or a fuse. Keep the operating and starting demands beside the daily schedule.
| Scenario | Loads running together | Running demand | Starting demand & duration | Evidence still needed |
|---|---|---|---|---|
| Example: evening | Lights, fan, fridge, laptop through inverter; pump may start. | Record battery-side demand and AC output demand separately. | Obtain pump and compressor startup data; daily hours do not describe it. | Actual ratings, inverter limits, battery/BMS limits and equipment manuals. |
| Your scenario | ________________ | ________________ | ________________ | ________________ |
Check both the continuous demand and any relevant surge with its duration against the selected equipment. An appliance's AC watts are not its DC input current; conversion and the battery's operating voltage matter. Collect those inputs before choosing an inverter or protection.
Turn the list into a plan
Make the remaining decisions in order.
Storage and operating limits
Use the desired time without charging and your daily scenarios to describe the energy requirement. Nominal Ah alone does not prove usable capacity: voltage, chemistry, discharge conditions, temperature and manufacturer limits matter. Check 12V vs 24V compatibility and battery-system compatibility before selecting a bank.
Charging opportunities
Record driving time, shore access and the location, season and shading for solar. Work out what each source can actually deliver during that window, including charging losses and equipment limits. Panel nameplate watts are not a daily yield. The DC-DC charger tool helps examine the vehicle charging path; it does not guarantee a recharge time.
Circuits, wiring and protection
Draw each charging path and load with its return. Gather actual cable lengths, routing conditions and terminal limits. Use the wire and cable tool and, for a LiFePO₄ bank, the battery fuse tool as separate checks. Confirm installation details against equipment manuals and the rules that apply to your vehicle.
Explore one state, then return to the schedule
The runtime guide explores a selected constant state. It does not integrate this daily worksheet, automatically cycle your fridge or model changing weather. Use it to compare conditions, then keep daily-energy assumptions in your own record. Read what Crimp checks before treating a drawing as a finished design.
Sources and scope
The method, and what it does not decide.
The references explain energy accounting and battery-monitor limits. The worked figures are invented arithmetic examples, not values taken from a product manual.
RenogySolar sizing: start with daily energy useThe load-list method in Step 1: power multiplied by operating hours gives energy. This guide does not adopt its example appliance ratings, battery sizes or solar-yield assumptions.Victron EnergySmartShunt: operation and time remainingSections 5.1–5.2 distinguish accumulated consumption, net battery flow and an estimate at the present load. Charging can mask consumption in a net battery reading.Victron EnergyBattery capacity and Peukert exponentRated Ah depends on discharge conditions. A nameplate capacity is not a promise of usable energy under every load.
This manual guide adds no automatic battery, inverter or solar sizing. Your output is a consumption inventory, a daily Wh subtotal with unknowns, and a list of simultaneous loads to investigate.
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