Spaziou tools · Energy

Battery runtime for your setup.

Enter battery capacity and daily consumption to estimate days without recharging. The calculation deducts the unusable fraction and system losses.

LiFePO4 batteries for campers
Runtime depends on usable energy, daily consumption and the battery fraction you can actually use.

Nominal capacity differs from usable capacity.

A 200 Ah battery at 12.8 V stores 2,560 Wh nominally. Do not design on the assumption that every Wh is always available: depth of discharge, inverter, wiring, temperature and BMS can reduce usable energy.

Continue the calculation.

If you do not yet know your daily use, start with the energy consumption calculator. Then check the required solar power.

Runtime reference

Enter usable capacity and losses because available energy is not a universal constant. Temperature, battery chemistry, BMS and discharge current affect the actual result.

Victron · official example of nominal capacity, Wh and temperature effect ↗

Method · Example · Decisions

Calculate usable runtime and compare options

Time without recharging depends on usable energy and demand, not just the Ah printed on the battery.

Formula used by this tool

Nominal energy = Ah × V. Usable energy = nominal energy × usable fraction × efficiency × (1 − reserve). Runtime = usable Wh ÷ daily Wh.

Reproducible example

At 200 Ah and 12.8 V, with 80% usable capacity, 90% efficiency and a further 10% reserve, estimated usable energy is 1,659 Wh. At 600 Wh/day, that gives 2.8 theoretical days without recharging.

Avoid double-counting reserves

The usable fraction limits how much capacity you choose to draw. Efficiency accounts for losses and the additional reserve sets aside a further fraction. Do not unintentionally apply the same reserve in several fields. Choose values that match your equipment and use.

Turn calculated days into a practical plan

The result assumes constant daily use and no recharging. Solar, alternator and external charging are not automatically included, nor are battery ageing or temperature measured. If winter consumption is higher, enter that scenario and compare.

Larger battery or better charging?

A larger battery adds reserve; a charging source replenishes energy. If the deficit repeats each day, adding capacity only delays depletion. Check daily balance with solar and charging while driving before choosing components.

Manufacturer's data on nominal capacity and operating conditions →

Portable Power · ALLPOWERS

Compare capacity before buying

Advertised capacity is nominal. Inverter losses, standby draw and starting surges affect actual runtime. These models are not automatic recommendations from your calculation.

Browse the official ALLPOWERS store ↗View Spaziou's ALLPOWERS selection →
Affiliate links: Spaziou may earn a commission on qualifying purchases at no extra cost to you. Check European version, accessories, price and availability in the store. Selection is based on specifications, not hands-on testing.