Off-Grid Days Calculator (Campervan)
Estimate how many days you can stay off-grid using your battery size, solar watts, daily Wh and weather. Summer vs winter results in seconds.
AGM vs LiFePO₄ — why do days change?
AGM is comfortable at ~50% depth of discharge; LiFePO₄ around ~80%. More **usable Wh** = more days before recharge, all else equal.
What counts as “solar-positive”?
When daily solar ≈ **≥ your daily Wh use**. In that case you’re limited by **bad weather streaks**, not battery size. Expect winter to be much tougher.
I don’t know my daily Wh/day — how do I estimate it?
List devices × hours × watts (fridge, lights, fans, laptop) and add **10–20%** margin. You can refine after a week of real measurements.
Why are winter results so low?
Short days, low sun angle and clouds slash production. Many vans need **driving, hook-ups or bigger banks** to survive winter off-grid.
Does driving help?
Yes. Alternator charging (ideally via **DC-DC**) can top up on transit days. Add that to your routine if winter shows only 1–2 days.