I killed my campervan battery on night one. So I built a power calculator.

The first night in the van, I ran the fridge, charged a laptop, and left a light on. By 11pm the battery was dead and my phone was at 2%. I'd "estimated" my power needs the way you estimate how much pizza to order — vaguely, and wrong.

Turns out off-grid power isn't that complicated, it's just unforgiving if you guess. You need to know how many watts each thing pulls, for how many hours a day, and then size a battery and solar to cover it with some margin. The math is simple; doing it in your head at a campsite is not.

So I built CampPowerCalc. You tell it the appliances you actually run — fan, fridge, laptop, lights, water pump — and roughly how long each runs, and it works out the watt-hours, then sizes the battery and solar you'd want for vanlife, RV, or just a weekend off-grid. It uses real appliance draw data and straight physics, no "trust me bro" fudge factors.

The thing I like is it shows the gap. My first plan was way under-sized; seeing the number made me buy one bigger battery instead of discovering the shortfall at 2am in the woods. Different setups need different answers, so treat the result as a solid starting point and sanity-check it against your own gear — but it beats guessing and eating cold food.

If you're planning any off-grid power, it's here: https://camppowercalc.com