Category ELECTRICAL

Camper van and RV electrical systems explained with real numbers: inverters, wire sizing, voltage drop and the faults that get blamed on the wrong component. Written from installations I’ve built and broken.

ELECTRICAL

Camper Van Hot Water: I Spent €1,000 and Got 20 Seconds

The shower it was all for. A €1,000 system feeding it, and in practice I used a kettle and a basin far more often.

Every guide to hot water in a van says the same thing about engine heat exchangers. Free hot water. Zero running cost. Uses waste heat you’re producing anyway. If you drive before you park, it’s the obvious answer. I paid…

gustavo Moré Sica
August 20, 2026

ELECTRICAL

Diesel Heater Power Consumption: The Startup Is Not One Spike

Vevor 8kW diesel heater installed beside a 150Ah AGM battery in a motorhome

If you go looking for how many amps a diesel heater draws, you’ll find numbers that don’t agree with each other. Eight to ten amps on startup, says one source. Seventeen or eighteen, says another. One to one and a…

ELECTRICAL

Your Power Calculations Are Wrong. Here’s by How Much

Inverter display showing real power draw in a camper van

Every van build starts the same way. You list your appliances, you add up the watts, you divide by 12, you multiply by the hours, and you get a number. Then you buy a battery slightly bigger than that number…

ELECTRICAL, solar-climate

MPPT vs PWM: Everyone Says PWM Is Fine for Small Systems. I Ran One.

The consensus on this is settled and it goes like this: PWM controllers are fine for small systems. Under about 150 watts of panel, on lead-acid batteries, save the money and spend it on something else. That advice is well…

BATTERIES, ELECTRICAL

Camper Battery Draining Overnight? How to Find the Parasitic Draw

Multimeter measuring parasitic battery drain in a camper van

You go to bed with a charged battery. You wake up and it’s low, and nothing was switched on. Two completely different problems produce that, and they look identical from the outside. One is something quietly drawing current all night.…

ELECTRICAL, solar-climate

12V Fridge Power Consumption: Why the Wattage Isn’t the Number That Matters

Almost every article on this answers the wrong question. They tell you a 12 V compressor fridge draws 30 to 60 watts. That’s true, and it’s nearly useless on its own — because that figure barely changes. A fridge in…

BATTERIES, ELECTRICAL

AGM vs Lithium in a Camper Van: What the Difference Actually Looks Like

Two batteries labeled “100 Ah” can behave so differently that comparing them by that number is close to meaningless. One of them will give you 50 amp-hours before you should stop. The other gives 90. One will feed a 1,000…

ELECTRICAL, solar-climate

Why Does My Inverter Keep Shutting Off? 7 Causes and How to Fix Each One

If your inverter keeps shutting off, it’s almost never broken. In most cases it’s doing exactly what it should: protecting itself because something in the installation isn’t giving it what it needs. Which means replacing it won’t help. What helps…

ELECTRICAL

Undersized Wire in a 12V System: The Symptoms and a 10-Minute Test

Initial messy wiring of the electrical panel in a 2005 camper van conversion, before cleanup

Undersized wire is the most expensive fault in a 12 V system, because it rarely gets blamed. Everything works at first. Then the inverter starts cutting out, the fridge cycles strangely, and the battery seems to be dying — so…

ELECTRICAL

Wire Gauge Calculator for 12V Systems: AWG by Amps and Cable

12V cable of different cross sections for a camper installation

Undersized wire is the most expensive mistake in a 12 V build, and the hardest to spot. Everything works at first. Then the fridge starts cycling oddly, the inverter reports a low battery that isn’t low, and you end up…