⚡ DC-DC Charger Calculator for Campervans

DC-DC Charger Size Calculator

The wrong DC-DC charger can burn your alternator (especially with Lithium). Calculate the safe charger size for your van.

OEM Alternator Rating

Alternator Type

House Battery Type

Optimal Safe Charger

0 Amps

Absolute Maximum Charger

0 A

⚠️ Lithium batteries have zero resistance. Without a properly sized DC-DC, your alternator will burn out at idle.

⚠️ Euro 6 alternators drop voltage when the starter battery is full. A "Smart" DC-DC charger is MANDATORY.

Why limit your DC-DC charger?

A vehicle alternator is not designed to run at 100% capacity for long periods, unlike a generator. If you install a Lithium battery (which offers almost zero resistance) with an oversized charger or a simple split relay, the alternator will instantly provide maximum current.

In traffic jams or at idle, the alternator's cooling fan spins slowly. As a result, it quickly overheats beyond 120°C (250°F) and melts, risking an engine fire. It is crucial to select a DC-DC charger that draws no more than 40% (ideally 25-30%) of your alternator's native capacity.

Calculate Wire Size →Back to Main Power Audit