What Are the Ways to Charge a Leisure Battery When Driving?

In this context, “charging while driving” doesn’t just mean when the vehicle is moving, it refers to any time the engine is running and the alternator is generating power. This includes idling as well as driving.

To safely charge a leisure battery from your vehicle, a dedicated device is required to manage the power coming from the starter battery and alternator. There are two main ways to do this:

• DC-DC Charger (Battery-to-Battery):
  The modern, all-in-one solution. A DC-DC charger regulates and boosts the alternator’s output to deliver a controlled, multi-stage charge tailored to your battery type, whether that’s Lead-acid, AGM, Gel, or Lithium.
  It works with both older and modern vehicles, including those with smart alternators and stop-start systems, making it the most versatile and future-proof option.
   
• Split Charge Relay:
  A simpler, older method that links the starter and leisure batteries together when the engine is running. This allows power to pass through, but without any regulation or control.
  Split charge relays are generally suited to older (typically pre-2015) vehicles with traditional alternators and standard wet lead-acid batteries. They are less effective with modern charging systems and not suitable for Lithium batteries.