T6 EURO 5/6 Regenerative Brake Energy & Camper Leisure Systems

Intelligent Digital Battery to Battery Charger

Conventional voltage sensing relays

This will be of interest to T6 owners who have opted for the Euro5/6 Blue Motion engines.

In order to achieve both EURO5/6 emission requirements and greater economy, VW have developed a brake energy regeneration system. The way it works is that  under normal driving and steady throttle conditions, the intelligent alternator developed for this system reduces it’s output (voltage) to reduce load on the engine and in turn reduce emissions and decrease fuel consumption. Under braking or coasting, the alternator output is increased by the on-board systems to a much higher voltage (15-18v) than conventional alternator charging systems (13-14v) – a bit like KERS on an F1 engine. Clever stuff!

In a normal camper split charge leisure set up, a simple voltage sensing changeover relay is fitted. This relay will switch the alternator charging voltage to the leisure battery when the main van battery is fully charged. The problem with fitting this type of device on a van with regenerative energy recovery is that the voltage from the alternator will modulate (go up and down) according to the driving style. So for example around town or in traffic where there is lots of acceleration and braking the fluctuation will be frequent. This would mean that a conventional split charge relay would be witching over very frequently. This is not good for either the relay or the leisure type of battery. The opposite is true on long motorway journeys under steady throttle. The alternator is virtually switched off all of the time so the leisure battery would receive little or no charge on the journey.

There is a secondary issue caused by the higher DC charging voltage from the intelligent alternator. This can affect/damage the fixed and any connected DC leisure equipment.

So what is the solution? One solution is to fit an intelligent digital battery to battery charge controller. There are only a few on the market but there are likely to be a few more as vehicle manufacturers adopt regenerative charging systems to meet the Euro 5/6 emissions.

Blue Sky have successfully fitted these devices and can advise you on requirements.

Please contact us to find out more using the contact form or by telephone/email if you prefer.