D= signal interruption

[Baileyme]

Advise pls.

Plan was/is to interrupt the D+ split charge with a normally closed 5 pin auto relay. However does anyone know if this is direct from the alternator, or in anyway connected to the ECU or other modules? (2017 Boxer based Bailey)

My concern is that as it's not a resistive/diode type relay and I'm wondering about potential surge/damage.

 

[autorouter]

Plan was/is to interrupt the D+ split charge with a normally closed 5 pin auto relay. However does anyone know if this is direct from the alternator, or in anyway connected to the ECU or other modules? (2017 Boxer based Bailey)

My concern is that as it's not a resistive/diode type relay and I'm wondering about potential surge/damage.

Are you referring to the snubber diode that is often wired across the terminals of the relay coil? This dissipates the spike that happens when the coil is turned off. You could easily add such a diode to an existing relay, but usually nobody does this for motorhome wiring, it doesn't seem to cause any problems. The relay is usually quite a long way from any ECUs, so there isn't the same problem that you get when relays are crowded together on a small circuit board.

If you want to wire in a diode, it has to be the correct way round, current only flows one way through a diode. Wire it so that current doesn't flow when it's normally connected. When the relay turns off, the reverse voltage spike is shorted by the diode.

 

[Baileyme]

Thanks for the reply. Just to be on the safe side I've purchased a micro replay which has a built in diode , I'll use that instead.

 

[Lenny HB]

I always fit or buy relays with diodes just to make sure there are no problems.
In most conversions the converter uses a relay distribution box for the D+ as so many items use the D+ for triggering in a modern van, it is done so as not to overload the D+ output of the alternator. It is best to make your additional connection via this box.