Where to locate my D+ signal

[ForeignShaws]

I've just purchased a Renogy Dcc charger to improve my leisure battery charging whilst on the move. The instructions indicate that, with a smart alternator, the D+ signal input on the charger should be connected to the alternator signal.
I have a 2021 Auto-Trail on a Ducato, so I'm assuming that this applies to my install, but is there a more convenient location to pick up this signal than going back to the alternator? Alternatively, can I just use the switched 12v supply to the fridge instead or is D+ something more than just an engine running switched 12v feed.

 

[Lenny HB]

There should be a D+ connection on the fridge you could tap into. Not sure how Sargent electrics do but there is probably a relay box the D+ gets distributed from.

 

[Two on Tour]

I've just purchased a Renogy Dcc charger to improve my leisure battery charging whilst on the move. The instructions indicate that, with a smart alternator, the D+ signal input on the charger should be connected to the alternator signal.
I have a 2021 Auto-Trail on a Ducato, so I'm assuming that this applies to my install, but is there a more convenient location to pick up this signal than going back to the alternator? Alternatively, can I just use the switched 12v supply to the fridge instead or is D+ something more than just an engine running switched 12v feed.

If you're struggling to find where you can tap into a D+ signal, then the easy option might be to use a D+ simulator which senses the vibration of the engine running.

Voltronic D+ simulator

 

[LithiumConvert]

or is D+ something more than just an engine running switched 12v feed.

No, it is nothing more than an engine running switched 12v feed.

 

[Carolyn and Kev]

Found this out from a very Knowledgeable gentleman on here who helped me with a similar issue. The D+ is actually for systems that do not have a Voltage Sensitive Relay. Apparently it is a low current 12 volt feed from the alternator switching on and off relays to suit. Therefore albeit 12v..its a low current feed only .

Kev

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[Lenny HB]

Found this out from a very Knowledgeable gentleman on here who helped me with a similar issue. The D+ is actually for systems that do not have a Voltage Sensitive Relay. Apparently it is a low current 12 volt feed from the alternator switching on and off relays to suit. Therefore albeit 12v..its a low current feed only .

Kev

Not quite as simple as that, it is a low current 12v feed direct from the alternator it is not designed to switch loads of relays. Motorhomes often have quite a few things switched by a D+ signal so they fit special relay boxes or simulators so as not to overload the D+ output from the alternator.

 

[jwells]

What model Autotrail do you have, it may have a split charge relay that will need to be isolated as well!

 

[RioRob]

There should be a D+ connection on the fridge you could tap into. Not sure how Sargent electrics do but there is probably a relay box the D+ gets distributed from.

There is a fused power distribution box i.e. the Sargent ec40 which is located behind the drivers seat. It provides a connection from the vehicle battery to the leisure battery system and has D+ switched circuits for the fridge as well as a D+ "booster".

 

[autorouter]

There will be an existing arrangement to charge your leisure battery. Either a split charge relay or a small DC-DC charger. Whatever it is, it is very likely turned on and off by a D+ signal. So the D+ signal will be present at the distribution box, or at the existing DC-DC charger if there is one. There should be no need to go all the way back to the alternator.

If the existing arrangement is a split charge relay then as jwells says it needs to be disabled, if not it will simply short the DC-DC charger input and output, so it does nothing. If the existing arrangement is another DC-DC charger, then that probably needs to be disabled too, but may be OK to leave it connected.

 

[Tombola]

I've just purchased a Renogy Dcc charger to improve my leisure battery charging whilst on the move. The instructions indicate that, with a smart alternator, the D+ signal input on the charger should be connected to the alternator signal.
I have a 2021 Auto-Trail on a Ducato, so I'm assuming that this applies to my install, but is there a more convenient location to pick up this signal than going back to the alternator? Alternatively, can I just use the switched 12v supply to the fridge instead or is D+ something more than just an engine running switched 12v feed.

make sure you do have a smart alternator, some autotrail requested non smart but none sure what date up to.
Mine was 2020 and was none smart, an autotrial imala

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[autorouter]

I've just purchased a Renogy Dcc charger to improve my leisure battery charging whilst on the move. The instructions indicate that, with a smart alternator, the D+ signal input on the charger should be connected to the alternator signal.

The D+ signal can be used to trigger the DC-DC charger, whether the alternator is smart or non-smart. It's the best and most reliable method of triggering. If it's a non-smart alternator you can get away with a voltage-sensitive trigger mechanism, but that doesn't work for a smart alternator because the voltage varies too much.

Since the D+ is already used in motorhomes to switch on the fridge while driving, and the existing DC-DC charger or split charge relay if there is one, then it shouldn't be a big deal to find a wire with the D+ signal on it.

 

[Barti Ddu]

I've got a 2021 Autotrail based on a Ducato. It has a standard (not smart) alternator and a Sargent split charge rather than a B2B.

I've recently fitted a Victron B2B. I removed the cab battery fuse in the main Sargent control unit to disable the original split charger. I anticipated having to connect to the D+ signal, but tried it first without using the Victron auto-engine sensing and it works a dream.

As soon as the engine starts the alternator puts out a steady 14v, and the B2B fires up a few seconds later. The alternator puts out 14v irrespective of idling, braking, accelerating. The joys of a non-smart alternator!

I don't know if the Renology B2B has engine sensing, but if it does give it a try.

 

[Carolyn and Kev]

Not quite as simple as that, it is a low current 12v feed direct from the alternator it is not designed to switch loads of relays. Motorhomes often have quite a few things switched by a D+ signal so they fit special relay boxes or simulators so as not to overload the D+ output from the alternator.

Think you need to read it again Lenny? I stated it is a low current wire only. Did not state it will operate anything other than a low current appliance by that a relay or fuse board feed for a particular circuit. May just be the way you read it or it could be the way i may have put it possibly?

 

[HarryML7]

If it helps this articles describes the convertors socket and d signal.

Converter's socket - MisterG

The Peugeot Boxer, Citroen Relay and Fiat Ducato can be equipped with an option for a “Conversion Interface” or Converter’s socket. Fiat: “Electrical Interface Supply Socket (For Conversions)” option 081 Peugeot: “Electrical connections interface box / Includes reinforced alternator” option JI01...

misterg.org.uk