Smart altternator battery to battery charger

[Bray]

I want too install a battery to battery charger to my fiat Ducato 2020 motorhome ,the only problem I am having is connecting the negative on the engine battery ,because it has a smart alternator there is a sensor box with two small wire coming off it directly on negative post .tThe wire that come off this box goes directly to chassis. My question is which side of this sensor box do I connect my battery to battery smart charger

[arthur49]

Bray - 2021-01-28 8:53 PM

 

I want too install a battery to battery charger to my fiat Ducato 2020 motorhome ,the only problem I am having is connecting the negative on the engine battery ,because it has a smart alternator there is a sensor box with two small wire coming off it directly on negative post .tThe wire that come off this box goes directly to chassis. My question is which side of this sensor box do I connect my battery to battery smart charger

What is the make and model of your motorhome? As it has a smart alternator I would have thought it was already fitted with a B2B?

[Derek Uzzell]

In mid-2019 Robert evidently owned a Benimar Mileo 286

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Charger-benimar-286/51987/#M606394

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Split-charge-relay-clicking/52024/

 

https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/Accelerate-fault/53369/

 

but, as Robert frequently changes his motorhome, that may well no longer be so.

 

It is certainly the case that recent Euro 6 motorhomes that have a ‘smart’ alternator tend to (should) be factory-fitted with a battery-to-battery (B2B) unit.

 

For example, this Elddis manual for the current Autoquest range

 

https://elddis.co.uk/uploads/handbooks/2021/Autoquest%20MH%202021_APPROVED.pdf

 

indicates that BCA-made electrical equipmant is used, plus (when there’s a smart alternator) a Schaudt WA 121525 “Booster” B2B unit.

 

https://www.ivt-hirschau.de/media/920003_Anleitung_WA121525_EN.pdf

[Bray]

It a Elddis GT. 20 year 2020 there is not one fitted or is not working , will have a look to see if I can find it. I must admit we have not been able to travel far to test it with the lockdown.

[mikefitz]

If the B to B charger has a common negative then the negative connection of the B to B charger can be to the van body/chassis or the wherever the leisure battery has its negative connection. On most motor homes the engine battery and leisure battery have a common negative that at some point will be connected to the van body/chassis. Since the optimum installation of the B to B charger is near the leisure batteries, there should be a suitable negative connection point nearby.

 

If a connection to negative near the vehicle battery is required for a B to B charger with isolated outputs there should be a connection point near to the engine battery via the van metal. The engine battery will always have the negative connected to the chassis /body. The additional unit fitted on the euro 6 van at the negative post is associated with battery 'condition' monitoring by the van electronics.

 

Since you have smart alternator the B to B may need a control signal ( depends on model) using 'key on' or 'D+'.

 

What model of B to B are you fitting? Is there any existing charging from engine battery to leisure battery?

 

Your vehicle may have the 'converters' option connection point at the base of the drivers B pillar. A fused 50A connection to the engine battery and 'key on' and 'D+' are available at this point.

 

Mike

[Derek Uzzell]

If the latest Elddis owner manual is to be believed, if one of their motorhomes has a ' smart' alternator the motorhome should also have a factory-fitted Schaudt B3B. Conversely, if there is no factory-fitted B2B, logically the vehicle does not have a smart alternator.

 

So the first thing for Robert to be sure of is whether his Elddis does indeed have a smart alternator and, if so, whether there is a Schaudt B2B to match.

[Bray]

I have found the Schaudt unit it was fitted down the side of the control panel /fuse box the only way I could get to it was take the top of cupboard off ,and unscrew it off wall with stubby screw driver.On checking settings it was set to having a temperature sensor fitted ,but it does not have one.I have changed the settings to what it should be, hopefully it will now work Thanks all for the advise

[Derek Uzzell]

A word in the ear of the vendor of your Elddis motorhome about this would be appropriate, particularly as there’s a fair chance that other recent Elddis models with a smart alternator will have the temperature-sensor option of their Schaudt Booster WA 121525 wrongly set. I note that the Schaudt advises

 

If the selector switch for the temperature sensor is in Position ”with” without a temperature sensor connected, the booster has no effect be- cause the output voltage in this case does not exceed 7.5 V.

This means the leisure area battery is no longer charged.

 

I also noticed the following guidance in the Elddis Manual

 

AUTOMATIC CHARGING SYSTEM

The battery charger will operate automatically when the motorhome is connected to the mains outlet on a motorhome site.

Note: The charging unit only charges the leisure battery not the vehicle battery.

When the motorhome engine is running the 12V system will not operate with the exception of the 12V refrigerator.

 

which is a decidedly unwelcome and technically retrograde approach.