2017 Fiat Ducato Alternator Output

[xsilvergs]

This post is for info only

Just back from the Motorhomer Straford-Upon-Avon and Hereford Camping weekends, a great time so thanks to all.

Over this weekend, one of the many subjects talked about raised the question of smart alternators. I have always thought my alternator to have a low output and slow to charge the AGM battery, there are a number of factors that can be attributed to that but they are not the subject of this post. It is to show alternator output.

The image below is data from a BMV-712 connected to the Starter Battery and shows the terminal voltage whilst driving from Hereford to Dorset, the route covered 'A' roads until the M5 and M4 followed by the remainder to home on 'A' roads again.

The maximum peak voltage recorded was 14.25 volts, the minimum peak, 13.64 volts.

The Leisure Battery voltage can be seen in the image below. The large step change at 15:45 is when the solar was reconnected at home (solar off while driving to show charge from alternator only). Prior to starting the LB was at 70% SOC and at the end of the journey ~4.5 hr journey it had achieved about 95% SOC.

Make up your own mind the to the type of alternator fitted to these vans and also whether a smart Victron relay is the correct way to go, but I will be fitting a B2B.

Comments appreciated.

 

[wildebus]

I would think by around half the journey the voltage should be at mid-14V really IF the alternator was capable of doing a 'proper' charge to the battery.
I agree that going by that data, a B2B is needed to give the battery the charge level it needs

Also, what that info also illustrates very well I think is that the STARTER battery is not getting a proper charge from the alternator either and why it is a good idea - for most vans AND cars - to use some kind of alternate charger on the starter at least periodically (the AMT12-12 you have could qualify for that I think )

 

[SquirrellCook]

It’s funny with what you found. I had the opposite problem with Murky, small bulbs getting a silver sheen. What’s good for the battery may not be good for other systems. I would expect a manufacturer to use a charge voltage that is adequate for the battery and systems.
Is there not some rule in euro six specifications that you are not allowed to tamper with or connect to the electrical system?

 

[wildebus]

It’s funny with what you found. I had the opposite problem with Murky, small bulbs getting a silver sheen. What’s good for the battery may not be good for other systems. I would expect a manufacturer to use a charge voltage that is adequate for the battery and systems.

I suppose if you felt that was a concern, you could have a B2B between starter and leisure batteries to give your battery the voltage it needs for best charging; and then have a DC-DC converter between the leisure battery and the habitation devices (such as lights) to give those devices the voltage they need for best results.

Is there not some rule in euro six specifications that you are not allowed to tamper with or connect to the electrical system?

I don't know if this is a rule. I doubt it TBH as how would Motorhome manufacturers be able to build their vehicles?

Putting that aside, a B2B is effectively just a load on the alternator in a similar way that headlights, a radio or anything else in the vehicle is a load. (for example, driving with headlights on full beam is actually not far off the load of a typical B2B, so what difference would a B2B vs Headlights make to the vehicle electrics?)