Update:
Well I have been running it a month - latest Ducato Euro 6 with 'intelligent' alternator, charging 2 secondary batteries (one a starter battery one a leisure battery) Both secondary batteries are 5 years old and were previously used as the secondary batteries in my old X2/50. Connected to the main battery with 25mm2 cables via a 500 amp relay activated by the ignition switch (from the cigarette lighter socket) Its worked well so far. Making more use of the 180 amp alternator than a 30amp B2B charger could.

I am not advising this for anyone else or even recommending it because there may be issues I have not discovered yet.

The only issue I can see at the moment is if something got left on in the habitation area so the secondary batteries were completely flat, they might sap the power from the engine battery when you turn on the ignition and prevent the engine starting. But they would have to be completely flat, below the level the voltage from the main battery falls to when connected to the starter motor, and I would know about it. I have a switch in between the cigarette lighter socket and the relay so in that case I could keep the batteries separated until the engine started. So its not a fit and forget solution the motorhome builders could use and sell to novices.
I have got a voltmeter on the dashboard and can see the voltage going up to 14.8 volts on deceleration. So it may be advisable to use 2 starter batteries as the secondary batteries to cope with this charge rate?
One of my secondary batteries is a starter battery which has been in use as a leisure battery for 5 years and is still performing well.
I intend to update this thread if I discover any problems.

Hello,
I’m new on here because I’ve just bought a 2021 Fiat based Pilote motorhome.
None of the new Pilote vans charge the vehicle battery from the electric hook up or solar because Fiat have told Pilote they will not honour any warranty if a battery to battery charger is installed!
I can only assume that this refers to all new fiat based vans.
My problem is that I often leave the van for up to 7 weeks unused and plugged in to EHU during which time the van battery will no doubt be drained by the alarm system rendering my insurance void because the alarm won’t work, despite the leisure battery being charged by solar and plug in.
So check with fiat before installing a BtoB on a new van.

Alan

544classic said:

Hello,
I’m new on here because I’ve just bought a 2021 Fiat based Pilote motorhome.
None of the new Pilote vans charge the vehicle battery from the electric hook up or solar because Fiat have told Pilote they will not honour any warranty if a battery to battery charger is installed!
I can only assume that this refers to all new fiat based vans.
My problem is that I often leave the van for up to 7 weeks unused and plugged in to EHU during which time the van battery will no doubt be drained by the alarm system rendering my insurance void because the alarm won’t work, despite the leisure battery being charged by solar and plug in.
So check with fiat before installing a BtoB on a new van.

Alan

Click to expand...

Welcome to the forum Alan
I have everything including the alarm running off the secondary batteries - and wonder if you could reconnect your alarm supply to them?
I keep an eye on the voltmeter on my dashboard and have seen it go as high as 15volts on deceleration with regenerative braking.
On the face of it this would appear to be faster and more efficient charging than a B2B charger. Its certainly keeping all 3 batteries well charged - especially after a journey over hilly terrain making use of regenerative braking. Slightly less charged after a long run on the flat but still settling at around 12.7v. And if the batteries are down it goes straight up to around 14.4v on tickover.
But its too early to say if there will be any long term problems. And since my secondary batteries (one leisure and one starter battery in parallel), are 5 years old, when they do expire I won't know whether its from this way of direct charging or from age. I used them as secondary batteries on my X2/50 but that was not an 'intelligent' alternator, and they were connected to the starter battery via a voltage sensing relay - using the same 25mm2 cables I'm using now with the new van.

The alarm isn’t being fitted until Monday and I was going to ask the fitter if he can use the leisure battery, so thanks for that.
How do I know if I have regenerative braking? I’ve only driven it from the dealers so far and it doesn’t seem to have stop start either.

544classic said:

The alarm isn’t being fitted until Monday and I was going to ask the fitter if he can use the leisure battery, so thanks for that.
How do I know if I have regenerative braking? I’ve only driven it from the dealers so far and it doesn’t seem to have stop start either.

Click to expand...

2021 model should have both.
The start stop won't begin until te engine is warm and the battery is charged up to about 80%. There is a button on the dash marked with a capital leter A, horseshoe around it and line through it. You have to press that to disable the start stop and it brings up a message on the dash to say start stop disconnected.
There was a guy on ebay selling an electronic device that effectively presses this button for you every time you turn on the ignition. But I can't find it now and suspect he has been stopped because its not legal - the van won't comply with Euro 6 emissions with the start stop disabled. But I have got into the habit of pressing it now, and if you forget you get a gentle reminder when the engine stops. Although its bad for the engine I believe in stopping the engine to cut emissions, but think when to stop the engine is a decision better taken by the driver than the computer. Because only the driver can see how long you are likely to be stationary, and whether you are in a built up area.
Says in the handbook that if you want to charge the main battery you should contact a Fiat dealer. But I have charged it in situ with an ordinary battery charger with no apparent ill effects.
Again I am not recommending any of this because there may be negative issues I have not discovered yet. I am just saying this is what I have done and it has worked well so far. But if you do it you do it at your own risk same as I have.

Would just like to emphasise I am not suggesting keeping engine running in built up area
people who do that should read this
https://www.theguardian.com/environ...-air-pollution-coroner-rules-in-landmark-case
9 year old girl killed by air pollution

544classic said:

because Fiat have told Pilote they will not honour any warranty if a battery to battery charger is installed!

Click to expand...

There is a slight misunderstanding here. What Fiat are saying, and they have this clause in the vehicle handbook, is that the engine battery must not be charged with a battery charger whilst its still connected to the vehicle system.

The battery to battery charger being discussed here, is a unit that is connected to the vehicle battery and its output connects to the leisure battery. Its designed to charge the leisure batteries correctly regardless of the voltage variations on the vehicle battery.
Because the B to B is designed as a charger with a correctly designed charge profile for different battery types, it will charge leisure batteries faster and safer than alternative methods.
Where you have a 'smart alternator' its designed to look after the starter battery and to help with emissions keeps the engine battery effectively 'under charged' with an average voltage in the region of 13.2 volts with high excursions to over 15 volts when the engine is on the overrun. This low average and intermittent high voltage is inadequate to charge any leisure battery directly connected. The battery is being continually undercharged and will have a short service life and the high peak voltage may damage camper electronics, and of course is stressing the leisure batteries.
Having the B to B between the engine battery and leisure battery is an effective solution used by all professional converters where Euro6 vans are the base vehicle.
In addition to providing correct charging to the leisure batteries, the B to B will not over stress the vehicle charging system and provides isolation between the leisure circuits and engine circuits.

Mike

PS regarding Mr REG 65. We may have had a similar discussion on a different forum concerning smart alternators and leisure batteries.

I recall about 10 years ago when I was fitting out my X2/50 being told by a professional on a forum that I needed a B2B charger. But I had done it with a voltage sensing relay and hefty cables connecting the batteries in parallel. It worked well enough for the 10 years I used it.
I don't think the system I am using now with the smart alternator could be recommended and fitted commercially because the secondary batteries are not autmatically isolated from the starter battery when you start the engine. So if they got totally discharged they could sap the power from the starter battery before it started.
It depends on me noticing the secondary batteries are totally discharged and flicking the switch to keep them separated from the starter battery when I turn on the ignition.
And you make a fair point about the 15volts produced with regenerative braking getting through to whatever is connected to the secondary battery. Which may or may not be a problem depnding on whats running from it at the time.

Does anyone know why Fiat say not to charge the battery in situ?
I understand that it raises the voltage whilst its charging.
But this is a system designed to take 15 volts under regenerative braking
Do they think you might use a charger that raises the voltage even higher
Handbook says if you need to charge the battery take it to a Fiat dealer.
Can't see many people doing that.
I have a cig lighter socket directly connected to it (which I use for my voltmeter) and have charged it through that with a 10 amp battery charger. I haven't noticed any ill effects. Again I must emphasise I am not recommending this and certainly am not trying to say Fiat are wrong.
I am just saying what I have done at my own risk, and it seems to have worked out OK so far. But if you do it you do it at your own risk same as me.

Just been in a motorhome dealership (for bottled gas). Found they have less stock than usual and its nearly all new Ducatos. Many of them don't have the ECO and Start Stop buttons on the dash. (Capital A with a line through it and a horseshoe around it) Which apparently means no start stop system, no smart alternator (both of which present difficulties for the motorhome converter) The salesman insisted they were all new latest Euro 6 and told me the ECO pack was optional.
I thought the ECO pack was compulsory with the current Euro 6 because the commercial price list gives no option to delete the ECO pack. ?
(Supplying Fiat dealer told me they couldn't alter the smart alternator because it would affect the emissions)

Well a lot of people said it wouldn't work, and in theory perhaps it shouldn't.
But it seems to have worked well for a couple of months.
The batteries are having an easier time in the summer though, and I became a bit concerned about the secondary batteries doing more work - a share of the starting and almost everything else, but only the same charge as the starter battery as they were both connected in parallel whenever the ignition was on, I was also a bit concerned about the secondary batteries getting so discharged they might prevent starting on a very cold morning.
So I decided to wire the relay to the D+ output of the alternator, so the batteries are only connected in parallel when the engine is running.
Fiat gives the maximum current to be taken from the D+ terminal as 300ma.
I put a meter on my 500A relay and found it used 740ma
I guess its a starter relay designed for intermittent use - a strong spring to ensure the contacts separate instantly, and a correspondingly power hungry coil to hold them together
So I got a standard 200amp relay off ebay (£6.50 posted from China) - which uses 170ma and am now using that, with the negative wired to the D+ terminal of the alternator
(using a 2 way switch which can be switched from alternator D+ negative to permanent negative to connect both batteries together for jump starting)
Took the opportunity to change the secondary batteries to 2x019 100ah varta starter batteries which just fit in the X2/50 or X2/90 Ducato seat base. The other batteries were still working OK but about 5 years old.
Seems to be working well and keeping all batteries charged - settling at around 12.8v so I'm well happy with that

I can't remember the colour of the D+ signal cable in the conversion socket on my van, but it's on pin 2. Were you checking for a voltage on the D+ signal cable, because that's not how it works? It's a simulated signal from the BCM which opens a circuit to ground, i.e. you use it as the switched earth for the switching circuit on a relay, taking the power feed from the 70 amp supply on the adjacent power connector.

RS3100 said:

Were you checking for a voltage on the D+ signal cable,

Click to expand...

No I knew it became negative when the alternator produced current. As I posted on another thread when I needed to find the Alternator D+ I looked at the converters guide and it shows it as a brown/white wire going to the converters socket.
My X2/90 Ducato van has this socket, even though it is not on the spec sheet or been charged for.
I tried to find it at the loom going in but couldn't
So took the socket out and found it was brown/black
I found a brown/black wire in the loom nearer where I wanted it, and cut that to find it wasn't the D+
I then found another brown/black wire and cut that to find it wasn't the D+ either
So I had to go back to the converters socket and cut the brown/black wire there to wire it in and run a cable back from there.
I can only guess the loom manufacturer must have run out of some colours, and substituted whatever other colour came to hand...

I think the reason this set up is working so well is there is very little resistance in the cabling between the main and secondary batteries so they both get the same voltage. I'm using 25mm2 cable and its only got to go from the battery box to the seat base. (And its got no fuses in which would create resistance - some people will baulk at that I know but I have got the cables well protected - the positive feed is triple insulated 25mm2 tinned copper 440v industrial cable and where it touches metal it runs inside reinforced garden hopsepipe for good measure.) I've seen motorhomes with the secondary battery much further away and fed by much thinner cable. So in that case the secondary battery wouldn't get much of a charge without a B2B charger to boost it.

RS3100 said:

taking the power feed from the 70 amp supply on the adjacent power connector.

Click to expand...

Well thats a comparatively long thin cabling taking an indirect route round by the opposite footwell, and only 10mm2, you probably would need a B2B with cabling like that. Especially if it had much further to go to the secondary battery. So I put in a new short one taking a direct route using 25mm2 cable to lower resistance and speed up charging without a B2B charger. It works

RS3100 said:

the 70 amp supply

Click to expand...

seems to me that the power rating they give to cable is the most you can put through it without risking it catching fire
But thicker cable is always better
- to reduce resistance and voltage drop - especially where its not a short cable run.

Of course they quote the maximum rating. What use would any other figure be?

For anyone reading this thread in future, you can buy the Tyco connector for the conversion socket and a set of pins for around a couple of pounds - much easier and less invasive than cutting cables on the base vehicle side of the connector, and the reason the connector exists

TE 1-480710-0 Universal Mate-N-Lock male connector
TE 350218-1 Universal Mate-N-Lock male contact pin

Reg 65 said:

Does anyone know why Fiat say not to charge the battery in situ?
I understand that it raises the voltage whilst its charging.
But this is a system designed to take 15 volts under regenerative braking
Do they think you might use a charger that raises the voltage even higher
Handbook says if you need to charge the battery take it to a Fiat dealer.
Can't see many people doing that.
I have a cig lighter socket directly connected to it (which I use for my voltmeter) and have charged it through that with a 10 amp battery charger. I haven't noticed any ill effects. Again I must emphasise I am not recommending this and certainly am not trying to say Fiat are wrong.
I am just saying what I have done at my own risk, and it seems to have worked out OK so far. But if you do it you do it at your own risk same as me.

Click to expand...

Because they have sensitive battery moniters connected to the battery that moniters how charged they arnt and these get damaged by the high voltages of external chargers often connected through them

RS3100 said:

Of course they quote the maximum rating. What use would any other figure be?

For anyone reading this thread in future, you can buy the Tyco connector for the conversion socket and a set of pins for around a couple of pounds - much easier and less invasive than cutting cables on the base vehicle side of the connector, and the reason the connector exists

TE 1-480710-0 Universal Mate-N-Lock male connector
TE 350218-1 Universal Mate-N-Lock male contact pin

Click to expand...

Yes I suppose most people use the proper plug so never know the wiring colours are not as shown in the diagram. But I did not have the plug, only wanted to use the D+ so just used what I had to hand - like the loom manufacturer I suppose

I saw on an electricians forum they don't use amperage rating for cable because its such a contentious subject. They just give the cross sectional area and you make up your own mind what it can carry. One electrician had installed a 9kw shower with 6mm2 cable, the building inspector wouldn't sign it off, so he had to rip it out and repace it with 10mm2. There was a long thread with opinion split on whether 6mm2 was ok or not. Things like how well ventilated the cable is to stop it overheating.

chris3234 said:

Because they have sensitive battery moniters connected to the battery that moniters how charged they arnt and these get damaged by the high voltages of external chargers often connected through them

Click to expand...

Yes, but it survives the 15 volts it gets up to with regenerative braking when I'm going downhill.
So I wonder what sort of charger you would have to use to get the charging voltage above that

Reg 65 said:

Yes, but it survives the 15 volts it gets up to with regenerative braking when I'm going downhill.
So I wonder what sort of charger you would have to use to get the charging voltage above that

Click to expand...

The alternator doesn't pit the voltage directly through the voltage Sensor like many people do when connecting up chargers