Technical New Ducato Stop Start Alternator

[RS3100]

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.

The cable ratings for domestic and commercial mains installations are set out in the Electrical Wiring Regulations tables, and they do take account of the differences between surface mounted cables and cables routed through conduit or contained in plaster etc. and length of cable runs. If a lekky can't understand that and work to the same standard that he should know is being applied by building regs, well...

But in Fiat's case, they make the van, and they publish the maximum design ratings for connections by converters. The rating for the conversion socket power cable is presumably determined by the chosen cable size, the fuse that Fiat decide to protect it with and protection of the BCM. Anyone who chooses to ignore that does so at their own risk, that of the vehicle warranty, or worse

 

[Reg 65]

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

I'm still learning and don't understand what you mean. When there is 15 volts at the battery, and the cigar lighter socket where I'm measuring it from, doesn't that mean there is 15 volts right though the system?

 

[chris3234]

I'm still learning and don't understand what you mean. When there is 15 volts at the battery, and the cigar lighter socket where I'm measuring it from, doesn't that mean there is 15 volts right though the system?

There a picture of a battery sessor here this is from a BMW nuts it's the same basic thing

People normally connect External chargers directly to them Which is what can damage them as the power is going through the sensor itself rather then through the battery cables and into the battery

 

[Reg 65]

https://www.samarins.com/glossary/images/battery-current-sensor.jpg

There a picture of a battery sessor here this is from a BMW nuts it's the same basic thing

People normally connect External chargers directly to them Which is what can damage them as the power is going through the sensor itself rather then through the battery cables and into the battery

Thanks for the pic - yes it does look the same as my X2/90 Ducato. As shown in the pic the only connection to battery negative is through the sensor, so the 15 volts must be going through the sensor when it comes from the alternator - because thats the only way in - there is nothing connected direct to the battery to by pass the sensor.
So I wonder what charger you would have to use to raise the charging voltage above 15 volts
Many years ago when I worked in a garage we had a fast battery charger that was so powerful it would start a car engine with the battery flat - it was so heavy it had wheels on it - like a suitcase with handle and 2 wheels at the bottom. Maybe that produced above 15 volts I can't remember. But I can't see anything the DIY mechanic would have producing above 15 volts.
A guy on another forum said he asked his local Fiat dealer how to charge the battery and the Fiat technician told him to connect the charger up as normal with the battery in situ - as I did with my 10 amp charger, and it all seems ok.
But again I'm not telling others to do it - just saying thats what I have done and it all seems to be working well.
But if you do it you do it at your own risk, same as me.

 

[chris3234]

The cable ratings for domestic and commercial mains installations are set out in the Electrical Wiring Regulations tables, and they do take account of the differences between surface mounted cables and cables routed through conduit or contained in plaster etc. and length of cable runs. If a lekky can't understand that and work to the same standard that he should know is being applied by building regs, well...

But in Fiat's case, they make the van, and they publish the maximum design ratings for connections by converters. The rating for the conversion socket power cable is presumably determined by the chosen cable size, the fuse that Fiat decide to protect it with and protection of the BCM. Anyone who chooses to ignore that does so at their own risk, that of the vehicle warranty, or worse

Yup the ratings for cables are pretty well set out in the 18th edition regs ( the late version is memory' serves me right)

 

[Reg 65]

Well I'm nowhere near up to date with the latest Editions, so have no opinion on which electrician was right about the cable size for the shower. Except that 10mm2 would be better than 6mm2 (whatever the regulations say) because it would be heating the water more and the cable less.
Just didn't want people to think Fiat's long 10mm2 cable is rated at 70 amp so its OK and no need for a shorter thicker one.
They might wire the batteries together through the longer thinner cable and blame me when its slow charging.

 

[RS3100]

I think you failed to understand my previous post. When I mentioned taking the power feed from the 70 amp supply on the adjacent power connector, that was in relation to the source of a positive feed to operate the switching circuit for a relay controlled by the simulated D+ signal from the conversion socket. The use of a relay permits the switching circuit to operate at a lower current rating than the circuit it controls.

The purpose of the conversion socket is, in Fiat's own words, "to prevent any kind of tampering or manipulation of the basic design, and to ensure function integrity and validity of the vehicle warranty" whilst avoiding modifications to "wiring or interconnection points that are the exclusive domain of the basic system, and as such must not be altered in any way by the persons responsible for the conversion".

The power connector is provided as a means of supplying power to accessories fitted by converters, which need to be supplied from the vehicle directly, rather than a secondary battery. Whilst the use of the conversion supply to connect to a secondary battery is not prohibited, "in no case should the increase in battery capacity exceed 20% of the standard battery capacity, to prevent damage to any component of the system".

And, "if it is necessary to make alterations to the system other than the ones described in this manual (for example, additional batteries in parallel), the works must be co-ordinated with FIAT CHRYSLER AUTOMOBILES S.p.A."

You might consider that the wording is a typical "covering their backsides" type of document, but it does allow Fiat to conveniently sidestep any warranty or other claim where their recommendations have not been followed!

 

[Reg 65]

You might consider that the wording is a typical "covering their backsides" type of document,

Well exactly - like Fiat say you should take it to a Fiat dealership to have the battery charged.
I ran 2x100 AH secondary batteries connected in parallel through a voltage sensing relay on my X2/50 for 11 years - still works well. Only electrical problems I had were wiper motor, horn button (water from windscreen leaking on it) and headlight bulbs. (which seem to overheat under the shroud they fit for the RHD market)
Probably increased the wear on the alternator etc but wearing the van out is a price I'm prepared to pay to make good use of it.

 

[Communicator]

https://www.samarins.com/glossary/images/battery-current-sensor.jpg

There a picture of a battery sessor here this is from a BMW nuts it's the same basic thing

People normally connect External chargers directly to them Which is what can damage them as the power is going through the sensor itself rather then through the battery cables and into the battery

Now I am getting confused.

The posted link is to a CURRENT sensor, which appears to be a Hall Effect device, with no direct connection to the battery negative pole. If I am correct, there is no way that the device is going to be affected by battery voltage, other than via a regulated power supply to the associated electronics.

An alternative reason for having the battery charged by a dealer, could be to ensure that the battery is charged via the current sensor, so that the battery moitoring system knows the state of charge of the battery. This however begs the question, as to what action to take when the battery is replaced. Does the system need resetting? However when I check my Fiat Owner Handbook, dated "IV/2005", I find in the section dealing with battery charging, "this operation shall only be performed at a Fiat Dealership".

As regards system voltage, I currently tend to agree with Reg, in that the system should be able to withstand the 15V that he has observed. I would expect that 15V is not the absolute limit, and that there will be some safety margin above that voltage.
RS3100 has quoted Fiat as saying that any increase in battery capacity must not exceed 20% of original capacity. Assuming original is 100 Ah, the this restricts any additional battery to 20 Ah, and adopting a DoD of 50% this results in a useable 10 Ah. In a vehicle which Fiat are keen to promote as a base vehicle for motorhome conversions, that is seriously less than adequate. Obviously nothing less than an escape clause.

 

[Reg 65]

The posted link is to a CURRENT sensor, which appears to be a Hall Effect device, with no direct connection to the battery negative pole. If I am correct, there is no way that the device is going to be affected by battery voltage, other than via a regulated power supply to the associated electronics.

Yes - and it concerned me that it was only measuring the current coming out of the starter battery and the secondary battery was doing more work - at least until I changed the relay to being activated by the D+ from the alternator so the starter battery is doing all the starting, glowplugs and day running lghts that come on before you start the engine.
Its working well now. Probably faster and more efficient than through a B2B charger because there is no wastage running the charger, and its charging with regenerative braking like the starter battery.
But remains to be seen how it will perform in the winter when the secondary batteries are doing more work.
If they don't charge well enough I might try unplugging the current sensor - a guy on you-tube did that with a similar vehicle and says it makes the alternator charge as normal. Its not going to be a perfect balance because the batteries are having different amounts of current taken out of them, but connected together for charging. Nevertheless, its working well - even though in theory perhaps it shouldn't.
I know I'm taking a bit of a risk here with experimenting, and charging more batteries may shorten the life of the alternator etc, but thats the price I pay for making good use of it as a camper van.

 

[Reg 65]

Well I didn't have to unplug the current sensor because its still working well as it is. I have added 2 more 019 100ah secondary batteries so now have 2 under each seat, total 400ah. It was OK before with 2, but I wanted to even out the weight of the batteries and have a bit more capacity in reserve.
Just a standard 200A relay activated by the D+ terminal, connecting the 4 secondary batteries in parallel with the main battery through 25mm cable with no fuses to offer resistance (which some people will baulk at I know but they are very well insulated and protected!).

 

[Reg 65]

Update:
Been running it a year now and still working well. Euro 6 Ducato with 'Smart' alternator charging 4 additional 100ah 019 starter batteries (2 under each seat)
Charging through (unfused but very well protected) 25mm2 cables and 200amp relay activated by the D+ terminal on the alternator - although it seemed to be working as well when it was activated just by the ignition switch, so that could be plan B if you can't find the D+ ? - with a switch to the relay supply to separate the secondary batteries whilst starting if they become totally drained - Its never going to be perfect.
Its only the standard Ducato alternator but its got serious power - taking the 510ah battery bank up to 15v with regenerative braking.

 

[Reg 65]

Thanks to everyone who has contributed.
I can see there is more than one way of doing this, and none is perfect
But its interesting to see how others have done it,
and the advantages and disadvantages of different methods

 

[Reavergy]

I read that it is advisable to have fuses on each battery when they are connected in parallel as if a cell in one of the batteries shorts then the faulty battery would draw high current from the other batteries in parallel and overheat (the faulty battery) with risk of fire. Is it true?
I put 4 x 46Ah battery connected in parallel (had them new and for free ). I put no fuse on them, but now got 4 inline fuses to put one on each battery.

 

[Reg 65]

Well in that situation the working cells in the faulty battery would be getting about 12/5 = 2.4 volts
Thats not going to set fire to them is it?

 

[murfm]

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.

Hi. I want to be able to charge the ducatto battery with a mains charger as well without disconnecting the stop start whilst charging which the Manual says to do. How have you connected your charger to the battery terminals?

 

[Reg 65]

Yes I have charged my starter battery with a normal 10 amp battery charger connected to the terminals under the bonnet (with the engine off) without any problems. But Fiat say that if you want to charge the battery you should take it to a Fiat dealer! So you must make your own decision what to do.

My set up is still working well (4x100ah batteries connected in parallel with the starter battery with very well protected unfused 25mm2 cable through a 200 amp relay) - although the start stop warning engine management light has come on and gone off again a couple of times.
It stayed on for a few days and I was concerned if this happened at MOT time next year it would fail.
I tried disconnecting the factory fitted current sensor on the starter battery by pulling out the plug - this did not extinguish the light and made matters worse because the battery stopped charging. But as soon as I reconnected the plug the battery was charging normally again. (I switch off the ignition close all doors and wait a minute for the computer to shut down before doing anything like that with the electrics)
I found that if I switched off my split charging relay so the charging set up was back to its factory state the engine management light went out after a few engine starts, and normal start stop opertation resumed. So I will do that before I take it in for the MOT.
Hope this helps.

 

[Reg 65]

Now discovered I can get the start stop/ engine nanagement light to go out by connecting a basic code reader and clearing the fault codes.
The reader says 'clearing falt codes failed' - nevertheless the engine management light goes out (and I can flick the switch disconnecting the secondary batteries to make sure the light stays off to get it through the MOT)
Still working fine but it seemed to be overcharging the 4x100ah secondary batteries a bit. So I am now running it with the relay connecting the batteries in parallel activated by the ignition switch, rather than the D+ from the alternator, so that starting load is shared by all 5 batteries.

 

[Reg 65]

LITHIUM BATTERY FIRES !

E-bike and e-scooter fires have injured at least 190 people in UK, data shows

Exclusive: Fires more than quadruple since 2020 after surge in popularity of battery-assisted travel

www.theguardian.com

Just seen this worrying report on Lithium Battery fires - apparently caused by incorrect charging.
So I just wanted to repeat I am using ordinary starter batteries as secondary batteries
Not Lithium Batteries - apparently you have to be much more careful with them

 

[sascha71]

One thing I did in my motorhome was to install a push button with wich I could shortly interrupt the fuse F33 which is in charge for the battery sensor. The battery management then do a full charge to sync again.
I did that because I don't want to keep my starter battery only around 80% before not using the van for some weeks because that will shorten lead battery life dramatically.
Now Ican decide to letting my battery charge to 100% while driving home.

Altenative you can just pull F33 or let it burn, then you have a "normal" Alternator instead a smart one...