Fiat Smart Alternator problems

[mark61]

I read on tinterweb that the charging parameters of a smart alternator can be changed by a computer re map .
My last motorhome had a smart alternator voltage could drop down to 12 v cruising on motorway then rise when going down hill , that is what smart alternators do , I would like to know if motor home manufacturers re program management systems to accommodate leasure batterys and motor home use

No idea about MH's but I know some vehicles with factory fitted tow bar and 13 pin plug will override smart alternator when towing a caravan.
I have factory too bar and 13 pin plug but never towed a caravan
I just turn headlights on to override smart alternator, so much for DRL's.

 

[Okta]

I read on tinterweb that the charging parameters of a smart alternator can be changed by a computer re map .
My last motorhome had a smart alternator voltage could drop down to 12 v cruising on motorway then rise when going down hill , that is what smart alternators do , I would like to know if motor home manufacturers re program management systems to accommodate leasure batterys and motor home use

Until September 2019 Fiat would disable smart alternators for motorhome constructors. Mercedes did not. This of course was a cheat because the approvals were based on unmodified vehicles. The new testing procedures from 2019 put paid to the cheating. I doubt that a manufacturer who wants to build a good reputation would now risk reprogramming for leisure constructors and their leisure batteries. Anyway there is no need, all the constructors have to do is stop using split charge relays and use B2B/boosters instead. It ain’t rocket science the solution has been known for years

 

[Okta]

No idea about MH's but I know some vehicles with factory fitted tow bar and 13 pin plug will override smart alternator when towing a caravan.
I have factory too bar and 13 pin plug but never towed a caravan
I just turn headlights on to override smart alternator, so much for DRL's.

I don’t think this is an override it is just the normal functioning of a smart alternator. When a heavier than normal load lowers the battery voltage the alternator is powered up to compensate for it. The heavier than normal load might be headlights, a B2B or a towed caravan. The idea is for the alternator to be smart and allow for different circumstances. What it can’t cope with is constructors fitting dumb split charge relays which join an extra battery to the engine system and confuse the smart alternator operation.

 

[merl]

The oil will be thin when cold, hence the 75/90, so very little drag, the more you use the clutch the faster it wears out, many of my toys have went round the clock 2/3 times without having to replace a clutch, mind you I made lots of money from folk wrecking cars over the years, esp the ones who sit at lights with the foot on clutch and brake, not forgetting the ones who drive with the foot resting on the pedal.

That'll be the Mrs Trev

 

[mark61]

I don’t think this is an override it is just the normal functioning of a smart alternator. When a heavier than normal load lowers the battery voltage the alternator is powered up to compensate for it. The heavier than normal load might be headlights, a B2B or a towed caravan. The idea is for the alternator to be smart and allow for different circumstances. What it can’t cope with is constructors fitting dumb split charge relays which join an extra battery to the engine system and confuse the smart alternator operation.

Well it's overriding the function where the alternator does the bare minimum , which is most of the time. I'd call them lazy rather than smart.

 

[gasgas]

. . . . . and by the way I hope you all turn off the stupid start/stop system whenever you start out. . . . ..
Unless of course you love unnecessary spending lots and lots of drinking vouchers on extra-expensive batteries and alternators.

 

[Okta]

. . . . . and by the way I hope you all turn off the stupid start/stop system whenever you start out. . . . ..
Unless of course you love unnecessary spending lots and lots of drinking vouchers on extra-expensive batteries and alternators.

One of our cars has stop start. It is 7 years old and is still on the original battery, alternator and starter motor. It not only saves fuel but saves wear on the clutch. With a DSG auto gearbox the clutch is being held whilst stationary. The same applies to the Fiat Comfortmatic and on balance I wish ours had stop start.

 

[gasgas]

My daughter's Ford Fiesta with startstop has had three batteries and three starter motors in two years. I do have startstop on my one year old auto Transit and I stick it in neutral if I am waiting for any reason.

 

[trevskoda]

. . . . . and by the way I hope you all turn off the stupid start/stop system whenever you start out. . . . ..
Unless of course you love unnecessary spending lots and lots of drinking vouchers on extra-expensive batteries and alternators.

Not forgetting starter motors and new ring gears, this requires the g box out, turn it of.

 

[campingnotoriousdeer]

Those smart alternators can be tricky to figure out. I've seen a few people mention similar problems online, but no real resolutions. Have you tried talking to Fiat directly to see if they can offer any advice? Good luck finding a fix!

 

[barge1914]

Well despite the occasional odd reading it’s worked perfectly well round Ireland. So I assume it’s just doing what it’s meant to do, seem something of a dark art these smart alternators. I’ve encountered very few so far who can claim to really understand them.

 

[Warwick Hunt]

One way of checking a smart alternator is to put it in gear and take your foot off the throttle - ideally when going downhill in a lowish gear to increase engine revs. (If you can't find a hill to go down maybe a fast road to get up enough inertia.) Then you should see maximum output - up to 15 volts. I also see voltage dropping at other times as though the alternator stops charging and power is being taken out of the battery to run the engine electronics etc. Then it puts power back in the battery with regenerative braking.
I have a 2021 Ducato with smart alternator, charging 4x100ah batteries (2 019 batteries under each seat) hrough a split charge relay. Quicker and more efficient than a b2b charger because you are charging them with regenerative braking like the main battery. The b2b chargers I have seen are only rated 30 amp - and in my experience these things never give the figures quoted. So I can't see them giving the charging power I am getting now - with the 510ah battery bank reaching 15 volts with regenerative braking downhill
The ony issue I have is with the yellow engine management light coming on saying start/stop not working when the extra batteries are connected (MOT fail) I can extinguish the engine management light by clearing the fault codes with a basic generic code reader, but it comes on again after a while if the secondary batteries are connected. So when MOT time comes around I plan to extinguish the engine management light by clearing the faut codes, and disconnect the split charge relay with my dashboard switch to get it through the MOT.
I don't suppose its worth paying Fiat £350 to look at it because FIAT say you shouldn't fit a secondary battery bigger than 20% of the size of the original!
So that would be a secondary battery of about 20ah, with a useable capacity of 10ah!

 

[Warwick Hunt]

The oil will be thin when cold, hence the 75/90, so very little drag

Are you sure? Its many years since I studied it, but I was taught that even multigrades get thicker when cold. They just don't get as thick as single grades do.
So at a certain cold temperature the 75/90 would be as thick as a 75w would be at that temperature
And at a certain hot temperature the 75/90 would be as thick as a 90w would be at that temperature
But it would still be thicker when cold

 

[Okta]

I don't suppose its worth paying Fiat £350 to look at it because FIAT say you shouldn't fit a secondary battery bigger than 20% of the size of the original!

In my opinion you need a B2B.

As soon as the split charge relay connects the two battery banks together you you have an enormous bank and are at risk of putting too big a load on your alternator (hence the 20% limit). Also at 15V it may be a higher voltage than suits the leisure batteries. Yes for brief periods you may be getting a good whack of volts on your leisure batteries but for the rest of the time you will be getting far less than they need. Short bursts of high voltage does not mean the batteries are getting the amps they need.

There are many B2Bs that have a greater charge rate than 30A. Votronic do a range up to 90A though I would check that your alternator and wiring is capable of supporting that load before going that high. A B2B protects the alternator and the leisure batteries. That yellow warning light is trying to tell you that you have a problem.

 

[Warwick Hunt]

In my opinion you need a B2B.

As soon as the split charge relay connects the two battery banks together you you have an enormous bank and are at risk of putting too big a load on your alternator (hence the 20% limit). Also at 15V it may be a higher voltage than suits the leisure batteries. Yes for brief periods you may be getting a good whack of volts on your leisure batteries but for the rest of the time you will be getting far less than they need. Short bursts of high voltage does not mean the batteries are getting the amps they need.

There are many B2Bs that have a greater charge rate than 30A. Votronic do a range up to 90A though I would check that your alternator and wiring is capable of supporting that load before going that high. A B2B protects the alternator and the leisure batteries. That yellow warning light is trying to tell you that you have a problem.

Sorry I should have said - my secondary batteries are not leisure batteries - just 4 of these 019 https://www.tayna.co.uk/car-batteries/varta/h3/
The yellow light comes with info on the display panel saying start/stop inoperative - which potentially affects the emissions, so I guess thats an MOT fail
My understanding is the computer has to work out whether the battery is sufficiently charged for start stop operation, and the extra batteries have made it unable to calculate whats gone in and out through the O/E current sensor on the main battery.
Fair point that the extra load may shortern the life of the alternator. Which is presumably why Fiat say don't have a seondary battery bigger than 20ah. Which I think is absurd for a vehicle they market as suitable for motorhomes and just an attempt to evade responsibility.
But maybe shorterning the life of the alternator is the price I have to pay because I can't manage with 20ah.
I understand that the B2B charger would charge the secondary batteries more fully (if it will work with 400ah) but with plenty of spare capacity I don't need to charge them fully everytime.

 

[Warwick Hunt]

I've done 22,000 miles with the X2/90 as above - but did 94,000 miles with the X2/50 before. That just had 2x 100ah secondary batteries wired through a split charge relay and also worked ok - didn't have the issues with the start stop inoperative light on of course

 

[Okta]

Sorry I should have said - my secondary batteries are not leisure batteries - just 4 of these 019 https://www.tayna.co.uk/car-batteries/varta/h3/
The yellow light comes with info on the display panel saying start/stop inoperative - which potentially affects the emissions, so I guess thats an MOT fail
My understanding is the computer has to work out whether the battery is sufficiently charged for start stop operation, and the extra batteries have made it unable to calculate whats gone in and out through the O/E current sensor on the main battery.
Fair point that the extra load may shortern the life of the alternator. Which is presumably why Fiat say don't have a seondary battery bigger than 20ah. Which I think is absurd for a vehicle they market as suitable for motorhomes and just an attempt to evade responsibility.
But maybe shorterning the life of the alternator is the price I have to pay because I can't manage with 20ah.
I understand that the B2B charger would charge the secondary batteries more fully (if it will work with 400ah) but with plenty of spare capacity I don't need to charge them fully everytime.

Doesn’t change my view, you still need a B2B. A smart alternator will not charge a leisure bank properly. The system is designed to keep the engine battery at a lower voltage so that there is always room for recovering the energy that would be lost when you are slowing down and braking. Having linked the batteries together using a basic split charge relay the system will keep all the batteries at a lower voltage instead of charging them fully, not just the engine battery. If it were me I would not just be worried about shortening the life of your alternator but about it going pop in a more dramatic way.

Aux Battery Charging With Smart Alternators | 12 Volt Planet

A guide to the benefits of using battery to battery chargers to overcome split charging problems caused by smart alternators on modern Euro 5 & 6 vehicles.

www.12voltplanet.co.uk

 

[Okta]

I've done 22,000 miles with the X2/90 as above - but did 94,000 miles with the X2/50 before. That just had 2x 100ah secondary batteries wired through a split charge relay and also worked ok - didn't have the issues with the start stop inoperative light on of course

Probably didn’t have a smart alternator either.

 

[Warwick Hunt]

Doesn’t change my view, you still need a B2B. A smart alternator will not charge a leisure bank properly. The system is designed to keep the engine battery at a lower voltage so that there is always room for recovering the energy that would be lost when you are slowing down and braking. Having linked the batteries together using a basic split charge relay the system will keep all the batteries at a lower voltage instead of charging them fully, not just the engine battery. If it were me I would not just be worried about shortening the life of your alternator but about it going pop in a more dramatic way.

Aux Battery Charging With Smart Alternators | 12 Volt Planet

A guide to the benefits of using battery to battery chargers to overcome split charging problems caused by smart alternators on modern Euro 5 & 6 vehicles.

www.12voltplanet.co.uk

So a company selling b2b chargers says I need a b2b charger (why am I not surprised)
They also say ' traditional split charge systems cannot be used.' - but I have been using one for over 2 years and 22,000 miles and its still working well (apart from the start stop which I don't need)
They say it might damage lithium or gel batteries or the contacts of a voltage sensing relay - but thats ok because I have none of those.
I can't see anywhere where they say it might damage the alternator more than a B2B charger
Why would it?
They say the B2B charges the batteries faster, and apparently so much power is lost through inefficiency it needs its own fan to cool it down
So it must be taking more power and working the alternator harder than my split charge relay?

 

[Warwick Hunt]

Probably didn’t have a smart alternator either.

It was just an ordiary alternator and half the secondary battery capacity because i just had 2 batteries under the driver's seat.
I didn't put any under the passenger seat because I thought I might need to take the single seat out and put the double seat back if I carried an extra passenger
But I never did carry an extra passenger, so when I got the new van, and aquired more power hungry appliances, I put 2 batteries uinder the passenger seat as well.