Bit of a long question I'm afraid. Swapping vans and the new one has a smart alternator. Assume an 8 hour drive on your way to Spain as an example. As I understand it once the cab battery has recovered from its start up surge the alternator switches off to save emissions. Does any one know what happens to the fridge after that while driving? Does it continue to draw from the leisure battery and eventually deplete it, does it draw from the engine and switch off when the alternator closes down and starts defrosting or neither of these two scenarios? Will I arrive at my Aire with either a ruined battery or ruined food? I am going to drop in a b to b and a lithium battery to resolve any issues, however, that will be a few weeks ahead so just wondering what will happen in the meanwhile
Smart alternator, 3 way fridge and 8 hour drive
- Thread starter Dolmen
- Start date
If the fridge it set to Auto it will normally run on gas as that’s the most efficient, once you start the vehicle it will shut down the gas and run on 12v from the alternator and keep the temperature constant, you won’t have a flat battery… once you turn the ignition of it will take around 15 minutes for the gas to turn back on. This is for safety if you stop at a garage and fill up with fuel.
If you plug into EHU it will run on 230 electric…
If you plug into EHU it will run on 230 electric…
Get a voltmeter that plugs into a 12v socket you or your partner can see while driving, you will see the alternator on at 14.4v then off about 12.5v. If the 14.4v period is too short for you switch your lights on to load the starter battery.
Lenny HB
LIFE MEMBER
- Oct 18, 2007
- 58,746
- 182,844
- Funster No
- 658
- MH
- Carthago Compactline
- Exp
- Since 2008 & many years tugging
Any reputable converter will fit a B2B so it will keep the alternator running to charge the leisure battery so the fridge will be OK.
Even if it hasn't got a B2B they are easy enough to fit so nothing to worry about.
Even if it hasn't got a B2B they are easy enough to fit so nothing to worry about.
Do I understand from your reply that you also believe the smart alternator will not charge the fridge once the cab battery is full, however, you can add a load eg lights to keep it powering the batteries? Do you know if switching the lights on is enough or is that just an example of what one could do? I travel solo and it will only be 5 weeks before i drop lithium and a b to b in so just looking for an easy fix to get me by, this could be it. Thanks
Subscribers do not see these advertisements
Thanks. You may have noticed in the OP that is exactly what I am going to do, just wondering what will happen on my travels while I wait to fit it (5 weeks)
From recent experience, where the manufacturer does not provide a dc - ac charger because of the ' smart alternator', your leisure battery will not receive any charge and therefore will deplete whilst the fridge is on 12v.
Yes, understand that is what will happen with a normal alternator, just wasn't sure if the same applied to a smart alternatorIf the fridge it set to Auto it will normally run on gas as that’s the most efficient, once you start the vehicle it will shut down the gas and run on 12v from the alternator and keep the temperature constant, you won’t have a flat battery… once you turn the ignition of it will take around 15 minutes for the gas to turn back on. This is for safety if you stop at a garage and fill up with fuel.
If you plug into EHU it will run on 230 electric…
Thanks. Think I have been reading too many articles, little knowledge dangerous and all that, however, that is the conclusion I was coming to
Mine is from the batteries with the D+ switching the supply on . But the same applies even with a btob and lithium, that's the load that keeps the alternator regulated. If your fridge is only powered from the alternator you still will need to know when it is on I.e. 14.4v
Subscribers do not see these advertisements
Lenny HB
LIFE MEMBER
- Oct 18, 2007
- 58,746
- 182,844
- Funster No
- 658
- MH
- Carthago Compactline
- Exp
- Since 2008 & many years tugging
A correction to my eairler post the B2B will only effect the leisure battery as the fridge will be connected to the starter battery. With the loa
D of the fridge on the starter battery the alternator will keep charging it so no problem.
D of the fridge on the starter battery the alternator will keep charging it so no problem.
Lenny HB
LIFE MEMBER
- Oct 18, 2007
- 58,746
- 182,844
- Funster No
- 658
- MH
- Carthago Compactline
- Exp
- Since 2008 & many years tugging
The fridge should have any effect on the leisure battery when driving.
On Brit vans the fridge will only be powered by 12v from the starter battery no 12v supply when the engine is off.
On my van and a lot of German vans the starter battery provides power to the fridge when the engine is running but when the engine is stopped it switches to the leisure battery so you have the option to run from 12v. Useful when you have big batteries and plenty of solar.
wuzzlewood
Free Member
My experiences with two such vans is that the fridge takes more juice than can be delivered by the alternator via the cab interface. As a result it takes charge from the habitation battery!
We are on site in many cases, in both vans that we have had, with a far from full Liesure battery!
Smart alternators are a nightmare and I am yet to find anyone local to me at least, that understands them and the effect/interaction with the Liesure battery and fridge.
In both my cases the dealer fitted a new battery to “ solve” tbe problem and it didn’t on tne last one and hadn’t on the present van!
I have just resorted to a b2b charger and still not entirely sorted but better!
Awaiting another replacement battery under warranty and someone to investigate further!
I hope you have better luck!
I am £700 down and still not found the full solution so far!
New charger and lithium batteries next I think for me!
Lenny HB
LIFE MEMBER
- Oct 18, 2007
- 58,746
- 182,844
- Funster No
- 658
- MH
- Carthago Compactline
- Exp
- Since 2008 & many years tugging
Not possible unless you have the wierdist wired van ever.
See above from Vanbitz
Subscribers do not see these advertisements
wuzzlewood
Free Member
I can only speak from experience with Bailey vans and what three different dealers have told me!
I am no expert myself so don’t pretend to know!
Thanks. AshVanBitz comments seem to mirror what I had been reading elsewhere and hence why I raised the question, although some of the comments above indicate the leisure batteries and fridge have no connection when driving and that the fridge should pull the load through from the alternator when driving. Seeing wuzzlewood's personal experience I guess I am going to have to suck it and see what experience I have, its only for 5 weeks (b to b and Lithium) so I'm sure I can manage with my 12v coolbox in the meanwhile if the problem is too great. Looks like there are many 'definitive' versions of what a smart alternator does and does not do, guess it will become clearer as they become the norm.
We have just fitted a 280ah Fogstar lithium, dc/dc (B2b!), 280ah solar system and a Battery Master from VanBitz to a brand new Auto Trail! The dealer had no idea of what they were selling and even gave me the wrong information regarding specific questions regarding the charging system! 
Just about to go out for a trail run to fully test the system, including the fridge while on 12v mobile. So far the static testing has all been good with the Battery Master doing a really good job of keeping the engine battery topped up from the solar /hab battery while just sitting on the drive.
I did follow the instructions from Sargent regarding the isolation of their charging system while the engine is running and using the B2b. So far all is looking good!
Just about to go out for a trail run to fully test the system, including the fridge while on 12v mobile. So far the static testing has all been good with the Battery Master doing a really good job of keeping the engine battery topped up from the solar /hab battery while just sitting on the drive.
I did follow the instructions from Sargent regarding the isolation of their charging system while the engine is running and using the B2b. So far all is looking good!
Wow, quite a set up there, goodbye ehu! I am going much simpler just a 230ah underseat lithium and a b to b, at this stage don't think I will need solar for my humble needs, I never stay more than 2 nights, usually 1 so hope to replenish battery from b to b as I drive. Fridge and heating on gas when stopped so only modest needs for power. In built battery charger will not fully charge lithium on ehu, however, close enough, perfect is the enemy of good and all that.We have just fitted a 280ah Fogstar lithium, dc/dc (B2b!), 280ah solar system and a Battery Master from VanBitz to a brand new Auto Trail! The dealer had no idea of what they were selling and even gave me the wrong information regarding specific questions regarding the charging system!
Just about to go out for a trail run to fully test the system, including the fridge while on 12v mobile. So far the static testing has all been good with the Battery Master doing a really good job of keeping the engine battery topped up from the solar /hab battery while just sitting on the drive.
I did follow the instructions from Sargent regarding the isolation of their charging system while the engine is running and using the B2b. So far all is looking good!
- Apr 3, 2018
- 4,235
- 12,096
- Funster No
- 53,151
- MH
- PVC
- Exp
- 1995-2004 & 2017》
wuzzlewood Interesting read..
That's exactly what mine does.. put it down to a mix up in the wiring when van was converted..
So.ething I have learned to live with
Subscribers do not see these advertisements
- Apr 3, 2018
- 4,235
- 12,096
- Funster No
- 53,151
- MH
- PVC
- Exp
- 1995-2004 & 2017》
That's all you need for the fridgectc Heard about this "easy" fix on here before.... but doesn't work on my van,
On starting 14.6ish Volts for first few minutes use and then 13.4 volts.
Nothing I do will then I crease this voltage.
It doesn't matter what the smart alternator voltage is, 14.4V or 12.4V, if the fridge is connected to it, it should work fine. It's only a 12V heating element, it doesn't need 14.4V like a leisure battery does.
Looks to me like it's the absence of a B2B that is causing the battery problems. If you connect a leisure battery to the starter battery with a split charge relay, (ie no B2B) then it will discharge until it is at the alternator voltage, ie 12.4V. If there's a fridge in there somewhere, it will discharge faster, I think. A B2B will at the very least prevent charge from the leisure battery from going into the starter battery. What happens with the fridge will depend on exactly how it is wired.
Looks to me like it's the absence of a B2B that is causing the battery problems. If you connect a leisure battery to the starter battery with a split charge relay, (ie no B2B) then it will discharge until it is at the alternator voltage, ie 12.4V. If there's a fridge in there somewhere, it will discharge faster, I think. A B2B will at the very least prevent charge from the leisure battery from going into the starter battery. What happens with the fridge will depend on exactly how it is wired.
To be fair when Bailey got into the motorhome business they thought we all wanted wider vans right up to the legal limit and they thought we wanted to store stuff on the floor and chuck it outside on site like a caravanner.
Granted the adamo looks like a step in the right direction, but if they have some weird implementation of the electrics I can't say I'm suprised.
Granted the adamo looks like a step in the right direction, but if they have some weird implementation of the electrics I can't say I'm suprised.
Why not simply defeat the smart alternater?
Subscribers do not see these advertisements
- Jul 18, 2009
- 12,036
- 20,407
- Funster No
- 7,543
- MH
- HYMER B644
- Exp
- 2004
can you fit one for us Lenny?
- Apr 3, 2018
- 4,235
- 12,096
- Funster No
- 53,151
- MH
- PVC
- Exp
- 1995-2004 & 2017》
- Sep 22, 2023
- 699
- 649
- Funster No
- 98,988
- MH
- 4 berth coachbuilt
Agreed. emphatically. I will even go as far as to say that, in my opinion, they are not fit for purpose on a modern motorhome. The starter battery is never fully charged and can not even deliver the power needed for the Stop Start.
Can you please tell us how to do that?
Answers only required from people who have actually done it on a 2022 Fiat Ducato.
Last edited:
Turns out that although it's easily possible it will cause a fault code from the engine ECU.
- Sep 22, 2023
- 699
- 649
- Funster No
- 98,988
- MH
- 4 berth coachbuilt
Thanks for the update.
Subscribers do not see these advertisements
Join us or log in to post a reply.
To join in you must be a member of MotorhomeFun
Join MotorhomeFun
Join us, it quick and easy!
Log in
Already a member? Log in here.