Leisure battery charging while driving

[Stevierox]

Hi, my leisure battery doesn't seem to get charged when driving! I've checked what i know but has anyone had the same problem with a benimar mileo 201 2020? Many thanks

 

[Lenny HB]

That year it will have a Smart alternator, if it doesn't have B2B fitted you will get very little charge to the leisure battery when driving.

 

[Spriddler]

Hi, my leisure battery doesn't seem to get charged when driving! I've checked what i know.......

If you outline what you know/have checked it'll save you getting a series of pointless suggestions about what to check.
What are the symptoms that lead you to think that the battery isn't being charged? Totally flat after a run/nothing 12v is working? Battery only has power for a short while after a run?
Have you checked the fuse(s)?
Have you checked the voltage at the battery terminals (with a test meter) when the engine is running?

 

[Stevierox]

Hi, yes it does have a B2B, which does light up but after driving some 500 miles there was no extra charge in the battery.

 

[Stevierox]

I have checked the fuse that is with the battery, it looks fine but I haven't the equipment to check the voltage

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[Spriddler]

Hi, yes it does have a B2B, which does light up but after driving some 500 miles there was no extra charge in the battery.

If you don't have a test meter how are you judging the (lack of) charging?

What do you mean by 'extra charge'? Once the battery is fully charged the charge rate will drop to near zero, or do you mean that after 500 miles none of the 12v equipment (lights, water pump, fridge control panel etc) was working at all or only worked for a short while?

P.S. It may just be that you have a dying/dead battery.

 

[Stevierox]

If you don't have a test meter how are you judging the (lack of) charging?

What do you mean by 'extra charge'? Once the battery is fully charged the charge rate will drop to near zero, or do you mean that after 500 miles none of the 12v equipment (lights, water pump, fridge control panel etc) was working at all or only worked for a short while?

P.S. It may just be that you have a duff battery.

The battery is brand new as I thought this may be the problem, I have a CSB2 fitted is this the B2B you mentioned?

 

[eddie]

Sadly lots of vans are coming through brand new, with split charge relays and ReGen (smart) Alternators!

Just add a compressor fridge for complete carnage!

 

[Guigsy]

There's been a few instances of this recently. Sometimes it's not that there's no charge, it's that the fridge in 12v mode eats pretty much everything that the alternator throws out. So do you turn the fridge off (or drive in gas mode ).

Also... wider question... what happens with solar? Will it produce a higher voltage than the alternator but not many amps???

 

[Chrisvh]

I had the same sort of problem on a 2020 Knaus. After 5 hours driving the battery was depleted. Tracked it down to the fridge ( limited expertise on my part ) and insufficient charge going into the batteries from the alternator. Fitted a Votronic 50w B2B and have had no problems since. Delighted with the improvement. Rarely use EHU.

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[Stevierox]

There's been a few instances of this recently. Sometimes it's not that there's no charge, it's that the fridge in 12v mode eats pretty much everything that the alternator throws out. So do you turn the fridge off (or drive in gas mode ).

Also... wider question... what happens with solar? Will it produce a higher voltage than the alternator but not many amps???

That's a thought, I do usually drive with the fridge on battery mode! Makes sense I guess , as for the solar panel, that only seems to give out anything good when it's super sunny, think it's geared up for abroad

 

[autorouter]

There are at least two fuses you need to check. There's the wire from the alternator/starter battery to the B2B, which will have a fuse very near the starter battery. There is the wire from the B2B to the leisure battery, which will have a fuse very near the leisure battery.

The B2B also needs a (low-power) signal to switch it on when the engine is running, and off when it stops. There may be a fuse on that signal wire, which could be anywhere, maybe in the distribution/fusebox or near the starter battery. That signal is used to trigger other things, like the fridge 12V power while driving, retracting the step and switching off the awning light when driving etc. So if you are also having problems with other things that might be a clue.

 

[sueandjohn]

Sadly lots of vans are coming through brand new, with split charge relays and ReGen (smart) Alternators!

Just add a compressor fridge for complete carnage!

I don’t understand but you do , and it don’t sound good

 

[autorouter]

The battery is brand new as I thought this may be the problem, I have a CSB2 fitted is this the B2B you mentioned?

The function of the CSB2 is exactly the opposite of what you want. It takes charge from the leisure battery while it is being charged from the solar panels, and tops up the starter battery so it doesn't gradually go flat if you are parked up for several days. It is very low-power, maybe an amp or two.

What we call a B2B, also called a charge booster, takes charge from the alternator while the engine is running, and uses it to charge the leisure battery. It will be quite high power, at least 20A, probably 30A. It is required because a smart alternator keeps the starter battery at much less than full charge. If you parallel the leisure battery to it, it will get the same treatment, and stay at much less than full charge.

A B2B is a proper multi-stage battery charger that takes power from the alternator and provides as much charging power as the leisure battery needs. Maybe your MH is one of those that eddievanbitz mentioned, with a smart alternator but no B2B.

 

[pappajohn]

If you're still reading, buy a multimeter and Google how to use it.
It's the most useful piece of equipment you can buy and only 5 to 10 quid for a basic meter.

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[roadwarrior]

What sort of money are we talking about for a b2b installation and who can do it ?
I like the sound of the type that takes power from the alternator rather than the starter battery, mainly as my starter battery after driving is usually little more than about 12.6 but the van starts very easily. I am off to Brean again tomorrow so will take stock of the result of a 150 mile drive with fridge on as always. I will also try the urban myth of driving with my headlights on. Although if it had any basis I would have thought the fridge would have forced the higher voltage anyway.

 

[Lenny HB]

What sort of money are we talking about for a b2b installation and who can do it ?

Depends on the B2B as they range fromm £200 to £500 and depending on the van one to two hours labour maybe longer on some vans.

 

[roadwarrior]

Picking up on what autorouter said,WHY does the smart alternator keep the starter battery at much less than full charge ?? Seems to me an alternator only has one job- to charge batteries,and if it doesn't do that it's a chocolate teapot.

 

[roadwarrior]

Depends on the B2B as they range fromm £200 to £500 and depending on the van one to two hours labour maybe longer on some vans.

Ouch thank you.

 

[ED O'DARAC]

Picking up on what autorouter said,WHY does the smart alternator keep the starter battery at much less than full charge ?? Seems to me an alternator only has one job- to charge batteries,and if it doesn't do that it's a chocolate teapot.

It is a newish thing where it's 'other' job is to reduce emissions by only charging batteries when it doesn't use diesel. This really reduces the effectiveness of driving on charging, especially when your AES fridge switches to 12v when you drive. Solar is the only real answer imo.

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[IRHP]

Loads of comments about smart alternator. I think you should confirm you actually have one first. I know it's a 2020 vehicle but some converters specifically ask Fiat for no smart alternator. I have a 2019 (2020 REG) with a dumb alternator.

 

[roadwarrior]

Yes I defo have a smart alternator, as far as I know it's compulsory on euro6 vehicles. But yes, it's the bain of my life currently as my new to me merc autosleeper winchcombe 2016 was doing funny things like starting at 14.4 v and dropping after an hour or less and driving along at 12.4 and going back to 14.4 or more if I braked or slowed down ect which blew my mind at the time.

 

[funflair]

It is a newish thing where it's 'other' job is to reduce emissions by only charging batteries when it doesn't use diesel. This really reduces the effectiveness of driving on charging, especially when your AES fridge switches to 12v when you drive. Solar is the only real answer imo.

No solar isn't the only answer or even an answer at all if you want/need big charge current on the road, B2B or charge booster is the way to go, solar is great when parked up especially if the sun shines

 

[MisterB]

Loads of comments about smart alternator. I think you should confirm you actually have one first. I know it's a 2020 vehicle but some converters specifically ask Fiat for no smart alternator. I have a 2019 (2020 REG) with a dumb alternator.

How would I know what alternator I have? I just assumed it was a smart alternator.
Would there be any conflict if I fitted a B2B without knowing what type of alternator I had?

Fiat Ducato 130 multijet 2018 (Adria 670)

 

[Lenny HB]

Yes I defo have a smart alternator, as far as I know it's compulsory on euro6 vehicles

If its a Fiat it will only have a Smart alternator if it is Euro 6D, Euro 6C will have a standard alternator.

Fiat Ducato 130 multijet 2018 (Adria 670)

That will have a standard alternator.

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[roadwarrior]

im jealous - and grateful for the explanation on 6d and 6c, that would explain why i had noooooo issues with my fiat i just swapped.

 

[ontheroadagain]

Is having a smart alternator related to having stop/start?
Our motorhome is a 2021 Ducato 6D which I assume has a smart alternator, but it doesn't have stop/start.
I also don't think it has a B2B. I have looked in the usual places but I can't see one.

 

[autorouter]

Picking up on what autorouter said,WHY does the smart alternator keep the starter battery at much less than full charge ?? Seems to me an alternator only has one job- to charge batteries,and if it doesn't do that it's a chocolate teapot.

It's part of an idea to reduce fuel consumption, more applicable to a commercial vehicle with no leisure battery.

Charging the starter battery from the alternator normally puts an extra load on the engine, which increases fuel consumption. If you could arrange it so that the load on the engine only comes on when you lift off the accelerator, or press the brake pedal, then the extra load will assist the slowing down, and put otherwise wasted energy to good use..

However if the starter battery is already full, the charge will have nowhere to go. So a smart alternator keeps the starter battery less than full so there is always some space for the extra charge.

That's the theory, the practice is that a leisure battery simply connected to the starter battery with a split charge relay will also be less than full, which is not what is wanted.

A B2B takes power from the alternator in the same way as lights, wipers and fans, and outputs an optimised voltage for charging the leisure battery.

 

[roadwarrior]

and excellent clear description autorouter.
i just need to find someone to install one now.. anybody ? and any particular recommendations on make ?

 

[Guigsy]

A smart alternator is designed for optimal use in a car or panel van to minimise wasted energy. It'll put just enough power into the battery to keep your headlights on and to charge the battery after cranked starts. What it was never designed to do was offset the load from 20 amps of 3-way fridge.