is charging the leisure battery from cab alternator a problem?

[Timbob1961]

I'm new to motorhomes and am picking up discussion of b2b equipment.
Is there really a problem needing solving, what is it exactly,are all motorhomes affected?
Why are manufacturers not implementing it?
Looking to be educated.
Thanks Tim

 

[Tombola]

Sorry Timbob, can you explain more.
SOme leisure batteries will have problems if charged form alternators, Lithium especially , but then some alternators send enough via relays.

What do you have and what are you looking to do

b2bs if required are great

 

[Timbob1961]

I am about to take delivery of an Adria Matrix 2018..Fiat Ducato based.
I am wondering if this will be an issue that needs solving...
Thanks

 

[Lenny HB]

I am about to take delivery of an Adria Matrix 2018..Fiat Ducato based.
I am wondering if this will be an issue that needs solving...
Thanks

Probably be OK, it is Brit built vans that are the worst as the cabling is way undersized.

 

[David and Sally]

Our 2014 Adria charged the leisure battery from the engine.

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[Timbob1961]

Thanks

Smart alternator is another topic, is this an issue?
ie alternator outputting only according to the needs of the cab battery

 

[pappajohn]

Charging the leisure battery from the alternator via a split charge system can take many hours of driving depending how discharged the battery is.
A B2B works by tricking the alternator into thinking the starter battery is flat so the alternator puts out much more current than it normally would.
If you have solar panels and mainly use campsites with hook up you won't need a B2B.
If, on the other hand, you don't use sites with hookup and don't drive far a B2B will help.
A B2B can charge at up to 60amps with the engine running.
A split charge system can be just a few amps if the wiring is a bit on the small side.

 

[David and Sally]

I think you may be worrying too much.

Put a multimeter over the hab battery and cab battery if you want to know if they are charging when the engine is running.

 

[Timbob1961]

Are smart alternators not used in motorhome conversions?

 

[Stealaway]

I've never managed to decide, I just fitted a Sterling B2B charger.
There are a selection of videos on YouTube from Sterling about installing B2B chargers that might give you a clue

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[autorouter]

It depends on your lifestyle. Some people mostly use the motorhome in the summer, are out walking all day, and sit outside chatting all evening, cooking on the barbecue. Their total electrical demand is very small, and a single 100Ah battery is perfectly adequate, especially if there's 100W of solar panel.

Others use the motorhome in all seasons and weather, use the laptop for work, watch TV for hours, and use a compressor fridge, microwave, coffee machine, hairdryer, and charge electric bikes. Their electrical demand is large, and even 300W of solar won't be enough. They'll want to charge up multiple leisure batteries fast as they drive.

For these people, a simple split charge relay that parallels all the batteries to the alternator won't be enough. Usually the alternator maximum into the batteries is about 30A, and often less. It falls off as the batteries charge. And that's before we mention smart alternators, which are designed to keep the batteries well below full charge.

A good B2B will consistently output 60A, and will keep charging until the leisure batteries are fully charged. It's the only way to charge up 300Ah of battery in finite time.

 

[Timbob1961]

It depends on your lifestyle. Some people mostly use the motorhome in the summer, are out walking all day, and sit outside chatting all evening, cooking on the barbecue. Their total electrical demand is very small, and a single 100Ah battery is perfectly adequate, especially if there's 100W of solar panel.

Others use the motorhome in all seasons and weather, use the laptop for work, watch TV for hours, and use a compressor fridge, microwave, coffee machine, hairdryer, and charge electric bikes. Their electrical demand is large, and even 300W of solar won't be enough. They'll want to charge up multiple leisure batteries fast as they drive.

For these people, a simple split charge relay that parallels all the batteries to the alternator won't be enough. Usually the alternator maximum into the batteries is about 30A, and often less. It falls off as the batteries charge. And that's before we mention smart alternators, which are designed to keep the batteries well below full charge.

A good B2B will consistently output 60A, and will keep charging until the leisure batteries are fully charged. It's the only way to charge up 300Ah of battery in finite time.

Thanks
I am considering off grid so topping up when moving sounds a good idea.. 1 hour of engine will top up the depleted leisure battery at 60 amps.

Sterling was mentioned, any others recommended?
Thanks

 

[Langtoftlad]

It often gets very technical here... and whilst not wrong, most of the suggestions are unnecessary.

Motorhomes just work as they're meant to for the vast majority of users.

Don't look for problems unless they arise.

 

[Timbob1961]

An excellent video by Sterling



thanks guys..
Tim

 

[Timbob1961]

It often gets very technical here... and whilst not wrong, most of the suggestions are unnecessary.

Motorhomes just work as they're meant to for the vast majority of users.

Don't look for problems unless they arise.

Will see how I go..

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[Phill D]

without doubt the best way is ..... wait until you get it " use it as you intend! as / when you get a problem or need additional power .... then fix it... unless you have a desire to cover every eventuality even though you may not need it ( and there is nothing wrong with that as long as you have deep pockets ). we all do a bit of it.

i like to keep a note pad handy as each time we go on a trip i come up with something i didnt know i needed

 

[Lenny HB]

Are smart alternators not used in motorhome conversions?

Mercs for quite a few years, Fiat since 2019 with the Euro 6D engine.

 

[ChrisL]

Another point to consider is that some (if not all) b2b's as well as boosting the current to the battery whilst charging, once the battery is fully charged will drop the voltage to the ideal float voltage depending on the battery type, some also have an optional temperature sensor input so that the battery is charged at an optimal voltage depending on the battery temperature.

 

[cmcardle75]

It often gets very technical here... and whilst not wrong, most of the suggestions are unnecessary.

Motorhomes just work as they're meant to for the vast majority of users.

Don't look for problems unless they arise.

The only problem there is that if you don't have enough charge, the lead acid batteries can be destroyed. Then you need to buy a B2B charger AND a new battery.

 

[filopastry]

Coupleurs-Séparateurs | Scheiber | France

Les coupleurs-séparateurs Scheiber sont indispensables pour gérer une batterie auxilliaire : disponibles en 12Vdc ou 24Vdc

www.scheiber.com

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[autorouter]

Sterling was mentioned, any others recommended?

Votronic, who also make solar controllers, make a B2B but they call it a booster, I think. They also do a combined mains/solar/B2B unit. Victron also do a B2B, called Orion. Schaudt, who make the popular Electroblock 12V charger/distribution box, also do a 'booster'.

 

[StuartB]

I think the OP is in a similar position to me, waiting what seems forever for your MH to be delivered. Whilst at the same time reading about all the plethora of mods you can fit to MH's, all implying that the delivered MH will be inadequate in many ways. After 6 months of this I have finally decided to do as Langtoftlad suggests, give the MH a good try and see what we need personally. Suspect if we are mainly on EHU the basic set up will be fine, and then it will depend on how much time we spend without EHU that will drive the need for any mods. The only thing we will do initially is to install a second leisure battery, and this only now because the MH will come with a lithium battery, and my time is limited to fit a second lithium alongside the new one.
Great to learn from all you guys and girls about motorhoming, and we can't wait to get started.

 

[TinaLes]

Charging Lithium's from standard alternators can have worrying consequences in that they can overheat, in delivering higher charge rates so have a look at this informative Victron film if worried before installing a B2B, or Lithium's to a standard alternator set up.
I know some vans sometimes have upgraded Alternators, but its worth checking beforehand. There seems to be many opinions on this, but I would always want to check by doing a full schematic showing batteries, BMS, and battery overcharge/SOC cut off protection, plus of course frost protection to stop charging below 6%C and getting it approved, before fitting. The Solar MPPT regulator also needs protection from BMS shutdowns.
LES

 

[TinaLes]

Just checked on Eurocarparts, I hope it correct when it states the standard alternator replacement for the Ducato 2.3 multijet X290 is Lucas one, rated at 140 amps and costs £274.99, The Balmar ones discussed in The Victron video with built in temp sensor & regulator, say goodbye to £800 plus
LES

 

[Kannon Fodda]

Interesting stuff on the alternator potential to overheat. What they don't show in that video is the rating of the standard alternator so no idea what sort of headroom there might be when you think the alternator is powering the vehicle electronics as well as trying to charge. That Victron test seems to be using the biggest rated B2B they could get, so they could pull all the current and more of their alternator, and also a battery needing some 150Ah of recharging (if they took the 300Ah down to 50%). But the max load they had only got to 75A off the standard alternator, suggesting the alternator they were using wasn't that heavy a duty?

It does seem that, ignoring any smart alternator type stuff, simply for my 2.3 2019 Ducato, on EuroCarParts there are a number of different rated potential replacements. I'd have to delve into the engine to see what I currently have, but they list everything from the compatible unbranded 110A rated up to a 180A Lucas annotated "climate control".

If a 60A rated B2B was too much, and burning out alternators, by now this forum would have heard about it.

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[autorouter]

That Victron test seems to be using the biggest rated B2B they could get, so they could pull all the current and more of their alternator, and also a battery needing some 150Ah of recharging (if they took the 300Ah down to 50%). But the max load they had only got to 75A In the videotoff the standard alternator, suggesting the alternator they were using wasn't that heavy a duty?

In the video they were not using a B2B. The lithium battery was connected direct to the alternator, much like it would be if using a split charge relay.

As the alternator speed drops, the voltage drops too. A lead-acid battery draws less current when that happens, but a lithium battery doesn't draw less current. However the alternator cooling is reduced at low speed, so is can overheat.

Using a B2B will control the current to the B2B spec, which would be enough to prevent overheating. However it's true that using too high a B2B current, or maybe two B2Bs in parallel (yes, at least one Funster does this) could still cause overheating at low speed.

 

[denisejoe]

our old van charges the leisure battery from the alternator and charges the engine battery from solar with the connections that the van was supplied with it all depends what the manufacturer has put in

 

[Maluisarot]

Loving all the information in this thread . Apologies in advance for hijacking it a bit.

We're new to motorhoming and just got a 2013 Chausson with a completely shot 100Ah leisure battery and deciding what to do about a replacement. We're pretty sure we'll want to spend most of our time off EHU, likely for a week at a time, so have been thinking a LiFePO4 upgrade would be good but given how expensive they are, we couldn't afford to be replacing the alternator soon after fitting the battery

Could it be possible our unit might have a B2B charger already and what would be the best way to check?

Trying to get my head around the different ways leisure batteries charge. Charging off EHU seems straight forward and I'm guessing this has nothing to do with the engine running. Split chargers have so many different types they really confuse me: Standard, Voltage sensing, Battery isolator, Diode Split. How would I find out which is fitted?

KS Energy, who we're thinking of getting the battery from, sell it as being a direct swap for a Pb battery. Does this sound right or is it marketing nonsense and the charging system of the van wouldn't appreciate it? Is it really as simple as swapping the battery or would I need to change the EHU driven charger and the charging system between the leisure battery and alternator?

 

[cmcardle75]

Loving all the information in this thread . Apologies in advance for hijacking it a bit.

We're new to motorhoming and just got a 2013 Chausson with a completely shot 100Ah leisure battery and deciding what to do about a replacement. We're pretty sure we'll want to spend most of our time off EHU, likely for a week at a time, so have been thinking a LiFePO4 upgrade would be good but given how expensive they are, we couldn't afford to be replacing the alternator soon after fitting the battery

Yes, LiFePO4 is ideal for going off-grid for long periods.

Could it be possible our unit might have a B2B charger already and what would be the best way to check?

It is unlikely that you wouldn't already know.

Trying to get my head around the different ways leisure batteries charge. Charging off EHU seems straight forward and I'm guessing this has nothing to do with the engine running. Split chargers have so many different types they really confuse me: Standard, Voltage sensing, Battery isolator, Diode Split. How would I find out which is fitted?

It doesn't matter. If you have split charge relay, it basically isn't acceptable for off-grid or Lithium usage.

KS Energy, who we're thinking of getting the battery from, sell it as being a direct swap for a Pb battery. Does this sound right or is it marketing nonsense and the charging system of the van wouldn't appreciate it? Is it really as simple as swapping the battery or would I need to change the EHU driven charger and the charging system between the leisure battery and alternator?

It's marketing nonsense. For off-grid Lithium usage, you need a B2B charger, and probably a decent mains charger when you get emergency EHU or are at home preparing to leave. Ideally, you'd also have an MPPT solar controller and lots of solar panels.

This depends on your usage profile. If you do lots of driving in winter, then the B2B is most important. If you do lots of sitting around in the sun on the beach, the solar/MPPT is more important. If you do lots of sitting around in northern Scottish winters, then god help you.

 

[Tombola]

Yes then if going for a new battery and wanting a week or so off grid then solar and b2b are ethe way to go.
You dont need to worry about changing the alternator.

What set up do you have at the moment, do you have solar, what size panel do you know and what solar regulator.

A decent solar set up with an MPPT regulator aswell as a b2b should see you fine.

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