B2B preference

[autorouter]

I think the extra 'voltage sense' wire that DBK describes is for connection to the habitation battery, and allows the B2B to compensate for any voltage drop between the B2B output and the habitation battery terminal.

Its purpose is precisely to overcome the problem of voltage drop that Raul describes. Sterling say it's only required for 'long cable runs', but don't say what they mean by a long cable run. However it won't do any harm to connect it even on a very short cable run.

 

[Raul]

Yes that second thin wire as DBK mentions is like a voltage sense to compensate for the voltage riple due to voltage loss. What I meant is, since these B2B are just dc-dc buck boost converters, on the input it doesn’t mater the voltage drop. It will take in anything from 7v to 18v and convert it according to the output setting.
AFTER the B2B(output) to the battery being charged the voltage drop should be almost null so you get to charge at that voltage setting.
I opted for a victron Orion, as these work to the voltage you adjust it to charge, and I got batt sense Bluetooth that is glued to the battery and terminal post for voltage. These feeds data to the charger and can compensate for voltage loss and temperature.

 

[Wagoneer]

For maximum efficiency, it's recommended to position the B2B as close as possible to the leisure batteries. It also makes it easier to connect the temperature sensing cable which is only approx 2m long.

I've just installed a Votronic VCC 30amp B2B. The terminals will take up to 16mm sq cable. It's possible to use larger sized cable but you'd need to reduce the cable size just prior to where it connects to the B2B terminals.

It would be useful to know the OP's 12v distribution system ie. CBE, Schault etc as this can impact on how you deal with disabling the existing split-charge relay.

 

[Stealaway]

When spring eventually comes the first job on the Moho this year is to fit a 30 amp B2B, I was just wondering about what make to go for.

Is Sterling really the best option or are there funsters who recommend others.

It will be fitted to a Euro 5 engine, and located at the rear with about 7 metres from the cab Bat.

Thanks in advance Alan

Why so far? Is there no where closer for it?

 

[Two on Tour]

Why so far? Is there no where closer for it?

Distance from the cab battery not as much as a problem as being too far away from the leisure battery. Shorter the cable run to the leisure battery the better.

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[AMK]

Why so far? Is there no where closer for it?

7mts is approx, I need to have a proper measure up before I order.

Trying to keep close to the Hab bat as possible.

 

[Bustup15]

Advice on fitting a Sterling B2B please.
All the diagrams show direct connection from engine battery to B2B and then to the leisure batteries. Do you need to do anything with the existing cables and connections to the Schaudt EBL e.g. Does this create a loop of some sort or confuse the existing electronics?

 

[Pausim]

Yes it will create a loop because the existing linking relay in the EBL will join the leisure and engine batteries when the alternator is running. This means that the power applied to your leisure battery by the B2B will also flow back to the engine battery through the original EBL linking relay and this in turn is powering your B2B. This could confuse the existing and new electronics.

My Votronic VCC1212-45 came with various wiring instructions for EBLs but I don’t see why the principles should not apply to other makes. This is the diagram I followed.

However if you use this arrangement your new B2B needs to be within the capacity of the Schaudt electronics, my Votronic unit has settings for input and output current that can be adjusted to be within the limits of the EBL and existing wiring/fuses.

I have now moved my B2B to a Carthago with a CBE DS not an EBL. The same problem of a loop arises, only this time I have resolved it by adding a relay that disconnects the leisure to engine battery link when the B2B is active.

 

[Wagoneer]

Advice on fitting a Sterling B2B please.
All the diagrams show direct connection from engine battery to B2B and then to the leisure batteries. Do you need to do anything with the existing cables and connections to the Schaudt EBL e.g. Does this create a loop of some sort or confuse the existing electronics?

The wiring diagram for the 30amp Votronic B2B shows how it is connected to a Schault EBL (connection plan no. 2). The existing EBL wiring is retained but the connection from the +'ve starter battery is disconnected.

However, best to discuss this with Sterling first, as they may have other views.

Edit: just seen the more detailed post by Pausim

 

[Bustup15]

Thanks for the replies and advice, I spoke with Sterling who were perhaps understandably non -committal due to the wide variety of models and manufacturer kit available.

I've emailed Schaudt to see if they can provide any definitive advice.

Failing that I can't see why disconnecting the existing + feed from the engine battery won't achieve the desired result?

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[autorouter]

The complication with an EBL is that some of the wiring is dual-purpose. For example, the starter battery is charged by the mains charger when the engine is stopped, along the same wires. The switchover is done inside the EBL.

The wiring for the Votronic B2B shows how this functionality can be retained, while still allowing the B2B to charge the Leisure battery separately. Instead of just connecting the batteries directly together when the engine starts, like a standard split charge relay does.

 

[Stealaway]

Have you seen Charles Stirling on You Tube?

 

[Pausim]

The complication with an EBL is that some of the wiring is dual-purpose. For example, the starter battery is charged by the mains charger when the engine is stopped, along the same wires. The switchover is done inside the EBL.

The wiring for the Votronic B2B shows how this functionality can be retained, while still allowing the B2B to charge the Leisure battery separately. Instead of just connecting the batteries directly together when the engine starts, like a standard split charge relay does.

The main EBL 50A connection to the engine battery is isolated from the the leisure battery by the the internal separation relay, except when the engine is running. I don’t think this connection affects the mains trickle charge to the engine battery. On the wiring diagram for the Schaudt EBL 29 there is a connection at 8 on Block 3 which is not cut off by the separation relay and seems to be the connection for the trickle charge. See diagram below.

This terminal connects to a different relay marked charging relay engine battery, which is fed and activated by the mains charger. In conclusion if your EBL is wired in this fashion interrupting or disconnecting the larger connection intended for engine charging of the leisure battery should not stop the mains charging of the engine battery. When I had an EBL and B2B the trickle charge was not affected, there was a separate 20A fused wire alongside the 50A fuse next to the engine battery, which I took to be the relevant one.

 

[autorouter]

When I had an EBL and B2B the trickle charge was not affected, there was a separate 20A fused wire alongside the 50A fuse next to the engine battery, which I took to be the relevant one.

That 20A fused wire takes power to the fridge 12V element (if there's an AES fridge) when the engine is running, and is also as you say used for the starter battery trickle charge when the engine is stopped and MH hookup is connected.

 

[Bustup15]

Here is the reply from Udo @ Schaudt. Not conclusive - yet!

'I would wire the sterling directly to the battery. The EBL is find with that.
Eventually you must cut the wire at the EBL starter battery entry. But this might not be a problem to stay like it is. (But it is a thing of testing yourself).

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[DBK]

Trying to keep close to the Hab bat as possible.

Ideally it should be as close to the cab battery as possible because the current flow from the cab battery will be greater than that going to the leisure batteries because of the voltage difference. However, with decent sized cables it won't be an issue and practical considerations around finding a suitable spot are likely to be the deciding factor.

 

[The Coops]

B to B is Business to Business in my old world, can someone explain what on earth the above conversation is on about! I understand the battery bit but once the physixs starts about ohms volts amps and wattage my brain switches off. Can someone do an *idiots* guide or explanation of what you are talking about I understands one battery to another and wired in series or parallel and then my physics class ended............

 

[Bustup15]

At the risk of being shot down

Battery to battery charger.

Using the engines alternator to efficiently and quickly charge the leisure batteries whilst the vehicle is in motion

 

[Stealaway]

B to B is Business to Business in my old world, can someone explain what on earth the above conversation is on about! I understand the battery bit but once the physixs starts about ohms volts amps and wattage my brain switches off. Can someone do an *idiots* guide or explanation of what you are talking about I understands one battery to another and wired in series or parallel and then my physics class ended............

Have a look at the videos

 

[dochiley]

Sorry to sound stupid/naive but if the 2nd battery is close to the first can't you simply wire them in parallel and use existing controller

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[Bustup15]

Sorry to sound stupid/naive but if the 2nd battery is close to the first can't you simply wire them in parallel and use existing controller

Not possible as my 2 leisure batteries are 7 metres from engine battery.
If you look at the Sterling videos it explains the issues of simply connecting them together.

 

[autorouter]

There's two ways to charge a leisure battery in a vehicle.

The standard way is to simply connect the leisure battery in parallel with the starter battery, so that the alternator thinks there's one big battery to charge. A split charge relay connects them when the engine is running, and disconnects them when the engine stops.

Another way is to have a 'Battery to Battery' (B2B) Charger to charge the leisure battery, which gives a controlled voltage and current to the leisure battery. The B2B input side draws power from the alternator/starter battery in the same way that fog lights, wipers or fans draw power. The electronics in the B2B boosts the voltage and current to whatever is best for charging the leisure battery.

Typically a B2B charger gives faster and more complete charging. B2Bs are more relevant nowadays, especially with 'smart alternators' that are designed to only partly charge starter batteries.

 

[Grimsbygranny]

There's two ways to charge a leisure battery in a vehicle.

The standard way is to simply connect the leisure battery in parallel with the starter battery, so that the alternator thinks there's one big battery to charge. A split charge relay connects them when the engine is running, and disconnects them when the engine stops.

Another way is to have a 'Battery to Battery' (B2B) Charger to charge the leisure battery, which gives a controlled voltage and current to the leisure battery. The B2B input side draws power from the alternator/starter battery in the same way that fog lights, wipers or fans draw power. The electronics in the B2B boosts the voltage and current to whatever is best for charging the leisure battery.

Typically a B2B charger gives faster and more complete charging. B2Bs are more relevant nowadays, especially with 'smart alternators' that are designed to only partly charge starter batteries.

Thank you 'autorouter' for an explanation I can understand!

 

[The Coops]

Thanks connect them in parallel if they are near each other or use a split relay or whatever a sterling is (was pounds, SAS hero or an engine in my book) if too far apart. Why all the fuss surely if a greater distance apart you reduce the resistance to ensure the correct charge with the connecting wire...........I'll get my coat

 

[Pausim]

B to B is Business to Business in my old world, can someone explain what on earth the above conversation is on about! I understand the battery bit but once the physixs starts about ohms volts amps and wattage my brain switches off. Can someone do an *idiots* guide or explanation of what you are talking about I understands one battery to another and wired in series or parallel and then my physics class ended............

I think Bustup15 and others have answered this but here is my take on it.

With most but not all motorhomes the charging of the leisure battery whilst driving is incidental to the charging of the engine battery. Historically not too much of a problem because we demanded less of our 12V electrical systems and the two batteries were probably of a similar chemistry (type).

However some of us now find that our leisure batteries are not keeping up and the nice manufacturers have found a new way of relieving us of our pocket money by making a B2B product that makes us happy again. This is happening even more often because some of us have been spending some of our pocket money on new toys like LiFePO4 batteries and these like to be charged differently from lead acid engine batteries.

On top of this motor vehicle manufactures have been told to stop polluting the planet and now have to call their engines Euro 6, or Euro VI if they are descended from a Roman. Before they can call their engines Euro 6 they are obliged to fit lots of clever devices. They even had to pass an easy home examination to show that their engines were properly called Euro 6. It seems that some of them were caught cheating in this exam. It is very likely that most of them were cheating because now that the examination has started to be supervised by external invigilators they mysteriously seem to be turning on or fitting all the clever devices. One of these devices is known as a Smart Alternator, because he has a couple of GCSEs. Being a smart kid with a couple GCSEs Smart Alternator read his Contract of Employment and noticed that his job description said he needed to keep the engine battery fully charged, no mention of a leisure battery. As a result he downed his tools as soon as the engine battery was full and read his daily comic instead, leisure batteries are not his problem. His canny employer has come up with a clever solution, called B2B. B2B is in charge of leisure batteries and takes some electricity from the engine battery to keep his batteries properly charged. Now Smart Alternator has to put down his comic and work harder because his job is to keep the engine battery full and nothing in his contract says that someone else can’t use electricity from it.

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[Pausim]

B2Bs are more relevant nowadays, especially with 'smart alternators' that are designed to only partly charge starter batteries.

Sorry don’t agree with that last bit, I think smart alternators fully charge the engine battery but then shut down, usually before the leisure battery is fully charged.

 

[Diabalo]

I have been looking into fitting a B2B but it's confusing. I have a Sargent EC500 Psu that has the split charging built in and Sargents advice is don't fit a simple battery master as it will confuse the Psu, so God knows what a B2B would do to it.

 

[leggings]

When spring eventually comes the first job on the Moho this year is to fit a 30 amp B2B, I was just wondering about what make to go for.

Is Sterling really the best option or are there funsters who recommend others.

It will be fitted to a Euro 5 engine, and located at the rear with about 7 metres from the cab Bat.

Thanks in advance Alan

I fitted a sterling B2B about 5yr ago and no problem. When a transferred it to my present vehicle I phoned for advice which I received straight away.

 

[autorouter]

Sorry don’t agree with that last bit, I think smart alternators fully charge the engine battery but then shut down, usually before the leisure battery is fully charged.

There's a bit more to it than that. Smart alternators are part of the 'regenerative braking' system. The idea is that alternators switch on during braking, and the extra load causes drag, so that otherwise wasted energy is used to charge the battery.

That can't be done if the battery is already full, so the alternator shuts off normal charging to leave space for the charge during braking. At about 12.2V, I think.

 

[Deneb]

There's a bit more to it than that. Smart alternators are part of the 'regenerative braking' system. The idea is that alternators switch on during braking, and the extra load causes drag, so that otherwise wasted energy is used to charge the battery.

That can't be done if the battery is already full, so the alternator shuts off normal charging to leave space for the charge during braking. At about 12.2V, I think.

Yes, smart charging systems, particularly with start/stop technology, aim to keep the vehicle battery about 80 - 85% charged, so that the battery is always able to accept additional charging under regenerative braking.

The charging system on my Volvo regulates the battery to 80% SOC. When I put it on a smart charger, which I do when we are away for any length of time in the van, it is fully charged, but as soon as the charger is disconnected the car electronics will fairly quickly return it to 80% SOC. The downside is that it is not as forgiving of being unused for more than a few weeks, as there is less capacity in the battery to cope with standby current draw.

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