# B2B Charger...my Tale of Woe



## TheFlups (Nov 9, 2012)

Before I begin with my tale of woe I should state that I have no knowledge of vehicle electrics or solar power and how it all works at all! I can string a few words together though, so here goes.

This is all about a Ctek Dual250S B2B Charger and whether it’s working properly or not! We spend a lot of time ‘off-grid’ so I had this unit fitted because I thought it would allow us a bit more freedom and that we wouldn’t have to worry as much about power.

Since getting the Ctek Dual250S B2B Charger fitted by my Bailey dealer on my new (May 2014) Bailey 750 Approach Autograph motorhome, I have suspected that it may not be functioning as Ctek intended.

A bit of background…I have 2 x Banner 100amp hour batteries on the domestic side and a 100 amp hour battery as a start battery. All 3 were new this year with the van and are Banner's. Also installed by my dealer are 2 x 130amp Solar Panels. The vehicle when delivered by Bailey to the dealer has fitted a BCA Power Distribution Unit and Control Panel and it can charge both leisure and starter batteries when connected to 230v AC.

The reasons I became suspicious of the Ctek charger and began the following thought process, were as follows:
1. The 20amp fuse between the Ctek Dual250S B2B Charger and the starter battery had blown...I am not sure when this happened and how long ago!
2. The BCA Control Panel on the motorhome, twice sounded an alarm saying 'low starter battery voltage' (the vehicle has never failed to start)
3. The BCA Control Panel indicates 13.0v at rest for the leisure batteries and only 12.5v for the starter batteries.

I am confident that the alternator is working as I have put a tester on the start battery when the engine is running and I am confident that the leisure batteries are being charged whilst the engine is running. I am also confident that the two 130amp solar panels are charging the leisure batteries. They appear connected via the Ctek Dual250S B2B Charger. The leisure batteries are monitored by a Victron 600S Battery Monitor and I can see the effect of the solar panels on the reading when it's bright outdoors and the engine is not running. Having replaced the fuse mentioned in 1. above, the fuse has not blown again!

The bit that I'm not confident about is I don't think the Ctek Dual250S B2B Charger is charging the start battery! It should do this when the leisure batteries are full which they are.

I have tried to digest as much information as I can on the internet and as a result I am now very confused and have further concerns which I will now detail.

a. I understand that the Ctek is also a MPPT controller...this begs the question whether or not the solar panels fitted by my dealer already had a controller built in and I now wonder if the fitter disabled the original (if there was one) as some research I have done recommends.

b. Has the BCA Power Distribution Unit's ability to split charge been disabled or indeed should it have been and could this lead to a conflict between the mains charger and the Ctek?

c. Is the BCA Control panel affected by the fitting of the Ctek and is it now accurate? I should say that in the whole time I have owned the van that this panel has been inaccurate on Inside Temp/Outside Temp, Waste levels and Fresh Water Levels! 


As far as I can tell with my limited knowledge, my dealer/fitter has wired the Ctek up correctly as per the simple diagram in the manual...however...the manual says nothing about other charging equipment that might already be fitted and neither does it comment about other solar controllers that maybe fitted already!

So as you can see, I am in a bit of a pickle and in all honesty, I have considered having the Ctek removed, which would be a shame because all the reading I have done on it indicates that it is a very good bit of kit!

I realise that I have rambled on a bit here but I felt it best if folk were aware of all the facts as I know them. I live in Dorset so Roadpro are a long way for me to travel but I think they are the main Ctek agent in the UK. Eddie at Vanbitz is closer and very good but I don’t think he does Ctek stuff or indeed would want to look into my can of worms!… If anyone knows of an expert who I could contact to help, that would be useful.

Any other help/comments please?


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## WildThingsKev (Dec 29, 2009)

I have a Votronic b2b which I fitted myself so have some knowledge of the complexity of these things - even on your own vans familiar electrical system.

Quick thoughts are.

1. The 20 A fuse that blew is not enough for a 20A charger, it should be at least 25A or even 30A. It probably blew when your batteries were low and since you replaced the fuse you haven't loaded the b2b to maximum charging. Put in a 30A fuse and no further worries.

2 + 3. After how long disconnected from mains? The Vehicle Battery on x250s will drop fairly quickly once off charge, mine will be down to 12.5v about 3 days after being fully charged.

Does the d250s show you what it is doing, ie are there lights indicating what charge is going where? It may be that the solar panels are not raising the batteries to a high enough voltage for the d250s to consider them fully charged, ie about 14.4v. It could be that the old solar reg is still in line and this would have that effect but I seriously doubt it is.

Also, presumably, after a long drive the VB is showing fully charged? Does the d250s continue to operate for long after stopping the engine or stop immediately the ignition turns off? (on mine there are several settings / installation options).

Mains hookup: mine is CBE but what happens is this. When it is on it obviously charges the leisure batteries but there is a control wire from the battery charger to the CBE unit which tells it to also trickle charge (2A) the vehicle battery.

Kev

edit; presumably the VB is being trickle charged when on hookup, it's just when on solar alone it is not charging?


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## coppo (May 27, 2009)

I posted a while ago about the ctek dual, have a search of my posts.

I am disappointed with the solar aspect of this unit, it is no where near as good as my previous votronic regulator.

When there is about 90% remaining in the batteries according the victron monitor the ctek puts in around 10amps when driving, which is about correct.

Paul.


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## DustyR (Jan 26, 2009)

I fitted the CTEK Dual 250 BTB myself and I have a 100w panel fitted and I also notice my VB drops to around 12.5v after a few days laid up.

However, when the LB is full I do notice the indicator lamp on the CTEK shows the VB charging and the voltage rises to around 12.9v for a day or so before dropping back gradually to around 12.5v. so I am happy that both batteries are being topped up.


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## camoyboy (May 9, 2005)

Hi,
If the fuse between the starter battery and Ctek was blown, and the leisure batteries showed a charge with the engine running, this would point to the original van split charge system still working. The van split charge must be disconnected for the Ctek to work correctly.

There is a light system on the Ctek which shows what is being charged, either by solar or alternator. When the leisure batteries are topped up and there is suficient power from the solar panels, then the starter battery lamp will illuminate to show it is being charged. Our starter battery has never dropped under 12.6V so I haven't seen this working yet.

I bought our Ctek secondhand and I contacted Ctek via email to find out if I could connect it into the CBE distribution board on our Rapido. They were very helpful is supplying a diagram with what to do. Although my Swedish is not great I managed to get it all working to my satisfaction. The only problem I have is the battery display gives strange readings for the amp output, but the voltage seems to be OK. I am planning to get a NASA monitor to hopefully get more accurate figures.

Colin


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## TheFlups (Nov 9, 2012)

> Quick thoughts are.
> 
> 1. The 20 A fuse that blew is not enough for a 20A charger, it should be at least 25A or even 30A. It probably blew when your batteries were low and since you replaced the fuse you haven't loaded the b2b to maximum charging. Put in a 30A fuse and no further worries.
> 
> ...


[/quote]

Hi WildThingsKev
Okay, I will try a 25amp fuse..understood. I will check time when I get van back...it's in Devon now having Air Suspension fitted.
When engine is running the Alt lamp is lit on the Ctek and when daylight so is the Solar Panel lamp and of course the battery lamp.
After a good run and turning off the engine the alt lamp goes out on the Ctek straight away.
Also my BCA panel has software built in where I can specify whether to charge starter battery as well as leisure battery...it's configured to 'on'.

Coppo
I have read your post...it was one that made me put pen to paper as it were...it's just that i smelt a rat on my set-up!

DustyR
Thats very similar to mine but I have not noticed the indicator lamp on the CTEK shows the VB charging when the engine is not running.

camoboy
Yes...I think this is possibly where the problem lies...the original van split charge system still working...I'm not sure how to check that but you're probably right. There ws nothing in the manual to say disconnect it!
I also have never seen the Alternator lamp on the Ctek on when the engine is not running.

Thanks everyone who is helping on this...I think in the most part it's working ok but there are so many red herrings it's easy to be sucked in! I'll get there in the end!! :roll:


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## nicholsong (May 26, 2009)

I have a Sterling B2B and my original charger is an Elektroblok.

I was advised to wire the B2B direct to the batteries and not through the Elektroblok. However like Colin above the ammeter gives strange readings but the system works.

Also a newish solar panel is wired via its own regulator direct to the batteries.

You could try separating the systems in this way.

Geoff


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## coppo (May 27, 2009)

Yes you definitely need to check the original split charge and disconnect this.

Remember it is only a 20amp charger and the most it will put in is 20amps. So if your batteries are at, say, 50% remaining then it will only put in 20amps. A good split charge system with thick wiring will probably put in more than this if there is 50% remaining.

It when there is, say, 85%-90% remaining that the split charge is useless, ours put in around 5amps and then as the battery gradually got fuller it trickled off to next to nothing, so the last few % took ages/hours with the original split charge.

This is where the B2B comes in and will continue to put in around 9 or 10amps until full, so the last few % are the important bits, as with the split charge system you never arrived at the next stop with full batteries.

The Sterling B2B will deliver 45-50amps so will charge much quicker than the ctek. Ours is doing what its supposed to do when driving, it is the solar asoect I am disappointed with. I was hoping for someone to check their dual against another mppt controller although no one has yet got back to me.

Paul.


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## DustyR (Jan 26, 2009)

TheFlups

I should have expanded my statement in that the VB indicator on the CTEK lights up only occasionally ( usually on a sunny day ) as a result of the solar panel having topped up the LB. 

I have not noticed the state of the indicator lamps when engine running as after a reasonable drive both batteries show about 13.2v


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## TheFlups (Nov 9, 2012)

Thanks Paul, Geoff and DustyR. There does seem general agreement that the original charger must stay out of the configuration...I've learned that at least and when I get the van back at the end of the week I shall set about disabling it.

What happens on EHU then though? Presumably the 230v still charges the leisure and the Ctek takes care of the starter hence B2B? I think I'm getting it!!

Paul...hopefully I'll be able to assist you if I get the Ctek operating as it should because I'll be in Spain after 12th Jan, hopefully in a drop of sunshine!


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## Jean-Luc (Jul 21, 2005)

I have a Stirling B2B which is connected directly to the leisure batteries.
Because of concerns about back feeding or 'circular circuits' I have fitted a relay which isolates the leisure batteries from the van system so that they are only connected to the B2B output once the engine starts charging.
The original split relay system is still in place and when the engine is running all the habitation stuff, fridge, water pump, lights etc. etc. runs as normal on the juice supplied from the engine battery.

This system is now in place for nine trouble free years.
Engine battery is now 10 years old and habitation batteries were replaced for the first time last year.

Obviously the charge from the B2B does not show on the control panel as when the batteries are being charged there is no connection to the van system.

See attached photo


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## WildThingsKev (Dec 29, 2009)

> "Jean-Luc" I have a Stirling B2B which is connected directly to the leisure batteries.
> Because of concerns about back feeding or 'circular circuits' I have fitted a relay which isolates the leisure batteries from the van system so that they are only connected to the B2B output once the engine starts charging.
> The original split relay system is still in place and when the engine is running all the habitation stuff, fridge, water pump, lights etc. etc. runs as normal on the juice supplied from the engine battery.
> 
> ...


I did exactly a Jean-Luc has posted after reading his earlier posts, one thing I was concerned about was whether the truma water dump valve would open during the milliseconds of changeover, it doesn't.

Kev


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## Christine600 (Jan 20, 2011)

I'm not sure what the B2B part means - I'm not sure I have that on my Ctek 250S Dual.

But I know that on scandinavian MH forums the Ctek 250S Dual is popular. But it's important that it's connected directly to the leisure battery and not trough the onboard charger logic in the MH. If so they step on eachothers toes and the 250S does not work properly.

This is contrary to what Ctek advice for motorhomes!

I managed without EHU the whole summer thanks to my 250S connected directly to my two leisure batteries.

We got our info about the best way to fit the 250S from a Norwegian and a Swedish forum. I'm sure both will understand English and help out if you are interested in knowing more. The threads I have bookmarked are:

http://www.bobil.dk/forum/viewtopic.php?f=8&t=783

and

http://www.husbilsklubben.se/forums/t68034-2/#post535532
(you may have to pay to post on this site)

On these fora a user named Rusken have posted a wiring diagram.


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## Christine600 (Jan 20, 2011)

This is the one I have - is it the same as yours?

http://www.ctek.com/lt/en/chargers/D250S DUAL


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## TheFlups (Nov 9, 2012)

Yes I have that image in my Manual and I have seen it on the SCtek site....the wiring diagram I found on the Norwegian Forum is attached...I have also pm'd you with it.


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## TheFlups (Nov 9, 2012)

Also here is the picture posted of the set-up on the Ctek charger itself...


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## Christine600 (Jan 20, 2011)

TheFlups said:


> Yes I have that image in my Manual and I have seen it on the SCtek site....the wiring diagram I found on the Norwegian Forum is attached...I have also pm'd you with it.


I will translate the labels:

Solcellepanel 
Solar panel

Jord 
Earth

Generator spenning 
Voltage from generator

Bodel batteri 
Leisure battery

Batteribank 
Battery bank

Spenning fra bobilens el-sentral til bodelbatteri 
Voltage from EBL to leisure battery

And the 30 85 86 87 87a is a relay switching between original EBL charging (when parked) and Ctek charging (when driving).
This because the Ctek breaks the connection back to the EBL when it is not charging. So we need the original conection to get power from the battery.

If the Ctek is connected to the EBL and not to the battery like Ctek suggests then we do not need the relay. But then it won't give the optimal charge to the battery either. So not much point.

In both cases (relay positions) power from the solar will charge the battery.

In addition to the diagram fuses should be added. On my van we needed a 70A fuse on the generator line.

I can try to explain further and answer questions - but I think I have explained all I know about this.


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