Split-Chargers & Bluemotion

[travelvolts]

I firmly believe that VW over looked the split charging aspect on BMT equipped vans when the smart alternator was introduced. Having said that it doesn't change the fact that using any relay based system will result in very poor charging of an aux battery. The answer to the problem posed in the post that you quote is to fit both VSR and DC-DC systems. Because the DC-DC system will pull power from the vehicle battery it will keep alternator output high and therefore allow the VSR system to pass the demands of the inverter. I would use a Redarc BCDC1240LV alongside one of our SC120 split charge systems which uses the Victron Cyrix-CT VSR.

 

[Dellmassive]

It depends whether you want an efficient system or not. Fit a VSR and you won't get much charging.
Fit a DC-DC system and enjoy rapid charging to 100%. It's a no brainer really.

Agreed, Though when we were monitoring the current flow before we noticed something.

the T5gp had a 180Amp alternator, a starter battery, split charge relay, a leisure battery.

even though the alternator was capable of producing 180A of current, when the starter battery was say 90% full we saw only 8amps going into the battery.

when the starter was 60% full we saw 25Amps going into the battery.

when the AUX battery was 30% full we saw 28amps going in, which slowly reduced as the charge topped up.

when both batteries were charging we saw the combined Amperage being drawn fron the Alternator @ about 60amps.......

but at no point did we see 180amps being "pushed" into the batteries.........(the max of the alternator)

so that being said . . . . . . . if we had a 60Amp Sterling DC-DC charger, the batteries have there own internal resistance etc, they wouldnt take the 60amps outright,

they would take say the 20-30amps each which would slowly decrease as the battery % charge increased......

Now my understanding of the CTEK and Sterling DC-DC chargers is that they are 4-7 stage "chargers" that will CC or CV the battery bank untill its reached bulk charge, then move to float charge.

so my point being that there is no "problem" fitting the 60amp sterling on a 110a leisure battery, as the battery wouldnt accept the 60amps charge current?

 

[travelvolts]

A 60 amp charger is totally unsuited to a 110 ah battery! Don't forget that these units initially charge at constant current close to the maximum rating of the unit.
Also, a "leisure battery" is not really ideal for this kind of installation. Rapid charge and discharge systems work better with deep cycle AGM or tubular cell GEL type batteries.
I'm not sure what point you are trying to press?

 

[Dellmassive]

Thanks for you advice Travelvolts,

the point im trying to make is that if i get the 60Amp Sterling as a DC-DC option , , , , The charger wont be able to RAM 60Amps into the battery, sure the charger can produce 60amps but the battery wont allow 60amps in.....more like 30 decreasing to 0 as it charges up (internal resistance increases as does the volt difference)...no?

Anyway.... All that aside, with the 60Amp sterling (in my situation) when im static parked, and have the engine running ill have 60amps plus whatever is left in the battery to run my kit for an extended amount of time.....

im sure that over 700w load on the inverter i will max out the 60amps supply from the sterling and start to deplete the AUX battery. Where as before i had on the T5 "upto" 180amps from the alternator to keep my split charge/inverter running all day long..

looks like i might not be able to run the inverter all day, if i can only supply it with a max of 60amps from the sterling for the extended amount of time.

Peace & Love to all VW owners =]

 

[travelvolts]

I think you have missed the point. Your battery will accept 60 amps if it's state of discharge is sufficient. It won't be good for it and will drastically shorten the life of the battery. The ideal CC charge rate is 20% of the battery capacity until absorption is reached.
If you re read my previous post you have the perfect solution. It is one that I have used several times, on OB vehicles in particular and it does what you want. You also have to accept that with this type of usage you cannot expect batteries to last a long time.

 

[Dellmassive]

I think you have missed the point. Your battery will accept 60 amps if it's state of discharge is sufficient. It won't be good for it and will drastically shorten the life of the battery. The ideal CC charge rate is 20% of the battery capacity until absorption is reached.
If you re read my previous post you have the perfect solution. It is one that I have used several times, on OB vehicles in particular and it does what you want. You also have to accept that with this type of usage you cannot expect batteries to last a long time.

Thanks Travelvolts,,,, are you referring to this setup?

"The answer to the problem posed in the post that you quote is to fit both VSR and DC-DC systems. Because the DC-DC system will pull power from the vehicle battery it will keep alternator output high and therefore allow the VSR system to pass the demands of the inverter. I would use a Redarc BCDC1240LV alongside one of our SC120 split charge systems which uses the Victron Cyrix-CT VSR."

which would be these........

travelvolts
travelvolts

how would you suggest they are all connected. in what configuration?

Redarc BCDC1240-LV from starter battery to leisure battery with ignition trigger feed. (50amp feed cable/fuses between each end)
inverter connected to leisure battery (120amp feed cable and fuse kit)
where would the SC120 VSR go?

 

[travelvolts]

Yes but I am advising this for a two aux battery set up with batteries in parallel. If only using one battery the Redarc BCDC1225 would be more appropriate.
Both systems would connect between vehicle battery and aux battery. The VSR can go wherever you want it but in my kits the cables are cut for the VSR to fit next to the aux battery.

 

[Dellmassive]

Yes but I am advising this for a two aux battery set up with batteries in parallel. If only using one battery the Redarc BCDC1225 would be more appropriate.
Both systems would connect between vehicle battery and aux battery. The VSR can go wherever you want it but in my kits the cables are cut for the VSR to fit next to the aux battery.

Fantastic. Do you sell a battery mounting kit to fit an additional leisure battery under the drivers seat?

The factory fitted AUX battery will be bellow the twin passenger seat.

And just to confirm both systems above connect between the starter and aux battery bank right.... (just disconect the factory relay and feed)

Can you explain the operation an a bit more detail for us noobs please.....

I'm assuming the Dc-dc system will provide up To 40amps to charge the aux battery bank and inverter when the engine is running. (Due to ignition trigger). This 40amps would shut off when the ignition was switched off.... and the batteries would be isolated via the dc-dc system......

So where does the VSR come into it?

And also even though the Dc-Dc is designed as a 4 step charger it will be fine supplying it's max 40amp current to the inverter under demand as the inverter will cause the aux battery Volt drop across it that will kick in the max current profile of the charger right?

Thanks in advance...

 

[travelvolts]

Yes I have a kit to mount a battery under the drivers seat. If you have the factory charging relay you won't need the SC120 kit. The DC-DC system will charge at constant current until the battery reaches absorption it will then charge at constant voltage until the battery is full when it goes to float. The factory fitted relay system will supply the high current demands of your inverter.

 

[Dellmassive]

Yes I have a kit to mount a battery under the drivers seat. If you have the factory charging relay you won't need the SC120 kit. The DC-DC system will charge at constant current until the battery reaches absorption it will then charge at constant voltage until the battery is full when it goes to float. The factory fitted relay system will supply the high current demands of your inverter.

Awesome, ill add the battery mount kit to my shopping list... thank you very much.

One thing that has me a bit confused with running the DC-DC charger and the VSR (or factory split charge relay) in tandem...... when the DC-DC is charging the AUX battery Bank (bulk/absorption/float) the starter battery is isolated from the Aux battery bank, obviously the alternator via the REGEN/BMT system will charge the starter battery independently upto its 80% BMT requirement. So the Aux battery bank and starter battery are charged via separate isolated systems....no problem there.

So when the VSR(or factory split charge relay) kicks in it will physically connect the starter and AUX battery bank together giving one big battery bank (STARTER/AUX/term 15A/etc).........so wont the DC-DC charger now try to start charging the starter battery too? (by back feeding via the Relay/VSR) and how will that effect the REGEN charging from the BCU as when the VSR(or factory split charge relay) connects all the batteries together wont it (Term 15A/BMC) see the higher charging voltages from the DC-DC charger and change its REGEN charge strategy? (basically wont the Relay or VSR just connect the DC-DC chargers output directly back to the same starter battery input? and a big loop?) - just cant get my head around it..... seems to me that the relay or VSR would in effect be like just using a jumper cable to bridge the starter and Aux banks together bridging out the DC-DC unit, so how does the DC-DC charger deal with having its output being bridged back to its input.? unless im missing something or are you using a battery-battery Diode block to keep the relay/VSR from back feeding the starter battery?

On side note re the SC1240, we had the "factory split charge relay" fitted to our T5.1..... (that we run the current setup on)........we had issues in the early days where if the van was running and the inverter was running too there was too much current being drawn from the alternator (by the inverter) via the factory relay and wiring (feeding the AUX bank that the inverter was connected to).......basically the relay run very hot and started to stink like burning/main fuse getting hot etc........ our solution to this was to run a separate 4AWG 100Amp feed direct from the starter battery, via a 140Amp relay to supply the Aux battery. The great thing was that we could use the existing 12v relay trigger from the BCU as it was already there under the bench seat......happy days...... so we kept the Relay trigger from factory, but replaced all the rest of it...i think the original factory feed was rated at 40Amps........so all that being said ill keep the SC140 kit in the basket as im assuming the T6 will have the same 40Amp feed to the Aux battery... which just isnt enough for a 1000W/1500W demand from the Inverter when the engine is running..

From what I've seen the T6 Factory split charge Aux Battery is the same AGM type as the starter battery(under the passenger bench) ...... what are you opinions on adding to the factory Aux battery (under the drivers seat) to build up the bank, add a Standard deep cycle leisure battery, or add another AGM battery.....?

TIA Travelvolts, You-Da-Man. =]

 

[travelvolts]

You are massively over thinking this.

One thing that has me a bit confused with running the DC-DC charger and the VSR (or factory split charge relay) in tandem...... when the DC-DC is charging the AUX battery Bank (bulk/absorption/float) the starter battery is isolated from the Aux battery bank, obviously the alternator via the REGEN/BMT system will charge the starter battery independently upto its 80% BMT requirement. So the Aux battery bank and starter battery are charged via separate isolated systems....no problem there.

When the DC-DC is charging the two batteries are connected together! How else do you suppose the aux battery will charge?

For current to flow in any direction there has to be a significant potential difference, so, there will be no back feeding over either charging system. If you are worried about the capacity of your existing charging relay then by all means go ahead and fit the SC120 in its place. You cannot mix different battery types in the same bank so you will have to fit AGM. I would advise this anyway for your planned usage. If the existing battery has had any significant use already I would advise fitting an identical pair of new batteries.

 

[amdowney]

So I just ordered a new petrol van with factory air heater and second batt and I am now told it is unavailable! Seems the configurator has been adjusted after my order (have been told I have to order front and rear sensors to get the rear cam too - not sure how this relates to having petrol?).

Anyway is it worth me speccing the 2nd batt from factory for £189 + VAT? I know the relay is pants but should I anyway and swap it out for any good reason?

Probably better to wire myself under the driver's seat for a fridge etc behind me isn't it but is anything else included that's worth while?

 

[xswind]

A 60 amp charger is totally unsuited to a 110 ah battery! Don't forget that these units initially charge at constant current close to the maximum rating of the unit.
Also, a "leisure battery" is not really ideal for this kind of installation. Rapid charge and discharge systems work better with deep cycle AGM or tubular cell GEL type batteries.
I'm not sure what point you are trying to press?

Not sure I agree with you there TravelVolts, would you kindly explain why an AGM or Gell is better as Sterling and Avarc both advise otherwise.

 

[travelvolts]

Using wet open cells on a rapid charge/discharge setup causes loss of electrolyte. Fine in a boat where the batteries are easily accessible for maintenance but when they are built in to furniture or underneath cab seats it leads to the batteries being neglected and consequently giving a short service life. AGM and tubular cell GEL are also more robust and will handle more cycles. Your average wet cell "leisure battery" is not much more than a standard starter battery after all and not at all suited to deep cycling.
You have to remember that both Sterling and Adverc are focusing their products on the marine market and the two disciplines are not always interchangeable.

 

[Alanmh]

Hi @travelvolts I wonder if you could help with a bit of advice. I have just taken delivery of a 2016 T6 with a new conversion. I found this thread when the leisure battery wasnt charging as I expected and I looked under the seat to find a green VSR!

I just want to know whether to go with the Ring RSCDC30 or CTEK 250 S/ SA device? They seem to be a similar price and I am leaning towards the Ring, but I just saw something about the CTEK250 SA having a specific smart alternator mode?

We have a Webasto fridge which as far as I can see is rated at 270 W/ 24 hours. and 12v lighting and USB chargers.

On a run down to Devon with the fridge on (about 2.5 hours) the leisure battery actually lost charge (by voltmeter reading). So in order to achieve our aim of some off grid camping or even days out we need a proper charging system. We are not talking weeks away without power, but a couple of days should work - especially if we add a solar panel?

Thanks in adance

 

[travelvolts]

Hi Alan, my advice would be to go for the CTEK. The Ring has had some issues and I am not yet convinced that they have been totally resolved! I would also speak to your converter and make him understand that what he is doing is wrong!

 

[Alanmh]

Thanks for the quick reply.

I am pretty clued up on electronics but not sure where to pick up the smart alternator feed? Apart from that it looks like an easy swap out with the VSR?

 

[travelvolts]

It just connects at the fuse box to an ignition signal. Piggy back off any fuse in the middle column, preferably the 15 amp at the top (easier to get to). I can supply everything that you will need to do the conversion.

 

[Alanmh]

It just connects at the fuse box to an ignition signal. Piggy back off any fuse in the middle column, preferably the 15 amp at the top (easier to get to). I can supply everything that you will need to do the conversion.

Thanks and don't worry. You will get the business. Is it the d250 S or SA you supply?

 

[Base1388]

Gentlemen Gentlemen
Hello, I'm very new to all this and have very little electrical knowledge.

I'm about to buy a new T6 LWB euro6 150bhp High-line panel van.
I plan to convert to a camper as time goes on.

Want to camp off grid in Europe for days at a time, I plan a Wallis diesel cooker/heater, fridge led lights charge phones, possibly a small TV.

Soon as I started to understand my current setup of a duralit split charge I have in my Toyota hiace wouldn't work in the T6 I started to try and understand an alternative.
​

I had hoped after reading all this thread twice I would understand more, unfortunately its give me a migraine and I'm no further on.

I hoped I had solved the problem myself by simply adding a VW second battery option from VW to my new van order.

I naively hoped when the van arrived I could connect a fuse board up to the second battery extend any cables if I needed to change position of second battery and happy days away I go !

AM I WRONG PLEASE PLEASE ????

If I am, I defiantly need a trusty sole to tell me as a lay person exactly what I need to do it

Many thanks everyone for advice and assistance, my brain is pickled now I'm off to bed. lol.

Thanks Romany