Improvements to leisure battery charging

[aandncaravan]

The problem with ripping out cables and replacing them is that you then have significantly fat cables but many 'DIY' electrical stockists only supply 6mm and below connectors. You also have nothing to follow once the old cables are ripped out.

 

As it says on our web page, running secondary 6 - 10mm cables to complement the existing ones usually gives an effective 'double the capability', which is obviously going to have a beneficial effect.

 

But also, just like it says on the website, it is the Fridge load on 12v and the way it is cabled that can drop the charge rate into the doldrums.

I would suggest that your figures were not too bad, until the Fridge was added to the mix.

So I would advise that you begin with the Fridge?

 

By fixing the Fridge cabling/routing you should also sort out the charging.

 

How about taking a cable from the Alternator.Starter battery (60amp fuse) to a fat £5 relay like on the web page : http://www.aandncaravanservices.co.uk/add-a-second-battery.php. Drive it from FA4 as per the above reply to Arthur.

Then take the output of the relay to the Pin2 (I think but check) cable on the 6 way MNL block.

Do this to bypass the MNL block as they usually only have an 18amp rating, so big potential for voltage drop if you have a big Fridge Freezer drawing 19amps..

 

Remove the Fridge fuse, so the fridge will then be operating from the Alternator, and retake the voltages.

 

You may find that if you reinsert the Fridge Fuse any 'spare' current might back feed through the old Fridge relay and 'charge' the habitation battery at a higher rate?

 

 

As for the improvements you can expect, unless there is a major wiring issue you are looking at maybe 50% max higher charge rate.

A typical CBE Alternator set-up charges at about 10amps per 100Ah battery, an ideal cabling/relay setup might get you 15amps per 100Ah battery (we are talking averages here not the peak you might see for the first 20 minutes of starting the engine on 40% discharged batteries)

 

If you boost the voltage into 'Battery overcharge' territory, like a Sterlings B2B's 14.7v to a 14.4v battery, you might initially gain another 3 or 4 amps (so 18amps'ish), but as the battery degrades from the overcharge it will take less real charge so drop down to about 12amps per battery.

 

 

So worst case for a typical CBE DS300 system might take 4 hours to recharge a 40% discharged 100Ah battery and with a modified, but not over boosted system, just under 3 hours.

 

 

Obviously those guesstimates are on quality modern batteries that are perfect, Gel and AGM battery charging times will be roughly twice as long..

 

[DavieR]

I can't find a decent local supplier, thank goodness for 12vplanet!

 

At the moment our answer to the fridge load is to not run it! In cooler times of the year anyway. But, thank you for the detailed explanation, it's something that I'll do (for ease, I'll thread the cable through along with the fatter cables). On my DS520AN the fridge is at Pin 2-3 on the No. 20 block.

 

I'll report back later when I've installed the fatter cables.

[DavieR]

It's been a while but I can now give you some results after my alterations to the charging system.

 

The leisure batteries are under the front seats and the control panel is just in front of the rear wheel arch which means long cable runs. After much thought and help from Alanb I decided to bypass the control box and alternator charging is now direct from the starter battery to the leisure batteries, about a 2m run with new 16mmsq cable. Obviously I had to fit a relay and I have a separate battery monitor installed.

 

I also rewired the 3-way fridge. 12v operation is now powered by the starter battery via a changeover relay ( the second outlet from this relay connects the starter battery to +B1 to allow mains trickle charge to the starter battery). Both relays are powered from the original +ve to the fridge. Everything works fine, the only thing missing is the alternator charging rate being displayed on the control panel, which is no big deal.

 

We have spent a few nights over New Year away in the van, so my alterations have been passed by the OH!

 

The results? After starting a cold engine on tick over, fridge off and with starter battery requiring a charge, the leisure batteries read 14.39v, up from 14.22v.

 

Apart from increasing our charging rate I have learnt one hell of a lot about 12v electrics and our van. From almost total ignorance I now have a good understanding of how our van works and where everything is. Its also been fun!

 

So, thanks once again to Alanb, Allan, welted plus many others for all your help.

 

 

 

[arthur49]

An old topic I know but one I followed and found interesting.

 

Our new van has 2 x Banner Energy Bull, CBE electrics eg PC380-BS Control Panel, CB516 charger, DS520-AN Distribution Box.

 

I was going to install Allan's beefed up wiring and chunky relay as I did in last van with great results, but this van has a Renault Master base which has a smart alternator and regen braking. Using a plug in cheapo volt meter whilst driving the voltage at the cigarette type sockets in the cab varies between 15.2v and 12.8v, usually settling about 13.2v most of the time on motorway driving.

 

I have not yet measured the voltage at the leisure batteries with engine running, nor the effect of switching on the fridge whilst driving - I know that is driven direct from alternator.

 

Subject to further checks, I may well install Allan's suggested WA121525 unit, but does anyone know an easy way to disable the existing split charge relay?

[mikefitz]

To disable the split charge relay in the DS520 a resistor on the circuit board has to be removed by carefully cutting its connections. The resistor is R37 shown as 2 in the picture, 1 is the relay.

The WA121525 unit seems to need a D+ signal to function, this may not be easy to find on your Renault with the smart alternator, perhaps an ignition on signal could be used.

The alternative Sterling B to B unit should work without any command signal just based on voltage levels, but can be used with an ignition on signal if needed.

 

Mike

[arthur49]

Thank you Mike

[aandncaravan]

The Schaudt unit is specifically designed for motorhomes and as such contains features for mains charging of the starter battery, which many units do via a 'reverse' feed back down through the Intelligent Alternator charge controller, to the Starter battery.

 

In a conventional Sterling B2B, this can't take place as when the engine is 'off' the B2B opens the relay in the cable from the Starter Battery to the CBE controller.

 

The Schaudt WA12125 and WA12145 contain bypass circuitry to carry the mains charge back to the Starter battery.

 

You don't even need to disable the existing Split Charge mechanism with the Schaudt units, they really are designed to work in harmony with what is already in a motorhome. Note in the instructions how they install completely differently to a Sterling B2B designed for Boats. The Schaudt design and installation should also result in a more efficient '12v' Fridge on the CBE set-ups.

 

As might be expected with the worlds biggest motorhome charger manufacturer, the Schaudt units are also very efficient. Very easy to install, half the work of a B2B, and so easy to remove to fit to the next motorhome.

 

 

If you look at the bottom of the "How to wire your own Camper" web page : http://www.aandncaravanservices.co.uk/wiring-your-camper.php you will find some schematics for a CBE DS300.

You will note that over to the right you will see Tag FA4 which is a usable D+ output for driving auxillaries, you may find the DS 520 has something similar?

 

The same web page contains info about conventional VSR's (plus many B2B's) and why they don't work with modern batteries, but it also contains details of a 2 part VSR that is much more efficient and works with all battery technologies. It is only £25 on ebay, more efficient than a Durite, etc.

So if you can't find a D+ trigger on the CBE, you can create one using the 2 part VSR.

 

 

If you are charging multiple batteries/big battery bank, then I would suggest you take a feed for the Schaudt direct from the Alternator B+ and an Earth from the Alternator body, rather than the Starter battery, if that is possible.

 

 

 

 

 

 

[arthur49]

Fantastic Allan thank you. Brilliant, being able to leave existing split charge in situ.

The DS520-AN does have a simulated D+ at point 17

I'll e mail a copy of schematic for your 'library'

Regards

Arthur

[aandncaravan]

I have added a manual for the WA12145 to the bottom of the CBE schematics if you want to study before you buy.

 

The "EBL" wiring looks complicated, but isn't.

In a Eur6/Brake recup vehicle, the Alternator Booster unit should install into the Starter battery feed to the CBE ensuring the CBE DSxxx is always fed with 14.4v, or whatever the battery technology needs.

The Intelligent Alternator Boost unit will adjust the feed voltage into the CBE dependent on the load to ensure it is always 14.4v therefore the CBE unit, AND all it's Alternator '12v' fed units will always receive the optimum 14.4v, not just the habitation battery.

 

That includes the Fridge because on the CBE solutions, the Fridge feed is 'sourced' in the DSxxx unit, not direct from the Starter battery. So it is very important on a Brake recup/Energy recovery, etc vehicle, where the Alternator feed to the Fridge can drop low, that it is the CBE that is fed with the Boosted voltage, not the Habitation area batteries directly.

 

This also means All CBE/Schaudt/Sargent/Calira, etc functionality performs exactly as before. The Alternator charge does not bypass the CBE/Sargent/Schaudt Power Controller so any meter readings of Amps, etc will still be displayed as before.

 

 

If you fitted a Sterling B2B as per it's usual wiring instructions you wouldn't address the poor Fridge feed, just bypass all the electronics that the Motorhome manufacturer has taken pains to put in to control everything!!!.

 

And yes we know that is exactly how the professional installers are doing it. They so love the CTEK DS250 style units we hate.

 

[arthur49]

Thank you Allan

[arthur49]

UPDATE

Well we're delighted with the Wildax Europa. The build quality is excellent. Still not very keen on the 'hidden' kitchen sink ....... We had a little concern that the tambour doors might be noisy in transit but dead quiet.

We went for the auto version on Renault Master base, with increased bhp to 170 and it really flies - great to drive.

There's always a BUT .............

As indicated in my earlier post it has smart alternator, recup braking and auto stop/start. With engine at tick over, fridge off, the charge at leisure batteries is a miserable 13.9v. The fridge is fed from starter battery via a relay and with fridge on, the voltage at leisure batteries drops very slightly - 13.85v.

This may be our last van as health issues prevail, so we are prepared to spend a bit extra to improve charging and I will probably go for Allan's recommended Schaudt WA121545.

Allan gave me some good tips off-forum yesterday - thank you Allan - and an initial check today quickly identified a simulated D+ signal - a vacant male spade terminal in the CBE Distribution Box just waiting to be used!

Therefore, wiring a WA121545 into the system looks dead easy.

Allan - is it necessary to use the voltage sensor from starter battery?

[aandncaravan]

Arthur, No and yes.

 

Most of the competing products don't have separate battery sense wires going to the Starter or Habitation area battery, so by not wiring up the battery sense wire all the way to the Starter battery, it will operate no worse than say a Sterling B2B.

 

However, because these other units sample the Starter battery voltage at the input into the device, where this cable will be subject to significant load, the voltage won't be accurate.

 

A total separate voltage 'sensor' cable to the Starter battery, that isn't under load and potentially suffering voltage drop, is obviously the best way of 'seeing' a true Starter battery voltage.

 

You could wire the Starter battery sense cable to the main feed coming in where it goes into the device, but it won't be optimum.

 

 

A similar separate voltage sensing cable goes to the Habitation area battery, again to get the most accurate voltage at the habitation battery as the sensor cable isn't subject to any 'load'.

That is also rare in other B2B devices, but you can see the value as the voltages will be optimised exactly at the point it needs to be, the Habitation battery, not the output from the B2B which can be quite different.

 

 

If the distance/route from the DS520 to the Starter battery is such that your illness makes running a cable all the way back to the Starter battery difficult, then wire the sensor cable to the same input port on the WA12125/Wa12145 as the Starter Battery cable entry point and see how it goes.

The critical cabling on most motorhomes that use the CBE equipment tends to be quite well sized and short, so you may find it still works ok?

 

 

[arthur49]

Thank you Allan :-D :-D

[arthur49]

Can I ask a couple of questions re CBE 516 charger and DS520 distribution box:-

 

1. The 516 has an S signal going to the 520. Is this 12v to tell the 520 that mains charger is 'On' ... and if so why?

 

2. Is the output of 516 connected to 520 + Out 12v, also shown as 12v Exit - why an Exit when its an input?

[Alanb]

Arthur,

 

1. The "S" signal from the CBE 516 operates the mains charging relay for the starter battery (B1). If you look closely at tho bottom RHS of either a DS520 or a DS300 you will see a small relay (about 12mm cube), a short cylindrical schottky? (low forward voltage drop) blocking diode, and a current regulating thermistor (pale blue disc). These are the mains charging components for B1. The diode prevents any back feeding from B1 to B2, and its presence means that on mains charging B! will eventually float at about 0.4V below B2 (habitation battery). The thermistor regulates the B1 charging, to a maximum of about 2A.

The "S" signal is also used to control the display of the mains connected (plug) display on the control unit, it is however limited to about 50mA maximum, so if used for other purposes a suitable low current driver must be included.

 

If a charger from another supplier, lacking the S signal is fitted, mains charging of B1 will not be available.

 

2. On the DS520 the " +ve OUT 12V" terminal is connected to the common node from which all loads are supplied, it also connects to the "+ve B2" terminal via the current sensing device. (The current sensing device is located above the +ve B2 terminal and may be identified by having a conductor passing through a central hole. I think that it is a Hall Effect device as used on DC clip on ammeters.) It follows that "+ve OUT12V" is the correct point to connect any charger, including solar, otherwise the system will not indicate the correct current for B2.

 

 

Alan

[arthur49]

Thank you Alan. So if I installed a better charger in place of 516 all I'd lose was mains charging of B1. Every day's a school day ......... even at 70 :-D :-D

[Alanb]

arthur49 - 2019-04-08 12:36 PM

 

Thank you Alan. So if I installed a better charger in place of 516 all I'd lose was mains charging of B1. Every day's a school day ......... even at 70

 

Arthur,

 

I thought perhaps you were thinking along those lines. The answer is not necessarily so.

 

To elaborate it should be feasible to use a low current voltage sensitive relay, available quite cheaply from Ebay. Connected to monitor B2 (habitation battery) voltage, this would not be a perfect solution as it would respond to solar charging as well as the mains charger.

 

Alan

[arthur49]

Cheers Alan

[aandncaravan]

Arthur, when we fit dual output Solar chargers, we connect the prime out put direct to B2+ and the secondary output to the B1+.

 

You could buy a Victron Marine charger designed for multiple battery banks and wire that the same way, but you would lose the 'mains connected' feature.

 

 

Be wary of the cheaper VSR's as they cut in about 13.1 and don't drop out until about 12.6v. For your AGM Starter battery with it's resting voltage of 13.0v it may trigger early and stay connected until the batteries are heavily discharged. 12.6 is not far off 50% discharged for AGM and modern batteries.

[arthur49]

Cheers Allan

[Alanb]

aandncaravan - 2019-04-08 1:43 PM

 

Arthur, when we fit dual output Solar chargers, we connect the prime out put direct to B2+ and the secondary output to the B1+.

 

 

................................................................................................................................................................

 

Be wary of the cheaper VSR's as they cut in about 13.1 and don't drop out until about 12.6v. For your AGM Starter battery with it's resting voltage of 13.0v it may trigger early and stay connected until the batteries are heavily discharged. 12.6 is not far off 50% discharged for AGM and modern batteries.

 

Connecting directly to B2 +ve, would be correct when installing solar to a CBE DS300 based system, but with a CBE DS520 system it would bypass the current sensor in the DS520, and consequently give incorrect battery current indication.

 

As regards the voltage sensitive relay, instead of cheap, perhapsI should have said inexpensive. The units to which I was referring are available on Ebay for about £6.10 from China. They are enclosed in a case and have a screw terminal block which would make for easy connection. The pick up, and drop out settings are adjustable, and I do not see how it is possible to criticise them as having unsuitable settings. Further this unit would be monitoring the habitation battery (B2), and not the starter battery. I would envisage using the VSR to replace the missing "S" input signal to the DS520.

 

Alan

 

[arthur49]

Alanb - 2019-04-08 6:39 PM

 

Connecting directly to B2 +ve, would be correct when installing solar to a CBE DS300 based system, but with a CBE DS520 system it would bypass the current sensor in the DS520, and consequently give incorrect battery current indication.

 

As regards the voltage sensitive relay, instead of cheap, perhapsI should have said inexpensive. The units to which I was referring are available on Ebay for about £6.10 from China. They are enclosed in a case and have a screw terminal block which would make for easy connection. The pick up, and drop out settings are adjustable, and I do not see how it is possible to criticise them as having unsuitable settings. Further this unit would be monitoring the habitation battery (B2), and not the starter battery. I would envisage using the VSR to replace the missing "S" input signal to the DS520.

 

Alan

 

Or I could connect both chargers to the DS520 and put a 230v rotary switch in the mains lead so I could select which charger to use.

A 30A Victron charger would better cope with bringing leisure batteries up to full charge after a few days off EHU without undue strain? Then flick switch and revert to 516?

[Alanb]

arthur49 - 2019-04-08 7:27 PM

 

Or I could connect both chargers to the DS520 and put a 230v rotary switch in the mains lead so I could select which charger to use.

A 30A Victron charger would better cope with bringing leisure batteries up to full charge after a few days off EHU without undue strain? Then flick switch and revert to 516?

 

Arthur,

 

Possible, but the switch would have to be enclosed. Suitable enclosures seem to be expensive. Perhaps an alternative would be to use a plug and socket for the mains supply to the chargers. Both methods would need to be mounted in an accessable location.

 

Another alternative is perhaps a CBE522 charger at about £200. I note that these use M6 studs for the output connections, better but not a drop in replacement. A 22A output represents a one third increase in output, and would meet the C/10 rule of thumb for battery charging.

 

Alan

[aandncaravan]

Alanb - 2019-04-08 6:39 PM

 

aandncaravan - 2019-04-08 1:43 PM

 

Arthur, when we fit dual output Solar chargers, we connect the prime out put direct to B2+ and the secondary output to the B1+.

 

 

................................................................................................................................................................

 

Be wary of the cheaper VSR's as they cut in about 13.1 and don't drop out until about 12.6v. For your AGM Starter battery with it's resting voltage of 13.0v it may trigger early and stay connected until the batteries are heavily discharged. 12.6 is not far off 50% discharged for AGM and modern batteries.

 

Connecting directly to B2 +ve, would be correct when installing solar to a CBE DS300 based system, but with a CBE DS520 system it would bypass the current sensor in the DS520, and consequently give incorrect battery current indication.

 

As regards the voltage sensitive relay, instead of cheap, perhapsI should have said inexpensive. The units to which I was referring are available on Ebay for about £6.10 from China. They are enclosed in a case and have a screw terminal block which would make for easy connection. The pick up, and drop out settings are adjustable, and I do not see how it is possible to criticise them as having unsuitable settings. Further this unit would be monitoring the habitation battery (B2), and not the starter battery. I would envisage using the VSR to replace the missing "S" input signal to the DS520.

 

Alan

 

On the DS520 that is very easy to resolve by keeping the Victron main output to the OUT+, rather than B2+.

 

On VSR's I said be wary of them.

The other issue with a VSR can be it's constant draw from the battery it is 'watching'. It isn't much but still enough to drop a battery into the sulphation zone in weeks when idle.

Because of the other issues with 'false triggering', I would leave them alone. For example in the operation suggested above, it would trigger every time the engine was started.

 

 

Arthur your idea of keeping both units in place and working together is a good idea, but why worry about switching them off, why not leave them both connected all the time?

Much of the time, or at least within about 10 hours of turning both chargers on, the CBE CBxx will shut down anyway and only restart if the voltage drops below about 13.0v.

 

If the Victron (which would now only need to be a single output unit) is working hard at 14.4v or in it's low power 13.2v storage mode, then the CBE won't re-activate.

The CBE is the only charger we know that fully shuts down after a short period of Float charging.

 

 

I assume you plan to use the existing CBE CB516 mains supply point to fit some sort of double mains plug?

May I suggest you do what we do when we add a second charger and terminate the cable with a 13amp socket and install a 13amp switched surge protector 'Adapter', as in attached photo.

Then plug both chargers into the surge protector. If you really want to have them on at separate times, the switches on the surge protector facilitate that.

 

Some surge protectors tend to be 'sacrificial' so having the ability to easily swap one out is useful.

 

[arthur49]

Looks good Allan, thank you.

 

On related issue, having a debate with Wildax who conceded immediately that charging whilst driving is inadequate due to smart alternator.

 

They thought it had a standard alternator so have recalled my van, and 12 others to install a 'module' - not sure what yet but I'm holding out for the Scahudt WA121545.

Fridge also switching on and off whilst driving so it needs a 'module' but I reckon if they fit the WA121545 it will fix the fridge issue as well