One For The Techies Amongst Us B2b Competing With Solar Etc

Discussion in 'Tech/Mech General' started by Nigel&Debbie, Jun 18, 2015.

  1. Nigel&Debbie

    Nigel&Debbie Read Only Funster

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    I have a 2013 Autotrail with the Sargent PSU. I have 200w solar system charging direct to both leisure and vehicle batteries ( by passing built in solar regulator in Sargent unit). I also have a sterling battery to battery charger.

    Question. Do the different form of chargers cancel each other out / work against each other i.e. My battery to battery charger is capable of charging at up to 50 amps but only when the battery is in the right stage (discharged) however when driving down road on a sunny day, solar system is charging batteries (albeit only a few amps) enough to raise voltage to over 13 amps. Does this then trick the b2b charger to think that the batteries are charged thus causing the b2b to enter float charging mode? When you then bring in the direct charging system via the Sargent unit when engine is running, do we actually have 3 systems working against each other?

    If the answer is yes, I can see an easy fix for b2b versus solar by simply fitting relay in solar system to cut connection to battery when engine is running thus allowing sterling b2b to do its job. However how do I get around the b2b versus Sargent 12v charger. I don't think it is a simple matter of installing another relay to cut connection as I have the fridge to consider!!

    Anybody any thoughts or even better has anybody a solution so that I get the best out of b2b charger when driving?

    Thanks

    Nigel
     
  2. tonyidle

    tonyidle Funster

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    Nothing competes. In simple terms the source supplying the highest voltage will take the bulk (or all) of the charging load. No additional control is needed or desirable.
     
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  3. Nigel&Debbie

    Nigel&Debbie Read Only Funster

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    Thanks for the reply. I agree that there is no 'competition' but the issue is that the B2B (or which ever is winning) charges according to the state of the battery, which it does by sensing the voltage present in the battery. If there are two other charging sources present, then it is going to read these charging voltages as opposed to the voltage of the depleted battery.

    The battery will charge eventually as when the b2b stops charging after detecting sufficient voltage the solar or Sargent chargers take over and this is repeated indefinitely. The issue is that if the other chargers were not present them the b2b would get there a lot quicker as this can charge at 50 amps.
     
  4. JJ

    JJ Funster

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    I understand that the clever way the B2B works is spoilt if there is a solar system running at the same time.

    I believe the B2B intelligent system will read the voltage across the battery terminals before deciding what charge to put in.

    If the panel is connected and it is sunny, the B2B charger will get a reading that makes it think the battery is full and reduce or stop it charging properly even if the battery is not full.

    I was told to have a switch to disconnect the solar system when the engine is running in order to get the full benefit of the B2B charger.

    JJ :cool:
     
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  5. Don Quixote

    Don Quixote Funster

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    Well I have the B2B fitted and no matter what charge the solar is or has put in the batteries after being parked up for 5/7 days when I start the engine after a few seconds the B2B will start feeding amps ( from 45amps depending on how long I have been parked ) then after 15/20 minutes static running or driving to next place will drop to 4/5 amps and then around 30 minute mark goes to .5amp. This is with solar connect as well. I must admit I have never been told or even thought of removing the solar feed whilst using B2B as always thought it make no difference.
     
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  6. Polar bear

    Polar bear Funster

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    I always switch off my solar panel when driving as it is not needed. I can select which ever battery needs charging. I had the sergeant charger fail and it was very useful to have the solar direct to batteries. Sargent are crafty they rivet the cover on the panel to stop easy access to do repairs
     
  7. funman

    funman Read Only Funster

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    I found that the Sterling overrides the solar panel, so if the battery is fairly well charged before starting a long drive on a sunny day, then I switch off the input to the Sterling (using a home-installed switch). My reasons for this are:

    1. Solar power is free; power from the alternator is costing me extra diesel.
    2. The Sterling makes a noise.
    3. The Sterling interferes with the radio
    4. The more I use the Sterling, the more likely it is to break down and have to be replaced for the 4th time.

    By the way, I know it says on the box that the Sterling is rated at 50 Amps, but even Sterling themselves admitted to me once that the 50 Amps is what they draw from the alternator / starter battery. What they give out to your leisure battery is considerably less - on mine, with a very flat leisure battery, about 35 amps is the most I've ever measured.
     
  8. JJ

    JJ Funster

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    Well, I am only repeating what I have been told and I am no expert...

    I am not really interested in the constant Amps, Volts, Watts discussions that are never far away when (male) motorhomers get together but...

    If your B2B is putting in "from 45 amps" for 15/20 mins (let's say 40 amps for 20 mins) I reckon that to be around 14.85 amp hours your B2B has put in before it drops down to the second phase of charging.

    I presume there to be all sorts of other factors involved (battery condition, temperature etc) but that doesn't seem like much of a first phase charge to me...

    but then what do I know?

    I still suspect that the B2B receives misleading information if, when it monitors the battery voltage at start up, the solar panel(s) are is pumping up that voltage at the terminals.

    But then what I really, really think is this...

    When you switch on a light, does it light up?

    When you open a tap to fill the kettle, does water come out?

    When you plug in your smartphone into the USB charger thingy in your cig lighter socket, does it go "beep" and start charging?

    If answer to the three questions above is "yes" then all is fine with your van electrics!

    Now... which route down to Faro did you take?

    JJ :cool:
     
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  9. hilldweller

    hilldweller Funster Life Member

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    What a delicious question. You'd get a PhD for giving a definitive answer.

    All will be measuring the single battery voltage.
    All will take different actions depending on that voltage.
    The voltage that trips different actions will be different for every one even if, say, all recognise a trip point of 13.6V. The tolerance will be different between them.

    Fire it all up:
    Unit A -- I'm dead simple I want 13.6V
    Unit B -- I charge to 14.2V then drop back to 13.6V
    Unit C -- I charge to 15V for 5 mins then 14.2V then 13.6V

    C wins for 5 mins cutting out A+B.
    B wins next because it outputs 14.25 with the clock ticking.
    B drops to 13.6 so is cut off by C which is still on it's 14.2 stage.
    C drops to 13.6 but is really 13.55 and B wins with 13.6.
    A says F*** This I can't compete.

    You are well set up for "gitter" the voltage gittering 0.5V or so as they interact under differing conditions.

    So god knows what could happen under the million combinations of charging conditions. Nothing bad but not as good as you would like maybe.
     
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  10. Neilfg

    Neilfg Funster

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    Just curious and there maybe an obvious answer to this but why by pass the solar regulator in the Sargent unit?
     
  11. Techno

    Techno Funster Life Member

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    It won't handle 200 watts and its crap too
     
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  12. Don Quixote

    Don Quixote Funster

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    Well, I'm changing nothing in my MH as all appears to be working as is.................
     
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  13. Techno

    Techno Funster Life Member

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    My B2B only charges my leisure batteries.
    My 300 watt of solar charges my 500ah inverter batteries and sends surplus to the leisures via a CBE CSB2
    My leisure batteries top up the engine battery via a "battery master"
    I can at the flick of a switch combine or change which bank feeds the habitation or charge everything from multiple sources
    The inverter is also a 3 stage mains charger so the inverter batteries don't draw from the CBE charger as it would struggle with 6 batteries.
    Usually everything stays topped up :LOL:
     
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  14. gibbon

    gibbon Read Only Funster

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    The idea of conflicting tech never occurred to me.
    I have an Amperor 3 stage power supply when plugged in to mains.
    130w solar going through a ctek 250s dual as an mppt controller which is also a dc to dc charger when driving.
    This seems to be keeping the hab & starter battery in a happy place.
    I think I'll be leaving well alone(y)
     
  15. Nigel&Debbie

    Nigel&Debbie Read Only Funster

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    Thanks for all the replies.

    After speaking with Sargent, sterling and a specialist auto electrician, here is their advice and solution.

    Firstly, as pointed out by @hilldweller there is definitely a conflict between the 3 chargers which will cause glitching as they compete /swap amongst each other as the voltage in the battery changes.

    All three specialists agreed that it is best to have only one charging system working at any one time.

    I have a Sargent ec500 control unit fitted to my autotrail which works by having a direct link from the vehicle alternator to the hab batteries when the engine is running. The vehicle alternator is effectively the charger when engine is running.

    To resolve the problem, I have done the following:

    1. On the feed from the hab battery to the ec500 unit, I have fitted a relay which is operated by an ignition operated live feed from the vehicle (taken from feed to the 12aux power supply).

    2. On the 12v positive from the victron mpp250 solar controller, fitted in series a relay (as above) and a second relay(closed type) operated by the live 12v feed from the mains operated battery charger.

    The result

    When driving, both the feeds from the solar regulator and ec500 unit 'charger' are cancelled, leaving the sterling b2b to fully manage the hab battery charging. The fridge 12v is totally unaffected by above and works properly.

    As soon as ignition is switched off, the first relay changes and the solar regulator takes over as the only charging unit.

    If I have 240v hook up, and I turn on the separate charger this causes second relay to operate on solar 12v feed to batteries, effectively turning solar off and allowing mains charger to control 12v system.

    Thanks for all the help on the forum and also to the 3 specialists
     
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  16. hilldweller

    hilldweller Funster Life Member

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    I think that's a No No.

    Normally you must connect the solar controller to battery THEN the solar panel. Stage one allows the solar controller to sense the battery voltage.

    So to kill solar fit the relay in the panel feed.
     
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  17. Nigel&Debbie

    Nigel&Debbie Read Only Funster

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  18. Techno

    Techno Funster Life Member

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    My mppt regulator does not conflict with my inverter charger it simply goes straight into float mode if the charger is switched on. If I put a large load like the kettle on the mppt will throw as many amps in as it can to support the mains charger until the load is removed and the voltage recovers
     
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  19. Don Quixote

    Don Quixote Funster

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    As I have the same MPPT as Andy and as I have stated "won't be changing a thing" to date works for me as is....... B2B / MPPT / on board EHU charger.......... all working...... sorted.
     
  20. eddievanbitz

    eddievanbitz Trader - Funster

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    I wonder how many days a year that it is sunny enough for the solar to make any difference what so ever?

    Many answers to questions are a "theoretical precise" answer over what actually happens. I personally am against adding relays (consume power) and switches people forget) and get into a pickle.

    Like mixing lead acid batteries in parallel with GEL batteries. Post on here that you've done this and you would be hounded out like a baying crowd chasing a witch lol.

    Hymer do!

    Eddie
     
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