Is a Sterling Latch Relay the answer?

Discussion in 'Tech/Mech General' started by Abacist, Jun 19, 2016.

  1. Abacist

    Abacist Funster

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    I am fed up waiting for a buyer for my van so have withdrawn it from sale and will let the current adverts just expire. Having just put a new battery bank, B2B charger and inverter in it I want to enjoy some of the improvements and our month's holiday in Europe had to be cancelled because my wife had a health problem which stopped us going so I am champing at the bit to get away when she gets the all fit again advice. In the meantime having decided not to sell I have decided to add more solar to our van so have 3 100 watt panels coming from Germany and one will feed the original habitation batteries along with its own controller and the other 2 will feed my new battery bank with their own controller, both being Techno's controller of choice, so hopefully these will keep both banks topped up when we are stationery on an aire or stellplatz. The 50 amp B2B will keep the new bank topped up when driving.

    I am now thinking that it might be a good idea to have a way of connecting the new battery bank to the old battery bank and have been wondering how to achieve this so that the original battery bank can benefit from the B2B or some of the energy stored in the bigger new battery bank. Techno uses a Sterling Battery maintainer to transfer 3 amps in this way but for me 3 amps is not sufficient as the original bank is 250 amp hours whereas the new one is 360 amp hours but also with better charging facilities.

    I see that Sterling advocate a latch relay in such circumstances which would cost about £100. The latch relay is used to prevent the 0.5 amp drain of a standard relay as a magnet holds the latch in place. This relay is used when there is both solar and another charging source and is rated at 80 amps as it needs to be bigger than the charging source. It evidently can be set up in one of four ways but I would use it in one way only and it evidently opens up when he charge exceeds 13+ amps and switches off at less than 13 amps.

    Has anyone else used this sort of relay which I think is also known as a split charge relay or is there a better product from a different supplier.

    My van is an Auto Trail Savannah 2010 with pretty standard electrics other than the new battery bank, B2B charger and inverter which is currently separate from the original Sargent set up, 2 125 amp hour batteries, single solar panel, charger and mains hookup.
     
  2. Abacist

    Abacist Funster

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    Bump?

    Has anyone got any thoughts on this idea or a better idea than a Sterling Latch Relay?

    Should I keep the 2 battery banks separate?
     
  3. pappajohn

    pappajohn Funster Life Member

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    Unless you're reserving one bank for an inverter I would link the whole lot together.
     
  4. Abacist

    Abacist Funster

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    I am looking for ideas as to how to achieve the linking of them together as it strikes me that my new bank has or will have better charging and battery resources than the original bank but that is what feeds the van with its mains and 12 volt supply, charger and solar panel controller which are all part of the Sargent 325. The Sargent manual warns against adding any equipment as it might be damaged by the charger in the Sargent:-

    "Battery Charger

    The EC325PSU incorporates an intelligent ‘offline’ battery charger that disconnects the leisure

    equipment from the battery while it is being charged. This process allows the charger to use higher

    charging voltages and to accurately control the charging current. No other equipment may be

    connected directly to the battery while charging is taking place. This intelligent battery charger draws

    power from the power converter (see 3.4) when the mains 230v supply is turned on and from the

    vehicle alternator when the engine is running, therefore the leisure battery is always charged via the

    intelligent battery charger.

    WARNING

    Higher voltages may be present at the battery (<=18v). Do not connect ANY equipment to the battery

    while the charger is operating. Failure to comply with this warning may lead to equipment damage and

    will affect the battery charger performance."

    I am therefore stuck as to how to achieve this!
     
  5. Abacist

    Abacist Funster

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    I'm still hoping that someone can advise on this and how to achieve it or tell me not to attempt it!

    I am just waiting for the solar panels to arrive and the cable and connectors for the roof. Everything else is here and ready to go! Once they are installed and working I shall be back to this question about connecting the 2 battery banks and if it is possible.
     
  6. Techno

    Techno Funster Life Member

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    As I've said before in words and pictures my banks are connected via a selector switch which can choose bank 1 bank 2 or both.

    I use 6mm from bank one to the switch 6mm from bank two to the switch. Both fused at 40 amps. From the switch to the distribution board in 6mm.

    Bank one has a 60amp B2B and feeds hab 12 volts
    Bank two has 300 watts of solar and feeds Inverter only

    The changeover switch facilitates all manner of permutations
     
    Last edited: Jun 22, 2016
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  7. Abacist

    Abacist Funster

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    Thanks Techno - I have just revisited some of the thread where you explain this and that is the answer that I'm looking for and had missed! Its when the original hab system is running out of power that I need to be able to access the new battery bank probably late at night when not on EHU and with no sun available!
     
  8. Techno

    Techno Funster Life Member

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    Sorry Robert, if I had a scoobie do where that was I'd have recalled it :LOL:
     
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