Interesting stuff re Sargent electrics

Discussion in 'Motorhome Chat' started by Jaws, Mar 23, 2016.

  1. Jaws

    Jaws Funster Life Member

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    I read in the book of words that the unit is designed to only utilise a few amps max off of the alternator when the engine is running.. and as I am once again upping battery capacity ( swapping out the pair of year old 145aH units for 3 x 110aH units ) I really wanted to ensure I was getting the best possible use out of the set up.

    This struck me as being pretty weird,. so I rang up the man that knows and asked Sargent tech what the situation is.

    The system will deliver up to 20 amps from the alternator if required.. and the info in the manual is actually wrong !

    Also....

    For those with an Autotrail and have two leisure batteries you will be aware there are actually two pairs of wires coming down from the main unit to said batteries
    Although I metered them out and found the two +ve's and two -ve's do SEEM to me directly coupled together they do actually go to different terminals on the Sargent
    YET !
    I get a very small difference in voltages on the two batteries
    According to the chap I spoke to the feed wires are rated at 37 amps each, so to my mind there should be no discernible / measurable difference in voltage on the two batteries as over such a short run there really should not be a voltage drop

    Chap was a bit baffled ( as I am.. ) so I asked if there was any reason I could not 'bus bar' the batteries together ( at the battery end of the cables )
    Absolutely fine as the wires are indeed connected together within the main unit any way..

    Now all I have to do is try and get somewhere NEAR the high standard of neatness Andy ( @Techno ) regularly achieves with his installs !
     
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  2. GWAYGWAY

    GWAYGWAY Funster

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    Haven't you thrown it out yet? next thing is the step will bouncing in and out.
     
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  3. andy63

    andy63 Funster

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    I did exactly the same thing on an autotrail a while ago...
    Couldn't understand why the batteries wernt connected at source when they seemed to be connected at the Sargent unit..
    I suppose there may only be one battery in some vans and it's their way of easily adding a second but I thought that the wiring looked inadequate for the distance from the battery locker to the Sargent. .. (without knowing what it was rated at )..
    If you add a 3rd battery do you run another set of wires from that to the Sargent or just use the existing wires??
    Ta andy
     
  4. Jaws

    Jaws Funster Life Member

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    Not needed Andy..
    Reason ?
    Cos the most amperage the system can deliver from any OE source is 20 amps.. The wires are more than capable of handling that, so no need to increase the capability of the delivery wires when the system canna supply any more :)
     
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  5. andy63

    andy63 Funster

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    Thanks jaws I'm with that but does that not beg the question why you need a set of wires from two batteries... as one set would cope ,and back to the point you made about why not parallel the batteries at source.... If you see what I mean..
    Ta andy..
     
  6. Jaws

    Jaws Funster Life Member

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    I think they fit two sets for a couple of reasons
    The first is, as mentioned, if the van came with one battery it is easy to upgrade
    The second is proly related to the fact it is FAR easier to route four thinner wires than two potentially stiff thick ones..
    Total guess of course but that would make some sense at least :)
     
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  7. Jaws

    Jaws Funster Life Member

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    Job completed
    I thought about it, and joined both pairs of feed wires together.. Than connected the other two batteries in parallel to that.
    Simple and neat :)

    Now on hook up to make sure everything is working as it should..
    Will report back in a while !
     
    Last edited: Mar 24, 2016
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  8. Revolvor

    Revolvor Funster

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    @Jaws. John, I know you have just completed your installation, but this is what Sargent sent me when I enquired about fitting an additional Leisure Battery. I have a Sargent EC225.

    "Most AutoTrail motorhomes have built in provision for a second battery, which makes installation easy. Have a look in your battery compartment, and trace the wires back from the battery - you will find the battery actually has a short harness fitted which just plugs into the main harness with a large black connector. In most models you should find another connector nearby with a blanking plug fitted. We have the battery harnesses on our website:

    http://sargentshop.co.uk/epages/eshop328964.sf/en_GB/?ObjectPath=/Shops/eshop328964/Products/WB1022

    If your van doesn't have the connector then you would need to use suitably rated cable and over sheathing to parallel the 2 batteries."

    I did not use the Sargent cables, and just connected the batteries in parallel.

    I have also just fitted a CTEK D250 Dual B2B charger to try and improve the efficiency of charging the leisure batteries when driving. I have not had much success though, as after initially working OK, it has now stopped working. See my latest post in this thread:

    http://www.motorhomefun.co.uk/forum/threads/ctek-d250-dual-installation-problems.124551/

    John
     
  9. Jaws

    Jaws Funster Life Member

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    As it was all working correctly to start with it could be a simple matter of a failed relay.. Most standard small relays are rated at 30 amps... trouble is, most come from China and do not use decent contacter metals ..
    Would it be possible to swap the relay out as a starting point ?
    I have just checked the spec of the D250 Dual B2B and it is rated at 20 amps.. the same as is delivered on the standard system as fitted by Autotrail.. so have to ask why the change ? ( just curious )
     
  10. Revolvor

    Revolvor Funster

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    I have checked the relay, and it seems to function correctly, when checked with a multi-meter. I also tried removing the in-line fuse from the Sargent charger, just to make sure it was completely isolated.
    Yes, I know that the CTEK only delivers 20 amps, but it is a 5-stage intelligent charger, so should charge the leisure batteries more efficiently. The main reason I chose the CTEK unit is that I plan to fit solar panels this year, and it is a MPPT Controller, suitable for up to 340 Watts, and also charges the Vehicle battery from solar. The cost was similar to buying a decent MPPT controller and a Battery Master, so the B2B function was just going to be a bonus. If I can't get it to work, I hope I can return it to CTEK under the 2-year warranty, and then I WILL get a MPPT controller ... either one recommended by Andy @Techno100, or a Victron, and get a Battery Master too.
    I am waiting for a response from CTEK, but will have to wait till after Easter now.
    John
     
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  11. jenny and mitch

    jenny and mitch Funster

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    John. What rate of cable did you use to link the 2 leasure batteries.
    And hows the step after the "mod".
    Mitch.
     
  12. Jaws

    Jaws Funster Life Member

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    Step has behaved impeccably since Sargent sent me the replacement '50' unit ( fingers crossed ! )
    I now have three batteries.. all linked with 6mm cross section cable.. The cable was to hand as it was off cuts when we had the solar panels installed on the house :)
    More than capable of handling the maximum charging amperage and indeed the maximum draw we are likely to put on the system
    Checked this morning after a few hours charge yesterday and the system is all working fine
    Unable to check the quiescent voltage of the batteries as we have 300 w of solar panel feeding them and there is a bit of sun out there today.. Charging from panels was sitting at 1.2 amps and the battery voltages were all 13.8v.. So spot on gassing levels where I would expect them to sit with a wee charge going it to them
    All batteries are reading EXACTLY the same voltage too, so a big improvement on what I was getting. ( albeit only about .2v between the batteries ) That discrepancy has now been eliminated..
    Reading how Autotrail set them system up, I now suspect one of the plugs was / is making a very slightly poor connection in the loom, which is what was causing the imbalance
     
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