2 Battery Banks for 2010 Autotrail Savannah - Is the Sargent charger up to it?

Discussion in 'Tech/Mech General' started by Abacist, Nov 21, 2015.

  1. Abacist

    Abacist Funster

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    I am thinking about connecting 2 pairs of batteries together to make 2 battery banks and connecting to the 2 battery connections in my Autotrail Savannah with one pair in the outside battery locker and the other pair under the seat behind the driver. The batteries will be 125amp hour sealed wet Hankooks so each battery bank will be 250 amp hours. I have the optional solar panel fitted and one of Eddie's battery master units. The Sargent is the 350 unit.

    The only concern is that the Sargent manual says that their charger can cope with batteries up to 110 amp hours so it presently copes with 2 batteries which were fitted from new so will it be able to cope with 4?

    Any other thoughts also welcome.
     
  2. Techno

    Techno Funster Life Member

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  3. PhilandMena

    PhilandMena Funster

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    No. Why should it be more than the manual states. i.e. maximum of 220 AH.
     
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  4. Jaws

    Jaws Funster Life Member

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    I have 2 x 145 Ah batteries on mine.. Been on 18 months without issue
    Bottom line is, the charger will only deliver what it is capable of.
    In other words it will just take a bit longer for the Sargent to charge a bigger battery bank
     
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  5. Techno

    Techno Funster Life Member

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    Possibly die trying.
    Really you should be able to do a one night stop on electric and fully recover overnight. I doubt the charger will fulfill that.
     
    Last edited: Nov 21, 2015
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  6. MyDogsTooBig

    MyDogsTooBig

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    The amount of batteries is irrelevant. It's the capacity that matters so no, you will never fully recharge them with that charger. As a side issue (there usually one or two lurking around)... When parallel connecting batteries i.e. positive to positive and negative to negative, two things are most important. 1) Ensure that there is a fuse (MEGA type is good) in every batteries positive lead as close to the battery as possible. The fuse rating should be appropriate for the battery rating. For connection to each other, try not to 'daisy chain' the batteries together. What I mean is, if for instance you have four batteries side by side; do not connect the left most positive to its neighbour and then that to its neighbour and so on, then take your supply out from the far end. This is not very good, honest. The same is true for all the negatives too. The best approach (in my four battery example) is to take all of the positive connections (via a fuse) to a central isolated connection and then take your equipment load off of that. It may be more work and a bit more expense, but what this does is to share the voltage drop and hence resistive loss through each battery cable. This way, all your batteries will more or less get current drawn equally from them and conversely, when they are being charged, they all get an equal share. The negative cable from each battery should all come together and connect to the chassis at one single point too. Parallel connected batteries should all be the same make, type, capacity and age too. This is because dissimilar batteries and even batteries from differing batches will have slightly different characteristics and internal resistances. Batteries from the same batch can be classed as 'matched'. Otherwise, what you will be doing is similar to putting a row of different wattage light bulbs together. They will all work, but one will out shine the other. This is important, because in the battery world, the battery with the highest static voltage wins. Same batch, all same voltage, the end. Different voltage equates to one battery or more not supplying as much current as its neighbour and also, conversely, not getting as much charge. I am talking about 0.1, 0.2, 0.3 of a volt, but what this also means is that when you leave your batteries alone, no load, no charge, the battery with the slightly higher voltage will discharge into the ones with the slightly lower voltage and this will go around in a loop continuously until they are all flat. It is a gradual slow process, but if the battery mismatch is great enough, this discharging can happen a lot quicker. You will then be wondering why you batteries are down a bit when nothing is drawing power. Sorry, I cannot do nutshell writings... Oh and keep battery cables very very very short!
     
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  7. Abacist

    Abacist Funster

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    Sounds as if I ought to stick to just 2 batteries as I don't want to spend too much money improving this van as we might change it. Happy to replace stuff that needs replacing but don't want to go to the expense of fitting an expensive beast of a charger. MoHo's are more sophisticated than I thought and I didn't know a battery charger had a limit as to what it could charge in terms of amp hours. Many thanks for all of you helpful money saving input!
     
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