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  1. #1
    Join Date
    May 2012
    Posts
    1

    Default Battery Configuration - Dual Purpose

    Hi,

    Just a quick query in relation to the configuration of batteries.

    I am renovating a cabin cruiser and nearing completition. I am happy with setting up the batteries, but I have a random issue that someone may be able to advise.

    I have installed a 110ah deep cell battery, which I am now going to add to inline, probably another 110ah. I have recently seen a dual purpose starter/leisure battery which look quite good. I know I shouldn't start the engine off the leisure battery so my question is...

    If I install the dual purpose in line (i.e positive to positive etc...) with the standard lesiure battery, could this be used as the starter battery or,. as they are inline, would this damage the standard battery.

    This may seem like an inane question, but if is preferrable to install a second 110ah deep cell with a dedicated starter battery it would handy to know.

    Thanks

    Steve

  2. #2
    Join Date
    Mar 2006
    Location
    Manchester
    Posts
    15,796

    Default

    Quote Originally Posted by sadbassa View Post
    Hi,

    Just a quick query in relation to the configuration of batteries.

    I am renovating a cabin cruiser and nearing completition. I am happy with setting up the batteries, but I have a random issue that someone may be able to advise.

    I have installed a 110ah deep cell battery, which I am now going to add to inline, probably another 110ah. I have recently seen a dual purpose starter/leisure battery which look quite good. I know I shouldn't start the engine off the leisure battery so my question is...

    If I install the dual purpose in line (i.e positive to positive etc...) with the standard lesiure battery, could this be used as the starter battery or,. as they are inline, would this damage the standard battery.

    This may seem like an inane question, but if is preferrable to install a second 110ah deep cell with a dedicated starter battery it would handy to know.

    Thanks

    Steve
    I think you mean Deep Cycle battery, rather than Deep Cell. If its truly deep cycle, it won't make a good starter battery. A leisure battery is better as a starter.

    Not normally a good idea to have deep cycle and leisure in the same bank, and better to have domestic and starters in separate banks.

    If none of that makes any sense, you need some help, or more education. Search batteries on here - there are loads of discussions.
    Narrowboating From Stretford!!

  3. #3
    Join Date
    Aug 2010
    Location
    Nottinghamshire
    Posts
    73

    Talking

    Quote Originally Posted by Richard10002 View Post
    I think you mean Deep Cycle battery, rather than Deep Cell. If its truly deep cycle, it won't make a good starter battery. A leisure battery is better as a starter.

    Not normally a good idea to have deep cycle and leisure in the same bank, and better to have domestic and starters in separate banks.

    If none of that makes any sense, you need some help, or more education. Search batteries on here - there are loads of discussions.
    I think I must need educating, in my train of thought knowing that each lead (plate) acid battery cell produces 2.2 volts at full charge, I would have thought that a deep cycle battery is one with thicker lead plates that don't distort so easily when getting hot due to producing more current as the voltage reduces. but I have found over the years that younger people know more than me, maybe one day they will say what a good idea wars are
    Last edited by Cheekybrat; 17-05-12 at 20:11. Reason: smiley missing
    Don't have much money, but boy if I did!

  4. #4
    Join Date
    Nov 2007
    Posts
    32,096

    Default

    Quote Originally Posted by sadbassa View Post
    Hi,

    Just a quick query in relation to the configuration of batteries.

    I am renovating a cabin cruiser and nearing completition. I am happy with setting up the batteries, but I have a random issue that someone may be able to advise.

    I have installed a 110ah deep cell battery, which I am now going to add to inline, probably another 110ah. I have recently seen a dual purpose starter/leisure battery which look quite good. I know I shouldn't start the engine off the leisure battery so my question is...

    If I install the dual purpose in line (i.e positive to positive etc...) with the standard lesiure battery, could this be used as the starter battery or,. as they are inline, would this damage the standard battery.

    This may seem like an inane question, but if is preferrable to install a second 110ah deep cell with a dedicated starter battery it would handy to know.

    Thanks

    Steve
    The most common setup is a dedicated starter battery - which does not have to be anything fancy, an ordinary vehicle battery for your size engine will do, and a separate "house" bank for evrything else. You then have a choice of different types, wet acid or gel batteries depending on your type of usage and depth of pocket. Youy also need to wire them so that you can isolate the two banks or parallel them if needed and a split charging device such as a VSR or a split diode to ensure both batteries are charged efficiently.

  5. #5
    Join Date
    Jul 2002
    Location
    Home: Kent. Boat: Chichester
    Posts
    42,350

    Default

    If you connect two batteries in parallel the first requirement is that they should both be the same type. Flooded, gel or AGM.

    Id not connect a leisure battery in parallel with a deep cycle battery. There would be point in one of them being deep cycle. You'd not be able to deep cycle it without also running the leisure battery below what would be an acceptable level

    If you need a larger capacity deep cycle battery for non-engine starting purposes then fit another deep cycle battery in parallel with it.

    As Tranona suggests fit a small engine starter battery specifically for engine starting.
    You can charge the two banks as he suggests using a VSR or by manual switching using separate isolator switches or a 1, 2, both, off switch according to your preferences.
    Diode splitters suffer from volts drop so to fully charge using a diode splitter you really need a battery sensed alternator.

  6. #6
    Join Date
    Sep 2006
    Location
    Gran Canaria
    Posts
    1,945

    Default

    Hi,

    Just came across this article...may be of some help to you?

    http://www.boatingbusiness.com/featu...urrent-affairs

  7. #7
    Join Date
    Mar 2006
    Location
    Manchester
    Posts
    15,796

    Default

    Quote Originally Posted by Cheekybrat View Post
    I think I must need educating, in my train of thought knowing that each lead (plate) acid battery cell produces 2.2 volts at full charge, I would have thought that a deep cycle battery is one with thicker lead plates that don't distort so easily when getting hot due to producing more current as the voltage reduces. but I have found over the years that younger people know more than me, maybe one day they will say what a good idea wars are
    What you say is correct..... Deep cycle have thicker plates and can be depleted further, but slower, than leisure/starter batteries.

    Thicker plates don't make for good Cold Cranking, and you will usually find that a true deep cycle battery won't have a CCA rating.
    Narrowboating From Stretford!!

  8. #8
    Join Date
    Feb 2009
    Location
    Home = Norfolk, Boat = The Wash
    Posts
    4,493

    Default

    Quote Originally Posted by VicS View Post
    <snip>
    Diode splitters suffer from volts drop so to fully charge using a diode splitter you really need a battery sensed alternator.
    Not really. Millions of boats with diodes out there that charge the batteries just fine.

    Yes, there is a volt drop. But, a decent diode won't have a huge drop. Do the sums between the alternator output voltage, minus the diode volt drop, and you'll be left with enough volts to fully charge a 12v battery. If there is a small shortfall, it's be so small that it'll be unnoticeable.

    The VSR concept is flawed and potentially dangerous. All the time the engines are running the VSR is running the battery banks in parallel. Having the banks in parallel defeats the point of having multiple banks. A single battery failure could leave you with all the batteries flat.

    There are also some potentially life threatening dangers involved in fitting a VSR how some manufacturers suggest. I've seen fitting instructions where there is no fuse between the VSR and either bank and the wiring sizes only take into account the maximum charging output. This can be very dangerous.

    For instance, you've sat at anchor for some time and the domestic bank is very low on charge. You start the engine and the VSR activates, connecting the banks in parallel. You press the windlass up button to haul the anchor. The windlass is wired to the domestic bank, which has nowhere near enough charge to haul the anchor, so all the power is drawn from the engine battery, via the VSR and it's wiring.

    Where'd you put that fire extinguisher ?

  9. #9
    Join Date
    Feb 2009
    Location
    Home = Norfolk, Boat = The Wash
    Posts
    4,493

    Default

    Quote Originally Posted by sadbassa View Post
    Hi,

    Just a quick query in relation to the configuration of batteries.

    I am renovating a cabin cruiser and nearing completition. I am happy with setting up the batteries, but I have a random issue that someone may be able to advise.

    I have installed a 110ah deep cell battery, which I am now going to add to inline, probably another 110ah. I have recently seen a dual purpose starter/leisure battery which look quite good. I know I shouldn't start the engine off the leisure battery so my question is...

    If I install the dual purpose in line (i.e positive to positive etc...) with the standard lesiure battery, could this be used as the starter battery or,. as they are inline, would this damage the standard battery.

    This may seem like an inane question, but if is preferrable to install a second 110ah deep cell with a dedicated starter battery it would handy to know.

    Thanks

    Steve
    Go check exactly what batteries you have and where they are (what they are powering). Post back with that information, along with how many engines the boat has and how it currently charges the batteries.

  10. #10
    Join Date
    Jul 2002
    Location
    Home: Kent. Boat: Chichester
    Posts
    42,350

    Default

    Not really. Millions of boats with diodes out there that charge the batteries just fine.

    Yes, there is a volt drop. But, a decent diode won't have a huge drop. Do the sums between the alternator output voltage, minus the diode volt drop, and you'll be left with enough volts to fully charge a 12v battery. If there is a small shortfall, it's be so small that it'll be unnoticeable.
    We are told that the volts drop across the diodes will typically be about 0.7 volt.
    dropping the effective cahrging volts from say 14.2 to 13.5. That's going to have more than an unnoticeable effect I think you will find.

    There are also some potentially life threatening dangers involved in fitting a VSR how some manufacturers suggest. I've seen fitting instructions where there is no fuse between the VSR and either bank and the wiring sizes only take into account the maximum charging output. This can be very dangerous.

    For instance, you've sat at anchor for some time and the domestic bank is very low on charge. You start the engine and the VSR activates, connecting the banks in parallel. You press the windlass up button to haul the anchor. The windlass is wired to the domestic bank, which has nowhere near enough charge to haul the anchor, so all the power is drawn from the engine battery, via the VSR and it's wiring.
    You would take this scenario into account when wiring the boat. Giving the battery supplying the windlass priority charging would solve the problem, even if you did not power the windlass from the starter battery anyway.

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