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  1. #71
    Join Date
    May 2016
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    Suffolk
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    4,753

    Default Re: Another one bites the dust

    Quote Originally Posted by BelleSerene View Post
    I have separate banks - a pair of really chunky lead acids running everything domestic (used to be AGMs when I could afford them) and a deep-cycle engine starter. Separate circuits, splitter and intelligent charger.

    For that rare occasion after some years when the engine battery gives up the ghost after some time unattended and off charge (happened a year ago, requiring just a replacement 110Ah deep cycle engine battery), is my backup plan of a pair of heavy-duty jump leads OK, to run between the battery banks for the time it takes to crank the starter motor? That’s my emergency ‘Both’ switch. Of course, I could always disconnect the engine battery or the domestic load with a spanner before using the leads to bridge from domestic bank to starter lead - but the simplest plan is just to jump-start in situ as we do with cars. If the experts agree...?
    Jump leads will work and would be a better solution than messing around disconnecting leads. If you keep all of the negatives permanently connected together you would only need the red lead for the positives.

    The setup in my OP uses a third switch in place of your red jump lead. It would be preferable to a jump lead if the engine battery had failed, as you can turn the engine switch off and the emergency switch on, starting and continuing to run the engine from the domestic bank. Same method can be used if the domestics fail (more unlikely) to run them from the engine battery. It is also quicker and easier than jump leads of course. A typical time to want to start the engine is when you drop the sails as you come into port, that might not be the best time to be looking for the jump leads.
    Rainbow Marine.
    www.rainbowmarine.co.uk

  2. #72
    Join Date
    Jul 2001
    Location
    East Coast
    Posts
    731

    Default Re: Another one bites the dust

    Paul R - I think I've installed a similar system in my boat, in that I have two batteries with individual on/off switches and charged through a VSR which I fitted last year , replacing the 12B switch. The VSR has a low power relay over-ride function; will this do the same as your central switch or is it more akin to the 'both' function on a 12B switch?

  3. #73
    Join Date
    May 2016
    Location
    Suffolk
    Posts
    4,753

    Default Re: Another one bites the dust

    Quote Originally Posted by Sniper View Post
    Paul R - I think I've installed a similar system in my boat, in that I have two batteries with individual on/off switches and charged through a VSR which I fitted last year , replacing the 12B switch. The VSR has a low power relay over-ride function; will this do the same as your central switch or is it more akin to the 'both' function on a 12B switch?
    The Victron VSR that i use has the same function, it basically overrides the voltage sensing circuitry and manually closes the relay. This means the bank are now in parallel, the same as my "emergency" switch, which is also the same as the "both" setting in the 12B switch.

    You are limited though by the max rating of the VSR, 120a for the Victron and 14a for the BEP, for instance. To get those ratings you also have to fit suitable cables, 16mm² for the Victron and 20mm² for the BEP. I think those cable sizes are a bit heavy for normal charging, the function has limited use and there is still now way to isolate one battery and run everything from the other, for an extended time, if a battery fails.

    So i prefer to limit the VSRs use to charging, connecting it with lighter cable and fusing according to those cables, then fitting the third switch to cover the other backup functions.
    Rainbow Marine.
    www.rainbowmarine.co.uk

  4. #74
    Join Date
    May 2016
    Location
    Suffolk
    Posts
    4,753

    Default Re: Another one bites the dust

    Quote Originally Posted by Rogershaw View Post
    No problem at all with those switches. I have one on my Jenson and we fitted them to rally cars as a main isolator in case of rollover. I also fitted one to my single outboard motor boat.

    That type has been around for years in the motor sport world.

    Sorry Roger, but i disagree. Fitting them to cars is not the same as fitting them to boats.

    Yes, the "type" has been around for years, but there are many versions of the "type". Quality is variable, as with everything, but more important current rating is also very variable. The Seaworld switch that GHA refers to is a low amperage device IIRC, about 100a max @12v, maybe 75a continuous ? Perhaps GHA could confirm this ?

    As i said, on a cruising boat (such as GHAs) i would't want to fit them. Connecting such a low amperage switch to the domestic circuits of a boat that may well have a windlass or bow thruster is asking for trouble, so is fitting one to something with a reasonably sizable inboard, bleeding the fuel system would be an interesting test for the switch.
    Rainbow Marine.
    www.rainbowmarine.co.uk

  5. #75
    Join Date
    Apr 2013
    Posts
    4,466

    Default Re: Another one bites the dust

    Seeing the thread on compact and relatively inexpensive emergency starting batteries (http://www.ybw.com/forums/showthread...on-boat-engine) made me wonder if such improvements in battery technology might render obsolete one of the principal arguments deployed against the 1-2-B-0 switch?

  6. #76
    Join Date
    Jun 2013
    Location
    Hopefully somewhere warm
    Posts
    7,242

    Default Re: Another one bites the dust

    Quote Originally Posted by PaulRainbow View Post
    The Seaworld switch that GHA refers to is a low amperage device IIRC, about 100a max @12v, maybe 75a continuous ? Perhaps GHA could confirm this ?.
    No markings on it - the link from google looks like the same says 100A continuous 500A peak.

    Regardless of that, I'm that not keen on anything I can't take apart and have a good look at so these might find some low power non critical use but won't be wearing the "big boys pants"

  7. #77
    Join Date
    Jul 2001
    Location
    East Coast
    Posts
    731

    Default Re: Another one bites the dust

    Quote Originally Posted by PaulRainbow View Post
    The Victron VSR that i use has the same function, it basically overrides the voltage sensing circuitry and manually closes the relay. This means the bank are now in parallel, the same as my "emergency" switch, which is also the same as the "both" setting in the 12B switch.

    You are limited though by the max rating of the VSR, 120a for the Victron and 14a for the BEP, for instance. To get those ratings you also have to fit suitable cables, 16mm² for the Victron and 20mm² for the BEP. I think those cable sizes are a bit heavy for normal charging, the function has limited use and there is still now way to isolate one battery and run everything from the other, for an extended time, if a battery fails.

    So i prefer to limit the VSRs use to charging, connecting it with lighter cable and fusing according to those cables, then fitting the third switch to cover the other backup functions.
    Thanks very much for that. Sorry for the digression

  8. #78
    Join Date
    May 2016
    Location
    Suffolk
    Posts
    4,753

    Default Re: Another one bites the dust

    Quote Originally Posted by Sniper View Post
    Thanks very much for that. Sorry for the digression
    No problem, we digressed from my original tongue in cheek OP a long time ago
    Rainbow Marine.
    www.rainbowmarine.co.uk

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