Monitoring your current draw and battery state.

Discussion in 'Motorhome Chat' started by GREENTUB, Jan 5, 2010.

  1. GREENTUB

    GREENTUB Read Only Funster

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    We have recently retired from sail boat cruising after 15 plus years of 'bouncing' around the Atlantic and Med and have ordered an Autocruise Augusta for an inland challenge. When it comes to life aboard it seems to me that a motorhome and a cruising sailboat are much the same thing with many of the same issues. Reading this site to suck up motorhome related information I can't help but note the number of problems people seem to have with 12v electrics. The best £90 I spent on the yacht was a 'NASA Battery Monitoring' instrument. It is a simple DIY fit and the instrument comes with 5 mtrs of cable and a 100 amp shunt. It constantly monitors current draw i.e whenever you switch on an appliance it incrementally shows the increased current draw. Moreover, it gives a % readout of remaining battery capacity, voltage and time required to recharge. If you are interested just visit any marine chandlery website for detailed information and pictures. I hope this is of help especially to those with a disinterested grasp of Ohms law. Cheers
     
  2. Diabalo

    Diabalo Funster

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    Welcome Greentub and a great tip, but £90 is a lot of beer:Rofl1:
     
  3. GREENTUB

    GREENTUB Read Only Funster

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    Thanks for the welcome - much appreciated. Yeah! you're right 'mucho-beero' but it really did take the worry out of battery management. I guess the difference with a yacht is that if you run out of wiggly or 'straight' amps in the middle of the briney it takes a fairly long set of jump leads to get out of trouble. On a more serious note, on the yacht we had a solar panel, wind generator and the engine alternator pouring the 'stuff' in and countless gadgets and widgets gulping the 'stuff' out. The NASA thingy does all the adding up and taking away for you. I found it totally reliable. Cheers
     
  4. MicknPat

    MicknPat Funster

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    Greentub,

    The NASA battery monitor could be exactly what I'm looking for.

    I have purchased an Owl monitor to keep an eye on what we draw from the EHU so that we minimise tripping the post.

    Now our motor home has 4x 6volt 235Ah wired to provide 12 volts @ 470Ahs, I also have 3x 125 watt solar panels.

    Now to allow max power from the EHU I switch off the Xantrex Inverer /Charger hoping that the solar panels keep the batteries fully charged, but either due to the lack of sun at this time of year or because of a high parasitic drain I'm have to keep turning on the charger every other day.

    What I would love to buy is a device that would read the power being drained from the 4 batteries, do you think the NASA monitor is what I need?

    Mick
     
  5. GREENTUB

    GREENTUB Read Only Funster

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    Hi there

    Personally I think it's exactly what you need but don't take my word for it - type 'NASA instruments' into Google and read the spec. It reads down to decimals of an Amp and is very useful in determining if you have an electrical leak. My wife even loved it (technophobe) and spent hours working out the best combinations of lights etc for minimum draw. Hope that helps. I'll be fitting one to my new toy when I get it.
     
  6. big map

    big map Funster Life Member

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    Hi and welcome Greentub.
    Thanks for the tip.:thumb:
    I see they now do a more compact version designed for motorhome and caravans, sold at Force 4 for £94.95.

    Mike.
     
  7. GREENTUB

    GREENTUB Read Only Funster

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    Thanks Big Map. Well blow me down - there's me thinking I might be adding something new to the motorhome community and NASA(I guess it's not rocket science) are well ahead of me. Good for them. Cheers :Doh:
     
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