Inverter DC Input Cable length

Discussion in 'OnBoard Electronics & Controls' started by 7228sedan, Feb 22, 2016.

  1. 7228sedan
    Joined: Nov 2009
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    Location: New Jersey USA

    7228sedan Senior Member

    I apologize in advance if this has been addressed elsewhere, I did look :). I am planning out the installation of the Xantrex Freedom 1800W Inverter/Charger. The manual recommends a cable length of 5ft (2/0 gauge). My installation prevents this based on the proximity of the batteries to the space I plan on mounting the inverter. The batteries are located in the engine compartment as far astern as possible. This area in my opinion is too warm & also potentially damp for the inverter's liking. I will be looking at a DC input cable length of roughly double the recommended 5 ft. Has anyone come across this dilemma?
     
  2. rasorinc
    Joined: Nov 2007
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    Location: OREGON

    rasorinc Senior Member

    I would think this happens often. I would call the company and ask what size wire to use
    for the extra footage.
     
  3. Mikas
    Joined: Feb 2016
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    Location: Lithuania

    Mikas Junior Member

    At maximum power inverter uses up to 150A current. For 2/0 cable at this current and 10ft cable length (both poles) you will have ~17W of power loss in cable,
    if you are going to use 20ft cable 2/0 cable will have ~35W of loses.
    My suggestion use cable 4/0 or even thicker if you find one. For 4/0 power loses must be ~22W but cable is longer so heat will be dissipated by bigger surface. Do not forget cable connectors. They must be fitable on both sides:battery and inverter
    Or just never run inverter at max power
     
  4. groper
    Joined: Jun 2011
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    Location: australia

    groper Senior Member

    Use minimum 50mm^2 cable and you will be fine for current carrying capacity and voltage drop.
     
  5. Barry
    Joined: Mar 2002
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    Barry Senior Member

    http://www.bulkwire.com/wireresistance.asp
    This site gives the voltage drop for various size wire.

    The 2/0 that Xantrex recommends is more than adequate to handle the 150 prox amps that your system will draw.

    Ensure that you use a tinned, copper wire cable, to reduce corrosion over time.
    Available at marine stores. Though the Xantrex installation manual suggested buying this cable at a welding shop and normally their cable is not tinned.

    If you went to 3/0 cable this should be more than adequate but check the calculator that I referenced above
    Even ABYC has a table that states if the cable is used in the engine compartment AND is at 90 degrees C or 194 degrees Fahrenheit, the max draw should not exceed 233 amps

    You made reference to 2/0 gauge. Ensure that you use "00" which is 2/0 and not #2 gauge which is significantly smaller

    But if you are worried about voltage drop, use the calculator and size up

    Groper has it but you could go to 3/0 to rest easy or make the call to Xantrex to find out why they limit the run to 5'
     
  6. 7228sedan
    Joined: Nov 2009
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    Location: New Jersey USA

    7228sedan Senior Member

    Thank you all for the advice. It looks like I'll be fine with 10 ft runs of 2/0 based on the voltage drop calculations at bulkwire.com. Once I confirm my length, I'll see if I need to up to 3/0.
     
  7. Barry
    Joined: Mar 2002
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    Barry Senior Member

    Not sure if Xantrex specifies a fuse in the line from the batteries to the inverter, you could always put a slow burn in line just for safetys sake
     
  8. 7228sedan
    Joined: Nov 2009
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    Location: New Jersey USA

    7228sedan Senior Member

    They do Barry; 250A max breaker or fuse
     
  9. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    The manual says flat out - "do not exceed 5' runs on the 1800". The issue may not be just voltage drop in the wires. Draw up your proposed install with PNs and specs and wire sizes and lengths. Include everything, Battery model nos, terminals, lugs, fuse holders, disconnects, etc. Be prepared to also provide inverter load information. Then call Xantrex tech services and email the proposal like Rasorinc suggested.

    The "rest of system" costs for adding one of these things can be pretty steep if you aren't working with a clean sheet. Warranty may require some documentation or a pro installer.

    The battery bank is also an issue if you need that kind of oomph. Sulfation is a problem for high current discharge even at fairly high states of charge. So adding an additional one or two batteries may let you safely discharge to a lower voltage or greatly extend battery life. This will be a change from if you only had small current draws before. From what I've seen of these systems in cruisers, three size 27 wet lead batteries do not survive long if discharged to 10.5 volts powering an inverter of this size (months, not years). If you have to add more batteries, add them close by.
     
  10. Barry
    Joined: Mar 2002
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    Barry Senior Member

    Hi Phil
    What other issues could there be besides voltage drop?
    5 feet of distance between can limit installation options especially when you need to have a properly ventilated battery box. Would you anticipate an induced current with other close proximity wires? 12V DC at 150 amps with either a 5 or 10 foot run does not seem to possess the parameters to make this a significant problem?
     
  11. 7228sedan
    Joined: Nov 2009
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    7228sedan Senior Member

    I will be using 2 8D wet cell batteries which are installed in boxes on either side of the engine compartment at the transom. Maybe I need to reconsider this unit? I doubt I will be utilizing the full capacity of the 1800. The batteries will be routed in parallel, however the unit only has a single bank charging output. I would actually prefer the charger to handle each battery independently as opposed to providing both with equal charge 100% of the time. I think I'm talking myself out of a inverter/charger and into seperate units.
     
  12. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    I will be using 2 8D wet cell batteries which are installed in boxes on either side of the engine compartment at the transom.

    Most but not all 8D are start batts , that do NOT handle deep cycling and house (or inverter ) loads well.

    IF you do find 8D in a deep cycle version the rating will be XXX AH at a 20 hour rate , not a CCA (cold crank amps) rating of a start batt.

    Many chargers handle 2 batts with ease on seperate circuits , just look before you buy.

    A large set of deep cycle batts , like the 8D will start most diesels quite well, if its not too cold out.

    The usual setup is start batts for the engine and house (deep cycle) for the reefer, fw pump , fans radio lights etc.

    Nigel Calder has a great basic book to get started.
     
  13. 7228sedan
    Joined: Nov 2009
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    7228sedan Senior Member

    Thanks Fred! My family business is a battery warehouse/distributorship, I have had great luck with these before. I will be using East Penn (Deka) 908D's they are not made with maintenance free materials however they are more of a "dual purpose" then a true deep cycle. They do have a decent amount of calcium in the plates which leads to their 1400 CCA rating. That being said, the plates are made up of a calcium/lead alloy which still lends to great cycling: (430 Mins @ 23A). My Inverter draw is going to be pretty low. I don't see me coming close to a constant 1500W ever. The primary purpose is for a small refrigerator (28W), and possibly a small microwave with very limited use. If I find that I am adding to the load, I will upgrade to a series of golf cart or floor scrubber batteries and modify my compartment. As for now, I have the boat set up for the 8D's due to their dual purpose nature.
     
  14. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    The usual hassle with 8D is the weight!

    Big PIA to haul,them down the dock and haul onboard.
     

  15. FAST FRED
    Joined: Oct 2002
    Posts: 4,519
    Likes: 109, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    The usual hasle with 8D is the weight!

    Big PIA to haul,them down the dock and haul onboard.
     
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