Adding an inboard to kayak?

Discussion in 'Boat Design' started by FishinCary, Dec 31, 2019.

  1. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Li Ion batteries can be charged safely at 5C, not 0.1C like old style lead/acid.
     
  2. Ilan Voyager
    Joined: May 2004
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    Location: Cancun Mexico

    Ilan Voyager Senior Member

    Not exactly true if you want that the battery lasts, and not all batteries will accept 5C without burning, it's a problem of internal resistance versus capacity of cooling. But 0.5C in Li Ion are common with high quality cells and accepting a shortened life.
    The safety problems of a no-marine gas engine in the kayak forbides to even think on this solution. Or a costly marinization will be needed.
    A LiPo bat allows also a quick partial charge of the bat if needed, and LiPo is cheaper than Li Ion per ah. On the Lipo we use in RC modelism the rule of thumb is to charge at 1C , so you get 80 to 90% of the full charge in just one hour. But we accept the short life.

    There are plenty of LiPo 12V 100 to 200 ah in waterproof boxes monitored by BMS with voltmeter and often 5V 2ah USB for the phone. The prices are around 400 USD the 100 ah and 700 USD the 200 ah direct from China. The weight is around 12-15 kilos.
    The chargers sold with the bats are the small cheap 12V 10 amps ones, so putting money in a powerful intelligent charger is a good investment. The BMS can limit the charging amps so you have to ask the seller for the BMS max allowed charging amps.
     
    Last edited: Jan 6, 2020

  3. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    I have worked in battery research for several years. 5C is normal for a Li Ion battery. Otherwise, you would have to plug in your phone for 14 hours a day to get a charge. Further LiPo is a type of chemistry for Li Ion batteries. Li Ion batteries need charge/discharge controls that take into account current and temperature. Some of the really cheap batteries and chargers that don't have controls can damage or even make batteries explode. Very small batteries, like for RC, have a large surface area for the volume in comparison to a car size battery. Therefore they cool more and have less need of precise controls. They can't be compared. Batteries, like most things, do not scale linearly.
     
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