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Thread: Starting Battery Back Up

  1. #1
    Join Date
    Dec 2007
    Posts
    100

    Default Starting Battery Back Up

    I went to my boat on Saturday morning to go for a sail, only to find two dead-flat batteries. Like 8.4 V flat. Indeed, I had left the battery switch on Both and all the sailing instruments, VHF, etc. still turned on. This was a first for me and I can only ascribe it to the madness of having had two actual humans aboard the boat earlier in the week for a day sail. Clearly I am not used to this kind of strange human-human interaction and it threw me off my usual routine.

    With no shore power or battery charger, I hauled my car battery down to the boat, jumped the starter, and ran the engine for several hours to re-charge the batteries. While waiting for the Ah's to accumulate I got to thinking about what I would do if I made a similar mistake in a place where my car was not handy - such as in an anchorage or, God forbid, half-way to Hawaii.

    I had seen advertisements for portable Li-ion battery packs marketed for jump-starting cars with dead batteries. They are small enough to fit in the trunk or glove compartment and come with a built-in set of jumper cables. After some web browsing, I found the Beatit 800A 12V Portable Car Jump Starter on Amazon Prime for $70. There are cheaper units, and much more expensive units, but this model seemed to have the best capacity/$ and the reviews were generally positive.

    This morning I gave it a try. On a cold engine (2 cylinder Yanmar 2GM, 50 degrees outside), I disconnected the internal batteries and attached the portable unit. One push and boom the engine started right up. I killed the engine and re-started it several times. No problem. The built-in monitor showed only 1% capacity loss. I was impressed.

    I am Velcro mounting the battery pack in the nav station with permanent charging via a cigarette lighter charge adapter (included). I like that it also serves as a back-up charging source for electronics (cell phone, tracker, cell phone, etc.) through its built-in USB charge adapters. All together, it seems like pretty cheap insurance for $70. See attached photos.
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  2. #2
    Join Date
    Jan 2014
    Location
    Arnold, CA
    Posts
    447

    Default

    Good idea.
    I was thinking of something similar for backup power for tracker, nav, Sat phone.

  3. #3
    Join Date
    Nov 2010
    Location
    Discovery Bay, CA
    Posts
    427

    Default

    Quote Originally Posted by Daydreamer View Post
    Good idea.
    I was thinking of something similar for backup power for tracker, nav, Sat phone.
    looks like a really good idea given the size and cost. Having a fully independent bu power source could be mighty useful.

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