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  1. #1
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    Jun 2013
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    Default 5v around the boat?

    Been hovering around the upper end of the list for a while now - fitting a few 5v usb fans (still HOT here!) & sockets for phone/tablet/kindle charging. The obvious route seems to be just tee off a nearby lighting circuit locally,current is next to nothing. Having a biggish single buck converter at the panel then running in new wires for 5v just seems a lot of pointless work.

    But....... you never know, always worth a quick ask - How do you lot do it?


    (what will take longer is going through the stash of 12v-5v converters to measure which ones keep the voltage up under load & don't spit out too much RF noise)

  2. #2
    Join Date
    Nov 2009
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    35,609

    Default Re: 5v around the boat?

    All the wiring around the boat is 12v, with individual 12v-USB adaptors next to each bunk and above the tray in the saloon where phones etc tend to get dumped. These are all on a "12v and domestics" circuit that also powers 12v lighter sockets in the same places and the stereo.

    Be aware that if you just wire a bare USB socket to 5v, most phones won't charge very fast. They need a particular resistance across the data lines to tell them that it's ok to draw more than the original standard 0.5 amps.

    Pete

  3. #3
    Join Date
    Sep 2001
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    Me - Zumerzet Boat - Wareham
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    12,291

    Default Re: 5v around the boat?

    Quote Originally Posted by GHA View Post
    (what will take longer is going through the stash of 12v-5v converters to measure which ones keep the voltage up under load & don't spit out too much RF noise)
    I have 3 12v-5v converters two are ok the other is noisy, strange as I thought I bought them from the same source.
    MontyMariner.co.uk
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  4. #4
    Join Date
    Sep 2001
    Location
    Home - Sothampton, Boat - Gosport
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    10,344

    Default Re: 5v around the boat?

    A decent USB adaptor will supply a couple of amps per socket so, allowing for some loss in bringing the volts down from 12 and a bit of fudge factor, that's a potential couple of amps. A lighting circuit designed for a few filament bulbs that's now driving LEDs will still be supplying less than it was designed for with an adaptor working flat out and all the lights on.

    As for fans, why not use 12v? It would be more efficient, though admittedly less convenient than being able to plug in to a USB one.
    Steve
    Never believe anything until it has been officially denied.

  5. #5
    Join Date
    Jun 2007
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    Oban
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    1,792

    Default Re: 5v around the boat?

    Quote Originally Posted by GHA View Post
    Been hovering around the upper end of the list for a while now - fitting a few 5v usb fans (still HOT here!) & sockets for phone/tablet/kindle charging. The obvious route seems to be just tee off a nearby lighting circuit locally,current is next to nothing. Having a biggish single buck converter at the panel then running in new wires for 5v just seems a lot of pointless work.

    But....... you never know, always worth a quick ask - How do you lot do it?


    (what will take longer is going through the stash of 12v-5v converters to measure which ones keep the voltage up under load & don't spit out too much RF noise)
    i'd be reluctant to tool up for the USB A standard with USB C on the rise. All my devices are USB C and I have 12v to USB C PD chargers. It is an order of magnitude more efficient in charging. Unfortunately you can't simply plumb it in around the boat because the charger negotiates the charging regime, including voltage, with the charged device. You can charge a USB C device from USB A but only at USB A speed. There is no way it'll do your laptop for example. Sadly, being more intelligent, the USB C chargers are noticeably more expensive. N.B. It matters which charger you get - it needs to be PD (power delivery). In my experience even some chargers that claim to be PD don't go all the way to the Max specified in the standard - 5 amps at 20 volts.

  6. #6
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    Default Re: 5v around the boat?

    Quote Originally Posted by Stemar View Post
    As for fans, why not use 12v? It would be more efficient, though admittedly less convenient than being able to plug in to a USB one.
    Local DIY store has some for about €6, close to completely silent and only about 200mA @5v , perfect next to the bunk so will be nice to dot a few around and still keep the coframo.

  7. #7
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    Default Re: 5v around the boat?

    Quote Originally Posted by Amulet View Post
    i'd be reluctant to tool up for the USB A standard with USB C on the rise.
    My boat devices lag well behind the bleeding edge of USB

    Anyway, really doesn't matter much if they charge a bit slow, not like there's a hurry..

  8. #8
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    Jun 2007
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    Default Re: 5v around the boat?

    Another quick thought - in you choose to disregard my warning there are still good reasons for not creating a 5v circuit around your boat. The lower the voltage the higher the current needed create the same power. That means thicker cables or more power loss along thin cables.

  9. #9
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    Jun 2013
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    Default Re: 5v around the boat?

    Quote Originally Posted by Amulet View Post
    Another quick thought - in you choose to disregard my warning there are still good reasons for not creating a 5v circuit around your boat. The lower the voltage the higher the current needed create the same power. That means thicker cables or more power loss along thin cables.
    5v ring round the boat had already been pretty much disregarded, that being one of the reasons. Or not quite power being dissipated, but decent cables being needed to stop too much voltage drop - one good reason not the skimp on usb cables if you want faster charging, your 5.1v at the charger can easily be 4.75 at the phone.

  10. #10
    Join Date
    Dec 2008
    Location
    Sweden
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    1,540

    Default Re: 5v around the boat?

    I ordered one of these:


    and then made a few voltage dividers like this, positioned near the USB sockets:


    This charges up Iphones, Ipads and other mobiles fine.
    No RF noise.

    However, I do not claim this route to be any better, easier or cheaper than installing a few 12V USB outlets. But it can be done and I learned something doing it.
    Last edited by BabaYaga; 19-08-19 at 14:35. Reason: addition

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