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Dave and Anke
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Saturday, August 26, 2023

5VDC Revolution for Smallish Boats?

MUSTELID's 5/12VDC Hybrid Electrical System
(Lithium Ion Batteries are HAZMAT, so we went with Lead/Acid)


An immense effect may be produced by small powers
Wisely and steadily directed.

-- Noah Webster

5VDC Revolution for Smallish Boats?

A while back I wrote about a simple 12VDC system, here.

For a very long time, 12VDC systems have been the go-to foundation for small vessels. There's been a host of products available both in marine and RV/auto markets that meet all the needs of the small scale sailor.

But there's a quiet revolution boiling along for the last decade or so, and it's reaching maturity. I'm speaking of USB charging, 5VDC systems. 

From charging arrays (PV) to controllers to lightweight, high-capacity batteries to products ranging from smart phones, laptops, GPS, VHF, depthsounders, navlights, cabin lights, spotlights... all has become available at generally lower up-front costs and considerably lower draw.

Many of these devices have rechargeable, onboard batteries, each of which can contribute to total power storage, eliminate runs of wiring and reduce the size of a central battery. USB 'hubs' serve as power strips for centralized charging and flexible power supply.

If your vessel is already set up for 12VDC, it's likely most economical to stick with it, or possibly hybridize with a USB hub to handle new acquisitions. 

But if you are outfitting a small vessel, particularly in the micro-cruiser range, The small footprint and low draw of 5VDC is well worth a look!


  1. Replies
    1. Hello Dave and Anke! Good to hear (read) from you.
      Nice topic! I share about your enthusiasm in low voltage systems for small boats and other off the grid uses. Now we live in a off the grid small house (not tiny) on fields area between the Atlantic Ocean and a vast Lagoon, an remote area, and uses off the grid solar power to iluminate, pump water from well to a gravity reservoir and communications, cell phone charge and internet hub. In a way much like you told.
      Liked your use of USB 6 hub - and it enters 12v and outs 5v? I don't had thinked about it! Will improve here! Many thanks!

    2. Hi Lucas,

      Yes, our USB hub (X6) is 12VDC in and 5VDC out. If we'd been able to get a lithium-ion battery in 5VDC, we would have tried it, but couldn't get it shipped to Alaska for any reasonable price. Things are changing, though.

      Good luck with your systems!

      Dave Z

  2. Funny, the low voltage stuff has been creeping into my projects on sort of an ad hoc basis and it never occurred to me to be systematic about it. Duh.

    1. Hi Sixberars,

      Pretty much same as you. When this one came around, though, we were shopping around and were surprised to find everything so available at far better prices! That and I can't stand cigarette lighter plug-ins.

      Kinda snuck up on us.

      Dave Z

  3. “… are hazmat…”

    And _lead_-acid batteries aren’t?

    Granted, Pb-acid are theoretically
    more recyclable, but much depends upon the where, the who and the how. Li-Fe-ion batteries have a much longer lifespan (assuming proper care), and far less vulnerability to over-discharging accidents (which can quickly damage or even ruin Pb-acid batteries).

    Also, wrt the recycling option, much work is proceeding apace toward good Li-ion recycling, and with their exponentially expanding ubiquity, much financial and technical effort is on that.

    1. Hi,

      Right you are on all points.

      The longish response is that 12VDC lead-acid batteries are routinely shipped to our remote village via barge (HAZMAT is allowed) in large, commercial volumes, so are locally available at a reasonable price. Meanwhile, Li-ion batteries of any voltage can't be shipped by air and in single units are prohibitively expensive by barge.


      In the longer term, we're hoping that one of the various common-material batteries breaks into main market supply. Aluminum-ion batteries are a top contender. Low flammability risk, low impact materials, high energy density. Win-win-win!

      Dave Z

  4. A source for appropriate sized Lithium ion battery banks are the new power packs designed to jump start engines. The one I have is charged by USB, has a high output USB port, and the 12v output.
    Example TYPE S Portable Jump Starter & Power Bank with Emergency Multimode Floodlight

    1. Hi,

      Thanks for the tip... we'll look these up. Our big issue is getting them shipped here. Hazmat makes it difficult.

      But a huge advantage over lead-acid is that we don't have to maintain a minimum 50% charge (to preserve the lead plate active surfaces).

      Not only are the Lithium-Ion batteries lighter, but that difference means one only needs half the amp hours to break even!

      Dave Z