ABYC TE-30 recommends being able disconnect battery banks into groups of no more than 48V (nominal) for servicing.
-Tom
--- In electricboats@yahoogroups.com, Arby bernt <arbybernt@...> wrote:
>
> Dear Kevin,
> There is a fundamental difference between mains power and battery power. AC vs
> DC. I spent many years working on residential and commercial electrical
> installations. I've been shocked many, many times by AC. I routinely use my
> fingers to test for 120vac. Sometimes I even need to wet them first to feel the
> tingle.
>
> DC, on the other hand, has no trouble making itself known. While 12 to 30vdc is
> just a little burn, 48vdc can deliver a good shock, and the 300vdc systems I'm
> now working with are absolutely deadly. I've been shocked by 300vdc twice, once
> passing a charger over a battery pack, where I had the inertia to disconnect,
> and a second time, where I moved my elbow into a live terminal. That time
> knocked me on my back, and burned my skin.
>
> UL recognizes this as well, and classifies DC into low voltage, less than 42vdc,
> and high voltage, over 42vdc. In my lab, I have an assistant with a six foot
> fiberglass watching me work when ever I go over 65vdc. I cannot imagine that you
> have felt a high voltage shock and made this posting. I hope you never do. DC
> across your chest will kill you. AC offers the chance to release, DC locks you
> up. The two are entirely different.
>
> I hope you have an assistant when you are working on your battery bank. One
> slip, especially in rough seas, and it would be your last.
>
> Be Well,
> Arby Bernt
> Advanced Marine electric Propulsion
>
> ________________________________
> From: luv2bsailin <luv2bsailin@...>
> To: electricboats@yahoogroups.com
> Sent: Tue, January 18, 2011 3:04:15 PM
> Subject: [Electric Boats] Re: voltage
>
>
> Kevin,
> Nice write-up on the "Green" conversion.
> Any chance you could give us a cost breakdown?
> Jim McMillan
>
> --- In electricboats@yahoogroups.com, "kjshepherdca" <kevin@> wrote:
> >
> > Hi all
> > I have been reading for 5 years but seldem post. This site and some regulators
> >seems to be stuck on 48v this voltage is ok for small boats, but we cannot
> >advance without accepting the facts. I am an electricain and work daily with 120
> >v to 600 v and I make these systems safe for the public. I use breakers and
> >mechicnal protection. This is not rocket science. The currents at low voltage
> >are hard to manage, they create heat everywhere . the heat losses are to the
> >square of the current.
> >
> > I read all the time of users having heat issues with controllers and building
> >noisey and inefficent gear reductions. I have a soloman 4.5 kw with an off the
> >shelf AMC controller ,cool, to the touch all day long even in summer. My sweet
> >spot is 4 A (600W) at 3.5kts in chop. Direct drive means only 1 moving part. low
> >currents make for happy batteries. Green is full keel sloop at 5 ton.
> > My regret is the propeller I was 16X7 27 hp diesel, I went to 16X16 3 blade I
> >wish for 4 blades or 16X20+ . The aggersive prop acts as a sea anchor so I spin
> >at low speed (150W) while sailing ,like a dynamic neutral, and for a 100 watts
> >more I can point a few degrees higher. I use a 3KW russco charger and Honda
> >2000i (1600w@ sea level,1400w up here on the lake) to reach amost hull speed, a
> >3000 would do it but they are too big.
> >
> > With recycled electric vechicles available in comming years we will go to 300
> >votls . Dont be afraid ,be safe..
> >
> >
> > PS good luck to the Soloman team in Florida wish I was there.
> >
> > Kevin Shepherd
> > E/SV Green
> > B.C. Canada
> >
> > www.green-power.info
> >
>
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