Any voltage rating 48 v DC and above will be fine. And you only need light wires to the big red panic button
Chris S
--- In electricboats@
>
> Thanks for the lead. It looks like the only DC breaker that handles the
> voltage I'm using (48 nominal) and the AIC I need (min 3000) is their
> "C" series double pole. I see the "T" class fuses would be another (less
> convenient) option. Probably not much difference in cost by the time you
> add the fuse holder and the spare fuses!
> -Tom
>
> Monte Gisborne wrote:
> >
> > Tom,
> >
> > Good luck with your project, it sounds very interesting!
> >
> > An emergency disconnect switch is a necessity, not an option, in any
> > EV traction system whether it resides on land or water (or potentially
> > air). It is a first-line safety device and anyone who has ever
> > experienced a power runaway situation, such as when main contactors
> > weld themselves shut, will inform that they are absolutely necessary.
> > This happened to me once in my homebuilt electric car and I was
> > grateful I had the presence of mind to heed these instructions. Mine
> > was a "big red switch" made by Albright, a UK company, but there are
> > many firms who build suitable disconnects.
> >
> > One may be tempted to think that there exists less potential for
> > mayhem in the water than on our roads but that belief is false.
> >
> > Another point well worth raising is the subject of overcurrent circuit
> > protection. I am particularly fond of products made by Blue Sea, which
> > seem uniquely and ingeniously designed specifically for our marine
> > purposes. For my preferred nominal voltage (48 volts DC), Blue Sea
> > carries a brilliant and professional looking product line called the
> > MRCB 187 http://bluesea.
> > <http://bluesea.
> > available in both a panel mount (on the helm) or a surface mount
> > (inside the battery box). It is available in a range of amperages from
> > 25 to 150 (for those using a Torqeedo Cruise 4.0R, use the 100-amp
> > unit). It is designed (and rated) to be safe in the marine environment
> > we are working in, unlike most other circuit protection systems. The
> > price for these is very reasonable (well under $100) and they are
> > readily available from most marine suppliers.
> >
> > Another benefit (keeping to the main premise of this discussion) is
> > that there is a reset switch built into the unit. While I still would
> > not recommend negating the "big red button", the MRCB 187 reset switch
> > (small yellow lever) does offer the opportunity to disconnect the
> > batteries in a pinch, especially if it is a panel-mount and mounted at
> > easy reach on the helm.
> >
> > Blue Sea offers DC circuit breakers in other voltages as well, as do
> > other manufacturers.
> >
> > As a final caution, I would never recommend using fuses on an electric
> > vehicle of properly-rated circuit breakers are available. Nothing
> > worse than being caught out with a dead motor and no fuse.
> >
> > Monte
> >
> > After 17 months of part-time building my 21' launch, I'm wrapping up
> > construciton and starting to work out wiring details.
> > I try to glean all I can from this group and the EV folks. Something I
> > see in the cars, but not so much in boats is an emergency disconnect
> > switch in case of powertrain runaway.
> > It seems that it might be really handy in the event of a failure to be
> > able to totally disable the battery bank without leaving the helm.
> > The EVs sometimes use "big red switches" within reach of the driver,
> > and sometimes use a mechanical cable to actuate a switch remotely.
> > Since I want to keep the battery bank wiring as short as possible, I'm
> > leaning toward the latter method.
> > This disconnect would be in addition to the keyswitch actuated battery
> > bank contactor and typical fusing.
> > Any thoughts?
> > -Tom
> >
> >
>
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