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.com/category/3/10/productline/overview/14
> <http://bluesea.com/category/3/10/productline/overview/14> which is
> 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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