I agree James. (but that's one of the reasons that I bought my system from you)
I looked at Blue Sea fuses for my system. The most common ones at my local West Marine are ANL fuses, but they max out at 32V, like most common types of fuses. The next ones that I saw were the Battery Terminal Fuses, little plastic cubes that look pretty slick. But the max voltage is 58V, which is too close for comfort for our 48V systems that charge up to 58-60V. Plus the contact area is fairly small, so there might be some heat buildup that would lead to more blown fuses. The interrupt rating (how much current before there may be arcing across the blown fuse) is 2,000A which sounds OK but it pales in comparison to the fuses that you supply with your kits or other Class-T fuses.
Finally, I looked at Blue Sea Class-T fuses. With great contact area, a max voltage of 160V and an interrupt rating of 20,000A, I have complete confidence that these fuses will work when I need them to and won't blow under normal conditions.
We can see that all high amperage fuses are not created equal, and I agree that looking at all of the specs and choosing the right components will lead to a more reliable and safer drive system. And while the prices aren't very different, I am a firm believer that safety systems are not the place to try to cut corners....
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, James Lambden <james@...> wrote:
>
> Jim,
>
> Another thing to remember is the voltage ratings of fuses.
> Many fuses are being used that are 32 volt, 48 volt, even 58 volt fuses. I am changing the battery pack out on an electric truck right now and they employed 32 volt fuse on a 96 volt truck. Not a good idea.
>
> But it's not just the rating that matters. Fuses need surface area otherwise a hot spot will be created on the fuse surface that ends up tripping the fuses.
>
> The next set of ratings for these fuses are at 175 volts, which is what we are now recommending and supplying with our drives.
>
> DC power is very inductive and does not want to stop flowing. If an arc is created, the length of the sustainable arc is proportional to the voltage. Using a fuse that is under rated, or even one that has no headroom is not a good idea. We are building and designing systems that are using huge currents on a continuous basis so everything will build up heat and even more so if it is not designed to dissipate heat.
>
> The ultimate in safety of a system is to have a circuit breaker capable of breaking under load for a system shut down, and fuses on each battery bank. An aluminum boat should have fuses on every battery that is near an aluminum structure.
>
> Most switches are rated at 48 volts but the electric drives regularly see 58 volts when charging so these 48 volt switches are under rated. 48 volts maximum is different from 48 volts nominal. Most Switches are not capable of switching under load, and they should be termed isolation switches and marked not to be switched under load.
>
>
> The safer we can make these systems, the better off we all will be, as a group and an industry.
>
> A comprehensive look at safety systems on boats would be a good idea, because the amount of electrical power stored in one of our large battery banks is huge.
>
> It does not cost that much more to incorporate adequately rated components in our systems.
>
> James
>
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