Check specs of this fuse for a 45A rated motor, 6mm^2 cable

[egokart]

Hi all

Looking at this fuse and holder. It's for a tar track DIY kart, 45A 48V Kunray controller with 6mm^2 cables. No uphills, all flat track.

I have a second kart that is 72V 45A, same setup. I think I can use the same spec fuse with both as all the cables are the same.

The 1 second rating of 6mm2 cable seems to be 640A and this fuse is supposed to open in less than a second at 180A, so it looks safe?

 

[Functional Artist]

Wow! that is one heck of a fuse (what does that thing cost?)

Seems like "over kill" to me

I've used these type of circuit breakers on several karts as a main cut-off switch & also, a resettable fuse (~$20.00)
...with no problems

https://www.ebay.com/itm/154739459376?hash=item240730c530:g:HzAAAOSwVBdhsNQr&amdata=enc:AQAHAAAA4NuMHM2L3lKlsjvrxOCQf63TKhdDkZJoh5FdCSHrXqu/6+kRb+IF4DeJny9Yxt7p8hsj+RPMbPlGy68jdKd18Iy+6GwxycuBldN/iYpBehiZvMp75zIpm5IR6mxW873l6dVSPU822YI/pARi0WdCpMkQqLFx0V3WmZ9WbFzwUFb4XNYWQOBuaBG8tzvKjvlE8TMsYKr8JPuf4MwztwRjwA9lUoKvRt1jZz8dRNbjvOdCIgVEK/nAT+zsf2+NtmTm2mLRMOnoUeZYJsGZlJnNotJdhXTX0RckdJ9y3tFm34gO|tkp:BFBM7t_QtqFg

50A AMP Circuit Breaker Fuse Car Boat Waterproof Manual Switch DC 12-48V

Description:
Combines switching and circuit protection into a single device.
Used in auxiliary and accessory circuits in truck, bus, RVs and marine applications. Others include battery charger and DC audio system.
Panel Mount,Termination:1/4-28 threaded studs.
Max Voltage: 48V DC, Interrupt Capacity: 3000A @ 30Vdc.
Comply with a standard SAE553J1171 ABYC E11 (Ignition Protected).


Specifications:
Rated Current: 50A
Voltage: 48V DC
Reset Type: T3, Manual Reset
Mounting: Panel Mount
Operating Temperature: -32°C to 82 °C(-25°F to 180 °F)
Interrupt Capacity: 3000A @ 30Vdc
Wire Connection: BAT LINE SHI for input wire, AUX LOAD for output wire.
Waterproof Rate: IP67.
SAE Standard: SAEJ553 SAEJ1171 SAEJ1625.

 

[egokart]

Hi Artist

The cost of it is somewhat painful..$40 for the fuse and around $40 for the holder. Cheaper than a trip to the hospital from having a battery short under my right elbow though.

Thanks for the link. I'm following the spec for the Texas Solar Challenge karts as much as I can, they specify 250V DC fuses at a minimum, apparently after having seen some problems with lower specs used in their racing league. There's a big gap in available fuses between 48VDC and 250VDC, I guess because of 48VDC being max for trucks and 250VDC being a common industrial rating.

When my 48V pack is fully charged it is at 51V or so, a bit over the max for this type of switch. My very rough calcs based on the battery datasheet says the battery could supply 9000A of short circuit current. 2xIxt = 2x9000x1=18000joules, this fuse melts at 1400 joules to open the circuit. Sorry was a bit late at night when I did that math so it probably is wrong. The breaker you linked is rated at 3000A, which I think means the guts of it would melt and provide a closed circuit instead of interrupting the current.

I think that breaker you're using would be perfect for tripping if there is a short inside a an appliance on a boat for eg, but a direct short across the chassis of the kart or battery + cable to battery - cable would not be interrupted.

 

[egokart]

On the other hand, the titan of scooters is selling a 32V fuse for a 48V motor kit:

48 Volt 1800 Watt Electric Go Kart Power Kit

48 Volt 1800 Watt Electric Go Kart Power Kit

cart.electricscooterparts.com

From the reading I have done, there is no guarantee that this fuse would interrupt a battery short. But it is a lot cheaper so I would like to use them if they are safe. Any thoughts?