[Selling] FatBoy Sparky Switch v1.0 300A 6S-14S Anti-Spark Switch

Hey guys, finally our FatBoy Sparky Switch v1.0 is available to buy.

FatBoy Sparky Switch is Anti-Spark switch for high current loads. It uses SOT-227 Mosfet in High-Side load switching setup instead of traditional Low-Side switches which means on this switch positive wire is switched. The Sparky Switch comes with a CNC machined aluminium block to increase thermal capacity for high load application.


  • Press to turn on / hold to turn off
  • Momentary push button support
  • LED output for power state (requires external resistor calculated for specific LED/input voltage values)
  • CNC machined aluminium block to increase thermal capacity (for high loads it needs to be cooled/attached to bigger radiator)
  • Screw terminals for high current ring connectors or busbars


Input Voltage 25V - 60V (6S - 14S)
Current rating Up to 300A (requires external cooling)
Dimensions 100 mm x 40 mm x 26 (with screws) 22 (without screws) mm
Weight 250g

Price is 70€ + (VAT if applies) + Shipping

Buy now from:



How much can the switch take without external cooling? :slightly_smiling_face:

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Without this aluminum or with it? If with it for normal esk8 loads impulses of high current for less than minute should be sufficient. If you going to run constant for longer than minutes you will need external cooling

This is kind of a basic spec, especially since your product is designed to address weaknesses in existing designs.

Do you think you can give a number for current it can handle continuously without supplemental cooling? Pessimistic is fine to cover all reasonable conditions (unventilated enclosure, summer, climbing hills on pneumatics)?

And ideally what “real world” vesc battery amps (total if multi motor) you expect it to handle?

Thanks for making this thing. I wish I caught this before putting in the PCB order lol.

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At ~50A continues without heatsink the mosfet was already really warm

And with heatsink?

How thick is the entire piece? Looks like more than 25mm

With screws on top its 26mm it looks big but it isn’t :wink:

@FredrikHems with heatsink its warm on 50A but not that warm as without it and it stays warm for I don’t know up to 150A then without additional mass or active cooling temperature rise pretty quickly :wink:


Here how the size looks compared to 107mm


:grinning: awesome

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I get the thermal absorption of the alloy, it’s a lot bigger than the A/S normally seen I guess that’s needed, does it have to be that long?

Is there a way to incorporate the pcb into the design of the focbox enclosure or too much heat combined?

Otherwise nice!

Do you want bulletproof or just bulletresistant? :wink:

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bullet avoidant

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Whats the internal resistance of the mosfet?

Mosfet Rds(on) 2.3mΩ and in case you wonder mosfet is IXFN420N10T

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I looked up that FET and it does not say “3D Servisas” on the side of it. Are you sure it’s that part? :stuck_out_tongue:

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Yes, it’s just hidden from plain sight :joy:

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First batch sold out. Next one will be available in 1-2 days after fabrication is done

What is the length and width of it? Will you include a pamphlet with the order that says which connectors do what and so on…?

10 x 4 cm (it included in specification if you would scroll up) The connections are marked on PCB that’s pretty much enough