Power soft-start

Thanks to Sebi, we’ve got some new 45A ESCs, which looks awesome.

While replacing the old ones, which burned out, it let us thinking about why we are actually getting so many burned out ESCs? Sometimes those burn without any actual load, just connecting them to a battery is enough to get a “smoke” situation.

Discussing this with Richard he suggested to implement a power soft-start design to reduce initial kick (inrush current) to those electronic components. THE ULTIMATE GUIDE TO SOFT START DESIGN article provides detailed description of this problem, including several options on how to address it.

The basic solution to this is trivially simple – limit the inrush current by adding a power resistor in series with the load primary.

Which very much correlates with Richard’s version (recommending to use 10 Ohm 5 Watt Wire Wound Resistor):

Intention here is to achieve something like on a the measurement below – reducing those current spikes to a level where our 100A battery won’t cause any harm.

After the inception phase, our project started with some decent shopping.

1 x 10 Ohm 5 Watt Wire Wound Resistor

2x DPDT IP56 Heavy Duty Toggle Switch

… well and to be little bit fancier – a Missile Switch Protective Cover!

We also couldn’t avoid bit of 3D design & printing for the switch case.

Finally, it’s just about putting it all together.

Final assembly done!

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