fuse

[hydroman2112]

wanted to know why there is not some type of [fuse] on esc 's that would blow in situation where there is a short or over heating that would then cut power from batteries to esc has anyone ever thought about it

[jamespl]

I can only assume because it would just generate too much heat and go pop anyway as any connector heats up.

[properchopper]

It's not that simple : (excerpt from a discussion on RRR)

1. The question is - what do you want to achieve? If you want to simulate a fuse, then this circuit together with a low IR shunt (0.1-0.2mOhm) is for sure better - kind of an electronic reusable fuse.

But would I want this behaviour of a fuse, that is, shutting everything down once I'm over a certain power limit? Me, no. First, too dangerous for the ESC. Second, too dangerous for the following boats. If one would want to have a power limited system, then I would suggest a overpower counter - a system that counts for how long you are over the limit. After 2s a first red LED comes on, and after 5s a second LED - then you are out. Change the times to whatever you like.

2. I have thought about such analog multipliers for an energy limiter. This would solve the problem of the error that happens at partial throttle when you first averaging voltage and current and then multiply them in the micro controller. But so far I have not found any of such analog multipliers with reasonable linearity and accuracy - and a reasonable price.

If one would use a 0.2mOhm shunt then 250A would equal 50mV shunt voltage. There you already have 0.8% typical inaccuracy. Going down to half throttle currents (50-100A) the inaccuracy is 2% and becomes much higher below this. The total accuracy of an energy limiter should be more in the 1% range - including all error sources.

Joerg