It is bad for the electronics, to be clear. The massive inrush current which is blowing up the resistor in the connector and making that big spark is also putting a big strain on your ESC.
The very short, but huge, current flowing into the capacitors when that spark happens can create a high voltage spike that can damage electronics. I don’t know if that is what happened to your AS switch but those sparks can damage more than the connector.
I suspect that you blowing up the resistor in his AS150’s has more to do with the amount of inrush current than the voltage.
All this length of wire, all those solder joints, each connector, etc. all adds to the total resistance of the system. When you plug in that final AS150 and complete the circuit, the inrush current trying to fill the capacitors in the ESC spikes really high because of all that resistance, and it pops the resistor in your AS150.
That’s my guess anyway. I would suggest swapping out all the connectors on each individual lipo with a lower resistance interconnect of some kind, such as 5.5mm or 6mm bullet connectors.
I agree. But I assure you that I am innocent!
My post was just referring to his statement about the now-occurring sparking only damaging the connector.
The resistance would actually decrease the voltage spike a bit since it would tend to limit current flow (a touch). However, the added inductance of any additional cable length would increase the voltage spike caused by the inrush to fill the caps.
The total energy of the current spike, which is what heats up the resistor and probably caused it to blow, might not change a lot though. It might end up just being a longer surge…brain not working well enough now to figure it out.
Would running a wire in parallel to the main lead with a power resistor that you connect first be a good solution? Probably annoying having two steps though.
Lipos connectors are EC5. I put in series already wired EC5 because I could’t get those connectors to go into their nylon housings. Worst connector ever IMO. I killed a lot of housings.
Unlike AS150, Jens from E-TOXX killed a lot of QS10. He just gave up them.
That’s what I figured, just making sure there weren’t any major flaws I wasn’t thinking of. I’ve done it on a smaller scale to connect a buck converter to my 18s onewheel.
You just have to size the resistor properly so it doesn’t burn out but still fills the caps up slowly enough to not create a voltage spike higher than the voltage rating of the ESC (or even near it IMO). This can usually be done in a fraction of a second.
I can’t say if that particular value has worked well with most ESC’s but if others have used that value successfully then go ahead. A higher value extends the pre-charge time but reduces the voltage spike even more…always a trade-off!
But I recommend significantly increasing the wattage rating for the one resistor (or using series, parallel, or series/parallel resistor combos to increase the wattage handling).
At 20s the voltage is 84v. A 5.5 ohm resistor would have 15.27 amps through it when you initially plug it in (84v / 5.5 ohm = 15.27 Amps). The instantaneous wattage the resistor would have to deal with would be over 1,200 watts (15.27 Amps * 84V = 1282). While this would drop dramatically as the capacitors charge up, this inrush current is likely what’s blowing the antispark. I bet a resistor like this wired to a pre charge switch as @JoeyZ5 suggested would work better. For a 16 ohm resistor it would only have an instantaneous current of about 5.25 amps, and one in this larger package would definitely handle it better then the 1/4 watt resistors they fit into the antispark connectors
