[major]

Originally Posted by dragonsgate

Precharge time is right at 15 seconds for me. About the amount of time it takes to get the seatbelt hooked and the tilt wheel in place. 15 seconds is not much except when one is waiting for it. I have seen it happen with computers over the years. This is not just me as I have heard others confess to this. When my pooter was on dial up it took for ever to load. When I got DSL it was OMG! That’s fast! Now after the new has worn off it’s still fast but you swear it is taking for ever to load. Same with ev. There is a good chance any one of you will catch yourselves tapping your foot waiting for the precharge some time in the future.

Then decrease the Ohmic value of the precharge resistor. Just put a second resistor of the same value in parallel with your existing precharge resistor and it will cut the time in half. Or put a few more in parallel with it and reduce the time further. There is no reason to wait more than a few seconds, like 2 seconds.

[dragonsgate]

I expected some advice like yours Major and was planning on doing something one of these days but Gees look how long it took me to get around to even putting the dang thing back on. One question though. If you lessen the resistance so it only takes a couple of seconds aren’t you increasing the inrush and defeating the purpose of the whole project?

[major]

Originally Posted by dragonsgate

If you lessen the resistance so it only takes a couple of seconds aren’t you increasing the inrush and defeating the purpose of the whole project?

The main purpose is to mitigate the 1000A plus inrush arc which occurs with no precharge resistor across the contacts. Using a resistance value which limits that current to 10 or 20A is sufficient. Commercial drives with 330VDC bus use as low as 1Ω precharge. As the resistance decreases, the wattage needs to increase. Adding an additional resistor, or two, or three as I suggested will take care of that.