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Old 07-28-2014, 09:44 AM   #6744 (permalink)
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Originally Posted by z_power View Post
I use 1 of 1000uF SBE cap, pack voltage is ~184V, precharge resistor is 15 ohm 40W and it takes less than a second to reach more than 90% voltage (RC=0.015s, 5*RC=0.075s, test with scope confirms this). 184/15 gives acceptable ~12A inrush current.
I set precharge time to 2s and it works
So the pre-charge is done in about a tenth of a second but you allow a delay of 2 seconds before main contactor energising to give a nice safety margin.
So the pre-charge can be less than what an ICE driver experiences waiting for their motor to crank and catch.
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