coulomb
Well-known member
Those pre-charge resistors suffer very high peak power demands for a short time (seconds or less). So ordinary resistors, even 10W rated ones, probably won't last in this application. You need to choose resistors with a high peak power rating.shuma89 said:i change 4,7ohm resistor, it was burned. car charged 3-4 times and it burned again, i change this resistor, after 2-3 charge it blows, there is 3 pieces of 4,7 ohm 5W resistor, i have changed all of them with 10W resistors 4,7 ohm.
But if the pre-charge relay doesn't turn on, or if the contacts are worn or pitted, then these resistors will attempt to pass many hundreds of power, in which case they'll blow regardless of their ratings.
It would be good to power the relay and check that it shorts the pre-charge relays successfully. You have to do this with the correct voltage an polarity, otherwise you'll just blow the diode that is directly across the relay coil.
The OBC is somewhat similar to the one in the iMiEV, so this long but very useful topic on the iMiEV charger may be valuable:
Troubleshooting and repair for On-board Charger (OBC) .
Edit: Oods! I see that you are well aware of the iMiEV forum, as you also posted there. Perhaps you can follow the guide for turning on the relay there, and find the equivalent diode so you can get the polarity right.