Join Date: Jan 2009
Location: Tri-Cities Washington
HID running current
Oh yeah, their current draw. We ran tests here at the shop. The ballast surges at around 18 amps, but only for about one second. It then runs about 8 to 10 amps and falls off as the HID element ‘’ramps up’’ to its full brightness. The current then settles at 3.8 amps for a 35 watt HID ‘bulb’ and that’s consistent with several HID’s we tested. It might take 20 or 30 seconds for the current to drop to that 3.8 amps.
One thing that’s VERY nice about HID’s… once the arc is fired off, battery voltage makes NO DIFFERENCE. The ballast compensates, and will hold a stable arc down to about 9.5 to 10 volts. In other words, if your alternator fails, and your battery is dying, the HID’s will NOT dim at all. They will eventually drop out and quit, and not restart, but your battery will be dead as a doornail by then anyway. So… you can keep going for a while with a dead alternator.
The reverse is true, if your power supply lacks, they HID’s might not start. Remember that 18 amp surge.