Originally Posted by The Jester
I know the problem you mean, the lamp flashes and the clocks go blank. With my first hid install (h4 hi/lo) I had this when I first switched on the ignition and after that, every time I had left the main beam on when the ignition was off. If I left it on low beam it was okay. I think it was something to do with the solenoid for high beam allowing the capacitors in the ballast to discharge. After a while it started tripping the clocks all the time.
With the new ballast it is back to only tripping when left on high beam.
The ballast is mounted on the back of the alloy plate with velcro but I don't believe it is down to mounting it too close as I had it mounted there without any problems using a second battery to power the light. This suggests it is likely to be a spike going through the wiring. I might try a car radio rf suppressor on the lamp wiring.
This might explain the issue.
This at least means that the system is not at risk of damage as the problem is being caused by a voltage drop as the ballast draws a much larger current on start up. Still inconvenient though. A sizeable capacitor across the battery may help maintain the voltage but it would need to be a very big capacitor. Better to fit the capacitor across the power supply to the clocks and fit a diode in line. The capacitor will provide power to the clocks, which require a minimal current draw, and the diode would prevent the capacitor discharging back down the wires to supplement the battery while it is powering up the ballast.
Good to see that my failed attempt at studying for an electronics degree in the late 80's isn't entirely wasted. Maplin's, here I come.