Bare Bones Headlight Driver

I need to run four high beam (9005XS) bulbs in parallel using either a battery or a power supply. The inrush current is killing my power supply. Can I use a current limiting supply that will provide, say, 45 Amps until the lamps reach steady state and settle back down to 20 Amps? Or, do I really need to supply 200 Amps for a brief period of time? How long does the inrush current last on a halogen bulb?

I currently have no relay or other harness type switches inline. Just the power supply or battery directly to the lamps. Can I do this with a car battery? Any danger in running the car battery directly to the lamps? (Other than the danger of shorting the battery....)

SHFOX

This may help. Add another headlight switch and rewire things so
one switch controls just 2 headlamps rather than one switch for 4.

2 switches, 4 headlamps 9005XS

Then when turning them on wait several seconds before turning on the second
switch.

This is the wrong forum. This is a forum for headlights on peoples heads, not their cars. We have an automotive lighting section, but, please, do not restart your topic there, ask a moderator to move this thread to that subforum.

Welcome to CPF, shfox

As JG says, this is the wrong forum - "headlamps" here means lights you strap to your head, and I'm not sure I would want 4 of these strapped to mine, lol.

I'm moving your thread to the Automotive section...

You'll be fine running your four headlights off of a car battery, although it won't run for long and car batteries don't like to be deep cycled. I'd advise putting a fuse right next to the battery, and make sure you use a switch and wiring big enough.

http://www.rivergatedist.com/capacitors.htm

Something like that. Wire it up with a diode and resistor so the inrush to the capacitor doesn't kill your power supply, but when you flick the switch for the bulbs the capacitor gives the power for the inrush.

The capacitor could help, but you would need a monster of a diode to handle that kind of current. Instead, initially charge the capacitor through your resistor, then use a switch bypass the resistor. No surge of current to charge the capacitor thanks to the resistor, and no current limiting thanks to the near-zero resistance through the switch.
Also worth consideration: big electrolytic capacitors like that have a significant amount of leakage current (current that passes through the capacitor once it's charged). That means if you leave it hooked up to an unmaintained battery for long periods, it will drain the battery flat. Though really, if you're using a lead-acid battery of any decent size (motorcycle battery on up), it should have little trouble providing the needed surge current, making the cap unnecessary. In fact, a sealed lead-acid battery and a trickle charger should be far cheaper, easier to find locally, easier to use and have an incomparably larger storage capacity than one of those big caps.