UPS Backup to prevent Power Surges

[BIGBudDug]

I am curious if anyone has tried this, I bought an UPS for a 400HPS Ballast the UPS is a 720 Watt backup 1500 Joules rated, But I noticed during a lighting strike our power went off then back on in 15 seconds and I noticed the HID Light was restarting the Bulb? Do 400 Watt HID ballast particularly the HPS use more than 400 Watts to run the Ballast capacitor? its a 400 Watt bulb. I'm just wondering if it is not either a big enough backup or maybe it is defective and needs taken back. Its made by Geek Squad, it does say not to run lazer printers in the manual, so there must be some limits to this producing enough watts to run the ballast is what I am thinking? But I would like some other opinions and if anyone has tried this? Just trying to keep plants healthy since power blank outs are commen atleast once every 2-3 weeks where I live but rarely lasting more than 5 to 10 seconds.