WARNING on the batteryspace HID - they recommend either the 13.2 or 14.4v pack. I bought the HID and the 14.4v pack. My light is now dead after 3 days of use.

I did some testing, and under load, the 14.4v pack delivers 15.8 volts at first, and only reaches 15v after over an hour of use. The max rated voltage on the HID light is 14.8v.

I'm currently trying to get them to replace the lamp, and remove the recommendation of using the 14.4v pack. I will probably wind up ripping a cell out of the 14.4v pack, making it a 13.2v pack.

(also, get a smart charger if you buy their packs; the included charger is crud)

I will post a followup somewhere in the commuting forum when I get a resolution (or lack thereof). Having used the HID for just 3 days, I do NOT want to go back to halogen (though I'm running my old 20W for now). HID just absolutely rocks. But a $120 lamp that lasts 3 days definitely does not rock.

DO NOT try to run the TrailTech HID off a 14.4v pack. I think it's a good light, but a bad recommendation on the 14.4v pack.