HID w/Nmh Burn Test

[DanL]

Corndog-
You probably have a 10 watt (W) HID light with a 4.5 amp-hour (Ah) NiMH battery pack.
It should burn, with a full charge, for up to 4+ hours.

You can burn test the HID bulb, but put it in a sink full of water to keep the lighthead cool.

A number of things could be happening that shorten your burn time - cold water and resulting cold battery; a bad charger (although your 13V sounds about right); a weak cell in the battery pack; a bad cord, switch or voltage regulator causing low burn voltage to reach the bulb (and therefore higher current flow and lower burn time), etc.

A simple equation to estimate burn time:

P= E x I, where P is power (10W for your bulb), E is the voltage at the bulb (probably about 12V for your light) and I is the current flow in Amps (A).

To get current flow, use I = P/E, or for the above values,
I = 10W/12V = 0.83A.

Your 4.5 Amp-hour battery should theoretically burn for
4.5 Ah/0.83A, or over 5 hours. That won't happen, but if all is working well, you should get 4 plus hours easy. My guess is that you ahve a weak cell or two in the battery pack, perhaps from moisture or corrosion. Do a full charge overnight, then a burn test in a bucket of water and see how long before the light dims.

Good luck.