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12-24-07, 08:22 AM
I built a diy lighting system with a 9.4 amp hour 11.1 volt litihium ion battery and a 13 watt Trail Tech hid headlight and an older Niterider 16 led taillight, connected to the same battery. Yesterday, I tested the runtime for the system and it was way less than I expected. Now I'm trying to figure out if my runtime expectations were too high or if the switch just cut off the light. The system went for about 4.5 hours before the headlight went out. The battery had been fully charged before the test. I had expected over seven hours of runtime with headlight only, based on the 13 watt draw and the (supposed) 9.4 amp hour battery. Does that taillight draw that much juice? The on/off switch for the system is the Trail Tech helmet mount switch, which displays different colored leds based on the battery voltage. If I turn the light on now the led flashes red, probably indicating a discharged battery. It could be the switch is designed to cut the headlight off once the voltage drops below a certain threshold. That could be an issue since the battery is only 11.1 volts and the light is designed for higher voltage. My (wishful thinking) theory is that the battery is not fully discharged but the switch cuts off the light when voltage drops too low. I went with the 11.1 volt battery because both Trail Tech and Batteryspace advised me that the higher voltage battery ran the risk of blowing out the light. Other than measuring runtime, is there any reliable test to determine whether the battery is actually the advertised amp hours? I have some doubts about mine.