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**DONOTDELETE**
Guest
I have two PLW-3 lights (3 LED, 3AA) that I recently replaced the batteries in. One happened to get Duracell Ultras, the other Costco Kirkland brand batteries.
When I turned on the Costco powered light, it was dim and _very_ blue, more blue than white, a symptom of being overdriven. I decided to let it run for a while, hoping to take the new "edge" off of the batteries. It didn't work out that way; after less than five minutes one LED failed. I turned off the Costco light and tried the Duracell one, which acted normally.
With a digital multimeter, the open circuit voltage on both sets of batteries was approx 4.52 volts. The Duracell light was pulling 240mA. The Costco light started at 270mA, but started climbing, reaching 340mA before I disconnected it. That's 340mA on the two remaining LEDs!
I connected the partially failed LED module to the Duracells, and ran it for 2 minutes. At the end of that time, it was noticeably warm. I then took the partially failed module and ran it on the Costcos for 2 minutes. During this time, a second LED failed. The module was uncomfortably hot, probably over 120F.
I suspect that the current limiting resistor in the failed module was undervalued, and combined with the apparently higher current capacity of the Costco batteries, resulted in extreme overdriving and failure of the LEDs. IMHO, even the 240mA being pulled by the good module on the Duracells is too high.
I'm glad this happened at home instead of some situation when I was really depending on the light. Lesson learned: thouroughly test each light before depending on it, and carry a backup light even then.
When I turned on the Costco powered light, it was dim and _very_ blue, more blue than white, a symptom of being overdriven. I decided to let it run for a while, hoping to take the new "edge" off of the batteries. It didn't work out that way; after less than five minutes one LED failed. I turned off the Costco light and tried the Duracell one, which acted normally.
With a digital multimeter, the open circuit voltage on both sets of batteries was approx 4.52 volts. The Duracell light was pulling 240mA. The Costco light started at 270mA, but started climbing, reaching 340mA before I disconnected it. That's 340mA on the two remaining LEDs!
I connected the partially failed LED module to the Duracells, and ran it for 2 minutes. At the end of that time, it was noticeably warm. I then took the partially failed module and ran it on the Costcos for 2 minutes. During this time, a second LED failed. The module was uncomfortably hot, probably over 120F.
I suspect that the current limiting resistor in the failed module was undervalued, and combined with the apparently higher current capacity of the Costco batteries, resulted in extreme overdriving and failure of the LEDs. IMHO, even the 240mA being pulled by the good module on the Duracells is too high.
I'm glad this happened at home instead of some situation when I was really depending on the light. Lesson learned: thouroughly test each light before depending on it, and carry a backup light even then.
