I'm returning my second Steriped Adventurer today after repeated struggles. I had hoped that my first was defective -- but seeing exactly the same problem with two devices leads me to believe there is a more systemic design flaw.

I had the "solid red light" error often when I tried to filter 1L of water, especially at high altitudes and with cold water. I never saw the "insufficient power" blinking red light.

Keeping the pen itself warm is necessary to prevent discharging the batteries, but not sufficient to prevent this problem which seems independent. One thing that helped was warming the *bulb and water detectors* between doses in my hands (it seems to get cold when used multiple times with <50 degree water). Using multiple 0.5L treatments with short doses was also more successful than attempting the longer 1L dose which usually fails.

I have a crazy idea based on trying two devices, ensuring fresh lithium batteries, and performing some (successful) home testing:

I suspect that testing a batch of units on 1L doses, with cold water, and potentially above 8K feet will reveal a problem with the water detection or lamp condition circuit. The resistance of metals changes with temperature: colder = lower resistance. The resistance of water is the opposite: colder water = less conductive.

I bet that the electronics in the head of the unit to ensure it's still in the water think that, when chilled by water, the unit has been removed from the water because the resistance is outside the expected parameters. Or, there is a safety circuit which is attempting to verify that the bulb is not blown and the resistance from a colder bulb is also out of parameters.

Of course, more data is really necessary since two data points and a hunch != trustworthy data. <img src="/forums/images/graemlins/wink.gif" alt="" />

I spoke briefly with the SteriPen people when having issues with my first unit. They were very friendly and offered to exchange the unit and clearly somewhat surprised about the issue. I hope that, given some additional data points, they will be able to modify the testing process to produce an updated unit which works consistently (given sufficient power in the batteries).

Question for you: Do any of you live in warm places AND have the issue above? How about those of you filtering cold water?

Best,

NB