99% of apparently faulty flowlight behavior is simply a battery issue. Charge/change you battery, clean your contacts, check the following:
Use only rechargeables or high quality alkalines. The circuitry is optimized for rechargeables. The light is bright and draws a lot of power, so cheapo batteries don’t last long, can’t keep up and makes the light dim out and turn off easily. The difference can be the light lasting under 30 minutes or 7 hours!
Your battery is low -Try a battery that you are sure is good; switch your batteries around to double check. It can be very hard to tell when the battery is low and the light may appear faulty, as it turns on at full brightness and quickly dims out or shuts off for no apparent reason. Note that rechargeable NiMH batteries do NOT come charged, as they discharge overtime. You need to charge them shortly before use. A few days is ok, but they might have lost more than half their charge if they were charged over 2-3 weeks ago. Li-ion batteries hold their charge, so you can charge them months ahead of time.
There is something obstructing battery contact - Check that the clear battery pull tab is not wedged between your battery and the battery contact. Check that your batteries are clear of physical debris. The battery connection is tight, so the plastic cover on some batteries gets torn off a little and sticks to the underside of the battery, preventing a good connection. We trim the extra plastic off all our batteries before sending them out.
There is oxidation on your battery contacts - Do the battery or spring contacts have black marks or debris on them? This is oxidation from the battery’s contacts caused by friction/vibration. Clean the battery and battery springs with your fingers, a clean cloth or paper towel and apply a tiny bit of petroleum jelly (vaseline) to the springs. This works wonders to ensure electrical conductivity and prevent future oxidation.
If you have checked the tips above and the problem persists, please contact us for warranty service. We'll be happy to help you get back into your flow!