Xiaomi flashlight - huge self-discharge

czAtlantis

Enlightened
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Aug 15, 2011
Messages
269
Location
Czech Republic
Hi guys,
I came across this nice xiaomi flashlight. This model: https://www.xiaomitoday.com/xiaomi-portable-led-flashlight-review-photo-heavy/ I decided to buy it as presents for my family members so I bought and in September and another one few weeks later. When I received it I just wanted to test it. In my surprise, it was completely dead - discharged. Both of them (so it was probably not some random battery issue). This was bit strange but I charged it and it worked fine. So I put it in my drawer and forgot about it.
Few days ago I remembered the Christmas is coming and I decided to wrap it and put it together with other Christmas presents. I decided to give the flashlights one final test and one of them was again completely discharged. WFT? It was charged like 2 months ago and now it is completely discharged again! I can't give this as Christmas present because you can't count on flashlight that discharges itself in 2 months! I ripped the non-working flashlight apart, desoldered battery from the circuit board and started measuring current consumption from the battery (standard 18650 cell inside - welded and soldered in).

The flashlight has endless twisting top (encoder) and with each click you increase/decrease the brightness. When you finally twist the end to switch it off it draws few mA but in half a minute it settles down to around 250uA...that is quite high number - I stopped liking the flashlight right here but this still does not clarify the two months lifetime. I played with the flashlight more and I discovered that when the flashlight is off and settled down to standby current and you click one more time to turn it off, the current increases and stays at 2.6mA forever! This discharges the battery down to 0% in less than 2 months. I even discovered that when you turn it more less than one click and it stays between the clicks it draws even more - around 3,5mA. If you turn it on and then off or plug into USB to charge it reverts to normal standby current.

I ripped apart the second flashlight and tested it and it behaves exactly as the first one. so it is not some random fault.
And why the one flashlight was discharged and the other was not? Well probably because I clicked one more time to turn it right before I put it away before storage.
I don't know if this issue was already resolved (so if you buy it now it will be fine) or they are producing them exactly the same.
I couldn't find any info about this issue - probably because not many people bought this and of course this issue is hard to discover.

I might add some photos/video later I just needed to vent my anger somewhere
 
Last edited:

archimedes

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Re: Xiaomi flashlight - huge self-discharge do NOT buy!

Please edit your post and title to avoid negative advisement to others.

Thank you in advance.
 
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