New 18650 strange behavior...Help

[Robocop]

I recently purchased a few 18650 AW branded cells and am using them in my M90 with various lamps. I had used them for one night only when the light shut off after what seemed like 30 minutes or so of total usage.

I charged them up for the first time and they showed fully charged after about 30 minutes. This seemed weird to me however showing fully charged on my volt meter I tried to use them again tonight. The light worked fine for about 30 seconds then shut off. I removed the cells and both showed 4.15 volts so I tried again when the light shut down after 10 seconds again. If I let it rest and keep trying it will work every other try however something seems to be triggering the cut off circuit of the cell or cells.

When I remove the cells and test with a meter they show both at 4.15 volts so I am having trouble finding which cell is malfunctioning or maybe it is both. I thought it may be the lamp or tail cap however the light is brand new and works fine with my other 18650 cells.

Any idea of what is going on? I thought if the protection circuit tripped the cell would read 0.00 until reset on the charger. Is it possible one or both of these cells is more sensitive to the current draw and is shutting down.

This has me puzzled and I appreciate any help. Right now I am using both cells in single cell lights trying to drain them so I can try re-charging from a lower voltage.

 

[kramer5150]

Going to guess its a poor solder joint on the protection circuit. Pressure from the springs is compressing the DC-DC board and causing it to trip.

 

[Robocop]

Ok the weird thing is that I always thought after a cell had tripped the circuit it would read 0.00 until reset by placing it in the charger. Each time the light cuts off I quickly remove the cells and find both showing fully charged on a meter.

It seems as if when I remove the cells one or both will reset instantly and I am unable to figure out which one of these two has a problem by simply testing the voltage. I was thinking the cell showing 0.00 would be the problem however again both seem to reset quickly after the load is removed.

Even more weird is that both cells seem to do fine when used seperate on a single 18650 light as I have tested both seperately trying to figure which one is acting up. Thus far I can not get the single 18650 light to shut down using the cells seperate however as soon as I pair them up in my M90 they shut down quickly???

The best news I have received yet is that the dealer has quickly shipped me two additional cells free of charge and I am comfortable the replacements will work fine (major cheer to follow in the cheer section)

Regardless of receiving two more cells I would still like to figure out what is wrong with one or both of these cells. I am still testing them seperate trying to get them to shut down and will post any more results here as I test a little more.

 

[AW]

Make sure you are having good solid connection when using two cells in series ( especially in incan lights ). It sounds like the cells are not making good connection.

 

[Robocop]

I have been trying different set ups trying to figure this out and discovered if I discharge both cells seperately to around 3.5 volts and then place them together in the same light they will run for much longer before shutting down.

It is still very short runtime around 2 minutes before shutting off however when fully charged they will usually go about 10 seconds. I ran both down to the low voltage cut off with both tripped cells reading 0.00 and fully charged them to 4.19 volts. They are holding the charge however I have yet to try them in the M90 to see if they still shut down early.

It seems as if they are somehow very sensitive to an electrical load and actual pressure from the tailcap has no ill effects. I removed the tailcap and used a small wire with no pressure and the light would power up however again shut down after a few seconds. I am not sure if it is a solder problem in the circuit or maybe a malfunctioning component of the circuit.