DBS v2 - felt asleep - empty cell

[andi555]

Hello!

Yesterday I turned on my DBS v2 3SD with unprotected 18650 li-mn cells in low mode and I felt asleep. Today the batterie was totally empty. I switched the light off, waited for 10 seconds and I turned the light on again. The light worked for about 3 seconds in low mode and became darker and darker. (like a cheap unregulated torch with empty batteries)

So when the protection of the 3SD pill cuts off and I don't switch the light off, is there still current flow?
Or does the protected just cut off in high mode??
How can this happen that I am able to switch the light on when the voltage of the cell is about at 1,5 volt?

I will try it today again with a unprotected lifepo cell, because the overdischarging has not so much bad affects on this type of cells.

 

[csshih]

it would be in your best benefit to get a multimeter to check the voltage of the cells.

what do you mean by "totally empty"?
if a lithium-ion cell is discharged past a certain point, it gets damaged, and may be unsafe to use.

 

[andi555]

When I putted the cell in my charger, the cell had 1,5 volt.
I think it is not so critical if you overdischarge li-mn (mangan) cells than Lithium Cobalt cells.

 

[mdocod]

Perfect example of why I have been running around telling people not to use IMR cells in their regulated LED flashlights, as this type of over-discharge is likely to occur.

The cell will likely recover after this one incident without too much ill-effect. doing this repeatedly will kill them.

 

[andi555]

Yes I checked the cell. Capacity and internal resistant are ok!

But I don't understand how this can happen? Why is there still current flow when the protection cuts off?

 

[mdocod]

I think this might be a question to direct at dereelight and see what they think... I wonder how many people have actually tested the over-discharge protection in the DereeLight modules... wonder if it eve works - eek?

Eric