DBS v2 - felt asleep - empty cell

andi555

Newly Enlightened
Joined
Oct 18, 2008
Messages
29
Location
Austria
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

Flashlight Enthusiast
Joined
Sep 21, 2008
Messages
3,950
Location
San Jose, CA
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

Newly Enlightened
Joined
Oct 18, 2008
Messages
29
Location
Austria
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

Flashaholic
Joined
Nov 9, 2005
Messages
7,544
Location
COLORado spRINGs
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

Newly Enlightened
Joined
Oct 18, 2008
Messages
29
Location
Austria
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

Flashaholic
Joined
Nov 9, 2005
Messages
7,544
Location
COLORado spRINGs
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
 
Top