Battery considerations - Zebralight SC600
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kwak
Enlightened
Re: ZebraLight SC600
Pretty good.
Never timed it but i would guess i get around 90 mins with the 3100mAh Panasonic cells.
The SC600 does have a low voltage cut-off it's very very low at 2.7v though, so i tend to replace the cell when i see the torch dim (mines the first generation so has no step down).
I find it crazy that these companies invest so much time and money into new lights, yet they do not have anyone that works there that knows anything at all about Lithium chemistry batteries.
Pretty good.
Never timed it but i would guess i get around 90 mins with the 3100mAh Panasonic cells.
The SC600 does have a low voltage cut-off it's very very low at 2.7v though, so i tend to replace the cell when i see the torch dim (mines the first generation so has no step down).
I find it crazy that these companies invest so much time and money into new lights, yet they do not have anyone that works there that knows anything at all about Lithium chemistry batteries.
ZebraLight
Enlightened
Re: ZebraLight SC600
Cell manufacturers recommended a higher cut-off (around 2.75V) for their low capacity 18650's 3-5 years ago. Cells such as the Panasonic NCR18650 (2900 or 3100) have a 2.5V cut-off in their specs.
Cell manufacturers recommended a higher cut-off (around 2.75V) for their low capacity 18650's 3-5 years ago. Cells such as the Panasonic NCR18650 (2900 or 3100) have a 2.5V cut-off in their specs.
kwak
Enlightened
Re: ZebraLight SC600
There seems to be some confusion there.
Many of the cells you describe have a "sleep mode" this should NOT be confused with a cut-off voltage though as for some cells if they drop to this "sleep mode" they are NOT recoverable and the cell is then rendered useless.
Panasonic very clearly state that their cells should NOT be discharged below 3v
http://www.panasonic.com/industrial/includes/pdf/Panasonic_LiIon_Precautions.pdf
Even this is only part of the story though, as if cells are stored for any length of time at 2.7v then they will quickly drop even lower.
At 2.7v even a small drop to say 2.2v will have a dramatic reduction in the cells life span IF it's recoverable at all.
Add to this temperature fluctuations, for example the torch will inevitably be hot as it discharges the battery, a 2.7v hot cell will drop voltage as it cools.
This article is a good read, it is more cell phone battery based, but the same chemistry as we are using, it shows the correlation between discharging a cell too far and reducing it's life.
http://www.panasonic.com/industrial/includes/pdf/Panasonic_LiIon_Precautions.pdf
There is absolutely no doubt, that by selecting 2.7v as a cut-off voltage you are costing us money in cell life.
Fenix give 3.3v cut-offs i personally believe this is a decent compromise.
2.7v is certainly far too low.
Cheers
Mark
There seems to be some confusion there.
Many of the cells you describe have a "sleep mode" this should NOT be confused with a cut-off voltage though as for some cells if they drop to this "sleep mode" they are NOT recoverable and the cell is then rendered useless.
Panasonic very clearly state that their cells should NOT be discharged below 3v
http://www.panasonic.com/industrial/includes/pdf/Panasonic_LiIon_Precautions.pdf
Even this is only part of the story though, as if cells are stored for any length of time at 2.7v then they will quickly drop even lower.
At 2.7v even a small drop to say 2.2v will have a dramatic reduction in the cells life span IF it's recoverable at all.
Add to this temperature fluctuations, for example the torch will inevitably be hot as it discharges the battery, a 2.7v hot cell will drop voltage as it cools.
This article is a good read, it is more cell phone battery based, but the same chemistry as we are using, it shows the correlation between discharging a cell too far and reducing it's life.
http://www.panasonic.com/industrial/includes/pdf/Panasonic_LiIon_Precautions.pdf
There is absolutely no doubt, that by selecting 2.7v as a cut-off voltage you are costing us money in cell life.
Fenix give 3.3v cut-offs i personally believe this is a decent compromise.
2.7v is certainly far too low.
Cheers
Mark
DM51
Flashaholic
Re: ZebraLight SC600
It's not as bad as you think. When you take voltage sag into account, the cells will rebound to >3V once the load is off. That won't reset the cut-off to enable continued use of the cell - it will need to be reset on a charger.
Re: ZebraLight SC600
I'll just add that not all Fenixs have a low voltage cutoff. I managed to run my Fenix TK12 R5 down to less than 3V (the turbo mode stopped working at some point, although this can be difficult to notice without changing the modes to check). I emailed Fenix and they informed me that this model doesn't have a cut-off as such.
I'll just add that not all Fenixs have a low voltage cutoff. I managed to run my Fenix TK12 R5 down to less than 3V (the turbo mode stopped working at some point, although this can be difficult to notice without changing the modes to check). I emailed Fenix and they informed me that this model doesn't have a cut-off as such.
kwak
Enlightened
Re: ZebraLight SC600
I agree, but in my (admitted limited) experience so far with torches, the voltage rebound is nowhere near that of my RC cells.
No concrete evidence, but my theory so far is that the heat of the torch is cancelling out any voltage sag (a hot 2.7v will give a lower voltage when the cell has cooled).
Either way the cut-off needs to be higher IMO, and in my experience (around 12 years of almost daily LiPo and LiFe use through RC craft) the higher the cut-off the better for the life of the cell.
If the cut-off was adjusted to say 3.4v the the voltage rebound would give around 3.7v which is around what i consider the ideal for storage.
Correct.
I also guess that if you have a older Fenix torch the cut-off may well be different.
Neither my TK35 or TK70 have a cut-off, but my TK21 is set at 3.3v, a LOT better compromise than 2.7v.
Cheers
Mark
I agree, but in my (admitted limited) experience so far with torches, the voltage rebound is nowhere near that of my RC cells.
No concrete evidence, but my theory so far is that the heat of the torch is cancelling out any voltage sag (a hot 2.7v will give a lower voltage when the cell has cooled).
Either way the cut-off needs to be higher IMO, and in my experience (around 12 years of almost daily LiPo and LiFe use through RC craft) the higher the cut-off the better for the life of the cell.
If the cut-off was adjusted to say 3.4v the the voltage rebound would give around 3.7v which is around what i consider the ideal for storage.
Correct.
I also guess that if you have a older Fenix torch the cut-off may well be different.
Neither my TK35 or TK70 have a cut-off, but my TK21 is set at 3.3v, a LOT better compromise than 2.7v.
Cheers
Mark
Re: ZebraLight SC600
I would rather it had a 3.3V cut-off - I thought it did have one when I bought it. I was a little worried that it was faulty when I ran it down, hence the email.
At least I now know that I need to be a bit careful with it.
I would rather it had a 3.3V cut-off - I thought it did have one when I bought it. I was a little worried that it was faulty when I ran it down, hence the email.
At least I now know that I need to be a bit careful with it.
Re: ZebraLight SC600
Well I guess I'll be waiting for V3.0 of this light. Neutral with higher cutoff point.
Zebralight is fantastic about making changes in their lights along the way, I've never seen a light manufacturer respond so quickly to flashoholic feedback, but it makes me leery of getting the first off the production line.
However, I can only wait so long! May have to settle for neutral and be mindful of the cell voltage. (We can discuss why I use unprotected cells elsewhere.)
Kudos to ZL for joining the ranks of manufacturers who use built-in battery protection.
Well I guess I'll be waiting for V3.0 of this light. Neutral with higher cutoff point.
Zebralight is fantastic about making changes in their lights along the way, I've never seen a light manufacturer respond so quickly to flashoholic feedback, but it makes me leery of getting the first off the production line.
However, I can only wait so long! May have to settle for neutral and be mindful of the cell voltage. (We can discuss why I use unprotected cells elsewhere.)
Kudos to ZL for joining the ranks of manufacturers who use built-in battery protection.
ZebraLight
Enlightened
Re: ZebraLight SC600
Right before AND during the light is ON, the driver measures and calculates the voltage and capacity. If the results cross certain thresholds in a list, then it steps down to a lower (user selected) levels. The capacity gauging is not a traditional coulomb counter based one, because it can only be in the driver of the flashlight, not with the batteries.
Right before AND during the light is ON, the driver measures and calculates the voltage and capacity. If the results cross certain thresholds in a list, then it steps down to a lower (user selected) levels. The capacity gauging is not a traditional coulomb counter based one, because it can only be in the driver of the flashlight, not with the batteries.
ZebraLight
Enlightened
Re: ZebraLight SC600
http://www.panasonic.com/industrial/batteries-oem/oem/lithium-ion.aspx
Small capacity (old) ones are speced at 3V cut-off. Newer ones such as the NCR18650 (2900, in production since 2006) have a 2.5V cut-off.
http://www.panasonic.com/industrial/batteries-oem/oem/lithium-ion.aspx
Small capacity (old) ones are speced at 3V cut-off. Newer ones such as the NCR18650 (2900, in production since 2006) have a 2.5V cut-off.
samgab
Flashlight Enthusiast
Re: ZebraLight SC600
I use Panasonic 2900's, and I'm GLAD the cutoff is at 2.7V for me, that's the perfect cutoff point. I'm quite comfortable discharging these cells to 2.5 Volts, as per the manufacturer. Some people are ridiculous. If I wanted to only discharge to 3 V, I'd just swap the cell more frequently. It doesn't matter if you swap the cell out too soon and recharge more often, at 3.8V or 3.5V or whatever. But if you're stuck in the middle of no-where; in the dark with no access to a fresh cell, having the ability to use the light beyond 3.0V could be the difference between life and death. Or at least between convenience and inconvenience.
Keep it how it is, George!
I use Panasonic 2900's, and I'm GLAD the cutoff is at 2.7V for me, that's the perfect cutoff point. I'm quite comfortable discharging these cells to 2.5 Volts, as per the manufacturer. Some people are ridiculous. If I wanted to only discharge to 3 V, I'd just swap the cell more frequently. It doesn't matter if you swap the cell out too soon and recharge more often, at 3.8V or 3.5V or whatever. But if you're stuck in the middle of no-where; in the dark with no access to a fresh cell, having the ability to use the light beyond 3.0V could be the difference between life and death. Or at least between convenience and inconvenience.
Keep it how it is, George!
Last edited:
Re: ZebraLight SC600
How about no true cutoff, just keep stepping down til it's at the lowest setting so you can use it til it's dead if you need to?
Either way, I'm just gonna get a neutral when they come out and sell it if there is some awesome upgrade later. You can only wait so long for the perfect lights.
How about no true cutoff, just keep stepping down til it's at the lowest setting so you can use it til it's dead if you need to?
Either way, I'm just gonna get a neutral when they come out and sell it if there is some awesome upgrade later. You can only wait so long for the perfect lights.
brightasday
Newly Enlightened
Re: ZebraLight SC600
I'm not in favor of raising the minimum voltage. The VAST majority of the time I change out the battery long before it gets to the cutoff. But I really want the extra runtime to be available in case I need it.
I'm not in favor of raising the minimum voltage. The VAST majority of the time I change out the battery long before it gets to the cutoff. But I really want the extra runtime to be available in case I need it.
Re: ZebraLight SC600
I wanted to check run time on high with step down and here is what i came up with.
First off I am using a AW 2900mah new cell. It was not at 100%. It was 4.16v off the charger and I did use it a few times before I started the timer. I checked it before I started and it was 4.12v.
It went exactly 5 min at 750lm before dropping to 500lm. I mean not a second before or later. Timer worked great:thumbsup:
It ran for a total of 1hr and 59min before dropping to medium. I stopped timer there and checked battery @ 3.16v , then again 30 min later and it went back up to 3.19v
Just thought i would share with anyone who was wondering new run times with step down regulation.
I wanted to check run time on high with step down and here is what i came up with.
First off I am using a AW 2900mah new cell. It was not at 100%. It was 4.16v off the charger and I did use it a few times before I started the timer. I checked it before I started and it was 4.12v.
It went exactly 5 min at 750lm before dropping to 500lm. I mean not a second before or later. Timer worked great:thumbsup:
It ran for a total of 1hr and 59min before dropping to medium. I stopped timer there and checked battery @ 3.16v , then again 30 min later and it went back up to 3.19v
Just thought i would share with anyone who was wondering new run times with step down regulation.
Overclocker
Flashlight Enthusiast
Re: ZebraLight SC600
thanks for the info, good to know that it doesn't step down prematurely
just a question. once it steps down to med, does it step down to low eventually?
thanks for the info, good to know that it doesn't step down prematurely
just a question. once it steps down to med, does it step down to low eventually?
ZebraLight
Enlightened
Derek Dean
Flashlight Enthusiast
Re: ZebraLight SC600
So, the more I use this light the more I like it, but like others here, the light I received had a green/yellow XM-L T6 LED... arrrrghh.
However, using my Lee Filter Swatch Book I was able to get it back in the liveable range of tints. I took some before and after photos that you can see here (scroll to my post at the bottom of page 4):
http://www.candlepowerforums.com/vb/showthread.php?320811-Changing-LED-Tint-With-Filters/page4
So, the more I use this light the more I like it, but like others here, the light I received had a green/yellow XM-L T6 LED... arrrrghh.
However, using my Lee Filter Swatch Book I was able to get it back in the liveable range of tints. I took some before and after photos that you can see here (scroll to my post at the bottom of page 4):
http://www.candlepowerforums.com/vb/showthread.php?320811-Changing-LED-Tint-With-Filters/page4
Re: ZebraLight SC600
I couldn't disagree more with this. First off the data sheet you attached in your previous post was too old (2007). The newer cells, as has been stated, have lower cutoff points.
Second, as the newer cells age, the voltage drop under high current loads get larger. I have a few slightly older AW 2900's that when pulled at the current levels of even this torch would sag below 3.4 volts when they still have PLENTY of life left in them. On high, I wouldn't be surprised if moving from 2.7 to 3.4 volts cut run time by as much as half on these slightly older cells.
No thanks!
I couldn't disagree more with this. First off the data sheet you attached in your previous post was too old (2007). The newer cells, as has been stated, have lower cutoff points.
Second, as the newer cells age, the voltage drop under high current loads get larger. I have a few slightly older AW 2900's that when pulled at the current levels of even this torch would sag below 3.4 volts when they still have PLENTY of life left in them. On high, I wouldn't be surprised if moving from 2.7 to 3.4 volts cut run time by as much as half on these slightly older cells.
No thanks!
kwak
Enlightened
Re: ZebraLight SC600
This is the exact same link as i posted.
If you click on the "technical data" tab in the box at the bottom of the page this takes you to the more detailed pdf file i linked to.
The "specifications" pdf files listed on the first page give no data with regard to low voltage cut-offs.
It's also worth noting that although there have been slight improvements in lithium cell technology over the past few years (mainly doe to new polymer designs) the basic chemistry still stays the same.
As long as it does the way this chemistry reacts at low voltages will stay the same.
George,
We all have our own preferences and experiences and many people disagree with those, to label them as "ridiculous" though is firstly dramatic to the point of being out of proportion and secondly kinda funny :wave:
A couple of things.
1/ It is impossible to judge a torches voltage by it's brightness.
In a lab with an extremely patient and attentive user it MAY be possible to notice a drop in brightness on the old type non step down torches.
Out in the real world though with shades, varying shine distances, reflections etc it's almost impossible.
Add to this the new step down function and it's even more difficult.
I have on occasion noticed my old type SC600 cell drop brightness and have swapped cells, this has only been possible out in the real world around 3 times out of 10 though.
2/ It very much DOES matter if you take Lithium chemistry cell voltages down low, both this and leaving them stored fully charged has a dramatic reduction in their usable life cycles.
This is no secret, cell manufactures, assemblers and users have known about this since they have been bought into production.
Couple more things.
Lithium cells do not have a linear discharge rate, after around 3.7v is reached their discharge rate drops dramatically, the lower the voltage the sharper the discharge rate drops, as shown below.
So although your statement
Is no doubt dramatic it does contain enough artistic license to render it impracticable.
In the real world the run time you get from say 3.3v to 2.7v is seconds.
I'd also suggest that if your using a torch in a "life or death" situation you take along a few spare cells :thumbsup:
Please see my response to ZL's post above.
As i said we linked to the exact same page.
Again please see my response to George above.
Your findings do not corroborate the basic chemistry of the cells nor the findings of thousands of Lithium cell uses, manufacturers or distributors over the last 20 years or so.
To substantiate my claim with regards to discharge rates i would like to recommend (very highly) an extremely through and well carried out test here.
http://lygte-info.dk/info/Batteries18650-2011 UK.html
As i say IMO there is absolutely no doubt that 2 things dramatically reduce the usable cell life of lithium cells.
1/ Storing fully charged
2/ Taking the voltage too low
Panasonic clearly state that they consider anything less that 3v detrimental to the cells life, this at 25c which many of our SC600's have no chance at when in high mode.
So unless you enjoy replacing cells every few years or having them expand in your torches i would recommend upping the cut-off to around 3.3v.
Cheers
Mark
This is the exact same link as i posted.
If you click on the "technical data" tab in the box at the bottom of the page this takes you to the more detailed pdf file i linked to.
The "specifications" pdf files listed on the first page give no data with regard to low voltage cut-offs.
It's also worth noting that although there have been slight improvements in lithium cell technology over the past few years (mainly doe to new polymer designs) the basic chemistry still stays the same.
As long as it does the way this chemistry reacts at low voltages will stay the same.
George,
We all have our own preferences and experiences and many people disagree with those, to label them as "ridiculous" though is firstly dramatic to the point of being out of proportion and secondly kinda funny :wave:
A couple of things.
1/ It is impossible to judge a torches voltage by it's brightness.
In a lab with an extremely patient and attentive user it MAY be possible to notice a drop in brightness on the old type non step down torches.
Out in the real world though with shades, varying shine distances, reflections etc it's almost impossible.
Add to this the new step down function and it's even more difficult.
I have on occasion noticed my old type SC600 cell drop brightness and have swapped cells, this has only been possible out in the real world around 3 times out of 10 though.
2/ It very much DOES matter if you take Lithium chemistry cell voltages down low, both this and leaving them stored fully charged has a dramatic reduction in their usable life cycles.
This is no secret, cell manufactures, assemblers and users have known about this since they have been bought into production.
But if you're stuck in the middle of no-where; in the dark with no access to a fresh cell, having the ability to use the light beyond 3.0V could be the difference between life and death. Or at least between convenience and inconvenience.
Couple more things.
Lithium cells do not have a linear discharge rate, after around 3.7v is reached their discharge rate drops dramatically, the lower the voltage the sharper the discharge rate drops, as shown below.
So although your statement
Is no doubt dramatic it does contain enough artistic license to render it impracticable.
In the real world the run time you get from say 3.3v to 2.7v is seconds.
I'd also suggest that if your using a torch in a "life or death" situation you take along a few spare cells :thumbsup:
Please see my response to ZL's post above.
As i said we linked to the exact same page.
Again please see my response to George above.
Your findings do not corroborate the basic chemistry of the cells nor the findings of thousands of Lithium cell uses, manufacturers or distributors over the last 20 years or so.
To substantiate my claim with regards to discharge rates i would like to recommend (very highly) an extremely through and well carried out test here.
http://lygte-info.dk/info/Batteries18650-2011 UK.html
As i say IMO there is absolutely no doubt that 2 things dramatically reduce the usable cell life of lithium cells.
1/ Storing fully charged
2/ Taking the voltage too low
Panasonic clearly state that they consider anything less that 3v detrimental to the cells life, this at 25c which many of our SC600's have no chance at when in high mode.
So unless you enjoy replacing cells every few years or having them expand in your torches i would recommend upping the cut-off to around 3.3v.
Cheers
Mark
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