Forums

Li Battery

Started by OldGuy November 12, 2015
I got a replacement battery for my laptop.
It is a Li-Ion type.
6 cell 4400 mAh 10.8 volt

In the package docs it states that I should cycle the battery all the 
way down, recharge it and do this several times to improve its 
capability.

What is happening to the battery doing this?

If not done what can I expect in terms of the amount of loss of use?



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On Thu, 12 Nov 2015 09:03:15 -0800, OldGuy <OldGuy@spamfree.com>
wrote:

>I got a replacement battery for my laptop. >It is a Li-Ion type. >6 cell 4400 mAh 10.8 volt > >In the package docs it states that I should cycle the battery all the >way down, recharge it and do this several times to improve its >capability. > >What is happening to the battery doing this?
Nothing. It's training the battery charging circuit to recognize the particulars of that battery,
> >If not done what can I expect in terms of the amount of loss of use?
Could be quite a bit because the charger may shut down before completely charging the battery.
Den torsdag den 12. november 2015 kl. 18.03.35 UTC+1 skrev OldGuy:
> I got a replacement battery for my laptop. > It is a Li-Ion type. > 6 cell 4400 mAh 10.8 volt > > In the package docs it states that I should cycle the battery all the > way down, recharge it and do this several times to improve its > capability. > > What is happening to the battery doing this? > > If not done what can I expect in terms of the amount of loss of use?
afaik you shouldn't do that for Li-Ion, it was the old NiCd that needed that -Lasse
On 11/12/2015 11:15 AM, Lasse Langwadt Christensen wrote:
> Den torsdag den 12. november 2015 kl. 18.03.35 UTC+1 skrev OldGuy: >> I got a replacement battery for my laptop. >> It is a Li-Ion type. >> 6 cell 4400 mAh 10.8 volt >> >> In the package docs it states that I should cycle the battery all the >> way down, recharge it and do this several times to improve its >> capability. >> >> What is happening to the battery doing this? >> >> If not done what can I expect in terms of the amount of loss of use? > > afaik you shouldn't do that for Li-Ion, it was the old NiCd that needed that > > -Lasse
That's what I found out too. You shouldn't run a Li-Ion down completely. The Li battery in my DSLR has been going strong for the last 8 years. The camera says it's in good shape.
On Thu, 12 Nov 2015 11:58:25 -0600, gray_wolf <g_wolf@nospam.com>
wrote:

>On 11/12/2015 11:15 AM, Lasse Langwadt Christensen wrote: >> Den torsdag den 12. november 2015 kl. 18.03.35 UTC+1 skrev OldGuy: >>> I got a replacement battery for my laptop. >>> It is a Li-Ion type. >>> 6 cell 4400 mAh 10.8 volt >>> >>> In the package docs it states that I should cycle the battery all the >>> way down, recharge it and do this several times to improve its >>> capability. >>> >>> What is happening to the battery doing this? >>> >>> If not done what can I expect in terms of the amount of loss of use? >> >> afaik you shouldn't do that for Li-Ion, it was the old NiCd that needed that >> >> -Lasse > >That's what I found out too. You shouldn't run a Li-Ion down completely. >The Li battery in my DSLR has been going strong for the last 8 years. >The camera says it's in good shape.
They can be run down but there is a limit. If it's never run down, how do you know its capacity? Laptop charging circuits have gas gauges and need to run down the battery to calibrate.
On Thu, 12 Nov 2015 13:32:57 -0500, krw <krw@nowhere.com> wrote:

>On Thu, 12 Nov 2015 11:58:25 -0600, gray_wolf <g_wolf@nospam.com> >wrote: > >>On 11/12/2015 11:15 AM, Lasse Langwadt Christensen wrote: >>> Den torsdag den 12. november 2015 kl. 18.03.35 UTC+1 skrev OldGuy: >>>> I got a replacement battery for my laptop. >>>> It is a Li-Ion type. >>>> 6 cell 4400 mAh 10.8 volt >>>> >>>> In the package docs it states that I should cycle the battery all the >>>> way down, recharge it and do this several times to improve its >>>> capability. >>>> >>>> What is happening to the battery doing this? >>>> >>>> If not done what can I expect in terms of the amount of loss of use? >>> >>> afaik you shouldn't do that for Li-Ion, it was the old NiCd that needed that >>> >>> -Lasse >> >>That's what I found out too. You shouldn't run a Li-Ion down completely. >>The Li battery in my DSLR has been going strong for the last 8 years. >>The camera says it's in good shape. > >They can be run down but there is a limit. If it's never run down, >how do you know its capacity? Laptop charging circuits have gas >gauges and need to run down the battery to calibrate.
If the battery sits on the shelf, then that self discharge does not show up on the gas guage. Plus the LI batteries I've used tend to increase with capacity in the first few cycles. Cheers

"krw" <krw@nowhere.com> wrote in message 
news:llm94bhmlbohudde8vpfmlfrfud5nq8s4h@4ax.com...
> On Thu, 12 Nov 2015 11:58:25 -0600, gray_wolf <g_wolf@nospam.com> > wrote: > >>On 11/12/2015 11:15 AM, Lasse Langwadt Christensen wrote: >>> Den torsdag den 12. november 2015 kl. 18.03.35 UTC+1 skrev OldGuy: >>>> I got a replacement battery for my laptop. >>>> It is a Li-Ion type. >>>> 6 cell 4400 mAh 10.8 volt >>>> >>>> In the package docs it states that I should cycle the battery all the >>>> way down, recharge it and do this several times to improve its >>>> capability. >>>> >>>> What is happening to the battery doing this? >>>> >>>> If not done what can I expect in terms of the amount of loss of use? >>> >>> afaik you shouldn't do that for Li-Ion, it was the old NiCd that needed >>> that >>> >>> -Lasse >> >>That's what I found out too. You shouldn't run a Li-Ion down completely. >>The Li battery in my DSLR has been going strong for the last 8 years. >>The camera says it's in good shape. > > They can be run down but there is a limit. If it's never run down, > how do you know its capacity? Laptop charging circuits have gas > gauges and need to run down the battery to calibrate.
Everything I've read so far says never fully discharge lithium. But I think the gas gauge could be the reason I've never had to buy cells for my DIY ecig. All my cells come from recycling bins in various shops, I've gone on the assumption that one weak cell causes the whole battery pack to be scrapped - but so far, I've never found that one weak cell. Presumably a chip in the battery pack informs the user that their battery is worn out, and they throw it in recycling - whether it is or not.
On Fri, 13 Nov 2015 20:23:18 -0000, "Ian Field"
<gangprobing.alien@ntlworld.com> wrote:

> > >"krw" <krw@nowhere.com> wrote in message >news:llm94bhmlbohudde8vpfmlfrfud5nq8s4h@4ax.com... >> On Thu, 12 Nov 2015 11:58:25 -0600, gray_wolf <g_wolf@nospam.com> >> wrote: >> >>>On 11/12/2015 11:15 AM, Lasse Langwadt Christensen wrote: >>>> Den torsdag den 12. november 2015 kl. 18.03.35 UTC+1 skrev OldGuy: >>>>> I got a replacement battery for my laptop. >>>>> It is a Li-Ion type. >>>>> 6 cell 4400 mAh 10.8 volt >>>>> >>>>> In the package docs it states that I should cycle the battery all the >>>>> way down, recharge it and do this several times to improve its >>>>> capability. >>>>> >>>>> What is happening to the battery doing this? >>>>> >>>>> If not done what can I expect in terms of the amount of loss of use? >>>> >>>> afaik you shouldn't do that for Li-Ion, it was the old NiCd that needed >>>> that >>>> >>>> -Lasse >>> >>>That's what I found out too. You shouldn't run a Li-Ion down completely. >>>The Li battery in my DSLR has been going strong for the last 8 years. >>>The camera says it's in good shape. >> >> They can be run down but there is a limit. If it's never run down, >> how do you know its capacity? Laptop charging circuits have gas >> gauges and need to run down the battery to calibrate. > >Everything I've read so far says never fully discharge lithium.
That depends on what you mean by "fully", I suppose. Discharge to zero? No, that's not a good idea (but not as disastrous as SLACs). However, laptops won't allow this anyway. There isn't much energy under 3.1V (from memory) so there is no point in discharging below that point.
> >But I think the gas gauge could be the reason I've never had to buy cells >for my DIY ecig. > >All my cells come from recycling bins in various shops, I've gone on the >assumption that one weak cell causes the whole battery pack to be scrapped - >but so far, I've never found that one weak cell. > >Presumably a chip in the battery pack informs the user that their battery is >worn out, and they throw it in recycling - whether it is or not.
I suppose that depends on what you define as a good cell, too. I've had batteries go bad. I know they're bad because they discharge significantly faster than a new cell.
Charge/discharge efficiency is not 100%, nor is leakage perfectly matched in 
the set.

So, over time, some cells get lower than others.  Without any cause at all, 
as far as the controller knows -- no terminal current was even flowing.

By recharging a flat pack, the most-charged cells go up from, say, 40% to 
90%, while the least-charged cells go up from, say, 20% to 80%.  There's 
less charge in the already-charged ones, and more charge in the less-charged 
ones.

Same thing happens on discharge, it's a decay process internally.  Not 
perfectly divided, coulomb per coulomb, among cells.

So having <100% charge efficiency actually helps, because that loss 
manifests as current-sharing resistors in your pack of near-voltage-sources. 
And over numerous cycles, the charge per cell gradually gets back in 
balance.

Cool, huh?

So if you leave your <anything with multiple cells> sitting plugged in too 
long, unplug it and give it a few cycles every once in a while.  Like every 
month or so.  Discharge until a warning pops up, charge until it's finished. 
You can use smaller cycles, but then you have to watch it intently, which is 
silly.  Hopefully... the manufacturer decided to treat their cells well, and 
set generous thresholds for "shutdown warning" and "stop charging".  But 
even at the limits (4.25V charged and 3.2V discharged, or thereabouts), 
you'll recover way more life through balancing than you lose by leaving them 
totally out of whack.  Battery life is only until the lowest cell drops out, 
and charge time is only until the fullest finishes.

I had one laptop that I left plugged in for over a year (didn't need it, had 
another -- only reason I left it running was f@h), the cells nearer the 
warmer insides died more or less.  The charge circuit completely refused to 
use it anymore.  Later, I opened the pack, and the one bank of them was 
under 1V.  (The rest were okayish, over 2.5V.)

My current laptop no longer reads battery charge correctly (it thinks it's 
at 100%, until it flips shit and panicks to standby), but varies between 1-2 
hours actual run time, depending on how much I've left it sit around between 
uses.

Tim

-- 
Seven Transistor Labs
Electrical Engineering Consultation
Website: http://seventransistorlabs.com


"OldGuy" <OldGuy@spamfree.com> wrote in message 
news:n22gov$2p2c$1@adenine.netfront.net...
>I got a replacement battery for my laptop. > It is a Li-Ion type. > 6 cell 4400 mAh 10.8 volt > > In the package docs it states that I should cycle the battery all the way > down, recharge it and do this several times to improve its capability. > > What is happening to the battery doing this? > > If not done what can I expect in terms of the amount of loss of use? > > > > --- news://freenews.netfront.net/ - complaints: news@netfront.net ---
On 11/13/2015 4:53 PM, krw wrote:
> On Fri, 13 Nov 2015 20:23:18 -0000, "Ian Field" > <gangprobing.alien@ntlworld.com> wrote: > >> >> >> "krw" <krw@nowhere.com> wrote in message >> news:llm94bhmlbohudde8vpfmlfrfud5nq8s4h@4ax.com... >>> On Thu, 12 Nov 2015 11:58:25 -0600, gray_wolf <g_wolf@nospam.com> >>> wrote: >>> >>>> On 11/12/2015 11:15 AM, Lasse Langwadt Christensen wrote: >>>>> Den torsdag den 12. november 2015 kl. 18.03.35 UTC+1 skrev OldGuy: >>>>>> I got a replacement battery for my laptop. >>>>>> It is a Li-Ion type. >>>>>> 6 cell 4400 mAh 10.8 volt >>>>>> >>>>>> In the package docs it states that I should cycle the battery all the >>>>>> way down, recharge it and do this several times to improve its >>>>>> capability. >>>>>> >>>>>> What is happening to the battery doing this? >>>>>> >>>>>> If not done what can I expect in terms of the amount of loss of use? >>>>> >>>>> afaik you shouldn't do that for Li-Ion, it was the old NiCd that needed >>>>> that >>>>> >>>>> -Lasse >>>> >>>> That's what I found out too. You shouldn't run a Li-Ion down completely. >>>> The Li battery in my DSLR has been going strong for the last 8 years. >>>> The camera says it's in good shape. >>> >>> They can be run down but there is a limit. If it's never run down, >>> how do you know its capacity? Laptop charging circuits have gas >>> gauges and need to run down the battery to calibrate. >> >> Everything I've read so far says never fully discharge lithium. > > That depends on what you mean by "fully", I suppose. Discharge to > zero? No, that's not a good idea (but not as disastrous as SLACs). > However, laptops won't allow this anyway. There isn't much energy > under 3.1V (from memory) so there is no point in discharging below > that point. >> >> But I think the gas gauge could be the reason I've never had to buy cells >> for my DIY ecig. >> >> All my cells come from recycling bins in various shops, I've gone on the >> assumption that one weak cell causes the whole battery pack to be scrapped - >> but so far, I've never found that one weak cell. >> >> Presumably a chip in the battery pack informs the user that their battery is >> worn out, and they throw it in recycling - whether it is or not. > > I suppose that depends on what you define as a good cell, too. I've > had batteries go bad. I know they're bad because they discharge > significantly faster than a new cell. >
Back in the day, I built an automated test fixture to evaluate laptop cells. Ignoring the obvious exceptions of shorted cells and those that had been obviously overheated, I found that virtually every cell from a "bad" laptop battery pack would produce it's full rated number of electrons if discharged at low current. The failure mode is increased internal series resistance. Battery management chips deal with that in different ways, but the result is pretty much the same...buy a new battery. Do the math. Using some round numbers, if your laptop takes 60W and has a 10V battery, that's 6 amps AVERAGE. The difference between full and empty for a lithium cell is about a volt. 1/6 of an ohm series resistance per cell or cell pair renders your pack useless for powering a laptop. And the peak current may be much higher than that. At far less resistance, you see the symptom that the battery gauge seems to be normal down to 50%, then instantly drops to zero, but the laptop may run for a long time at that level, if it's not working too hard...depending on how the battery management system is programmed. Even if it's a coulomb counter, the voltage drop caused by the peak current demand can trip the voltage level safety limit.