when to throw away rechargeables

[qazx]

ive seen it mentioned that when a rechargeable (aa/aaa) battery holds 80% of the batt capacity (measured by the maha c9000) is when you should throw it away, is this correct?

when i got the c9000 i measured a few of my bad ones that dont hold charge for very long and theyre about 70%. It seems that when they drop to this level, even though theyre still holding 70%, the drop in performance is big but i dont know why.

 

[TooManyGizmos]

The chemistry has crystalized .
.

 

[amigafan2003]

Not only is the capacity affected when cells age but also the amount of current they can deliver and the voltage they can sustain.

"dispose of responsibly when capacity is 80%" is a good mantra.

throw it away

No, no, no, no, no!

 

[Trashman]

They get sent off to battery heaven, when the charger says, "null."

 

[TooManyGizmos]

Hav'nt you noticed that they get VERY hot .... when you try to charge them ?

Another reason to throw a batt. away - b4 it vents wit flames .

 

[PeAK]

.
.
.
... even though theyre still holding 70%, the drop in performance is big but i dont know why.

The drop in capacity coincides with the battery being unable to put out enough voltage for a given current draw.

In the plot above, I show two different batteries, but it can also be used to show what happens when a battery gets older and loses capacity. This would be the case of the yellow line marked "Kodak". A new battery will appear more like the red line marked eneloop.

To see how this graph can be used. Draw a vertical line starting below the "S" in phrase marked Slope=-Ro
The point(s) where this vertical line intersect the red and yellow battery curves are the output voltages when both batteries are outputting the same current.

Last the slope of the line can tell you about how constant the voltage of the battery is for different "loads" of current draw. The flatter the better and the lower the "internal on resistance" of the battery

​

 

[amigafan2003]

Another reason to throw a batt. away - b4 it vents wit flames.

So nimh cells vent with flame now? :mecry:

 

[TooManyGizmos]

They might if they get too hot.

A charging defective battery could do anything .

It could certainly cause flames .

Or it could cause a charger malfunction and overheating/melting .
.

 

[TranceAddict]

dont throw, if it is LSD cell like eneloop, keep it and use in low power consumption devices - remote control, clock ...

 

[palomino77]

I've had 6 panasonic AA batteries for a few years now, I don't know how many times they have been charged, never kept records. Now I have a C9000 and am doing averything that is recommended on this forum. well anyway I've cycled, broke-in, refreshed etc. they are soppose to be a nominal 2100 mAH and now they are after discharge cycle:

1, 1696mah / 1.20v
2, 1541mah / 1.22v
3, 1441mah / 1.21v
4, 1397mah / 1.21v
5, 1553mah / 1.23v
6, 1560mah / 1.23v

They don't get hot at all, very slightly warm either on charge 1000mah or discharge 500mah, as you can see they are at less then 80% of nominal capacity.

I know this is not good, but should I despose of them?

I also have some newer energizer 2500 mah that seem to be alot better, I'll test them tomorrow and give results.

A little off topic, I have a new pack of 4 eneloops AA and a new pack of 4 energizer 850 mah AAA I don't need right now, should I keep storing them in the new pack or should I open pack and Break-in? Thanks

 

[MarioJP]

I still have 4 blacktop Duracell that has all the above symptoms you guys have mentioned. It gets hot when charging and even when its discharging at high current rate.

You guessed it. To those that already know my history of these cells that were thrashed by the now retired energizer 15 min charger lol. These are my last 4 cells.

Only reason I have not recycle them is because I am curious to when the cells actually stops working.

Despite having high internal resistance, these cells are quite usable for low drain devices.

what I want to do with these cells is actually wear them out to the point they can't even hold a charge lol. I just want to see what happens. I have noticed that the higher the resistance the hotter the cell gets during charging/discharging. Is this correct?? I no longer use these cells in my 4 AA universal usb charger used to charge mobile devices, because they get way too hot. I now use these cells as a led flashlight batteries now.

 

[SilverFox]

Hello Palomino,

2100 mAh cells sometimes have a minimum capacity of 2000 mAh. 80% of 2000 gives us 1600 mAh. It looks like all but one of your cells has dropped below 1600 mAh. If the others don't come up above 1600 mAh, they are crap.

The Eneloop cells can just stay in the package. The Energizer cells should be periodically cycled through a charge/discharge cycle, and stored discharged. I try to do a charge/discharge cycle on my stored cells every month.

Tom

 

[TakeTheActive]

...I've had 6 panasonic AA batteries for a few years... ...Now I have a C9000 and am doing averything that is recommended on this forum... ...they are soppose to be a nominal 2100 mAH and now they are after discharge cycle:

1, 1696mah / 1.20v
2, 1541mah / 1.22v
3, 1441mah / 1.21v
4, 1397mah / 1.21v
5, 1553mah / 1.23v
6, 1560mah / 1.23v

They don't get hot at all, very slightly warm either on charge 1000mah or discharge 500mah, as you can see they are at less then 80% of nominal capacity...

First, a small 'nit' - CAPACITY is determined by a 0.2C DISCHARGE. So, for your 2100mAh Panasonic AAs, that would be 420mA. The closest C9000 setting is 400mA so use that. While CAPACITY readings don't vary much on cells with LOW Internal Resistance, they do when the Internal Resistance climbs as the cells get older (or are neglected / improperly maintained / etc...).

"...slightly warm..." @ ~1.0C is GOOD sign! What's their Impedance Check Voltage (more on that below)?

As for RECORD KEEPING, *IF* you decide to start, here's an example of mine (kept in plain text via NotePad):

Kodak 2000mAh AA LSD             |  #1    #2    #3    #4
---------------------------------+---------------------------

10/25/09 C9000 Cycle2:  1000/ 400| 1984  1996  1981  1993 mAh
10/24/09 C9000 Cycle1:  1000/ 400| 1975  2001  1988  1991 mAh
10/23/09 C9000 Discharge:  100   |   27    21    21    24 mAh
10/23/09 C9000 Discharge:  400   |  323   319   333   298 mAh
10/23/09 C9000 Impedance Check:  | 1.51  1.51  1.51  1.50 VDC

06/27/09 C9000 Charge: 1000      |  550   550   550   550 mAh (partial)
06/27/09 C9000 Impedance Check:  | 1.58  0.32  0.71  0.26 VDC
04/04/09 C9000 Impedance Check:  | 1.64  1.68  1.66  1.65 VDC
04/04/09 C9000 Cycle3:  2000/ 400| 1982  2001  2016  1995 mAh
04/xx/09 C9000 Cycle2:  2000/ 400| 1983  2004  2019  1997 mAh
04/xx/09 C9000 Cycle1:  2000/ 400| 1990  2013  2031  1987 mAh
04/02/09 C9000 Discharge:  100   | 2125  2125  2122  2124 mAh
04/01/09 C9000 Break-In: 2000    | 2032  2040  2052  2034 mAh#
03/30/09 C9000 Discharge:  400   | 1648  1615  1669  1615 mAh
03/30/09 C9000 Impedance Check:  | 1.51  1.55  1.55  1.54 VDC
[Bought: 11/dd/08;
 04/04-06/27/09:HP215 Camera - Camera OFF discharged *ALL* to 0VDC!!! NG!]

HP215: 9.2mA OFF; 520-640mA ON w/LCD.

I also recommend tracking Maha MH-C9000 Impedance Check Voltage since it's directly related to INTERNAL RESISTANCE and gives you a good idea of the cell's health and current delivery capability.

ive seen it mentioned that when a rechargeable (aa/aaa) battery holds 80% of the batt capacity (measured by the maha c9000) is when you should throw it away, is this correct?...

dont throw, if it is LSD cell like eneloop, keep it and use in low power consumption devices - remote control, clock ...

+1 :thumbsup:

...I know this is not good, but should I despose of them?

IMHO, NO!!!

Please read: Do You Maintain *CRAP* NiCD/NiMH Cells?

 

[OpenGuy]

I have some old Sanyo 2100 mAh cells that have a remaining capacity in the range 1600-1700 mAh. I use them everyday (in winter) to power some Fenix L2D for about 30 minutes. They usually take about 600-700 mAh to recharge every day. They appear perfectly adequate for this task.

Are you saying I shouldn't I keep using them?

I figure that although they're not great batteries, they're saving my Eneloops from an everyday charge/discharge cycle. This keeps the Eneloops in better condition for the devices that really do need them (like my new camera).

I do carry a spare set of either Imedions or Eneloops just in case I need extra light and cycle these on a different schedule.

 

[palomino77]

Hello Palomino,

2100 mAh cells sometimes have a minimum capacity of 2000 mAh. 80% of 2000 gives us 1600 mAh. It looks like all but one of your cells has dropped below 1600 mAh. If the others don't come up above 1600 mAh, they are crap.

The Eneloop cells can just stay in the package. The Energizer cells should be periodically cycled through a charge/discharge cycle, and stored discharged. I try to do a charge/discharge cycle on my stored cells every month.

Tom

Thanks Silverfox please ignore other thread I started today with same question. I would take it off but don't know how.

 

[palomino77]

First, a small 'nit' - CAPACITY is determined by a 0.2C DISCHARGE. So, for your 2100mAh Panasonic AAs, that would be 420mA. The closest C9000 setting is 400mA so use that. While CAPACITY readings don't vary much on cells with LOW Internal Resistance, they do when the Internal Resistance climbs as the cells get older (or are neglected / improperly maintained / etc...).

"...slightly warm..." @ ~1.0C is GOOD sign! What's their Impedance Check Voltage (more on that below)?

As for RECORD KEEPING, *IF* you decide to start, here's an example of mine (kept in plain text via NotePad):

Kodak 2000mAh AA LSD             |  #1    #2    #3    #4
---------------------------------+---------------------------
 
10/25/09 C9000 Cycle2:  1000/ 400| 1984  1996  1981  1993 mAh
10/24/09 C9000 Cycle1:  1000/ 400| 1975  2001  1988  1991 mAh
10/23/09 C9000 Discharge:  100   |   27    21    21    24 mAh
10/23/09 C9000 Discharge:  400   |  323   319   333   298 mAh
10/23/09 C9000 Impedance Check:  | 1.51  1.51  1.51  1.50 VDC
 
06/27/09 C9000 Charge: 1000      |  550   550   550   550 mAh (partial)
06/27/09 C9000 Impedance Check:  | 1.58  0.32  0.71  0.26 VDC
04/04/09 C9000 Impedance Check:  | 1.64  1.68  1.66  1.65 VDC
04/04/09 C9000 Cycle3:  2000/ 400| 1982  2001  2016  1995 mAh
04/xx/09 C9000 Cycle2:  2000/ 400| 1983  2004  2019  1997 mAh
04/xx/09 C9000 Cycle1:  2000/ 400| 1990  2013  2031  1987 mAh
04/02/09 C9000 Discharge:  100   | 2125  2125  2122  2124 mAh
04/01/09 C9000 Break-In: 2000    | 2032  2040  2052  2034 mAh#
03/30/09 C9000 Discharge:  400   | 1648  1615  1669  1615 mAh
03/30/09 C9000 Impedance Check:  | 1.51  1.55  1.55  1.54 VDC
[Bought: 11/dd/08;
 04/04-06/27/09:HP215 Camera - Camera OFF discharged *ALL* to 0VDC!!! NG!]
 
HP215: 9.2mA OFF; 520-640mA ON w/LCD.

I also recommend tracking Maha MH-C9000 Impedance Check Voltage since it's directly related to INTERNAL RESISTANCE and gives you a good idea of the cell's health and current delivery capability.



+1 :thumbsup:


IMHO, NO!!!

Please read: Do You Maintain *CRAP* NiCD/NiMH Cells?

Thank you lovecpf

 

[TooManyGizmos]

Edited , reader error

 

[Linger]

re:

.....

Please Palomino77, I ask you do not quote entire posts. Please include only sections essential to your own post.
Thank-you:wave:
Linger

 

[TooManyGizmos]

Re:

It would be helpful and appreciated .

 

[gtwace]

Re:

One important point that decides whether you should throw away that Rechargebale when it reaches 80% capacity is whether you will mix that old battery with new ones in a single device. Eg. in a 2 cell light. If it is only for use in a single cell light, you can juice it further down if you don't mind the less than optimium performance and runtime. However, if you mix it with new cells in a 2 cell light, the new cell e.g. 2100ma will try to balance its charge with the old 1680ma (80%) cell. This will reduce the life of the new cell as charge and discharging occurs in the process and poses a danger of battery leakage.