moldyoldy
Flashlight Enthusiast
This is the question that has kinda bothered me for years - rechargeable battery EOL. primarily the Ni-Mh cells.
I mentally eliminate the obvious failures - damaged case, will not accept a charge (shorted or open terminals), etc. I am also trying to ignore people like my older daughter who will attempt to use a laptop battery pack (Li-Ion) until it does not supply more than about 5 minutes of run time and then wonder about a replacement "this" week. I also acknowledge that Li-Ion cells seem to have a expectable lifetime after initial use (3 years?).
Soooooo, Depending on which battery reference book you review, Eveready and GE state that EOL is when the actual cell capacity has reached 80% of the stated cell capacity, the battery has reached End of Life. ummm, well, maybe. Other considerations are:
1. excessive self discharge. sure, but what is excessive? full discharge in a week? in a month?
2. inadequate capacity. meaning that the original capacity and run time was OK, but has since deteriorated to an inadequate run time _and_ any number of refresh cycles do not improve the situation.
3. too-low voltage under load even if the capacity is "acceptable". This is almost the same as too-low capacity, but not quite. The intention is that originally the cell voltage held up under the load, but no more, and the demonstrated capacity to a cut-off of 1.0 volts is still "ok".
Some of my tentative answers:
1. A recycle point for my uses is when the cell has self-discharged in a month. Why? I normally attempt to check/charge all cells once a month, unless I am testing them for self-discharge. An example of a recycle point is seeing a voltage of 1.1 on my BC-900 when I insert the unused cell for charging. Sometimes I fiddle with the BC-900 settings just to see how much capacity is left in the cell, but that requires that I be present before the cell begins recharging.
2. I tend to wait until I observe maybe a 50% decrease in capacity in use. If I am sufficiently irritated by an obvious way-too-short run time, I may actually run a test on the cell.
3. Too-low voltage under load. this is probably the most subjective evaluation as to why I recycle a cell. If the equivalent 'battery-low" indicator turns on, I think about the elapsed time since last charge and how much the cell was used. I may then run a test. FWIW, I do have a couple Ni-Mh cells that have test with a reasonable capacity, but simply do not hold an acceptable voltage under load. That is observable when running a discharge test on the BC-900. For much of the discharge time, the voltage for a Ni-Mh cell at maybe a 500ma load should be somewhere in the 1.2v range. These particular cells run most of their discharge time in the 1.1 and less range. This effect is also observable in a Fenix L1D-Q5 where there is no difference between "high" and "turbo" outputs, yet with most new'ish cells, the difference is obvious.
Thoughts?
I mentally eliminate the obvious failures - damaged case, will not accept a charge (shorted or open terminals), etc. I am also trying to ignore people like my older daughter who will attempt to use a laptop battery pack (Li-Ion) until it does not supply more than about 5 minutes of run time and then wonder about a replacement "this" week. I also acknowledge that Li-Ion cells seem to have a expectable lifetime after initial use (3 years?).
Soooooo, Depending on which battery reference book you review, Eveready and GE state that EOL is when the actual cell capacity has reached 80% of the stated cell capacity, the battery has reached End of Life. ummm, well, maybe. Other considerations are:
1. excessive self discharge. sure, but what is excessive? full discharge in a week? in a month?
2. inadequate capacity. meaning that the original capacity and run time was OK, but has since deteriorated to an inadequate run time _and_ any number of refresh cycles do not improve the situation.
3. too-low voltage under load even if the capacity is "acceptable". This is almost the same as too-low capacity, but not quite. The intention is that originally the cell voltage held up under the load, but no more, and the demonstrated capacity to a cut-off of 1.0 volts is still "ok".
Some of my tentative answers:
1. A recycle point for my uses is when the cell has self-discharged in a month. Why? I normally attempt to check/charge all cells once a month, unless I am testing them for self-discharge. An example of a recycle point is seeing a voltage of 1.1 on my BC-900 when I insert the unused cell for charging. Sometimes I fiddle with the BC-900 settings just to see how much capacity is left in the cell, but that requires that I be present before the cell begins recharging.
2. I tend to wait until I observe maybe a 50% decrease in capacity in use. If I am sufficiently irritated by an obvious way-too-short run time, I may actually run a test on the cell.
3. Too-low voltage under load. this is probably the most subjective evaluation as to why I recycle a cell. If the equivalent 'battery-low" indicator turns on, I think about the elapsed time since last charge and how much the cell was used. I may then run a test. FWIW, I do have a couple Ni-Mh cells that have test with a reasonable capacity, but simply do not hold an acceptable voltage under load. That is observable when running a discharge test on the BC-900. For much of the discharge time, the voltage for a Ni-Mh cell at maybe a 500ma load should be somewhere in the 1.2v range. These particular cells run most of their discharge time in the 1.1 and less range. This effect is also observable in a Fenix L1D-Q5 where there is no difference between "high" and "turbo" outputs, yet with most new'ish cells, the difference is obvious.
Thoughts?
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