Bolster
Flashlight Enthusiast
So I purchased a good battery tester that tests under load, giving 20-40-60-80-100 readings. For long life and health of my new Eneloops, at what amount of discharge should I be recharging them? Thanks...
Eneloop Noob Asks: When to Recharge?
- Thread starter Bolster
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VidPro
Flashlight Enthusiast
whenever you want 
preferably before they get completly depleated below the speced .9 or 1V thing under load. then you wont reverse charge them.
the test silverfox did , do show that over time they act a Teeney bit like any other cell, and the voltage was a bit droopey.
so just like any rechargable a cycle of them once in a while would be good.
relative to the self discharge, that would probably mean once in year or 2 . vrses once in 3-6 months like the others.
but that is just a guess, based on what par is for rolled electrolyte plate cell things.
if they start acting funkey on you , run a low discharge cycle and see if they perk up under load. the rest of the time, just top em off whenever.
then it gets a bit more complicated like how were you going to top them off? because the charger can be a bit harsh on them, specially chargers that terminate only on overcharge.
so on the other hand, redundantlly topping them off into oblivion on a fast Vdrop termination charger, is just going to be hurting them for no reason.
dang, why does there always have to be caveats.
topping them off with a slow charger when they only need a bit of juice, like the end topping charge alogrythm would be a good way to squeese them back up to the top, without going over overcharge spec.
life is simpler than this, isnt it?
preferably before they get completly depleated below the speced .9 or 1V thing under load. then you wont reverse charge them.the test silverfox did , do show that over time they act a Teeney bit like any other cell, and the voltage was a bit droopey.
so just like any rechargable a cycle of them once in a while would be good.
relative to the self discharge, that would probably mean once in year or 2 . vrses once in 3-6 months like the others.
but that is just a guess, based on what par is for rolled electrolyte plate cell things.
if they start acting funkey on you , run a low discharge cycle and see if they perk up under load. the rest of the time, just top em off whenever.
then it gets a bit more complicated
like how were you going to top them off? because the charger can be a bit harsh on them, specially chargers that terminate only on overcharge. so on the other hand, redundantlly topping them off into oblivion on a fast Vdrop termination charger, is just going to be hurting them for no reason.
dang, why does there always have to be caveats.
topping them off with a slow charger when they only need a bit of juice, like the end topping charge alogrythm would be a good way to squeese them back up to the top, without going over overcharge spec.
life is simpler than this, isnt it?
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Bolster
Flashlight Enthusiast
Thanks for the answer! Wish I understood better...sorry I am slow, I have newbie brain, can I get some clarification:
"...preferably before they get completly depleated below the speced .9 or 1V thing under load. then you wont reverse charge them."
My ZTS tester indicates as low as 20%. If I recharge when they hit 20%, will that take care of the problem of possible reverse charging? (No V markings with this tester).
"so just like any rechargable a cycle of them once in a while would be good.
relative to the self discharge, that would probably mean once in year or 2 . vrses once in 3-6 months like the others."
So, does a cycle mean complete discharge all the way to 0? What exactly is a cycle? If a cycle means complete discharge, doesn't that go against your warning above?
"if they start acting funkey on you , run a low discharge cycle and see if they perk up under load. the rest of the time, just top em off whenever."
Would a low discharge cycle be like running them in my L2D on low until the light's out?
" how were you going to top them off? because the charger can be a bit harsh on them, specially chargers that terminate only on overcharge."
I was going to use the bundled Eneloop 4-slot charger...which seems extraordinarily slow...overnight, basically. I don't know how it terminates. Would you consider the Eneloop charger that came with my Costco special "blue suitcase" Eneloop pack to be a slow charger? (I hope so!)
"topping them off with a slow charger when they only need a bit of juice, like the end topping charge alogrythm would be a good way to squeese them back up to the top, without going over overcharge spec."
So that's the heart of my question, really...most of my Eneloops are at 40 or 60%, and I want to know: should I go ahead and top them off when they reach the 40-60 range? Or should I let them drop further (say, to 20%) before recharging?
If there are only so many recharges available to these batteries (I read x1000), then that would indicate I should let them get low before recharging, and that topping off might just be using them up prematurely. (Sort of like guys who clean their gun barrels so often that they cause 'cleaning wear' to otherwise new guns)
Basically I want to learn good battery care habits as early as I can, and I 'preciate your help!
"...preferably before they get completly depleated below the speced .9 or 1V thing under load. then you wont reverse charge them."
My ZTS tester indicates as low as 20%. If I recharge when they hit 20%, will that take care of the problem of possible reverse charging? (No V markings with this tester).
"so just like any rechargable a cycle of them once in a while would be good.
relative to the self discharge, that would probably mean once in year or 2 . vrses once in 3-6 months like the others."
So, does a cycle mean complete discharge all the way to 0? What exactly is a cycle? If a cycle means complete discharge, doesn't that go against your warning above?
"if they start acting funkey on you , run a low discharge cycle and see if they perk up under load. the rest of the time, just top em off whenever."
Would a low discharge cycle be like running them in my L2D on low until the light's out?
" how were you going to top them off? because the charger can be a bit harsh on them, specially chargers that terminate only on overcharge."
I was going to use the bundled Eneloop 4-slot charger...which seems extraordinarily slow...overnight, basically. I don't know how it terminates. Would you consider the Eneloop charger that came with my Costco special "blue suitcase" Eneloop pack to be a slow charger? (I hope so!)
"topping them off with a slow charger when they only need a bit of juice, like the end topping charge alogrythm would be a good way to squeese them back up to the top, without going over overcharge spec."
So that's the heart of my question, really...most of my Eneloops are at 40 or 60%, and I want to know: should I go ahead and top them off when they reach the 40-60 range? Or should I let them drop further (say, to 20%) before recharging?
If there are only so many recharges available to these batteries (I read x1000), then that would indicate I should let them get low before recharging, and that topping off might just be using them up prematurely. (Sort of like guys who clean their gun barrels so often that they cause 'cleaning wear' to otherwise new guns)
Basically I want to learn good battery care habits as early as I can, and I 'preciate your help!
VidPro
Flashlight Enthusiast
Thanks for the answer! Wish I understood better...sorry I am slow, I have newbie brain, can I get some clarification:
"...preferably before they get completly depleated below the speced .9 or 1V thing under load. then you wont reverse charge them."
My ZTS tester indicates as low as 20%. If I recharge when they hit 20%, will that take care of the problem of possible reverse charging? (No V markings with this tester).
Yes that would be perfect
"so just like any rechargable a cycle of them once in a while would be good.
relative to the self discharge, that would probably mean once in year or 2 . vrses once in 3-6 months like the others."
So, does a cycle mean complete discharge all the way to 0? What exactly is a cycle? If a cycle means complete discharge, doesn't that go against your warning above?
Yes it does go against my warning, if you dont know or have a machine that will discharge it to some safe level, then dont bother trying.
"if they start acting funkey on you , run a low discharge cycle and see if they perk up under load. the rest of the time, just top em off whenever."
Would a low discharge cycle be like running them in my L2D on low until the light's out?
An L2d as in series light, is not a great place to run then to the .9v, series meaning used with another cell stacked end to end. if that light goes OUT, stop using it (like dont keep retriggering it to work again) and recharge the cells.
" how were you going to top them off? because the charger can be a bit harsh on them, specially chargers that terminate only on overcharge."
I was going to use the bundled Eneloop 4-slot charger...which seems extraordinarily slow...overnight, basically. I don't know how it terminates. Would you consider the Eneloop charger that came with my Costco special "blue suitcase" Eneloop pack to be a slow charger? (I hope so!)
the enloop charger is sorta medium speed (only from the specs i saw) need more input, can you tell us more about the charger, and mabey what the back of the charger or the manuel says about the ma used to do a charge and termination method. or the exact time it takes in reality for it to fully charge. it should be ok. but i dont know enough to answer.
"topping them off with a slow charger when they only need a bit of juice, like the end topping charge alogrythm would be a good way to squeese them back up to the top, without going over overcharge spec."
So that's the heart of my question, really...most of my Eneloops are at 40 or 60%, and I want to know: should I go ahead and top them off when they reach the 40-60 range? Or should I let them drop further (say, to 20%) before recharging?
If there are only so many recharges available to these batteries (I read x1000), then that would indicate I should let them get low before recharging, and that topping off might just be using them up prematurely. (Sort of like guys who clean their gun barrels so often that they cause 'cleaning wear' to otherwise new guns)
Exactally, you said it right, clean the barrell carefully and when needed
at any rate it would be FAR better to have topped it off then for it to reach a fully discharged state in a series configuaration, and getting a "reverse charge"
Basically I want to learn good battery care habits as early as I can, and I 'preciate your help!
its funner to just have a reasonbly good charger, , and just dont sweat the small stuff. i got 6 chargers, some 80+ cells and there aint nothing you can do that makes everything perfect.
if the charger is really nice, and the discharger (you) stops using them when they take a dive in output (light dims) , they will live forever.
if you slow charge below the 200ma , they will never get smacked hard on the charger. if you fast charge, then you do it in a way that the charger hurts them as least as possible and go on about life, because they can only do what they can only do.
which only leaves why sanyos enloop charger doesnt follow thier own specs exactally
but i think they know what they are doing, as well as any of the rest of the stuff does.
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Bolster
Flashlight Enthusiast
Excellent answers. I am much enlightened.
To your question about the bundled Eneloop charger, the back says:
Output DC 1.2 V
300mA x4 AA
150mA x4 AAA
Well, this does sound like more than a slow charger (for AA), b/c you pegged slow at 200mA.
The charger doesn't say what happens when you charge two batteries at a time...would you get more mA when charging 2 as opposed to 4? I wonder if it's safer to always charge four at a time.
Also I read in the Eneloop FAQ that you must at least charge 2 at a time, and if doing two, they should either be together in the middle slots or to the slots at either edge.
One other question: I did my first charge of four AAs the other day (questions from which, and suspected screwups on my part, caused me to post here!). Two were discharged to 20%, two were discharged to 60%. I put them in 20-20-60-60 from left to right. I bet I screwed up, right? I was charging a 20 with a 60. I'm guessing that's bad :shakehead and I should not do that again? Next time: wait till they're all 20, and/or never charge mismatched pairs? (Guessing?)
To your question about the bundled Eneloop charger, the back says:
Output DC 1.2 V
300mA x4 AA
150mA x4 AAA
Well, this does sound like more than a slow charger (for AA), b/c you pegged slow at 200mA.
The charger doesn't say what happens when you charge two batteries at a time...would you get more mA when charging 2 as opposed to 4? I wonder if it's safer to always charge four at a time.
Also I read in the Eneloop FAQ that you must at least charge 2 at a time, and if doing two, they should either be together in the middle slots or to the slots at either edge.
One other question: I did my first charge of four AAs the other day (questions from which, and suspected screwups on my part, caused me to post here!). Two were discharged to 20%, two were discharged to 60%. I put them in 20-20-60-60 from left to right. I bet I screwed up, right? I was charging a 20 with a 60. I'm guessing that's bad :shakehead and I should not do that again? Next time: wait till they're all 20, and/or never charge mismatched pairs? (Guessing?)
Bolster
Flashlight Enthusiast
It appears that Eneloop's 2 cell charger (faq lists it recharging 2-4 hrs) is faster than its 4 cell charger (listed as taking 4-7 hrs). Could I conclude the 4-cell charger is therefore gentler on the batteries?
AND, the 64-dollar question, should I just buy an after-market slow charger? If so, can ya make me a recommendation that won't cost an arm or a leg?
AND, the 64-dollar question, should I just buy an after-market slow charger? If so, can ya make me a recommendation that won't cost an arm or a leg?
VidPro
Flashlight Enthusiast
in referance to POST #5
egzactally right again, me think you know what is going on.
the charger is a BIT hot for a slow charger :-( good healthy enloops will handle it fine.
as you noted its a team charger, and prefers to have teams of 2 put into it. potentally it can balance out the charge of a missmatched team, by slow overcharging.
because that charger is caught between a slow charger and a fast charger and is neither we just hope that sanyo knows what they are doing.
meter tests would show that they know what they are doing.
what is the Max voltage for the channels
what is the actual current that flows across the actual cells when almost full
when the voltage of the battery tapered off to not increasing any more does it stop Delta 0 or whatever they call that.
tests YOU could do to see if they knew what they were doing
at the end of charge , does it get the bateries really hot
when they start getting hot does it just keep staying hot endlessly till it times out
can you hear the batteries farting , and gassing (ok that would be really bad
egzactally right again, me think you know what is going on.
the charger is a BIT hot for a slow charger :-( good healthy enloops will handle it fine.
as you noted its a team charger, and prefers to have teams of 2 put into it. potentally it can balance out the charge of a missmatched team, by slow overcharging.
because that charger is caught between a slow charger and a fast charger and is neither
we just hope that sanyo knows what they are doing.meter tests would show that they know what they are doing.
what is the Max voltage for the channels
what is the actual current that flows across the actual cells when almost full
when the voltage of the battery tapered off to not increasing any more does it stop Delta 0 or whatever they call that.
tests YOU could do to see if they knew what they were doing
at the end of charge , does it get the bateries really hot
when they start getting hot does it just keep staying hot endlessly till it times out
can you hear the batteries farting , and gassing (ok that would be really bad
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VidPro
Flashlight Enthusiast
you could buy a slow or a fast charger if you dont trust the enloop.
i dont like team chargers, so a single channel charger would be good.
you got the TIME to wait for a slow charger? enough batteries to let some stay on the charger? dont mind overnight?
do you have so many batteries you need like 8 cell charger?
do you want to See what the heck is going on with the batteries?
do you think you need a charger that will discharge? usually because you dont USE the batteries enough, if you just use them, then you probably dont need a discharge function.
do you want to plunk down 20-30-40-50- or 100 dollers?
VidPro
Flashlight Enthusiast
see here
http://www.candlepowerforums.com/vb/showthread.php?p=2208275#post2208275
bones says it terminates just fine, i figured it would do something to survive. but then . . . ahh you can read it.
its just like any consumer thing, it cheap easy barely gets the job done, and made some corporation Stinkey ritch
after all people are Seeking out the kit , it cant be that bad.
http://www.candlepowerforums.com/vb/showthread.php?p=2208275#post2208275
bones says it terminates just fine, i figured it would do something to survive. but then . . . ahh you can read it.
its just like any consumer thing, it cheap easy barely gets the job done, and made some corporation Stinkey ritch
after all people are Seeking out the kit , it cant be that bad.
daimleramg
Banned
Power Me Up
Enlightened
Just to expand on what VidPro is saying...
As long as the ZTS is giving you at least 20%, you should be fine.
I'd suggest just charging the cells when it's convenient to you. Depending on your use, you might want to recharge whenever they get down to 80% - e.g. if you're using them in your L2D as an EDC or emergency light, it'd be worthwhile having them close to full most of the time in case you need it - no point in carrying it around nearly empty...
For other things, it might be easiest to just leave them until the device complains about the battery being low.
I wouldn't worry too much about wearing them out too quickly. Even if you charged them every week, and if you only got 10% of the rated number of cycles, they would still last you for 2 years...
If you ran it on turbo, you should notice that the light starts to dim before either of the cells is damaged. Ideally though, you would be better off with something that could discharge the cells individually to ensure that one doesn't end up reverse charging the other.
As long as the ZTS is giving you at least 20%, you should be fine.
I'd suggest just charging the cells when it's convenient to you. Depending on your use, you might want to recharge whenever they get down to 80% - e.g. if you're using them in your L2D as an EDC or emergency light, it'd be worthwhile having them close to full most of the time in case you need it - no point in carrying it around nearly empty...
For other things, it might be easiest to just leave them until the device complains about the battery being low.
I wouldn't worry too much about wearing them out too quickly. Even if you charged them every week, and if you only got 10% of the rated number of cycles, they would still last you for 2 years...
No - you should never discharge NiMH cells down to 0 Volts. Once they get down to around 1 Volt, you've got pretty much all of the energy that you can out of them.
A cycle is just a discharge followed by a recharge.
No - that would be a bad idea. Because the L2D uses the same head as the L1D, it will discharge both cells down until their combined voltage is down to 0.9 Volts or so, which would mean that their average voltage would only be 0.45V and one of them could be even lower if they're not perfectly matched (i.e. one cell is capable of holding more charge than the other, so one cell runs out before the other and can go to zero or even be reverse charged)
If you ran it on turbo, you should notice that the light starts to dim before either of the cells is damaged. Ideally though, you would be better off with something that could discharge the cells individually to ensure that one doesn't end up reverse charging the other.
Personally, if I was you, I'd charge them up before use, but if you need to use them first, that's also fine as well.
Like I said earlier, even if you charge them once a week, you'll probably get well over 2 years from them, so I wouldn't worry too much about wearing them out just from topping them up.
Bolster
Flashlight Enthusiast
Thank you, my friends. This is good information.
First my caveat - I am by no means an expert on batteries - but because of the advent of the eneloop and other LSD batteries I have now read quite a bit.
A charge current of 200mA for the eneloop (2000mAh capacity) is C/10 or 0.1C which is considered "slow" charging - although slow seems less harsh than "fast" charging - with a wider margin for error - might want to read this thread started by one of our more respected and experienced battery persons SilverFox -
A look at slow charging
Another very good and authorative source of information is the BatteryUniversity.com -
Charging nickel-based batteries
about 2/3 down the page -under
Charging nickel-metal-hydride -
"Nickel-metal-hydride should be rapid charged rather than slow charged. Because of poor overcharge absorption, the trickle charge must be lower than that of nickel-cadmium and is usually around 0.05C. This explains why the original nickel-cadmium charger cannot be used nickel-metal-hydride.
It is difficult, if not impossible, to slow-charge a nickel-metal-hydride. At a C?rate of 0.1-0.3C, the voltage and temperature profiles fail to exhibit defined characteristics to measure the full charge state accurately and the charger must rely on a timer. Harmful overcharge can occur if a partially or fully charged battery is charged with a fixed timer. The same occurs if the battery has aged and can only hold 50 instead of 100% charge. Overcharge could occur even though the battery feels cool to the touch."
This explains the preference of fast charge over slow charge on the basis of end of charge detection.
BUT there is also the third point under Simple Guidelines:
"nickel-based batteries prefer fast-charge. Lingering slow charges cause crystalline formation (memory)."
Other references -
Duracell - Ni-MH Technical Bulletin Collection - Download PDF (only about 1/2Mb) - on page 14 -
"Charge Rate ... Termination Technique
(Note: my highlighting in Red)
Notice the "Not recommended" range of C/3 to C/10 -
so for eneloops rated at 1900(min) to 2000mAh
- the approx range to avoid is
190 to 667 mA charge currents.
(doesn't mean one can't use these, or they won't work -
they're just not as reliable for detecting full charge and avoiding possible damage)
Comments please?
A charge current of 200mA for the eneloop (2000mAh capacity) is C/10 or 0.1C which is considered "slow" charging - although slow seems less harsh than "fast" charging - with a wider margin for error - might want to read this thread started by one of our more respected and experienced battery persons SilverFox -
A look at slow charging
Another very good and authorative source of information is the BatteryUniversity.com -
Charging nickel-based batteries
about 2/3 down the page -under
Charging nickel-metal-hydride -
"Nickel-metal-hydride should be rapid charged rather than slow charged. Because of poor overcharge absorption, the trickle charge must be lower than that of nickel-cadmium and is usually around 0.05C. This explains why the original nickel-cadmium charger cannot be used nickel-metal-hydride.
It is difficult, if not impossible, to slow-charge a nickel-metal-hydride. At a C?rate of 0.1-0.3C, the voltage and temperature profiles fail to exhibit defined characteristics to measure the full charge state accurately and the charger must rely on a timer. Harmful overcharge can occur if a partially or fully charged battery is charged with a fixed timer. The same occurs if the battery has aged and can only hold 50 instead of 100% charge. Overcharge could occur even though the battery feels cool to the touch."
This explains the preference of fast charge over slow charge on the basis of end of charge detection.
BUT there is also the third point under Simple Guidelines:
"nickel-based batteries prefer fast-charge. Lingering slow charges cause crystalline formation (memory)."
Other references -
Duracell - Ni-MH Technical Bulletin Collection - Download PDF (only about 1/2Mb) - on page 14 -
"Charge Rate ... Termination Technique
1C to C/2 ......... Voltage or temperature based
C/2 to C/3 ........ Voltage based
C/3 to C/10 ...... Not recommended
C/10 and below . Time limited
C/2 to C/3 ........ Voltage based
C/3 to C/10 ...... Not recommended
C/10 and below . Time limited
Table 6.3.1 Recommended charge termination techniques
for particular charge rates."(Note: my highlighting in Red)
Notice the "Not recommended" range of C/3 to C/10 -
so for eneloops rated at 1900(min) to 2000mAh
- the approx range to avoid is
190 to 667 mA charge currents.
(doesn't mean one can't use these, or they won't work -
they're just not as reliable for detecting full charge and avoiding possible damage)
Comments please?
VidPro
Flashlight Enthusiast
well you said it all right there unknownVT.
only thing i would comment is that at 1/10c and below, as long as there is a voltage max to the charger, the cell does not go into an "overcharge state" and we have devices that use that method with medium capacity cells, and they have been low rate charged slow for Years, and have survived and still functinally operate the device.
i like 1/10 c and below, also because its the only safe way to fully balance out a set of series cells. EVEN if you do that as the second stage of a more complex charging scheme.
nothing is perfect, but not going over the overcharge spec seems to last better than pulverising and Vdrop. also it might depend totally on the cell itself. and every charger has different methodologies applied to it, i can think of no way to summarize all chargers that exist, each has thier methods that vary greatly. so the best summary you can make, is chargers that are "smart", and chargers that are dum and slow, but everything inbeteen exists too, and combos of all that, then turn around and one uses Pressure instead.
i always say check the specs on the actual cell item your using, there ARE differences in how some cells act over others. it wont always apply that a Duracell 2600, has the same intended build as a Sanyo 2000. examples of that are ni-mhys uses in hybrids.
only thing i would comment is that at 1/10c and below, as long as there is a voltage max to the charger, the cell does not go into an "overcharge state" and we have devices that use that method with medium capacity cells, and they have been low rate charged slow for Years, and have survived and still functinally operate the device.
i like 1/10 c and below, also because its the only safe way to fully balance out a set of series cells. EVEN if you do that as the second stage of a more complex charging scheme.
nothing is perfect, but not going over the overcharge spec seems to last better than pulverising and Vdrop. also it might depend totally on the cell itself. and every charger has different methodologies applied to it, i can think of no way to summarize all chargers that exist, each has thier methods that vary greatly. so the best summary you can make, is chargers that are "smart", and chargers that are dum and slow, but everything inbeteen exists too, and combos of all that, then turn around and one uses Pressure instead.
i always say check the specs on the actual cell item your using, there ARE differences in how some cells act over others. it wont always apply that a Duracell 2600, has the same intended build as a Sanyo 2000. examples of that are ni-mhys uses in hybrids.
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SuRgE
Enlightened
Ok guys.
I just bought some Eneloops AA and have them install in a FM 8AA holder wired in series. I have read the above and decided not to slow charge. I have a Tekin charger that I use to charge RC car batteries and it has all kinds of settings to choose so I basically can charge any way I want.
Now I somewhat understand the "C" thing but I'm a simple guy that needs layman advise.
According to the "C" thinging, I can safely charge my Eneloop pack at 1000ma-2000ma correct? This would be consider a rapid charge? And if I want to slow charge it, I should use somewhere between 200-500ma?
Thanks all
I just bought some Eneloops AA and have them install in a FM 8AA holder wired in series. I have read the above and decided not to slow charge. I have a Tekin charger that I use to charge RC car batteries and it has all kinds of settings to choose so I basically can charge any way I want.
Now I somewhat understand the "C" thing but I'm a simple guy that needs layman advise.
According to the "C" thinging, I can safely charge my Eneloop pack at 1000ma-2000ma correct? This would be consider a rapid charge? And if I want to slow charge it, I should use somewhere between 200-500ma?
Thanks all
TorchBoy
Flashlight Enthusiast
Use 200mA for 16 hours. But Tom says charge at the rate you expect to discharge at to keep them vibrant.
SilverFox
Flashaholic
Hello Ian,
Did I say that...?
Yes, I did, but let me put it into context and perhaps expand on it a little.
The battery manufacturers recommend two charge rates.
The slow charge rate is 0.1C for 14 - 16 hours using time as a charge termination criteria. If your expected runtime in your application is in the 5 - 20 hour range, the 0.1C charge rate will probably give you the best results.
The fast charge rate gives you a reliable end of charge termination signal throughout the life of the cell. The fast charge rate is in the 0.5 - 1.0C range. If your charger utilizes -dV or change in temperature as a termination criteria, you will get better life from your cells if you charge in this 0.5 - 1.0C range. If your application runtime is closer to 2 hours, charge at 0.5C. If your application runtime is closer to 1 hour or less, charge at 1.0C for best results.
To summarize:
If your application runtime is in the 5 - 20 hour range, you can charge at 0.1C without problems. You can also charge at 0.5 - 1.0C if you are in a hurry, also without problems.
If your application runtime is less than 5 hours, you will enjoy better performance by charging in the 0.5 - 1.0C range. You can "tune" your performance by charging at the rate you expect to discharge at.
If your charger utilizes -dV or change in temperature as a termination criteria, you will get better life from your cells by charging in the 0.5 - 1.0C range.
With Eneloop 2000 mAh cells, 0.1C = 200 mA, 0.5C = 1000 mA, and 1.0C = 2000 mA.
Tom
Did I say that...?
Yes, I did, but let me put it into context and perhaps expand on it a little.
The battery manufacturers recommend two charge rates.
The slow charge rate is 0.1C for 14 - 16 hours using time as a charge termination criteria. If your expected runtime in your application is in the 5 - 20 hour range, the 0.1C charge rate will probably give you the best results.
The fast charge rate gives you a reliable end of charge termination signal throughout the life of the cell. The fast charge rate is in the 0.5 - 1.0C range. If your charger utilizes -dV or change in temperature as a termination criteria, you will get better life from your cells if you charge in this 0.5 - 1.0C range. If your application runtime is closer to 2 hours, charge at 0.5C. If your application runtime is closer to 1 hour or less, charge at 1.0C for best results.
To summarize:
If your application runtime is in the 5 - 20 hour range, you can charge at 0.1C without problems. You can also charge at 0.5 - 1.0C if you are in a hurry, also without problems.
If your application runtime is less than 5 hours, you will enjoy better performance by charging in the 0.5 - 1.0C range. You can "tune" your performance by charging at the rate you expect to discharge at.
If your charger utilizes -dV or change in temperature as a termination criteria, you will get better life from your cells by charging in the 0.5 - 1.0C range.
With Eneloop 2000 mAh cells, 0.1C = 200 mA, 0.5C = 1000 mA, and 1.0C = 2000 mA.
Tom
Turbo DV8
Flashlight Enthusiast
Hello Bolster,
This is news to me, having been told and then confirming that the 4-bay Sanyo Eneloop charger charges and terminates it's cells independently. I did a search, but could not find the Eneloop FAQ you refer to where they state to charge pairs in specific slots in the charger. Would you please provide a link? Thanks.
