what ma setting should I use when "reconditioning" old batteries? La Crosse Technology Alpha Power Battery Charger, BC1000

I want to recondition some old batteries with my new charger, and it seems the recommended thing to do is to use the ma 200 setting when using this charger. However, it seems that if the charger needs to recharge and discharge the battery repeatedly in order to recondition the batteries, this could take days.

Any recommendations from someone who is not so electrically challenged?

asked by Douglas W. McKeehen on March 1, 2012
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The 200mA setting for charging current is suitable for AAA batteries, but not for AA.

For AA cells (with capacity of 2000-2500mAh) I recommend using 700mA for charging (350mA for dischargeing). This reduces each REFRESH cycle to about 9 hours (3 hours charging plus 6 hours discharging). So the whole REFRESH operation (which typically takes 3-4 cycles) can be completed in about 1.5 days.

Some people will tell you that using a low charge rate of 0.1C (200mA for a 2000mAh battery) is the best for battery lifespan. But that is a mis-conception left over from the days of dumb chargers (where you just blindly charge your batteries for 15 hours at 0.1C). With a smart charger such as BC-1000, the best charge rate is between 0.3C and 0.5C. That translates to 700mA or 500mA for AA cells. Using lower charging rate of 0.1C may cause the smart charger to miss negative dV/dt detectiion, and end up over-charging your batteries.
NLee the Engineer answered on March 2, 2012

For recharging AA cells (of capacity around 2000-2700mAh), you can use either 500mA or 700mA. If you notice your older cells getting too warm for comfort during charging, then reduce to 500mA. For eneloop either setting is fine. Don't worry about the minor difference in battery lifespan between these two settings.

The discharging current is always 50% of charging current. So selecting 350mA in Discharge/Refresh means 700mA charging.
NLee the Engineer answered on September 19, 2012

Oh wow...I always charged EVERYTHING (AA and AAA) @ .1C (200mA) because I heard the lower the coulombs, the better it is for the life of the battery. Its also what the BC900 defaults to when I put my eneloops in there, so I figured that is the best charging current.
Alan answered on May 20, 2012

Dear NLee,

I am totally embarrassed to ask this moronic question, so please forgive me! Obviously I need to do a lot of homework on battery science. In the meantime, can I just use the default (700) for all of my AA batteries for starters, before I have time to study? And I need to bump down to 200 for AAA? For discharging/refreshing, it appears I need to change the discharge setting? I see a combo discharge/mode, for which I changed current to 350. May I assume that this current change applies to the discharge (only) mode? This process I am applying only to older rechargeables that have been used a bit, not my new eneloops? Many thanks in advance.
LR answered on September 3, 2012

Yeah, 200 is best for longetivity of batteries, though it is the slowest. You're right, it can take days. I've had batteries that have been in the unit for four days or more at a time. But, that's how it goes. :)
Mike answered on March 2, 2012
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