Rechargeable Battery Question - discharge batteries completely?

[haring]

Some people say that I have to discharge my batteries fully after each wedding before I charge them again to preserve my rechargeable batteries for a long time. Some people say I should never completely discharge my batteries...I use NIMH rechargeable batteries AA for my flash...
So who should I believe...?

Do you completely discharge your batteries before you recharge them?

[groovyone]

The newer batteries do not usually have the same memory effect that was seen in the older tech rechargables. I do not drain mine prior to charging them before an event. I typically wait until they are dead to charge in normal use, but I would not hesitate to top one off if it was only slightly down. This goes for my camera batteries and my AAs.

[KdLaneJr]

Buy a Maha "MH C-9000" battery charger. Use it to "break-in" new batteries, check suspect batteries and cycle batteries you want to refresh.

[ualymerej]

my usual routine is if my flash starts to take longer and longer to recycle, I switch out the batteries and charge them when I get home. I have a smart charger that regularly will discharge the batteries and then recharge them. this is usually referred to as "refreshing" the batteries. if you're constantly charging batteries that are only partially used, this will eventually cause the batteries to hold less charge. a refresh will usually restore the majority of the original charge capacity. obviously over time, batteries will hold less and less charge, but the occasional refresh should extend their life. the worst thing you can do though to rechargeable batteries is to use those 15 minute chargers.

[tc95]

Originally Posted by KdLaneJr

Buy a Maha "MH C-9000" battery charger. Use it to "break-in" new batteries, check suspect batteries and cycle batteries you want to refresh.

+1 with this...it has broght back to life old batteries of mine...they don't hold a full charge...but if you need an emergency set...

[groovyone]

I used a Maha 8001D and it did revive some of my older Energizer rechargeables. I use em in my kids toys.

[kenw]

What we have is a misunderstanding of "completely discharged".

Most devices that use rechargeables will not completely discharge the cells; once they reach a particular voltage the device shuts down instead. When the device (camera, flash, R/C car...) shuts down the cell is NOT completely discharged, it just doesn't have enough voltage to power the device.

This issue was real for NiCad and many NiCad chargers had circuitry to completely drain the cell prior to recharging to prevent developing the memory effect at that particular voltage where the device shut down. This is not necessary for NiMH or LiIon, and they should NOT be completely discharged; but using them until the device shuts down is NOT completely discharging them.

Technically, completely discharging a LiIon battery is incredibly dangerous. But not to worry, your camera can't discharge it that much anyway.

[haring]

Originally Posted by KdLaneJr

Buy a Maha "MH C-9000" battery charger. Use it to "break-in" new batteries, check suspect batteries and cycle batteries you want to refresh.

This sounds promising! I will have a look at it!

[haring]

Originally Posted by kenw

What we have is a misunderstanding of "completely discharged".

Most devices that use rechargeables will not completely discharge the cells; once they reach a particular voltage the device shuts down instead. When the device (camera, flash, R/C car...) shuts down the cell is NOT completely discharged, it just doesn't have enough voltage to power the device.

This issue was real for NiCad and many NiCad chargers had circuitry to completely drain the cell prior to recharging to prevent developing the memory effect at that particular voltage where the device shut down. This is not necessary for NiMH or LiIon, and they should NOT be completely discharged; but using them until the device shuts down is NOT completely discharging them.

Technically, completely discharging a LiIon battery is incredibly dangerous. But not to worry, your camera can't discharge it that much anyway.

Thanks! It does make sense!