Reconditioning M9 Batteries

[mweiner]

Advertisement (gone after registration)

The M9 manual states (p 106):

 

"A new battery only reaches it's full capacity after it has been fully charged and --by use in the camera -- discharged 2 or 3 times. This discharge process should be repeated every 25 cycles."

 

Does this mean that every 25 cycles I should fully discharge/recharge _once_ or 2-3 times? (Possibly the German version is clearer.)

 

Ordinarily I'd search general information about lithium batteries, but none of the other lithium powered devices I have recommend the 2-3 discharging process for new rechargeable batteries or periodically thereafter.

 

Also, how necessary/helpful have folks found it to do this process during the life of the M9 batteries?

 

Thanks in advance for any advice.

 

Michael

[elgenper]

Welcome to Battery University

[mweiner]

Elgenper, thanks; that was very helpful.

 

Just to summarize for the thread:

 

In general, for lithium batteries, full discharging decreases battery life. It is better to only partially discharge and then recharge. The battery itself does not develop "memory" issues, BUT

 

In devices that monitor the battery charge (like the M9), the device does develop memory issues and every 30 cycles or so a full discharge is required to recalibrate the device's monitoring apparatus. (A "cycle" is defined as however much partial discharging/recharging would be equivalent to a full discharge/recharge.)

 

Thus there is a trade off. Occasional (every 30 cycles) full discharging is helpful; more frequent full discharging is harmful.

 

It wasn't directly stated, but my interpretation from what I read at the University was that after the initial conditioning, if done every 30 cycles or so, one discharge/recharge process would be sufficient to recalibrate the device to the battery.

 

I now imagine another interesting question: Does the device need to be recalibrated for each battery one has or it is sufficient to use just one to calibrate. Could the device remember the calibration performed with one battery (eg the last one) -- which calibration would be inapppropriate for other batteries used in the camera. Possibly further reading at University will provide the answer.

 

Michael

[elgenper]

Yes, that ref is one of my top bookmarks... Glad you found it helpful.

 

In my reading, you do have to "workout" Li batteries for a couple of cycles to reach full capacity when they´re new. After that, it shouldn´t be needed any more; they have a slow but inevitable deterioration whatever you do (but running them down completely will accelerate the deterioration, if I read correctly..).

 

Calibration is something else. That´s for keeping the battery charge scale in the camera accurate; the software behind it has to be adjusted for the above-mentioned deterioration, or it will become misleading. My portable Mac´s are the same; one can´t trust the displayed remaining time unless the software can observe the actual limits of the battery regularly. But calibration DOES involve one of those complete rundowns, so don´t do it too often...