Archived posting to the Leica Users Group, 2012/05/20

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Subject: [Leica] Battery "Rules" as it applies to Leica 14464
From: red735i at earthlink.net (Frank Filippone)
Date: Sun, 20 May 2012 08:20:40 -0700

I have dome some research into the life of rechargeable Li-ion Batteries.
These are used in our M8 and M9 cameras ( and others I suspect).

 

With Nicads, we were taught to allow them to fully discharge and then charge
them up.. Not with Li-ion. In fact, these new batteries are a lot different
than I thought..and how I was using them

 

"Similar to a mechanical device that wears out faster with heavy use, so
also does the depth of discharge (DoD) determine the cycle count. The
smaller the depth of discharge, the longer the battery will last. If at all
possible, avoid frequent full discharges and charge more often between uses.
Partial discharge on Li-ion is fine; there is no memory and the battery does
not need periodic full discharge cycles other than to calibrate the fuel
gauge on a smart battery.  "

 

"Lithium-ion suffers stress when exposed to heat and kept at a high charge
voltage."

 

"The worst condition is keeping a fully charged battery at elevated
temperatures, which is the case when running a laptop on the power grid. The
pack does not die suddenly but will produce decreasing runtimes as part of
aging.

 

"Equally stressful is leaving a battery in a hot car, especially if exposed
to the sun. When not in use, store the battery in a cool dry place. For
long-term storage, manufacturers recommend a 40 percent charge. This allows
for some self-discharge while still retaining sufficient charge to keep the
protection circuit active. Finding the ideal state-of-charge is not easy;
this would require a discharge unit with an appropriate cut-off. Users
should not worry too much about the state-of-charge; a cool and dry place is
more important.

 

"Besides common aging, a Li-ion battery can also fail because of
undercharge. This occurs if a Li-ion pack is stored in a discharged
condition. Self-discharge gradually lowers the voltage of the already
discharged battery 

 

The message:

Charge your battery BEFORE it goes to zero.  Best seems to be "daily" on a
working trip / vacation.

Store your battery in a cool place.  I suspect a refrigerator is too humid.
but maybe a plastic bag could get around this issue.

Store when the battery is at less than 100% charge...but not fully
discharged.

 

Some of this also applies to Laptop use.  Read the reference to find out
more info... some of it is specific to the way Laptops are used...

Reference:
http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batt
eries

 

 

Frank Filippone

Red735i at earthlink.net