[672]

With my 645Z i noticed it was eating batteries. Then i noticed that i was still using batteries acquired at the time of my 645D purchase. Dated 2009 , 2010 , 2011. So , I then ordered two Watson batteries. Those work even less well than old pentax batteries. Useless, garbage. So now I got hold of a new pentax battery dated late 2016. So far so good.

So , fellow 645Z shooters, how long do you keep your batteries in service? Three years?

[Adam]

I think the OEM batteries are officially rated for 500 cycles, so that works out to quite a few clicks! I've only held on to batteries for 3-4 years and never noticed a dropoff, but having them go bad after 5-7 years of regular use sounds fair enough.

[Alex645]

Generally, I have found the length of time or age of a lithium-ion battery is less of a factor than the number of recycle charges and if the battery is allowed to drop dead and for how long it is dormant.

They are all rated for x amount of recharge cycles before they begin to be unable to hold a charge. So if you recharge them constantly, even if they are only partially drained, you are effectively shortening it's usable life.

On the other hand, if you let them completely drain down to the point where the camera doesn't turn on, and even worse, allow it to remain dormant dead for a long time, it can damage the power cell.

The 645Z comes with a D-LI90(E) Lithium-Ion Battery 7.2V, rated at 1860mAh and 14 watt-hours.
The Watson equivalent is 7.4V, rated at only 1800mAh and 13.32 watt-hours. Not a bad trade off for less than half the price, but not the same quality or performance and in some cases even consistency in manufacture.
Also note the D-Li90 (no "e") made for the 645D has generic Li-Ion versions from 7.4V with only 1700mAh to my favorite third party battery Wasabi at 7.2V and 2300mAh.

So the batteries themselves can be part of the problem/solution, but it is also affected by how you maintain them.

[dafbp]

Lithium batteries lose capacity not just by number of charging cycles, but also by depth of discharge: the bigger the depth of discharge, the worse the permanent capacity loss. Battery life is extended by using partial discharge cycles, so, in a long shooting session, rotate the batteries way before they reach empty, as much as is practical.


They shouldn't be kept at high temperatures (above room temperature), and also not stored fully charged, to prolong their life. So charge only before use (as practical), and NEVER let them go empty, that's a killer (like forgetting to give a small charge to a nearly empty battery before long term storage).