08-26-2019 01:39 PM
Thanks. I think it provides corroboration that these expensive little guys (I have 6 of them, all branded official Canon batteries, all made in China) can be problematic if we don't maintain some kind of means to ensure we check their status periodically to ensure they are still "healthy" , able to take a charge, able to retain a charge, and are, indeed, charged when we need to rely on them. Thanks for substantiation. The other items in this thread give a lot of important info on this topic. DQ
08-26-2019 10:06 PM
Thanks to all. This afternoon saw a visit by a beautiful hummingbird. I fetched my 7D2 with 300 4/fL IS and 1.4x, turned the body on, and (wait for it!) nothing happened. Turns out that this battery was also totally discharged without my being aware of it -- as was the battery in my other 7D2. That makes 5 out of 6 LP-E6N batteries that were depleted (three in active camera bodies) at one time. Is it time for Canon to question the quality of this cell, and perhaps consider a recall or at least credit toward a new, improved version of this battery? The original LP-E6 that came with my 7D (not MkII) does not seem to have this problem.
Issue#2: we are told not to store fully-charged batteries. Does this mean we need to remove the battery from the charger as soon as the 75% winking light comes on, instead of letting it run a bit longer? What is a bit longer? If this is so important, why do the Canon chargers not have a percent charge meter on them other than just the blinking winking lights. Canon could then come out with a sensible recommendation that batteries should be charged until they are 89.65% "full, " or some such. Why tell us not to charge them fully without telling us how to quantify and measure that?
10-17-2019 02:25 PM
Lithium based cells storage is optimal on 20% charge which means 7.4 volts on a two cells 7.2 volts pack, like the LP-E6 [N]. Professional chargers / dischargers (Like IMAX B6AC - beware of it's clones!) have "storage mode" which discharges / charges the cells to 7.4 volts (depends on the level of the actually held charge). 7.4 volts indicates 50% battery level in my 5D3, 55% battery level in my 5D4 - you can correlate to that.
10-19-2019 03:01 PM
Those use/storage requirements are for those who want to absolutely optimize battery life however lithium ion batteries hold up well under a wide profile of usage and storage as they must since the majority of consumers aren't going to provide a high level of battery care. Other than rotating through the battery packs for my 1DX and 1DX 2, I don't do anything special with them however my cameras rarely sit very long between events. But I have a number of power tools witth lithium ion batteries and the usage and charge of those is very irregular. Two weeks ago I went through a couple of dozen complete charge discharge cycles with the four battery packs for my Bosch drill and Bosch impact driver while building a large outdoor kennel and doing final installation work on a diesel standby generator but prior to that they sat for several months in an unknown (probably fully charged state).
It sounds like the 7D2 itself has some significant parasitic current draw whenever a battery is mounted in it and this is probably the reason your battery packs are dead after a few days or weeks of sitting in a camera. Many modern electronic products are like this with "vampire" current draw and in many cases power switches no longer disconnect the battery or power source but just command the internal controller into a standby or low power mode; this is done for convenience of allowing functionality and also avoids having a switch contact that has to carry high current and causes power loss in the process. A lot of modern cars are no different and if I am not planning to drive my 2016 Corvette for more than a week it goes on a battery maintainer to keep its battery in good health because the remote sensing and alarm systems are still active.
And make sure to store batteries with the proper cap in place instead of some other material. A friend bought a bunch of replacement lithium coin cells in bulk and wrapped each cell up in foam to protect it until it was needed. Unfortunately the handy foam he had saved and used for this application was conductive foam used to protect semiconductors from static discharge until they are installed and it nicely discharged all of his spare batteries.