How much TLC do you give your batteries?

I read an article a few days ago that unfortunately I can't now trace, but came sharply to mind this morning when one of my li-on batteries wouldn't charge.

The article (written in 2010) stated that storing li-on batteries fully charged caused premature failure due to oxidation, that li-on batteries should be stored at 40% charge, and NEVER let one fully discharge as the internal protection circuitry would (should) not allow it to be charged again.

Here's a little bit of reading on the subject of li-on battery storage I found this morning> http://batteryuniversity.com/learn/article/how_to_store_batteries

(There's plenty more on the Battery University site).

In my case the Pentax battery would not charge on a Pentax charger, but would after I had tried it for a short spell on a charger branded 'DSTE'. The significant difference between the chargers is the absence of a 'T' terminal on the DSTE one, which is, I assume, something to do with the batteries internal charge state monitoring circuitry? I'm assuming that using the DSTE charger bypassed the batteries internal protection circuitry, putting enough 'juice' into the battery to subsequently allow the Pentax charger to get on with charging again by changing the batteries internal 'don't charge me' flag? (Maybe this is why over the years by trying different chargers I've found batteries that would accept a charge again and continued to perform well thereafter.)

I'm in the habit of charging batteries before I go out to play, so know there will be some in my collection which will have been fully charged and put in storage unused. I also know that I have too many batteries and there will be some that have probably self-discharged over time to 0v.

So, the question I have is what do 'you' do to care for your batteries, or don't you bother, just accepting that you have to replace them from time to time?

Can it be assumed that refers only to long-term storage? My spare batteries are always fully charged and kept in my camera bag, typically to be swapped with the partially used one from the camera as needed (irregular, but possibly averaging fortnightly). They seem to hold their charge OK, the oldest probably being about three years old. How long should they be expected to last?

Cheers.
Philip

If you aren't using the batteries for quite some time a 40-50% charge is best, but mine are kept fully charged and swapped out as required. They get stored for quite long periods (months) at full charge. I know it is not what you are supposed to do, but that is just how it works out for me. I can't be keeping all my batteries at half charge just because I might not use them for a few months.

You should never let a Li-On battery die completely, which applies to a mobile phone, or a lap top, battery too. That is worse for a battery than keeping it at full charge. They don't have a "memory" like old rechargeables did, and certainly don't need running flat and recharging a few times from new

Mr B. There was nothing in the article to define what period constitutes 'storage', but I doubt a couple of weeks would hurt.

Gwyn. How do you determine 40-50% charge? Also, I have too many battery powered things around to be able to keep on top of their battery state and therefore avoid fully discharged batteries. I'm guessing it needs discipline or a good diary in order to check them all regularly.

As said, part of my issue is charging batteries in anticipation of use, but then not using them and putting them on one side for weeks or months.

There used to be battery discharge devices around some years ago. Can't find then today, compounded by the fact that there are a lot of battery formats.

I rotate three batteries, never totally exhausting any one of them.

As there is no memory effect I change my battery when it shows a "black section"in the lcd. I use a "grip first" routine so it's convenient to change a battery quickly if ever needed. I asume because the main camera switch has to be On as well as the grip for the camera to function a small amount of power is used from the main camera battery so it's not stored fully charged. Like others I seem to have more batteries than I need and don't take so many photos now. On the plus side the K-70 has a smaller battery so doesn't last as long as the K-3 size. Once a battery dies I'll replace it and because they seem long lasting theres time to pop money into the "Camera Fund" for the replacement.

I've got 1 Pentax original, 1 Maximafoto and two Energiser which go straight into the charger on exchange for a fresh one out of rotation storage in my desk drawer (freshly charged to the back of the line up). None has ever given any problem on the K5. Now I have the K3 I got a new battery with it which I have left wrapped in the drawer. Perhaps it ought to join the line up?
With ordinary AAs for the *1stDS I keep a set of Eneloop and a set of Duracell but always remove them from the camera when I'm done with it as it will discharge them in a couple of days. I charge these when the camera indicator shows the first sign of discharge.

Always charged, ready to use. Still have and use the original K7 battery. Third party replacements are so cheap and good that short of the 'recycling' aspect; not really fussed if one was to die on me prematurely. It is yet to happen though.