Short answer: a 950mAh LP-E17 that will sit unused should be stored at four to six tenths of charge, at 15-25°C, and topped up every three to six months. Charging it fully before putting it away is the most common mistake: at a full charge the cathode sits at a high potential, side reactions are more active, and a few months of that can cost more capacity than a year of normal use. Storing it completely flat is just as bad, because a deep over-discharge can kill the battery outright.
The 950mAh sits in the middle of the three tiers, neither small nor large, which makes it the easiest to forget: it is not carried as a casual spare like the 750mAh, nor used daily as a primary like the 1050mAh, so it often sits for six months at a time. This tier needs a clear set of storage rules more than the others.
Why four to six tenths and not full
A lithium-ion battery is most stable at a moderate state of charge. At a high charge the cathode material is strongly oxidizing, side reactions with the electrolyte run faster and the SEI layer thickens sooner. At a low charge the anode potential rises, the copper current collector is at risk of dissolving, and an over-discharged battery may never charge again.
Four to six tenths is the balance point between those two risks. You do not need to be precise: two bars on the camera gauge, where full is three or four, lands roughly in that range, or you can pull the battery off the dock partway through a charge. Approximate is fine.
Temperature matters as much as charge level. Side reactions accelerate noticeably in the heat, so keep batteries away from balconies, radiators, cars and anything that runs warm. Dry, dark and 15-25°C is ideal.
How often to top up
Self-discharge in a lithium-ion battery typically runs at 2-5% a month, and the protection board’s quiescent draw adds a little more. At that rate, going from five tenths down to below two tenths takes roughly three to six months, which is where the top-up interval comes from.
| Planned storage | Starting charge | Top-up interval |
|---|---|---|
| One to three months | About five tenths | Usually none; check once before use |
| Three to six months | About five tenths | One top-up midway |
| Six months to a year | About five tenths | Every three to four months |
| Over a year | About five tenths | Check every three months, restore to five tenths |
A top-up does not mean a full charge. Take the battery off at around halfway and put it back into storage; charging it fully every time recreates the harmful full-charge state. If your dock has no way to stop partway, timing it with a watch gives a close enough estimate.
A storage routine you can follow as written
- Clean the contacts. Wipe the metal contacts on the battery and in the body with a dry soft cloth to remove fingerprints and oxidation. Do not use much alcohol and do not scrape.
- Set the charge level. Bring the battery to four to six tenths. If it is already full, fit it in the body and run it down for a while, or shoot a few dozen frames.
- Take it out of the body. Do not leave it in the camera long term. Even switched off, a body draws a little, which can drag a battery into over-discharge, and the battery compartment is also where moisture collects.
- Store it separately. Use the original box or a battery case with dividers, and keep it away from keys, coins and metal fittings to prevent a short across the contacts.
- Choose the place. Cool, dry and dark, away from heat. A small sachet of desiccant in the case helps, especially in a humid season.
- Set a reminder. Put a date three months out in the calendar to check the charge and restore it to five tenths. This step is the easiest to skip and the one that decides the outcome.
If you store several batteries, label each one with the date it went in and its charge at the time, so the next retrieval needs no guesswork. That habit pays off most for anyone mixing capacities.
Three common mistakes
Mistake one: the fridge will extend life. Not advisable. A domestic fridge is humid, condensation forms on the battery as you take it out, and moisture working into the case seams adds risk. Repeated temperature swings also increase internal stress. A cool spot at room temperature is enough.
Mistake two: charge it full so it is ready next time. Convenient, but it accelerates aging. If you really need a battery that is ready at any moment, keep one emergency battery full and store the rest at five tenths, accepting that the emergency battery will have a shorter life.
Mistake three: leaving the battery in the camera counts as storing it. A camera is not a storage box. Removing the battery when the camera is not in use is basic practice, as the LP-E17 overview also notes. Fit the battery compartment cover afterwards to keep dust out.
One more point: if a battery swells, smells odd or becomes unusually hot during storage, do not charge it and do not keep it. Dispose of it under your local electronic waste rules. This is uncommon, but there is no recovery once it happens.
When you bring a battery back into use after several months, check first that the case is flat, then charge it on the dock and watch whether the process behaves normally. On the first use after a full charge the runtime may come in slightly below what you remember; that is usually a normal dormant state, and two or three full cycles bring it back close to where it was.
If it is still clearly short after two or three cycles, that is genuine degradation. Use the method for judging capacity fade as a reference, or check the capacity and compatibility guide to decide whether a replacement is due. For this tier, allow some margin on the first two shoots after a long rest and avoid scheduling anything that cannot be interrupted.
FAQ
How often does a stored 950mAh need a top-up?
Usually every three to six months, depending on storage temperature. Warmer storage means faster self-discharge, so in summer shorten it to three months; in a stable cool place four months is fine. Top up to five tenths, not to full.
Can long storage ruin a battery?
It can, but it is usually avoidable. The real risks are the two extremes: sitting fully charged for months, or sitting fully discharged for months. Kept at four to six tenths and checked regularly, most batteries lose very little capacity over a year. Left completely flat and never recharged, a battery may never come back.
Can I store batteries in the camera bag?
Yes, with two conditions: the batteries come out of the body, and each one goes in its own case or pouch. A camera bag is not sealed, so add desiccant in the humid season and avoid leaving the bag on the floor or against an outside wall.
Should I drain a battery before storing it?
No, that is a habit from the nickel-cadmium era. Lithium-ion batteries have no memory effect, and draining one only adds over-discharge risk. The goal before storage is a middle charge, not zero.