Is it bad to drain batteries to the limit?

Chomeur

I bought a Canon EOS 700D camera in China a few months ago and the battery started not charging a few weeks ago, while I was in Madagascar. I was completely unable to charge the battery. I took it into a big Canon store in Antananarivo and they refused to help. They had no other batteries in stock and wouldn't let me try to recharge my battery using a charger that they had in a box with a new camera, even though there was no seal on this. They said I needed to go back to where I bought the camera in China. So much for the "Canon Warranty" that Canon promote widely.

Anyway it seems finally that the problem is with the battery, not the charger, and I now have a new battery. I did drain the old battery very fully before it failed to charge, i.e. it ran out, then I took it out of the camera, shook it a bit, and put it back in and got a couple more photos. Is that a bad thing to do?

Nodding_Donkey

If you drain a lithium ion battery below a certain level you won't be able to charge it again.

grumbler

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries says that the number of cycles drops dramatically with increase of the depth of discharge, but is still 300-500 for 100% depth of discharge. My understanding is that full discharge is harmful, but doesn't kill the battery.

Re the "Canon Warranty", I don't think that the one you have is worldwide.

esuhl

With lithium-ion batteries, if you discharge them below a certain amount, the internal resistance when recharging will become so high that the cells could explode. Also, they can be damaged and explode by overcharging.

Consumer devices (that aren't dodgy Chinese imports!) have a charging circuit that will prevent the battery from charging if the charge becomes too low or too high. So when they become "flat" and no longer work, you haven't actually fully discharged them.

If you're storing batteries, you want to make sure they have enough charge that they won't drop below the minimum safe amount. Also, storing them fully charged will cause them to deteriorate (causing a reduction in total capacity) more quickly.

Chomeur wrote: »

I did drain the old battery very fully before it failed to charge, i.e. it ran out, then I took it out of the camera, shook it a bit, and put it back in and got a couple more photos. Is that a bad thing to do?

It shouldn't be if the battery's charging circuitry is any good! The battery should refuse to work if it will be discharged too much, even if you try to get in a few sneaky extra shots before it dies. However, it's possible that poor design could mean that this damages the battery.

Otherwise, if the batteries were stored for a while before recharging, the charge might have dropped too much, preventing them from being subsequently recharged.

grumbler wrote: »

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries says that the number of cycles drops dramatically with increase of the depth of discharge, but is still 300-500 for 100% depth of discharge. My understanding is that full discharge is harmful, but doesn't kill the battery.

I think that the "wear" on a li-ion cell just depends on how much it's been charged/discharged overall. Fully discharging a cell will result in twice as much deterioration as if it had been 50% discharged. So I don't think you need to worry whether you fully or partially discharge the battery.

In fact, if you're wasting energy to make sure the battery is discharged before you charge it, you're unnecessarily making the battery wear out faster.

Chomeur

esuhl wrote: »

Consumer devices (that aren't dodgy Chinese imports!) have a charging circuit that will prevent the battery from charging if the charge becomes too low or too high. So when they become "flat" and no longer work, you haven't actually fully discharged them.

If you're storing batteries, you want to make sure they have enough charge that they won't drop below the minimum safe amount. Also, storing them fully charged will cause them to deteriorate (causing a reduction in total capacity) more quickly.



It shouldn't be if the battery's charging circuitry is any good! The battery should refuse to work if it will be discharged too much, even if you try to get in a few sneaky extra shots before it dies. However, it's possible that poor design could mean that this damages the battery.

Otherwise, if the batteries were stored for a while before recharging, the charge might have dropped too much, preventing them from being subsequently recharged.

Thanks. Even though I bought the camera in China I can't believe that the battery would have been a copy - it came with the camera, in the box. So perhaps it was just a dud. I only waited a few hours between it running out and first trying to recharge it.

Canon is supposed to be a very good brand, and obviously people travel a lot with their cameras, so I'm not impressed that their warranty isn't global.

The moral is probably to always take a spare battery in future.