Refreshing Ni-MH Batteries

[sdemetri]

My very limited understanding of how batteries work is that when they get older the internal resistance increases. When resistance becomes so great to not allow a sufficient flow of electrons and deliver the promised voltage, the battery is ready to be recycled. Does this internal resistance present a problem when refreshing the battery, or does the discharge cycle not even see this effect?

We have some older Canon Ni-MH batteries, for our 1Ds Mark II's, that I suspect are ready for the recycle bin...they don't hold a charge for nearly the number of exposures they use to... which is not surprising, but they seem to take an inordinate amount of time to refresh when I do refresh and recharge them. Anyone have any insights on this?

[NYRich]

My very limited understanding of how batteries work is that when they get older the internal resistance increases. When resistance becomes so great to not allow a sufficient flow of electrons and deliver the promised voltage, the battery is ready to be recycled. Does this internal resistance present a problem when refreshing the battery, or does the discharge cycle not even see this effect?

We have some older Canon Ni-MH batteries, for our 1Ds Mark II's, that I suspect are ready for the recycle bin...they don't hold a charge for nearly the number of exposures they use to... which is not surprising, but they seem to take an inordinate amount of time to refresh when I do refresh and recharge them. Anyone have any insights on this?
[a href=\"index.php?act=findpost&pid=107752\"][{POST_SNAPBACK}][/a]

I'm not an expert either, but I do use NIMH AA batteries quite a bit. Not the same size that you use in your 1Ds Mark II, but NIMH is NIMH.

What I've found is that once the batteries no longer hold the same charge that they originally did, or after a long period of non-use, they need to be "re-conditioned".

I use Powerex batteries and chargers which allow for this by fully discharging the batteries and recharging them at the push of a button. At times, it's neccessary to go through 2 or 3 cycles to attain a full charge, but they do charge fully after that.

There does come a point when nothing will help. That's when it's time to recycle the batteries and buy new ones.

I'm not sure if Canon chargers work the same way as Powerex. If they do, then you already know all this.

[sdemetri]

Thanks, Rich.

That is how the Canon chargers work as well. There is a "refresh" button to activate to discharge the remaining charge before the charging cycle starts up. I plugged two older batteries in yesterday morning around 9:00 am to discharge them... at 5:00 they were still in the refresh cycle. They took a charge when I stopped that and simply recharged them, but I am suspecting they are ready for retirement.

[francois]

Thanks, Rich.

That is how the Canon chargers work as well. There is a "refresh" button to activate to discharge the remaining charge before the charging cycle starts up. I plugged two older batteries in yesterday morning around 9:00 am to discharge them... at 5:00 they were still in the refresh cycle. They took a charge when I stopped that and simply recharged them, but I am suspecting they are ready for retirement.
[{POST_SNAPBACK}][/a]

I'm not a battery expert or genius but you might find some useful info [a href=\"http://www.batteryuniversity.com/]here[/url].

[boku]

I know this sounds crazy, but in the old days of NiCad, batteries could be refreshed by hitting them onto a hard surface with a snap. It dislodged gas bubble inside, no kidding.

I saved a lot of Honeywell Strobonar NiCads this way.

[larryg]

I know this sounds crazy, but in the old days of NiCad, batteries could be refreshed by hitting them onto a hard surface with a snap. It dislodged gas bubble inside, no kidding.

I saved a lot of Honeywell Strobonar NiCads this way.
[a href=\"index.php?act=findpost&pid=107874\"][{POST_SNAPBACK}][/a]

Isn't that what you do with your camera when the images aren't working or even the computer that gives you fits.  A good nokkin  does wonders, or not

[Jack Varney]

"I know this sounds crazy, but in the old days of NiCad, batteries could be refreshed by hitting them onto a hard surface with a snap. It dislodged gas bubble inside, no kidding."

I know this works because my wife has used the technique on me several times.

Seriously, I have read, on woodworking forums, that the cells can sometimes be restored by freezing for twelve hours and then recharging. I have tried this once without success.

Actually the combination treatment, not unlke the wife prescription, may work. Hit him up side of the head and put him in the deep freeze over night. Works for her.

[NYRich]

I'm not a battery expert or genius but you might find some useful info here.
[a href=\"index.php?act=findpost&pid=107873\"][{POST_SNAPBACK}][/a]

Francois,

That's for the link. There's a lot of useful information there.

[francois]

Francois,

That's for the link. There's a lot of useful information there.
[a href=\"index.php?act=findpost&pid=108055\"][{POST_SNAPBACK}][/a]

Glad you find it useful.

[Ron Steinberg]

Thanks, Rich.

That is how the Canon chargers work as well. There is a "refresh" button to activate to discharge the remaining charge before the charging cycle starts up. I plugged two older batteries in yesterday morning around 9:00 am to discharge them... at 5:00 they were still in the refresh cycle. They took a charge when I stopped that and simply recharged them, but I am suspecting they are ready for retirement.
[a href=\"index.php?act=findpost&pid=107857\"][{POST_SNAPBACK}][/a]

It is not unusual for a SINGLE Canon battery to take up to 12 hours to refresh, so two of them would take quite a bit longer. It all depends on how much charge is left in them. I would suggest you put them on refresh overnight and let the complete discharge/charge cycle complete, only way of really knowing if they will still hold a decent charge.

Ron