Electronics, Lighting, & Gadgets - what's the deal on battery charging?

Got myself a Lacrosse charger and am now confused. The manual is seriously lacking by the way. Especially with someone as ignorant as me on the subject.

Anyway, I went to the battery university web site and found a contradicition and wanted the low down.

It says that you should trickle charge new nickel based batteries prior to use but later it says that it is difficult if not impossible to slow charge a nickel metal hydride battery. Am I missing something?

i got a lacrosse charger and, between the manual an unintuitive interface on the unit, i'd say i'm a pretty confused puppy as well.

I can tell you how the C-9000 does it for new batteries.

1) Discharge the battery fully, just to be sure. If it's not a low self discharge battery, it will probably only have a 10% state of charge anyway, so this happens very quickly.
2) Put the battery in the charger and enter the battery capacity. It can then charge at 0.1C on a timer to what should equal the full capacity.

The key there is having a mode where you can enter the capacity of the cell and let it charge to that capacity. For example, say I buy some brand new 800mAh AAA cells. I'd first use the discharge cycle to run them down to empty. Then, I'd put them in the charger and program the charger to see they are 800mAh cells. It then charges at 80mA for 15 hours on a timer. The reason it goes for 15 instead of 10 is because a huge amount of the energy is lost as heat when you charge that slowly.

Likewise, if you put a 2700 AA in there, you'd program it for 2700 and it would charge at 270mA for 15 hours. Same deal; the key to doing a slow charge is that it needs to be completely flat before you start followed by running on a timer since it's virtually impossible to detect the voltage change and temperature spike that you'd look for on a 0.6 to 1.0C charge rate.

I think the bottom line here is that if your charger can't do a timed charge, I'd personally just run the battery to 0.9V discharge to make sure it's flat, then charge at 0.5 or 0.6C rate, which is around the slowest rate that you can charge and reliably detect the voltage or temperature peak.

A .1c charge for 16 hours, a .2c discharge, and another .1c charge for 16 is a standard break in for a Ni-Mh battery. For some reason they respond well to a .1c charge, but the next highest charge you should use is .5c; between .2c and .4c things can get wacky and they can overcharge.

See CPF for lots more on the subject.

"It says that you should trickle charge new nickel based batteries prior to use but later it says that it is difficult if not impossible to slow charge a nickel metal hydride battery. Am I missing something? "

The battery university web site means that after you charge the new batteries (by whichever method you choose), to leave them in the charger (which will have switched over to trickle charge) for an additional 24 hours.

I can tell you how the C-9000 does it for new batteries.
enter the battery capacity

The Lacrosse won't let you enter battery capacity. Am I right? Or did I miss something on that too?

The Lacrosse won't let you enter battery capacity. Am I right? Or did I miss something on that too?

I think you are correct. The Maha is a much better charger.

The Maha is a much better charger.

Well, that doesn't help me much now. I got a nice buy on the Lacrosse and now I'll deal with it. Given the limitations of the charger I'm still trying to figure out how to proceed with the initial charge.

I think you folks need to act like I'm an elementary school student.

One post says give it a fast charge and let it continue to trickle charge for 24 hours. It seems I've also read that once a battery is charged, it's best to get it off the charger as soon as possible.

Well, that doesn't help me much now. I got a nice buy on the Lacrosse and now I'll deal with it. Given the limitations of the charger I'm still trying to figure out how to proceed with the initial charge.

I think you folks need to act like I'm an elementary school student.

One post says give it a fast charge and let it continue to trickle charge for 24 hours. It seems I've also read that once a battery is charged, it's best to get it off the charger as soon as possible.

Here are some threads from CPF which might help.

http://www.candlepowerforums.com/vb/showthread.php?t=121873

http://www.candlepowerforums.com/vb/showthread.php?t=148552

http://www.candlepowerforums.com/vb/showthread.php?t=103802

http://www.candlepowerforums.com/vb/showthread.php?t=112962

http://www.candlepowerforums.com/vb/showthread.php?t=100382

http://www.candlepowerforums.com/vb/showthread.php?t=129250

A .1c charge for 16 hours, a .2c discharge, and another .1c charge for 16 is a standard break in for a Ni-Mh battery. For some reason they respond well to a .1c charge, but the next highest charge you should use is .5c; between .2c and .4c things can get wacky and they can overcharge.

See CPF for lots more on the subject.

With the Lacrosse I can give it a .2c charge a .25c discharge followed by a .5c charge. How does that sound?

Maybe I should just throw the suckers in, fast charge em and be done with it. Does it really matter that much?

btw, thanks Ziemas. This was posted after I saw your links. That should take care of it.

yet another edit: I see that most of these links are telling me how crappy my charger is. :(

With the Lacrosse I can give it a .2c charge a .25c discharge followed by a .5c charge. How does that sound?

Maybe I should just throw the suckers in, fast charge em and be done with it. Does it really matter that much?

btw, thanks Ziemas. This was posted after I saw your links. That should take care of it.

As the Lacrosse has a nasty habit of melting it sounds like a bad idea to me.

As the Lacrosse has a nasty habit of melting it sounds like a bad idea to me.

So once again, let's say you have the Lacrosse, no other choice, how would you proceed. So far I've heard the Maha is better and the Lacrosse melts.

So once again, let's say you have the Lacrosse, no other choice, how would you proceed. So far I've heard the Maha is better and the Lacrosse melts.

Relax. Let's not go all studded tires again. ;)

I'm not sure how to proceed, but I do know what I wouldn't do, and that is charge the battery at less than .5c. The threads I gave you links to all deal with using the Lacrosse for an initial charge. They almost all deal with melting chargers too, so the two just might be related......

OK, thanks Z. :)

Uh, and "go all studded tires"? Are you serious? Z, you need to get a life if you remember a post of mine from a couple years ago! I barely remember it myself. :D

The version 32 was the one that melted down, the version 33 is supposed to have fixed that problem. You should have the version 33 if you bought yours recently, the display for the 4th battery will indicate which version you have when it's powered up.

The instructions don't explain things very well, do they? I figured they meant to use the 200 ma (default) setting for the current with the discharge refresh cycle for maximum life for new cells. It's still charging the AAs that came with the one I just bought, so I can't tell you if that works best or not.

The version 32 was the one that melted down, the version 33 is supposed to have fixed that problem. You should have the version 33 if you bought yours recently, the display for the 4th battery will indicate which version you have when it's powered up.

The instructions don't explain things very well, do they? I figured they meant to use the 200 ma (default) setting for the current with the discharge refresh cycle for maximum life for new cells. It's still charging the AAs that came with the one I just bought, so I can't tell you if that works best or not.

I do have version 33 and you are very right about the poor explanations. They apparently assume that anyone who buys it has some knowledge of batteries and charging. Not me. :o

There have been reports of V33 melting too.

I have the "33" and it has always worked fine for me. At first I put a lot of thought into discharge cycles and charge rates and such. Now I just put the batteries in and let them charge. When I need them I pull them out. I don't believe it is necessary to overthink this. It may be the case that I don't get as much life out of a battery as someone who pays more attention to the details but I have no complaints. My guess is that the differences are small.

the display for the 4th battery will indicate which version you have when it's powered up.Thanks for the tip. I bought my Lacrosse BC-900 charger recently and it is indeed a Ver. 33.:)

I have the "33" and it has always worked fine for me. At first I put a lot of thought into discharge cycles and charge rates and such. Now I just put the batteries in and let them charge. When I need them I pull them out. I don't believe it is necessary to overthink this. It may be the case that I don't get as much life out of a battery as someone who pays more attention to the details but I have no complaints. My guess is that the differences are small.Mine works well too.

I have the "33" and it has always worked fine for me. At first I put a lot of thought into discharge cycles and charge rates and such. Now I just put the batteries in and let them charge. When I need them I pull them out. I don't believe it is necessary to overthink this. It may be the case that I don't get as much life out of a battery as someone who pays more attention to the details but I have no complaints. My guess is that the differences are small.

You are probably right and that is precisely what I have been doing so far as well. I just thought I might give a try at doing what is recommended for new Nimh that I just got.