NiMH batteries and chargers

klr.b wrote in post #10455115
of course! i stock up on eneloops and now there's a newer and better one coming out.

3 years! that's crazy.

Well, why not, the same thing happens with our camera bodies. Sooner than I bought my 40D, the 50D came out with its tongue out to mock me... However, no need to despair.... Having 500 extra recharge life comes with price, after all. I for one have a long way to go to recharge my eneloops 1,000 times and see their natural death, as it is. Now, the rate of initially impressive LSD rate of 3 years? Hmm... unless you have the need of the sleeping beauty who, upon waking up after a year or two of being soundly asleep, and start shooting pictures of her photogenic prince, I think just a year of LSD rate would more than suffice for just about everyone else's normal needs.

I'd have been more impressed if Sanyo came up with the exact same rate of LSD as the original but at much higher mAh. That would cause me to despair...

I think Ansmann are getting close with their MaxE Plus AA 2500mah battery, if the advertising is right.

http://www.ansmann.de …mh/maxe-accu-battery.html

Purely by accident, I'm currently using some 1.5V Lithium disposables in my new 580 EXii and I was struck by how fast it recycles! Got me to thinking.

Here's an interesting point. Ni-MH AA batteries are only 1.2V. Alkaline and Lithium AA are 1.5 volts. The Canon 580EX ii specs rates the refresh rates using alkaline batteries.

I realize disposable batteries pose an environmental (and pocket-book) un-friendliness but do we sacrifice a little on flash recycle speed? Wikipedia mentions that some devices don't even support 1.2V AA battery use. Canon's flash specs do, but it doesn't go into details.

If this is all true; I'd like to see NiMH AA batteries available at 1.5V at some future date.

Also; the mAh rating system is skewed by the voltage. So; it's not exactly a "gas gauge". For example; a 9V NiMH rechargable may "only" retain 300 mAh but that's actually nearly the same energy as a 1.2V AA that's holding 2000 mAh. Well; maybe it is a "gas gauge" but the 9V is like a truck and the Alkaline/Lithium AA is like a big American SUV, where the NiMH is more of a European sports car (and incapable of towing a camper, let's say).

So; the mAh ratings on Alkaline and Lithium are not directly comparable to NiMH mAh numbers without doing some conversion.

Here is a nice 3 stage review on AA batteries

http://wolfeyes.com.au​/news/?p=6

the test after 3 mths is a third of a way down this page

http://wolfeyes.com.au​/news/?cat=5

NBEast wrote in post #10456547
Purely by accident, I'm currently using some 1.5V Lithium disposables in my new 580 EXii and I was struck by how fast it recycles! Got me to thinking.

Here's an interesting point. Ni-MH AA batteries are only 1.2V. Alkaline and Lithium AA are 1.5 volts. The Canon 580EX ii specs rates the refresh rates using alkaline batteries.

I realize disposable batteries pose an environmental (and pocket-book) un-friendliness but do we sacrifice a little on flash recycle speed? Wikipedia mentions that some devices don't even support 1.2V AA battery use. Canon's flash specs do, but it doesn't go into details.

If this is all true; I'd like to see NiMH AA batteries available at 1.5V at some future date.

Also; the mAh rating system is skewed by the voltage. So; it's not exactly a "gas gauge". For example; a 9V NiMH rechargable may "only" retain 300 mAh but that's actually nearly the same energy as a 1.2V AA that's holding 2000 mAh. Well; maybe it is a "gas gauge" but the 9V is like a truck and the Alkaline/Lithium AA is like a big American SUV, where the NiMH is more of a European sports car (and incapable of towing a camper, let's say).

So; the mAh ratings on Alkaline and Lithium are not directly comparable to NiMH mAh numbers without doing some conversion.

Refresh rate isn't affected by the voltage as much as by the battery's ability to handle high current draw, and alkalines are terrible at that. Typically NiMH cells in a flash give you about 30% faster refresh than alkalines, and many manufacturers spec their flashes with both. The only advantage to alkalines over 1.2V NiMH is a longer life under use. And you won't see 1.5V NiMH because the chemistry is wrong for that voltage level.

Waking this old thread to life again..

I recived my C800S charger today, and I have 4 probably crap 2400mAh NiMH's.. However, reading loads about NiMH's and how to take care of them I decided on this charger due to the low charge rate and other features.

So there I go, popping one of the 4 batteries in, pressing the conditioning button, pop the rest in and watch the magic happen.. So far so good, after an hour I checked up on it and touched the batteries and they were really hot.. Barely touchable for more than a second. After all my reading I thought to my self, "well this can't be good".

So here I am, with a rather expensive charger that makes my batteries hot. It should be mentioned that it's only the last 10-20% of charge time they get really hot.

I got some eneloops coming in tomorrow I think, now the question is.. Should I just go on and feel comfortable with this charge-temperature? Should I return the charger? Also, is it possible to do the soft and conditioning at the same time to reduce the heat?

Wow.. Never thought charging normal batteries could be such a science.. The camera batteries just pop in and gets charged :P

How old were the batteries? NiMH dies from old age as well. If you can still touch them, they are not all that hot. I think they can be charged/discharged at low currents to something like 45C.

J.

JohnJ80 wrote in post #13026744
How old were the batteries? NiMH dies from old age as well. If you can still touch them, they are not all that hot. I think they can be charged/discharged at low currents to something like 45C.

J.

I don't know really.. They came with a flashgun and says "Tdi 2400 mAh Made in china", blue/silverish color.. No package at all. However, this was the first time I charged them (conditioning to be correct).

Well I guess maybe I'm just paranoid from all the reading.

Well, if they are getting that hot, it means that either they are being charged improperly or they have a high internal resistance. If they have a high internal resistance, they are probably either old or crap batteries. Either way, I'd get rid of them and use good batteries.

NiMH batteries typically don't have much, if any, memory to them. The only reason to charge and discharge them is to get them set when they are brand new. Truthfully, I just don't worry about it and let them charge and discharge in normal usage.

The Eneloops are fantastic.

J.

Thanks alot.. I'll give it a shot with the Eneloops, it might just be crap batteries and that's why they got so hot.

I hate it, there's always something to get worried about when you get something new ^^

true story.

J.

Allrigt, got my eneloops (2010-12 stamped) and put 8 to a recycle charge + soft mode.. With the other, probably cheapo batteries it took about 6h for a full recycle charge to be done.. With the eneloops (in soft mode) it took no less than 26 (!!!) hours. So I guess there are some difference after all. I don't feel the eneloops getting that hot either, but the recycle with the cheapos wasn't in "soft mode" so I guess that has it's impact too. Just wanted to share this if someone searches and find this thread later on.