battery chargers

I assume that the charger is designed for your battery type?

The chargers commonly available are quite simple devices so I'd be more inclined not to believe a green led on them... Are you sure the battery is a good one? and if so is it one of the type that have a built in charging regulator in it?

I don't like those so called green / red leds.... I wouldn't believe them unless it had proved to my satisfaction it was correct... I'm an analogue designer so I don't like digital red / green indicators!!

John.

yes , the charger is designed for our kind of battery and its a good, in fact we tried with 50 odd batteries and chargers and they all seem to have same kind of pblm. yes it does have a charging regulator.

Electroman,

Don't you know that analog is so un-cool?

Except for people that really want to know what is going on.

People come aboard my boat and look at the dash and all the gauges for the twin engines and always remark that my gages are all all messed up, turned in all different directions except straight up. Most of them blush when I start the engines and when they come up to operating temp and all needles are pointing straight up. I learned this trick at NASA.

Ahhhhh you sound like a man of the same faith as me.... who cares about 1s and 0s its all the fiddly noisey bits inbetween which are interesting....

I luuuurve analogue electronics..... John.

Perfect and simple, a single quick glance shows if something is wrong!!!

......or everything AOK!

Sounds like a memory effect problem. However...

A friend of mine had a similar problem and I told him that it might be due to the memory effect (showing my age here). Then he said that Li-Ion batteries don't have the memory effect.

Really? I checked and found that he was right. I checked a lot of references and Wiki has a good summary of everything that I've learned so far.

Li-Ion

Depending on the age and storage/operating temperature of your battery, it may deteriorate rather quickly.

About the LED thing, my only gripe with it is that they used two color LEDs on my cellphone charger, Red/Green. Being colorblind, I have trouble telling whether my batteries are finished charging or not. I'm planning to change it to two LEDs, one for "charging" and one for "done".

I thought I'd heard that more advanced batteries (as opposed to the older NiCd) can enjoy the opposite memory effect. I may be wrong but is it possible that aftera few charges from new, the capacity of Lithium ion batts increases?

Perhaps that's gibberish.

We use a similar Li-Ion battery in one of our pieces of equipment. The battery charger IC we use wil provide a "full charge" indicator at somewhere in the 75-90% capacity range. To get to 100%, you would need to leave it charging some additional time. There is a "end of charge cycle" output on the IC as well, and from what I remember, it could be over an hour from the time the "full charge" LED would light, to the time the "end of charge cycle" would go. The last part of the charging is called the float charge, because you've already made it back to the batteries nominal voltage, but there is still room to cram a few more electrons in there, they just don't go in as fast as the first 75-90%. Most chargers are set up this way because most users are more interested in "when can I use this thing?", not "have you gotten every last electron you're going to get?". Have you tried to leave it on the charger a few more hours to see what you get?

None of what I've said takes into account what method you are using for low-voltage cutoff, this can make a big difference as well. This is the point where the smarts of the battery say "you're not getting any more out of me until you charge me". This point can be controlled by different methods as well. You need to look at all the information available before you can say with any certainty who is causing your short run-time. Sometimes, "smart" batteries don't seem to live up to their name

Tom

Since we are all brainstorming this issue, I'll add my 2 cents worth. If the battery was used in a situation that rapidly drew down the battery it may have warmed up in that process. When recharging a warm battery, the charging characteristics for the battery charger may be different.

For example, when I used my portable screw gun to drive some 70 odd 3" screws into wood the battery (not a li-ion battery) got very warm and was warm until the battery died. At that point I put it into the charger and the charger showed through the LEDs that it was charged (green) which was false. It wasn't for another 20 minutes till the battery cooled down that it switched to red (recognized the discharge) and started charging. I don't have any idea if this helps or not, just more info to cloud the issue. Perhaps the point is that there is more to charging batteries than meets the eye.

there is a right way of doing this with Li-ion, and there is a sure fire way of doing it wrong. I have used Li-ion for many yrs and if done wrong they will blow up. have enclosed a good read...http://www.batteryuniversity.com/print-partone-12.htm

You have received some good posts, in fact I think all of them were good, no bad ones at all, I hope you took the infos to heart.

The only points that I would like to make are the following:-

1) a good charger for such batteries should have more than a Red/Green LED to tell you whats going on. This charger is for me completely suspect. these are probably the most problematic cells to charge fully correctly of all cells available....

2) I personally feel that your trust in the charger is probably misplaced, get something better asap. A bad charger, will severely reduce the life of the batteries as a minimum....or worse.

3) As others have said, these batteries, incorrectly charged or used can blow up....this is not a fun thing to happen, especially if you are silly enough to do this charging/using without at least eye protection....

I have the impression (you writing to CR4 for instance for help) that battery charging is not quite your speciality, I would in your position, read all I could find on this subject asap....

I know Lead Acid chargers very well, I have even built chargers for Lead Acid and for Nicad and NIMH. I wanted to re-use some Li-Ons, but after reading about them, I put them in the battery disposal - as they are just not for amateurs....

i accept ANDY... thnx for ur suggestion

No problem, have a great day....