Cell phone battery charging surprise

Hi folks,

thought i'd report an interesting and maybe useful observation.

like many here i like to "play"..i recently converted a mains 24 hour timer to a one hour (actually 45 minute) timer with set points of 50 seconds each...but not the point of this post.

after changing the mechanical gear ratio and re-assembling the timer i found myself looking for something to plug in to it to give it a run. ended up finding an old Nokia cell phone and charging adapter. this phone battery was "dead".. has been several years since i gave up on it as the battery would not charge AT ALL..anyway i pluged it in just so i could hear the beep of it going on/off every other 50 second cycle to know from the next room that my timer was working.

well after two days on the timed charger the darn thing (3.6v Ni-MH) seems to have recharged and is holding a charge! anyone think it was the start/stop of the recharging that did it? or perhaps the long period of dormancy? or something else?

dave

[Gotwind Ben]

Here is an official very technical Nokia PDF on the latest 2mm pin diameter charging Interface specification.
The older 3.5mm pin connector would be similar I suspect.

It opens as a download rather than a link - safe enough.
It may answer your question Dave, quite interesting, well for me anyway :)

http://sw.nokia.com/id/3378ff2b-4016-42 ... 1_2_en.pdf

Ouch! That was some rough sledding there. lot's of that was over my head (well o.k. most of it) but it may be that the start of each of the charge cycles was able to get us into the charge "box" if only briefly on each trip and the off time keeps us out of thermal trouble?

have not had a chance to try to charge it in a normal fashion yet as it still has a charge! :D

currently attempting a pair of AA's that should have gone to the reclaimer long ago.


cheers, dave <-who is afraid to throw anything away..


p.s. thanks for that pdf ben, i may have come away with a few bits that will stick and good dose of humility. :oops:

Sometimes batteries can be so low that they pull enough juice to trip the charger out after a few seconds. If yours was doing this but was going on and off all the time it may have put just enough in to start it charging properly again. :?

thanks guys,

shawn may be on to a plausible theory, -kind of tricking the charger into working.

we lasted just over three days on stand by..used to go close to a week. but still not bad at all. we have since charged it back up in the regular manner without issues.

no luck at all with the AA's, they would not budge :(

..i still can't bring myself to get rid of them though. :roll:

dave

Dave, I have been using a 1.8 watt solar panel to charge sets of 8 AA's in series. So far it's been performing great in that the batteries charge in a day or two with about 4 hours a day of good sun inside the house on a SW facing window ledge.

I have yet to feel the difference in battery temperature compared to room temperature although I am sure the charging batteries are a few degrees warmer anyhow. I have left sets of batteries charging for days on end with no ill effects so far.

The same panel shown here...

http://www.4lots.com/browseproducts/Bat ... arger.html

I got it on sale for about $10 at Canadian Tire (something like your Harbor Freight I believe?) about 20 years ago. On a cold winter day that little panel can make your car battery act like it's about 10F warmer than the actual temperature outside. I don't think the panel owes me anything any more. :lol:

thanks guys,

no luck at all with the AA's, they would not budge :(

..i still can't bring myself to get rid of them though. :roll:

dave

Google "Spark the whiskers nicd".
G-

BW, looks like you have a nice match with that module and 8 AA's. sounds like about ~100 to ~125 mA max charge for a few hours a day... the finger test can sometimes beat a briefcase full of meters, depending on who is holding them :lol: and holy cats! 20 years from a HF/CT module.

G, was aware of the ni-cd zapping but first i have seen of folks using the tecnique on Ni-MH? cool- worth a shot, and i get to make some sparks! (on purpose this time) :lol:

dave

I was unaware of nicd "zapping". I happen to have several 18V battery packs that are for all intents and purposes "dead"; I will certainly give this a try! I will likely go the capacitor route and leave the welders and other large current sources out of the loop. Call me chicken.

Thanks!

Fish