Some updates!

I just bought 6 different BL-5J batteries So I have "meat" to feed my developing charger without blowing up the good original battery.

BUT, I'm having soma strange behaviour with some of the FAKE batteries:

When they are charger and left on the bench they became sensibly... COLD!!

Really!

A discharged fake battery is at room temperature (the table is wood).

The orginal nokia battery, charged or discharged is at room temperature.

A CHARGED fake battery is sensibly COLD.. I'll try to read the temperature in some way, but at the touch it'ws definately colder than anything else laying on the table.

Weird issue!

As a note, I noticed their lower temperature also when charging, but I was thinking at some thermal reaction of Lithium (still documenting).

I know NI-CD become hot during charge (and hotter at the end of charge) and Ni-Mh become slighty colder during recharge (they absorb heat during recharge as reaction).

Let me know if anybody experienced some of this (expecially dr_frost_dk).

Thanks for that

Well i will say from my experience that Li-Ion & LiPo battery's get hot when charged "Hard"/fast, and just a little hotter then room temp when charging below 1C, but it is so little that you almost need measuring equipment (temp) to detect it.

An infrared thermometer could be able to measure the temperature..

Nimh also gets warm, most notably towards end of charge.

In general, the internal resistance of batteries causes heating both on charge and discharge.

lol I dunno, cold fusion?

I've never heard of anything on this planet that gets cold when you give it energy. You can make one part hot and one part cold but you can't make the whole thing colder, that defies the laws of thermodynamics. You're gonna be rich with this invention.

Ever thought about monitoring the charging process by the phone itself?

Is it possible? What is needed?

Ok, I'm assembling a quick and dirty temp sensor with an LM35, a PIC and a display, this would solve the mistery.

But, I can *triple* assure you that, among 7-8 batteries I have, when they are left in upright position, on the table, one against each other, with no special events affecting the room and all the other initial conditions we might discuss here.. well, one of the (fake) fully charged battery IS colder than the others!

I have a peltier cell, a small one, when I power it up with a 9V battery I can feel one side sligtly colder, and the other a little hotter, nothing serious, well, that's the feeling - it's a subtle reaction.

Also, I say "colder than" like the fakes are "lighter than" the original.. and you can feel holding the original against a fake.

I know! Either it's free energy............... (but I'm not a believer) or, as I suspect, it is internally eating itself (the voltage remains relatively high at 4.13).

I know, before doing the experiment there are a lot of factors that could get in the way of the experiment:

_ I could put in the fridge the battery, then later take it's temperature (..)
_ I could alter the video documenting the issue (..)
_ There could be really a colder spot on the table
_ The temp sensor, on the suspected battery (by chance), will not make full contact thus falsifing the reading..

.. and many more! I don't have a lab and controlled environment.. nor an independent observer..

But I'll do my best to solve the mistery!

P.S. If you don't see me anymore on the forum.. it means I'm heading to China, buying the factory that made "that" cell

At first you could read the voltage applyed on the battery, just make contact with the internal pins of the battery - Nokia charger at the end of charge is applying a pulse charge profile.

Not yet checked the current.

Gosh!

And it's a portable-battery-powered one!!

In my room!! that would be the nerdiest thing ever happened!! I can forget the story of the talking frog so

P.S. That was an engineering joke

To get back in the topic, about the charger.

I put an objctive: NO fancy ICs. The one I mentioned at the beginning, the Maxim one, fully integrated, automatic cycles, 5 pin to solder.. puah! too easy..

Super current sensing? ideal constant current source? bla bla bla... can't afford!! Everything must be made from scraps/low grade parts, this is the first goal of the design (dot).

..even if I found that assembling such charger from common components.. is somewhat a mess

And for common, I mean pnp are already too exotic

No well, I just don't feel I want to BUY new components just like that - living outside the city leads to expensive shipping cost AND it's not yet the time to make a cumulative order.

I decided the charge current to be 500mA, and I don't have a pnp able to handle currents of that size so this takes out grounded load solutions - but I don't want to tell you all about the details now

Using poor parts, it works, oh really.. the circuit is crude and Spice got to solve the simulation using the "alternate solver" cause the standard one was stalling :\

I'll test all the parts of the charger, one by one, but they should work just fine together!