|
Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
I bought days ago this cheap external battery charger (I have a 5800xm, BL-5J battery):
http://img197.imageshack.us/img197/7790/chargerm.th.jpg I think they are all the same, the price was right, 1.99 Gbp (inc shipping), and it is the only thing which is right with this unit. The quality is next to nothing: http://img848.imageshack.us/img848/2...7593934.th.jpg http://img98.imageshack.us/img98/726...2011120.th.jpg http://img27.imageshack.us/img27/333...2011122.th.jpg The screw was already broken, both two wire fell off as I opened the unit, the plastic assembly feels (is) very cheap. So, before letting it torture my batteries in a unspeakable way, I was wondering about it's regulation circuit.. so I opened it and took a couple of photos: http://img807.imageshack.us/img807/7...2011117.th.jpg http://img195.imageshack.us/img195/5...2011119.th.jpg I know that "reverse engineering" is not good, in some places this leads to bad things.. but with this cheap object, I think I can still sleep thigh in the night, so I tryed to trace back it's circuit: http://img714.imageshack.us/img714/8...entside.th.jpg http://img860.imageshack.us/img860/2368/wireside.th.jpg And produced this schema! http://img641.imageshack.us/img641/8428/circuits.th.png http://img641.imageshack.us/img641/8428/circuits.png (I inserted the full link to the image of the circuit, handy). Now.. Much work is still to be done, currently I have a terrible split-by-two headache, so I'm going to link the last file, is the archive with everything inside: _ images _ models _ datasheets _ circuit file (LTspice) Link --> http://www.megaupload.com/?d=7EYM531E <-- The circuit actually is simuable, it tends to a voltage of 4.4 circa. I do not know if it is right (the simulation!), I measured with a multimeter the output (before wires broke up) and it was around 4.2 - must check later. First thing to do is: 1. Verify traces and plotted circuit, the two images (PNGs - in the above archive) are overlappable, one of them is mirrored so it is easyer to check traces; can someone help me veryfing them? reports here all the suggestions, rights and wrongs. Then: 2. Find reliable substitutes for the original transistors or reliable models. 3. Find correct component value I'm 90% they are correct, there are some normal 4 band resistors, a couple of 5 bands resistors and one ceramic cap which reads "104" -->180pF? The very-very-very last step will be to... err.. improve the design :D Now, I must really go to sleep, aber I'll pass out :( I was inspired in making this post by a thread on replacements batteries BL-5J where battery capacity was verified - playing around this charger could be usefull to many people around here ;) See you later! |
Re: Chap external BL-5J (and other) battery charger: reverse engineering
I have the same style of unit but it has the micro usb connector - never tried it but I'm gona hook it up and see if the thing actually works. The ceramic cap value= 0.1uF
|
Re: Chap external BL-5J (and other) battery charger: reverse engineering
UPDATE I'm finding some errors in the circuit tracing, I'm working on the new schema, meanwhile I'm posting a new image of the back of the PCB without the pen marking.
http://img845.imageshack.us/img845/3...2011123.th.jpg Full size --> http://img845.imageshack.us/img845/3162/31052011123.jpg I found I included a wrong datasheet in the above archive on megaupload, the right one for transistor S8050 is: http://pdf1.alldatasheet.com/datashe...RON/S8050.html As soon as I have some satisfactory result I'll post a new archive :) |
Re: Chap external BL-5J (and other) battery charger: reverse engineering
All right, here are the latest news:
The latest circuit is this: http://img38.imageshack.us/img38/1665/circuit11.png Full size: http://img38.imageshack.us/img38/1665/circuit11.png I'm 90% confident it's correct and without big mistakes, even if I wish.. why? All right, simulating this we get some interesting results: http://img696.imageshack.us/img696/94/diag.png Open this in a new window: http://img696.imageshack.us/img696/94/diag.png As you can see from the graph, the upper pane, the current going into the RED led cut off when battery voltage reach 4.2, which is acceptable; so, when we put the battery in the charger, RED led turns on. When battery goes up to 4.2V the led turn OFF. Nice, uh? battery is full :cool: What is not so *nice* is the remaining current flowing into the battery past 4.2V: (bottom pane) there's still 64mA going! :confused: - at 4.3V battery voltage, mAmps are only 10 left.. but the charger is still pushig the voltage up to 4.4 circa. :eek: :eek: :eek: So, I'm in a good mood, and I want to see some fireworks happening! here's the setup ;) http://img707.imageshack.us/img707/1152/fireworkss.jpg I'll let you know, if I don't get too distracted at the computer, I'll keep a watchfull eye on that multimeter reading :rolleyes: Ka-boom? :D P.S. The battery, don't get confused by that hologram.. for 2.88$ I got it (shipping included) from eBay.. :D - so it's perfectly expendable. |
Re: Chap external BL-5J (and other) battery charger: reverse engineering
Quote:
Are you sure about the cap value? where you referring to yours or mine? |
Re: Chap external BL-5J (and other) battery charger: reverse engineering
Yours mate - I've not opened mine (yet).
The capacitance value is often marked using a 3 digit code. This works in the same way as resistor coding but using numbers instead of colours. The first 2 numbers give the value and the last number is the multiplier. These give the value in Picofarads (pF), e.g. code 103 = 1 0 000pF (=0.01uF). Alternatively the value may be marked directly, for example 2n2 is 2.2 Nanofarads (nF). |
Re: Chap external BL-5J (and other) battery charger: reverse engineering
Quote:
I'm finding an incredible number of errors in my diagram when I traced the circuit!! I must have been drunk in those last 3 days 'couse otherwise I should change hobby ;) Moreover, I found in my charger the red LED indicating the charge was going on and off every 5-10 minutes.. very odd. I should have found the cause: apart the bad solder job made on this board, one of the wires going to the battery terminals is burnt inside, the insulator is transparent, and is possible to see a black area.... I'll fix that, and other issue; meanwhile I'm correcting the diagram of the circuit inside LTspice and publish new finding - for now just assume the material linked is.. "terribly" wrong :( |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Howdy!
New update: revised and corrected schema, 98% sure it's right.. for now ;) http://img830.imageshack.us/img830/9210/schemax.th.png Full image What I still don't like, maybe I'm wrong, is the direct +5V connection to the emitter pin of the PNP transistor.. more than 80mA will flow out of it's base.. Then, removed all those cheap-burnt wires and put some more serious ones. Then applyed the charger to a test: a nice 1F@5.5V capacitor! the perfect battery replacement ;) http://img101.imageshack.us/img101/6...2011129.th.jpg And the charge was done in 5-10 seconds, topping up to 4.25V... uhmmm http://img694.imageshack.us/img694/6...2011131.th.jpg But I'll check again circuit tracing (other info are on the schematic). |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
I've got one of these too. Very pleased with it so far...but I'm intrigued if you found problems. I usually pull my batteries as soon as the led goes green though.
|
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Non-terminating chargers are rather common, and they do wear out batteries faster. Some would even consider them dangerous, though I think with this low rate trickle, it'd take quite some time for overcharge damage to accumulate (and it IS an accumulating damage).
How much extra would it have cost them to make the circuit "stop" once the "Done" led is triggered? Because that led is triggered at the correct stage in charging process :) |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Quote:
I'm working now in refining the circuit traces and perform some more testing :) |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Quote:
Yes, at battery voltage 4.2 it is still pushing 13mA - the battery is able to reach 4.22V (and beyoind) but I stopped the charge and did not yet measured the current. Charge current is slow though, limited by a 10ohm resistor; it starts at 180mAh and goes down in a strange way. The RED led goes off.. the control ciruit for it is a dirty PNP with the base connected to the input line for the current going to the battery. While the charge current decreases, the base voltage increases until it reach 4.3 - at that moment the PNP is slowly turned off, because base voltage must be 0.6V (depends on transistor model) less than Emitter voltage (which is connected to +5).. a dirty trick :\ The only good part, is the TL431, which safeguard the final battery voltage and block it from going over 4.25V by turning off the base of the final transistor. The first mod would be to half that 10ohm value, and thus increase the initial charging current. I'll also tweak the output network o lower the final voltage threshold to 4.22, which is more than reasonable - I might check the final voltage of the battery when charged by the original Nokia adapter. When the RED led is off, the battery is still far from being fully charged - mine the red led is dimming until you can see the red "dot" inside the green led. http://img4.imageshack.us/img4/6892/circuitx.png Full size Diagram If you need the schematic file to use in LTspice just drop me a private message - at now still I don't want to post it straight to the public, I don't feel satisfied yet (accuracy is somewhat random..). :rolleyes: |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
My cheapo RC-Charger i use for my phone is luckily good at shutting of at the limit of 4.23V, since you are new here you can check it out, link in my signature (the battery test one :D)
|
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Quote:
Did you post some schema/circuits? I've read the first posts, nice work with those batteries :D - I was thinking that the 5800 was subdimensioned respect it's battery, but sseing the N900 with the *same* one.. well, someone at Nokia played dirty :mad: However, before coming in hsi forum, I started collecting (so far) 5 fake BL-5J batteries, circa 2.5$ shipped from various eBay seller and trying them too. The charger was more for the curiosity, than real need. -- Back to the charger: the schema is cheap, components cheap, cables.. cheap! there's really nothing, up to now, to do to improve that charger.. at the moment I lowered the charge threshold from 4.25 to 4.22V and I'm feeling alredy safer now (I can "literally" go to sleep with that thing ON). To improve it.. that circuit is a lie in every part! it's almost impossible to hack it without loosing some functionality! the way even the RED led is connected, it helps the battery to charge.. and the "main line" where the charge should come, it's just used to provide little current to keep things running, but nothing more. I couldn't even hook to it some kind of current control, cause.. ther's no clear point of control :mad: There were at least a dozen ways to assemble it.. they did it in the worst possible way. At this point, either, I keep it "as is", or I start with a new design. Well.. to let the steam off (I'm frustated!) It just costed 2,3$ shipped :o |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Well im my thread post 1-3 are the most relevant, else i link to other mods etc.
----------------- And on the cheap charger i also link to a cheap DX 18650 charger which also like the one you submit goes a bit higher then it should, but it will take many hours before it will go critical (>4.23V) Generally speaking of cheap chargers they are all the same in the sense that they all do float charging in the end, and this is not generally good for Lithium battery's. But good work here on the circuit, there are other users here like you and me that makes electronic mods to accessory's or the N900 it self Like 'Wonko' with his modded wireless charging |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
The battery would be full when floating at 4.20V and current dropping to less than C/20.
|
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Quote:
So 3% of 1320mAh is 39mAh.. but this ""charger"" (double quotes needed) is arriving at 4.21V @ 3mA so so. ... .. . I'm already designing a custom charger :D |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Some other updates.
Before starting the design of a new charger (just for phun) I found a nice trick to pimp this charger. I was stuck in increasing the efficiency of the circuit given fixed the input voltage! With the charger, arrived also another cheap e disposable 5v adapter with usb port output, so I could charge batteries even without a computer. The v_output of the PSU was little disappointing, 5V when open circuit, 4V and something under load. :( A quick inspection of the internal circuit revealed a common technique of using a 5V1 Zener to stabilize the output to 5V.. BINGO - Applied immediately a dirty trick, not having a zener with nearly 6V of reverse voltage, I soldered in serie to the zener but, in reverse direction, a 1N4148 to get an additional .6~.8 reverse voltage barrier. So the output of the charger is at 6.1V open circuit, 4.9 someting under 100mA of load :D Now the charger has reached a satisfactory level of functionality. I should apply, more often, that "anything worth doing, is worth overdoing" rule ;) |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
so the charger you are making is also a "dumb" charger or is it a shut off when done "intelligent" charger?
|
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Quote:
I've read some suggestion here and there, nothing of professional but: _there are several IC that would already do the job, one over all the Microchip MCP73831/2 (http://ww1.microchip.com/downloads/e...Doc/21984e.pdf) - order, configure, solder-5-pins, plugs for cable --> done! But that would take out all the phun!!! Right now I'm deciding a current sensor, then a constant I/V source, finally I'll model something around a PIC, something like: _ check cell voltage, if below 3.6 charge at 100ma _ then constant current 500ma up to V=4.15 _ constant V_charge until I<40ma (3% of 1C). Basically that's all is needed; I'll add some other safety checks, some charge holding logic (connect the battery and forget it until use) and bells and whistels as the opportunity will dictate. ETA? ..none! :p |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Some updates!
I just bought 6 different BL-5J batteries :D 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!! :eek: Really! :confused: 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). |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Thanks for that :D
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. |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
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. |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Quote:
|
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
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.
|
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Ever thought about monitoring the charging process by the phone itself?
Is it possible? What is needed? |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Quote:
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 :D :D :D |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Quote:
Not yet checked the current. |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Quote:
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 :rolleyes: |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
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 :D 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 :cool: 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! ;) |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Charger il 97% done, I've lost some time with a differential amp with a soul on it's own, voltage trimming here and there and some issue with an old Lithium cell with an higher than expected resistance due to wearing that was causing trouble to the threashold system regulating chrge current.
At the moment the charger is: _ precondition the cell @50ma if voltage detected is lower than 3.4V _ Full charge current @500ma from 3.4v to 4.10v _ Top charge @150ma from 4.1v to 4.2v _ Finalize charge @50ma from 4.2v to 4.23v Actually I was measuring cell voltage when applying current, but it turned out to give only false reading, so now I'm modifying the structure of the code - but then I hit the memory limit of the PIC16F690... so now I'm back at optimizing code before continuing :\ Update: I was getting false reading of the voltage due to too high input resistance seen by the PIC, lowering it solved the main problem. Another issue is present here, the sensitivity: there's a 10bit ADC reading a 5V span: 5/1024 = 0,004mV step, so it's quite a guess distinguishing anything in between, 4,19..4,23 is a hit and miss job. Even with filtering, hardware and softeware, I end up slightly off target. |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
98% ready!
Here's the pic of it charging a standard cell, on the left, the grey thingh. http://img692.imageshack.us/img692/893/22072011154.jpg Full size The charger.. simply grew up on it's own.. and sure, it looks more complicated than it really is.. really! :D Add this, add that, fix, improve, expand.. wiring is also messy, never intended to be a final setup. The core is a PIC16F690 and the true charger is the program written for it; hardware consists of a Pic, couple of opamps, a power mosfet, a small power transistor, 2 power resistor, a differential amplifier, LM317, 7805 and a nice display ;) The battery is treated like a motor, push it from one side and discarge itselft, push it on the other side and you can charge; check voltages, check temperature and regulate current. I might pots a video of it.. or not, it's nothing special about it. The final pad for the battery will be that "black" thingh you see on the left side, near the LCD, it has embedded a LM35 to sense temp, and the battery will stay there when in charge. Code is 98% done, I've still to fine tune the mAh count when discharging, so I can know the true capacity of the various batteries. See you nexxxxt!:cool: |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
looks good, can you make a simple charge only with monitoring of battery voltage and no display.
Then i would make one myself. Not that i need chargers. |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Quote:
My charger seems big, ugly and with a lot of uneeded parts.. but they are are all essentials. Voltage monitoring is done via a differential amplifier, current sensing involves just a resistor and NO opamps. Current control allow me to run this circuit with voltage from 9 and up. Removing current sensing (removing 1 resistor) makes impossible for the PIC to know or limit the charge current.. Disaply again, is just wired to the PIC, I can remove it straight on, but then it's like flying in the fog :D :D :D It would be possible to remove discharge features, you'll save 1 transistor, 2 resistor and 2 caps.. again. You could remove temp sensing too, but it's the *only* safety external loops/barrier available, I wouldn't do ;) Really, the cheapest charger is the one on the first page :) By the way, I'm tuning it more and more and I'm taking out those false voltage reading when in charge caused by various contacts resistance that are causing increased sensed voltage.. I might.. build a board for it after all the work that's been done to now. Still, I've to fix mAh metering :\ |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Hey, that was most interesting blog/thread about reverse engineering thread I've gone by in ages :) Not that this Chinese charger was so interesting, it's rather about style and passion, I think?
Anyway, what about our "cold fusion" :D battery? Have You measured it? It's like waiting for new episode of "to be continued" science/criminal serial ;) |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Quote:
Ooppss! Sorry! the summer was good enough to scramble all my habits ;) - but I kept working on it in a steady manner ;) The charger has reached a decent working stage! Hardware hasn't changed since the beginning, software went to about 30 major "releases" and is currently in stage v1.01. Every release added functions, Monitor, Charge and Discharge cycles. The biggest problem was the small program memory of the PIC in the way that floating point operations are not used because when just one decent division is programmed, the compiler sucks 18% of program memory.. so, all integer inside! Or better, only fixed point math is used and some tricks are done trying to optimize all the various calcs.. The discharge cycle now is trying to meter mAh spent, I know, it would be better to measure Wh, but believe me, there isn't enough (or yet) space to datalog V and I for every second with the right precision. At least, at the end of discharge cycle I know the starting and ending voltage of the battery; if I remember right, the nokia 5800 turns off at v_batt of 3.3V (or not?). The discharge cycle if done: _ @150ma until 3.6V _ @75ma until 3.4V _ @40ma until 3.3V It's clearly not a real discharge profile, but I just want to measure the capacity of my cheap batteries. The charge cycle works by: _ v-batt<3.3v precondition @50ma _ v-batt<4.1v charge @500ma _ v-batt<4.22v charge @200ma _ v-batt<4.23v charge @50ma _ v-batt<4.24v charge @25ma Each stage works by pumping the constant current for 10s, pause 500ms, sample v-batt for 500ma and take the average, then compare v-batt with the current stage and so on. I've done this way because when you push current throug the battery AND sample voltage it gives obviously a false reading. The 3 final stages are done because even pausing after pushing 200ma inside the battery it still isn't enough, the battery looks like it's charged, but the voltage then drops to 4.13 like; so my profile is still time-un-optimized, but nice enough to fully charge the battery at the end :D Also, I've checked the nokia battery during recharge inside the phone and with the standard nokia adapter it looks pulsed too, like each second charge, stop, sample and pulse again the current. Give me a couple of days/week, I can start to get out some battery numbers, see if they a reasonable, then I'll post the final hw schematics and the source code of the charger (C lang.). I don't think it would be ever usefull to anybody, but who knows! |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
So, long time no see :o
Here (link to google sheet) you can take a look at the performances of different batteries, tested with the charger, read the notes to get more info. The charger: the hardware is the same, the software went throug various tuning but the main ideas remain (charge profiles and so on), I've done some fixing, counting mistakes, cicles and little else. Temperature: I've got a IR thermometer, now I'll measure why (some) od those batteries are colder than the others. It only happens after a full charge, with my charger. Sooner or later I'll ran the remaining test of how much is the Nokia charger charging vs my profiles.. but now life has changed a lot since my last post, moved out, found a job, paying my bills and got a QWERTZ keyboard and a lot of accents to deal with :> My time is now shared among job/survival/hobbyes - being the first one quite compulsory, and the last two thread locking each other out :> - I could survive without food/cleaning for up to 1 week however... better not try :eek: |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
Good Nickel Cadmium cells do cool down slightly when charging actually, then warm up when they are full. Because of this, some chargers detect the temperature change to tell when the cells are full. Though NiMH also warm up when full, they don't cool down as notably as NiCd during charge.
I don't think you could get away with running NiCd batteries in the N900 or with a Li-ion charger, however. |
old thread, but anyway: experimenting with this is extremely dangerous!
i had 2 examples in my neighborhood: 1 burned his bed because of a battery starting to burn while loading, he only noticed, because his dogs began to bark the other one burned down his house, because of an exploding battery while he was sleeping. better spend 20 bucks more on your battery and charger, it can save your house and your live. just my 2 cents |
Re: Cheap (chinese) external BL-5J (and other models) battery charger: reverse engineering
While you are correct, messing around with Li-ion batteries is EXTREMELY dangerous, foxontherun has proven he knows exactly what he is doing.
|
| All times are GMT. The time now is 01:12. |
vBulletin® Version 3.8.8