# NiCd - NiMH PC Based Smart Charger - Discharger

How to build a low cost great features PC based smart charger- discharger which can charge any NiCd or NiMH battery packs.

- The circuit uses the PC power supply , or any 12V power source.

-The circuit uses The "Temperature slope" method which is the most accurate and safe method, in this case the packs are charged by monitoring the temperature and end the charge when the charger sense the end of charge dT/dt, which depends on the battery type.

Two parameters are used as a backup to avoid over charging:
- Maximum time: The charger will stop after a predetermined time according to the battery capacity
- Maximum temperature: You can set the Max. battery temperature to stop the charging when it becomes too hot ( about 50 C ).

- The charger uses the PC serial port, i have built the software with Microsoft Visual Basic 6 with an Access database to store the battery parameters and charging profiles.

- A log file is generated with each charging process showing the charged capacity, charging time, cutoff method ( time or Max. temperature or Max. slope )

- The charging characteristics is displayed online through a graph ( Time versus temperature ) to monitor the battery temperature.

- You can discharge your packs as well as measuring it's actual capacity.

- The charger has been tested with more than 50 battery packs, it realy works great.
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## Step 1: The Schematic

The circuit can be divided into e main parts:

Measuring the temperature:
This is the most interesting part of the project, the purpose is to use a low cost design with a low cost components along with a good accuracy. i have used the great idea from
http://www.electronics-lab.com/projects/pc/013/ , review it , it contains all the required details.

A separate module in the program has been written to measure the temperature, as it can be used in other purposes.

The charging circuit:
================
- I used LM317 in the first design, but the efficiency was too bad and the charging current was limited to 1.5A, in this circuit i used a simple adjustable constant current source, using one comparator of the LM324 IC. and the high current MOSFET trannsistor IRF520.
- The current is adjusted manually using the 10Kohm variable resistor. ( i'm working on changing the current through the software ).

- The program controls the charging process by pulling Pin(7) high or low.

The discharging circuit:
===================
- I have used the remaining two comparators from the IC, one for discharging the battery pack and the other for listening to the battery voltage and stop the discharging process as soon as it drops to a predetermined value ( for ex. 1V for each cell )

- The program monitors pin(8) , it will disconnect the battery and stop charging when it's logic level "0".
- You can use any power transistor can handle the discharge current.
- Another variable resistor ( 5K ohm ) controls the discharge current.
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noahw says: Sep 4, 2007. 12:00 PM
Hello, and welcome to the Instructables community! This currently does not meet our criteria for an Instructable. A completed Instructable:

- details a finished project with instruction (not just links to instructions)
- has clear images that you took of your project (web-found clip-art is not acceptable)
- uses proper spelling and grammar
- contains appropriate cautions or safety considerations
- does not violate someone else's copyright
- is typically written about something you are very passionate about and want to share.

If this is a comment, a question, a small tip, or something that cannot truly be a finish project, please post it as a forum topic. If you are looking to start a collaboration, post a topic in the forums. Look here for tips on writing a great Instructable.

http://www.instructables.com/id/ELHMNOA69REUF10WM7/

So, it has been unpublished. Please do not republish until it has been corrected. When you republish, if everything is fixed, I'll remove this note. Multiple attempts to republish without correction will result in deletion.
hosam_eldin (author) in reply to noahwSep 5, 2007. 1:51 AM
Hi noahw, Thanks for the note, kindly be informed that i didn't finish my instructable, i'm still preparing the materials, images .. etc. i thought that it can be published until i finish my work. I will update it soon and publish it when it's ready. Thank you Hossam
noahw in reply to hosam_eldinSep 5, 2007. 12:50 PM
You generally want to get your instructable all finished before you publish it. That way people can see the final product. Thanks for your submission and I am looking forward to seeing the finished project!
offtherails2010 says: May 17, 2012. 10:26 AM
Hi Hosam,

Just wondering if you managed to complete this instructable ?

i know its been a few years since the original posts but this software and the schematic would be greatly appreciated for my home project, i have recently become severely mobility impaired and started learning electronics (now that im stuck in one room full-time!) and have over two dozen (28!!!) varying sizes battery packs that would greatly benefit these tests using you excellent 'ible !

Please could you say if this is complete and/or if you could email me all the info including full parts listing so i too can make one of these 'super battery pack charger/discharger's' ??? !!!! ???

many thanks in advance for any or all help given through pm and i'll post you my email addy !!!

keep up the great inventive work !!!
hosam_eldin (author) in reply to offtherails2010May 17, 2012. 6:03 PM
Hi,

Thanks a lot for your e-mail,
Actually i have made this project long time ago, all the info i have is posted to the website, but i think the schematic is a little bit missing some parts numbers, i think this can be sent.

But the final version of the software is the one on the website

By the way, i still have the circuit in the picture, i don't need it any more, but the shipping cost is high, better to build it at home.

Regards
Hossam
offtherails2010 in reply to hosam_eldinMay 17, 2012. 7:04 PM
Many many Thanks for the LIGHTENING FAST reply Hosam !!!!! i am truly grateful !

I'm gathering the components at the moment and have downloaded all the software and schematic but the link for the research i need does not work anymore and i would very much like to see the extra information from the dead link (understandable considering how much time has past !)

here is the text from your 'ible that i need the link for:

Measuring the temperature:
This is the most interesting part of the project, the purpose is to use a low cost design with a low cost components along with a good accuracy. i have used the great idea from http://www.electronics-lab.com/projects/pc/013/ , review it , it contains all the required details.

Would you be able to remember the name of the project from the electronics-lab.com website that has all these required details ?

or if you could write me down the full list of exactly which components (capacitors, resistors, IC's etc) your original circuit used and all values so that i can start ordering the parts?!!!?

Once again, thanks for the great help in Reviving this Old But EXCELLENT Project as i need to breathe New-Life into it !!!
loopingz says: Mar 31, 2012. 11:51 AM
Interesting build, did you think about mixing temperature and voltage peak? It would be perfect this way.
Inducktion says: Oct 22, 2011. 1:58 PM
Could it be possible to make it so this same charger charges Li-ions, NiCd's, and lead acids, too?

It would be a whole lot more useful if it was universal!
pekili says: Aug 8, 2011. 3:14 AM

Hi.
I think that your diagram is not well. First, the diode at pin 2 LM324 is turned. I think ,anode have to go at pin2 ,cathode at gnd to establish 0.6v at pin2.
Second,I have 3 v to 4v at fan with slow moving ventilation.Which type of the fan I must use: at 5v ,or 12v?.When I put 82k resistor between VCC and the baseof the transistor (I put BC639 ) I have about 8v to 9v, but BC639 is just warmer(about 40 to 50 Celsius degree.Third , cooling fancontacts need to be turned (oposite).
Fourth,100kOhm resistor at trimer 10kOhm#pin12 LM324,I think it should be there.Without 100kOhm , don't have current adjustment at all. With resistor ,have
current range from 0 to 0.65 A max..Why is that?.And,finally , In software you have a bug when I turn CHARGE button, next PAUSE,and again CHARGE button the program says '55 error' and close the program.
minglett says: Apr 22, 2011. 10:04 AM
charger_setup_WinXp.rar file will download fine if you follow these instructions. BTW it only took me a minute to figure this out. Everybody gives up too soon.

Right mouse click on the link, "Save target as", let it download to your computer. It will save as FA2OIVDFDO2058V.htm. Once the download is completed change the .htm extension to .rar. Then open the file and it will unpack properly. Note: you will need Winrar or another program that opens RAR compressed files.
amitava.hcl says: Sep 25, 2010. 5:00 AM
charger_setup_WinXp.rar file appearing as tmp file and archive corrupted. Please help me to work with and to try.
moris_zen says: Nov 10, 2009. 1:20 PM
Great work man!
I just love batteries too (Link) . Just made a dis charger with Arduino .
Nice work .
giga97 says: Aug 6, 2009. 3:36 AM
thank you. will try to construct one.
giga97 in reply to giga97Aug 8, 2009. 12:13 AM
encounter a big problem, charger_setup_WinXp.rar 45 MB seem impossible to download . server keep on reset after few minutes on download, and can not resume, waste a lot of bandwidth.
ReCreate says: Apr 29, 2009. 5:17 PM
How big is the Program?
hosam_eldin (author) says: Feb 16, 2009. 12:54 AM
Hello all, I have uploaded the source code, i'm realy sorry for all that delay ( it was out of my hands) . Please if anybody has modified the software or enhanced it, just drop me an e-mail with the new version so i can upload it for everybody. Regarding polymer52's comment, actually the software worked for me over a year and also for many friends. YES it needs some enhancements like any software BUT i think it's not fair to say that it's "useless" as he mentioned. Anyways polymer52, thanks for the great comment !! Thanks Hossam
jhesy in reply to hosam_eldinMar 1, 2009. 6:23 PM
hello! where can i get the source code?? i need it as soon as possible because the deadline of our prototype is nearly coming..we don't have much time to wait..please bear with us...please help us, for us to be able to pass our electronic subject ur response would be a great help for our group.. thanks!god bless!
polymer52 says: Feb 15, 2009. 7:27 AM
Don't waste your time and money on this one guys. The hardware will work okay but the software is unfinished and useless. I've contacted the author a number of times. Usually he doesn't respond. When he does he says he is going to upload the source code so we can fix it but he never does. No flame intended. I'm just trying to save you guys some headaches, money and frustration.
necrotopsy says: Jan 30, 2009. 6:57 AM
Can this circuit without the computer? I am looking to build one into a car to charge single cells.
whitetiger says: Jul 1, 2008. 7:22 AM
Hi Hossam: This project is great... I'm under construction... but i have some questions on it.... i need more data for the "temperature wire" Thanks. (excuse me for my English, i'm from Argentina)
Da_Fudge in reply to whitetigerNov 14, 2008. 2:35 PM
I've just finished building, so maybe I can help. The temperature wire is not special wire, it's just whatever you want. He used headphone wire because of it's sheilding properties. Whatever wire you use, just add a 10K thermistor to it. THAT is what does the sensing.
polymer52 in reply to Da_FudgeJan 8, 2009. 4:38 PM
Did you actually get this circuit to work with XP? It seems to have issues with the serial port (com 1). Gives errors and wont pull RTS (pin 7) high. Also there is no setup and calibration instructions.
Da_Fudge in reply to polymer52Jan 12, 2009. 2:24 AM
Yeah. Admittedly, the program has some MAJOR bugs, but works well enough. Also, Hossam, a major feature I think you should impliment is PC controlled current, both charging and discharging. THe trimpots are way too annoying. It shuldn't be too difficult to impliment. Cheers, Fudge
polymer52 in reply to Da_FudgeJan 20, 2009. 5:17 PM
Does your copy of the software have the discharge button as shown in the text? The ones I have doesn't. The zip file is a scrambled mess of different (versions?) programs. If I had the source code I could possibly help with some of the problems but I e-mailed him and got no reply.
hosam_eldin (author) in reply to polymer52Jan 22, 2009. 1:58 PM
Hello all, I'm sorry for not replying i was very busy. Regarding the software,i think the discharge button was disabled in this version, but the source code contains everything. I will upload the whole source code soon, sorry now i don't have a good Internet connection I will appreciate if anyone has modified/improved the software to upload it to be available to everybody. By the way the program is working good on XP it's right, the program does not include a setup for this part, sorry i didn't have time to add this feature.
hosam_eldin (author) in reply to Da_FudgeNov 26, 2008. 1:22 AM
Hi Da_Fudge I'm so happy to hear that you have built my project please test it and send me your feedback tel me if you need any assistance Thanks Hossam
hosam_eldin (author) in reply to whitetigerJul 2, 2008. 1:34 AM
Hi Whitetiger, Thanks for the update, It's a simple one, i used a wire from an old headphones just to decrease the noise, but i think any wire can work.
hosam_eldin (author) says: Nov 27, 2008. 2:46 PM
Hi everyone, I have made this project long time ago, i don't need it at the moment and would like to sell it with the source code of the software, if anyone is interested please send to my private mail hosam_eldin@hotmail.com and we can arrange. Thanks Hossam
hosam_eldin (author) says: Oct 13, 2008. 2:31 AM
Hi all, I have uploaded a more clear schematic, Schematic.zip Thanks Hossam
codyke says: Oct 9, 2008. 2:04 PM
could you please send me the scemetic? I have a hard time making something out of it even enlarged it pretty unclear :(.

hosam_eldin (author) in reply to codykeOct 13, 2008. 2:17 AM
Hi codyke, I will upload a more clear image to my instructable Thank you Hossam
patmb says: Sep 23, 2008. 11:11 PM
This charger/discharger project is great! But I have problem downloading the software (i.e. charger_setup_WinXp.rar). I know for some reason it will be downloaded as "FA2OIVDFDO2058V.tmp", and I just have to rename it for decompression. But I can only download it as an empty file (zero-byte in size)! Do you have any idea about what's wrong? Thanks!
Sandisk1duo says: Jun 23, 2008. 8:07 PM
can you drw the diagram again? only this time just so you can charge batteries, and nothing else? sorry i'm a noob
carrierpilot1357 says: Jun 8, 2008. 6:53 PM
this is a great instructable. i like how neatly the schematic was written. i would make this but i would mess it up soldering.
babu03 says: May 24, 2008. 6:37 AM
please draw the schematic neatly by using MS-PAINT or the like.
jomarx says: Apr 28, 2008. 10:41 AM
very nice! will be making this when i have the budget! there's a slight problem on the schematics, its not very clear. if its possible for a high res pic? thanks!
hosam_eldin (author) says: Mar 11, 2008. 4:32 AM
Folks, - I have uploaded the software ( the exe version for Windows XP) - your comments are welcomed.
n0ukf in reply to hosam_eldinMar 13, 2008. 6:32 PM
Where is the program for this? I tried clicking the .rar file to download but it brings up the cryptic (meaningless) name FA2OIVDFDO2058V.tmp instead. What do I do with this?
hosam_eldin (author) in reply to n0ukfMar 30, 2008. 3:27 AM
Try to rename it to the original name after downloading it. actually i don't know why this behavior is happening
BFeely in reply to n0ukfMar 18, 2008. 1:55 PM
Simply rename it to charger_setup_WinXp.rar and open it with WinRAR (or a compatible program).
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