Beginners Guide to Processing 18650 Cells | Cell Database


Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
64/128 cells - DIY Multi Battery Tester Charger / Discharger
#11
(09-13-2017, 06:28 PM)srk Wrote:
(09-13-2017, 03:54 AM)SimonW Wrote:
(09-12-2017, 07:19 PM)mrconstantin Wrote: Yes i will make the other 32 module with constant current discharge. in few days. And after that i will make an comparation.

Cool, I look forward to seeing how you go.
Just one extra resistor and an NPN transistor, maybe also change the 10 ohm so you get a higher current draw toward the end(say 500mA instead of your 250mA with the 10 ohm), and you're set.
The mosfet will go from being a switch to an automatic variable resistor Big Grin
Would need some heatsinking, but it's only a few watts per mosfet.

Simon, would you be willing to sketch out the placement of the additional resistor and transistor based on his initial design? I have all the parts coming my way to build out his initial design. Thanks!

hi

    tomorrow i will make an other movie with the constant current version. 
    In theory Ohm Low is : 
              I=U/R 
    So u know the U will be changing from 4.2 to 2.5V on discharge of the cell.
    For I to be constant u have tow option:

             1 - to change the R value : this can be done like that use an fixed R + RDSon of MOSFET so if u want to discharge with max 1A at 2.5V u will need an 2.5Ohm resistor at the end of the cycle. So u will need an 2.5ohm 5W at end and 2.5ohm + RDSon of MOSFET  4.2ohm on start. So will need to control the mosfet to have a resistor of 1.7 ohm. 
            Because IRLZ44n is an logic mosfet u will need few mV to have that resistance because if u look to data sheet u will have less then 0.8 ohm on 2V and at 5V u have 0.028 ohm.
            Also the RDSon will depend of the temperature of the MOSFET, so from my point of view cant be done with an logic mosfet!!!

             2 - the second option is to control the voltage to make that U/R constant. so if u will have same 2.5ohm 5W resistor and can make an voltage regulator controlled by the microcontroler u can also have an constant current discharge. 
 
             I will try the second version an i will make the presentation video tomorrow. All the parts u brought are ok but on constant discharge will discharge with only 250mA. if u want to reach 500mW put 2 resistors 10 ohm in parallel to reach 5ohm and if u want 1A u need 2.5ohm resistor or 4 10 ohm in parallel.
 
            Also form other test is better to use  different MUX one for Vbat reading and one of Vres reading, in my presentation i use the odd inputs (0,2,4,6,8,10,12,14)  of mux for Vbat and even inputs (1,3,5,7,9,11,13,15) for Vres. I use also 2 mux but was easy to wiring with odd and even but better is to be separate one mux all 16 inputs for Vres and one mux for Vbat.  Because I see the circuit need few millisec after the mux change the input to drop the voltage from 4V (battery voltage) to 0.018V (voltage droped on mosfet), for that i need to ad an 50milisec delay on each reading. when u have 32 batttery will and some sec of delay.


best regards
srk likes this post
Reply


#12
(09-13-2017, 06:28 PM)srk Wrote: Simon, would you be willing to sketch out the placement of the additional resistor and transistor based on his initial design? I have all the parts coming my way to build out his initial design. Thanks!
Google is your friend Big Grin
Mosfet dummy load: https://www.google.com.au/search?q=mosfe...4&bih=1192
Mosfet Constant current : https://www.google.com.au/search?client=...UyL2b3MA9Q
While you can use an NPN transistor to drive the Mosfet, as you can see at the links, an Op Amp is the preferred method.
Reply
#13
Constant Current programabile Discharger:

Constant Current vs Constant Load

       

Constant Current with variabile resistor theory

        


Constant Current with constant voltage controlled by arduino PWM  - Parts & Schematics 

       
daromer and srk like this post
Reply
#14
Constant Current Complete Boards

jdeadman likes this post
Reply
#15
So nice setup you got there. Thats proper DIY Smile
Korishan likes this post
Follow me! >> YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcomming: 14S 18650~30kWh | Automatic trip breakers, and alot more
Reply


Who read this thread?
61 User(s) read this thread:
BatMan (09-24-2017, 09:10 AM), DarkRaven (Yesterday, 11:02 AM), hookemdevils22 (09-14-2017, 08:00 PM), sunseeker (09-18-2017, 07:29 PM), SimonW (Today, 02:54 AM), floydR (09-13-2017, 03:23 AM), NZ55 (09-20-2017, 10:27 PM), Ivo Staelens (09-09-2017, 06:05 AM), Jon (09-13-2017, 06:53 AM), SWEwall (09-06-2017, 07:30 PM), Rad (09-21-2017, 06:12 AM), Geek (09-15-2017, 06:00 AM), ivnz (Yesterday, 07:01 PM), Mazlem (09-12-2017, 11:01 PM), mupp (09-04-2017, 05:39 PM), mrconstantin (Today, 05:54 AM), Tostaki (09-20-2017, 10:00 PM), mormor1971 (Yesterday, 12:29 PM), ICEMAN (09-14-2017, 05:07 PM), Jeffrey Martin Smith (09-23-2017, 02:29 PM), NicZa (09-13-2017, 07:12 AM), Lucian Macota (Yesterday, 08:47 PM), Aelio (09-08-2017, 05:47 PM), hOOPSNAKE (09-20-2017, 09:57 PM), srk (09-20-2017, 07:20 PM), nautal (09-13-2017, 09:46 PM), Swake (09-06-2017, 06:56 PM), Gerard Achternaam (Today, 07:20 AM), Patrick Moreau (09-05-2017, 12:44 AM), KtB (09-04-2017, 05:10 PM), Shade (Yesterday, 09:25 PM), N00bPwr (09-14-2017, 07:17 PM), charlie246 (Today, 09:05 AM), jdeadman (Yesterday, 12:23 PM), flight4900 (09-20-2017, 02:47 PM), egam (09-07-2017, 01:58 AM), Darmok (09-14-2017, 01:20 PM), PAF (09-15-2017, 12:19 PM), A + A (Yesterday, 01:14 PM), Korishan (Yesterday, 03:25 PM), Majorphill (09-09-2017, 12:57 PM), RudyLiPower (09-13-2017, 01:53 PM), owitte (09-05-2017, 12:14 PM), PaulKennett (Yesterday, 08:12 AM), mike (Yesterday, 02:57 PM), wim (Yesterday, 03:24 PM), frnandu (Today, 01:12 PM), Terry (Yesterday, 12:25 PM), Nitroghost (09-20-2017, 12:15 AM), SolarWind (09-14-2017, 06:26 PM), Chris Evans (09-08-2017, 12:47 AM), Chiptosser (Yesterday, 05:57 PM), zimo (09-11-2017, 10:20 AM), Stefaan De Ridder (09-13-2017, 06:47 PM), kazbach (09-04-2017, 05:13 PM), Hanssing (Yesterday, 05:56 PM), jesusangel (09-04-2017, 07:49 PM), watts-on (Yesterday, 01:20 PM), rebelrider.mike (09-13-2017, 10:33 AM), neilmc (09-13-2017, 02:10 AM), daromer (Yesterday, 12:10 PM)

Forum Jump:


Users browsing this thread: 3 Guest(s)