64/128 cells - DIY Multi Battery Tester Charger / Discharger

M

mrconstantin

Guest
Hi,

I decide to make an multi battery tester module. I think a lot of people will deal with this problem, dont have time to test a big number of cells.
My charger will be a smart charge up to 128 cells. Will report by email and web server when the cycle are completed.
I will document this work on youtube and also on my PowerWall thread!

Best regards.


First of video from the series: - sorry for my english is not very good!

Parts

Schematics

Anslabled Boards

Test Unit Video


32 Cells Working Module


Constant Current vs Constant Load


Constant Current with variabile resistor theory



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


Constant Current Complete Boards


Software: V0.3 Beta

All Software will be on: http://secondlifestorage.com/t-Constantin-PowerWall

30 Cells Constant Current

 
That's practically exactly what I was wanting to do :) I really like this work! Nicely explained and laid out :) Nice walk-through. And your english was just fine!

However, why don't you use an A2D (I think this is what it is) with I2C interface for the analog reading. Wouldn't that allow you to read all the values somewhat at the same time?
Though, I do like the CD4052B variant, as it looks to me like it has 2 leads that switch from pairs of pins at a time (pin 1&2, then 3&4, then 5&6, ...). This would effectively isolate the grounds, yes?

Now, could we use a digital mux for the fets? Reason I ask is cuz I have nano's and would like to use what I already have.

I did notice that you didn't post the code anywhere. I think I can follow the schematic based on what you showed in the video, though.
 
Looking good! :)
 
Very Nice
 
Looking good.
By the way, it wouldn't be too difficult to make the dis-chargers constant current, you've almost got everything there already.
 
SimonW said:
Looking good.
By the way, it wouldn't be too difficult to make the dis-chargers constant current, you've almost got everything there already.
Click to expand...

Yes i will make the other 32 module with constant current discharge. in few days. And after that i will make an comparation.
 
mrconstantin said:
Yes i will make the other 32 module with constant current discharge. in few days. And after that i will make an comparation.
Click to expand...

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 :D
Would need some heatsinking, but it's only a few watts per mosfet.
 
SimonW said:
mrconstantin said:
Yes i will make the other 32 module with constant current discharge. in few days. And after that i will make an comparation.
Click to expand...

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 :D
Would need some heatsinking, but it's only a few watts per mosfet.
Click to expand...

Simon, would you be willing to sketch out the placement of theadditional resistor and transistor based on his initialdesign? I have all the parts coming my way to build out his initial design. Thanks!
 
srk said:
SimonW said:
mrconstantin said:
Yes i will make the other 32 module with constant current discharge. in few days. And after that i will make an comparation.
Click to expand...

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 :D
Would need some heatsinking, but it's only a few watts per mosfet.
Click to expand...

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

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 ohmin parallelto reach 5ohm and if u want 1A u need 2.5ohm resistor or 4 10 ohm in parallel.

Also form other test is better touse 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 Vbatand 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. BecauseI 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
 
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srk said:
Simon, would you be willing to sketch out the placement of theadditional resistor and transistor based on his initialdesign? I have all the parts coming my way to build out his initial design. Thanks!
Click to expand...
Google is your friend :D
Mosfet dummy load: https://www.google.com.au/search?q=...qPWAhUFULwKHUBYCZUQ_AUICigB&biw=2304&bih=1192
Mosfet Constant current : https://www.google.com.au/search?cl....0....0...1.1.64.psy-ab..9.7.1713.2UyL2b3MA9Q
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.
 
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

 
So nice setup you got there. Thats proper DIY :)
 
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