Charge Several Lithium Cells

Thread Starter

william.in.rs

Joined Jul 14, 2012
22
Is it possible to connect several PCBs like this one
upload_2016-7-9_12-59-14.jpg
to a circuit like this:
Code:
         |   |                 |          |          |
         |   o-------|<|-------|          |-----     |
         |   |                 |          |    |     |
         |   |                 ------------    |     |
         |   |                                 o-----o    
         |   |                 ------------    |     |
         |   |                 |   USB    |    |     |
         o---|-------|>|-------| charging |-----     |
         |   |                 |protection|         ===   3.7V          
         |   |                 | PCB with |        -----  Lithium
         |   |                 |   4056   |          |    cell        
         |   o-------|<|-------|   DW01   |-----     |
         |   |                 |   8205   |    |     |
         |   |                 ------------    |     |
         |   |                                 o-----o
         |   |                 ------------    |     |
         |   |                 |          |    |     |
         o---|-------|>|-------|          |-----     |
         |   |                 |          |         ===
     +5V |   | GND             |          |        -----  
      from PC PSU
to charge several serila Lithium cells from a single 5V (PC) power supply?
 
Last edited by a moderator:

ScottWang

Joined Aug 23, 2012
7,400
You could have a common ground and only using one Schottky diode to reducing the Vf from 0.7V to 0.3V~0.4V.

If you use two diodes then the Vin of charge module only have
Vin = 5V-(0.7V*2) = 3.6V, that is too less for the module to charge the Lithium battery as 3.7V (full charge 4.2V or some are 4.3V).

The TP4056, Input voltage: 4v-8v.
I'm not sure does it has raise the voltage(boost) or not, if no then you should do as what I suggested, if it has boost then using one 1N4001~4007 could be ok.

Code:
         |   |                 |          |          |
         |   o-----------------|          |-----     |
         |   |                 |          |    |     |
         |   |                 ------------    |     |
         |   |                                 o-----o   
         |   |                 ------------    |     |
         |   |                 |   USB    |    |     |
         o---|-------|>|-------| charging |-----     |
         |   |                 |protection|         ===   3.7V     
         |   |                 | PCB with |        -----  Lithium
         |   |                 |   4056   |          |    cell     
         |   o-----------------|   DW01   |-----     |
         |   |                 |   8205   |    |     |
         |   |                 ------------    |     |
         |   |                                 o-----o
         |   |                 ------------    |     |
         |   |                 |          |    |     |
         o---|-------|>|-------|          |-----     |
         |   |                 |          |         ===
     +5V |   | GND             |          |        ----- 
      from PC PSU
 

Thread Starter

william.in.rs

Joined Jul 14, 2012
22
Sorry, I didn't expect font change. This is the real schematic:
upload_2016-7-9_17-37-47.png
As you can see from schematic cells are connected serial, not serila, sory for typo.
 

Thread Starter

william.in.rs

Joined Jul 14, 2012
22
Thank you @ScottWang!
As far as I know the PCB doesn't boost voltage.
I was wondering about if it is possible to charge several serial connected cells from a single power supply rather than thinkihg about voltage drop. However, the advice to use Schottky diodes is great.
As I intend to repack used laptop batteries I need some protection circuit which would turn the whole pack off and request charging whenever voltage of any cell goes below some limit. Any idea?
 

ScottWang

Joined Aug 23, 2012
7,400
Because the batteries are in serial, assuming that you using 3 batteries, the total voltages of batteries should be 12.6V, and you only have about 4.2V for charge modules, so this circuit only for one battery, if the batteries are not charge at the same time then it will be ok, but they can't charge at the same time.

If you want to match your original idea then you have to using the boost circuit, and do some modify, or using 5V to charge the batteries as in parallel, but not really.


TP4056_3.7V-Lithium-cel_william-in-rs.gif
 

bertus

Joined Apr 5, 2008
22,277
Hello,

The circuit scott shows you will only work if the charging controllers are isolated from the 5 Volts.

Bertus
 

Ylli

Joined Nov 13, 2015
1,087
Simple answer is NO. These charge modules do not look like they isolate the output from the input, and you will end up shorting everything out through the common terminal. You would need charge controllers that isolate the output from the input so that the output was floating.
 

Papabravo

Joined Feb 24, 2006
21,225
That is one kind of ASCII code art and used the ASCII code to draw the circuits to save the space of hard disk.

ASCII code art.
Assorted ASCII Schematics.
Dear Scott,
Nobody needs to save space on a hard disk any more, and I don't need you to tell me what it was, I was there when it was created. It was an abomination when it was created and it still is. In the original post the code tags were missing and it was unreadable.

Your diagram at least makes sense.
 

Thread Starter

william.in.rs

Joined Jul 14, 2012
22
Thank you all guys, now I am allmost convinced that I will have to disconnect batteries from serial connection to charge them separately and to reconnect them to get higher (needed) voltage. However, monitoring each cell voltage for overdischarge protection should be done in serial cell connection. I would appreciate any idea.

The original question arouse from my thought that following circuit might work (charging several serial connected battery cells from single winding of a transformer):
AC_charge.jpg

When I moved from AC to DC I have got following circuit which would work if previous is working:
DC_charge.jpg
And this was the unreadable circuit from my original question.

Can somebody open my eyes and tell me where I was wrong?

P.S.
My intention was not not to save space on hard disk, I am just (from ancient times) used to draw schematics that way. As this was my first post to AAC I haven't expected that it could get unreadable form for which I apologize once again.
 
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