0
\$\begingroup\$

I am new to electronics and just getting started with a project to make a BT speaker. I bought some quality protected 18650 Li-ion cells from Orbtronic. I would like to build a charger myself for these batteries using a 5V,3A wall adapter that I have.

Most people use the TP4056 to charge unprotected cells, which is fine, but

  1. Do I need a TP4056 to charge my cells (one TP4056 per cell)?

  2. If I don't need them, am I okay to hook up the 5V,3A wall adapter directly to the 18650 cells and rely on their protection circuit to charge them? Is this okay? It seems like the more dangerous of the 2 options.

I would appreciate any help or, better yet, any links you can provide.

\$\endgroup\$
5
  • 2
    \$\begingroup\$ Do NOT connect 5V direct to the battery - even though you have a protection circuit you don't want to risk 5v going across those battery terminals - there is risk of fire or explosion. Use a TP4056 to charge it. \$\endgroup\$
    – QuickishFM
    Jun 16 '20 at 21:03
  • 1
    \$\begingroup\$ What they said. | Direct connection is a very very bad idea indeed. | TP4056 x N IN PARALLEL will work. IC has settable charge current limit with max of one Amp. \$\endgroup\$
    – Russell McMahon
    Jun 16 '20 at 21:20
  • \$\begingroup\$ Thanks for the quick feedback all. This kind of quality advice is why I asked, and it keeps me from doing something dumb. \$\endgroup\$
    – user11585
    Jun 16 '20 at 22:40
  • 1
    \$\begingroup\$ The protection circuit shouldn't interfere with normal charging so your plan should work OK. I didn't do a detailed review of the TP4056. As long as the charge rate it uses is OK for the cells it should be OK. \$\endgroup\$
    – mkeith
    Jun 16 '20 at 23:21
  • 1
    \$\begingroup\$ You can use 1 x 5V source to feed N x PARALLEL TP4056s with each cell isolated. || If you have N cells isolated you can use N x 5V sources each ISOLATED , with 1 TP4056 per cell. | Each cell and TP4056 combination works independently. The fact that there are N-1 other cells being charged is unseen by any given cell. \$\endgroup\$
    – Russell McMahon
    Jun 16 '20 at 23:41
5
\$\begingroup\$
  1. TP4056 is a charger chip for one (1) cell. If you plan to charge multiple cells simultaneously, each charging slot for a cell needs it's own TP4056.

  2. Please don't even think about connecting a 5V 3A power supply directly to a lithium cell. Even though the cell has built in protection, it is not a charger. It is the last line of protection to prevent catastrophic failures by disconnecting the cell under abnormal conditions - unless the protection does not work.

\$\endgroup\$
6
\$\begingroup\$

The protection circuitry on a Li technology battery is not a charging profile controller. The protection circuit only tries to protect the battery from over voltage, too deep of discharge and over temperature detection in some cases. The web page that you linked to specifically specifies the protection features and applicable parameteric limit.

Protection specs:

  • Over-current (Activated @ 10A)
  • Over-charge (Activated @ 4.29V)
  • Over-discharge (Activated @ 2.45V)
  • Over-temp. and short circuit protection
  • Protection circuit designed by Seiko

Devices like the TP4056 are charging profile controllers what you adapt to your system design to properly design the charging process for your selected battery technology. You will need a charge controller for your design.

\$\endgroup\$
1
\$\begingroup\$

I created a LIPO battery from many smallers cells for a bluetooth speaker last year.

I used a 2S4P configuration to ensure I had a high enough voltage as well as a large enough capacity.

I used a different chip to yours but I can't imagine it would be much different.

Circuit

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.