2
\$\begingroup\$

I recently purchased a 32650 LiFePO₄ 6 Ah cell, and I'm looking for simple ways to charge it.

I can't find LiFePO₄-specific chargers that charge single cells, and I was wondering if I could use this TP4056 module to charge it.

Would it work? Are there any other charging circuits I could solder together myself to charge this cell? And could you show me a few examples of dedicated chargers for a single-cell LiFePO₄?

\$\endgroup\$
6
  • 1
    \$\begingroup\$ Look at chargers for radio control models, especially really tiny models. Do not use a LiPo or Li-Ion anything with a LiFe. It has to specifically support LiFe. \$\endgroup\$
    – DKNguyen
    Commented Oct 5, 2020 at 4:44
  • \$\begingroup\$ Don't use the TP4056, its a hobbyist device, thats not good. You need a circuit of your own, the datasheet should specify the charging mechanism, you need to build a circuit that will detect a full charge and perform various maintenance techniques. \$\endgroup\$
    – CFCBazar
    Commented Oct 5, 2020 at 6:45
  • \$\begingroup\$ The TP4056 is designed for more traditional lithium ion chemistries and most likely has wrong voltages programmed. It is not suitable for your LiFePo4 cell and can be seriously dangerous if used with it. \$\endgroup\$
    – crossroad
    Commented Oct 5, 2020 at 7:14
  • \$\begingroup\$ Where you want to use this cell please tell, then only we can tell what kind and quality of charging chip you will need. \$\endgroup\$
    – Deepak
    Commented Oct 5, 2020 at 8:41
  • 1
    \$\begingroup\$ @Deepak How does the application affect the choice of the charging circuit? Doesn't it depend purely on the cell chemistry and cell parameters alone? \$\endgroup\$
    – Aditya Rajendran
    Commented Oct 5, 2020 at 11:07

3 Answers 3

Reset to default
2
\$\begingroup\$

LiFePO4 cell may be charged by CN3058E or MCP73123, if you want to make the charger yourself, condensers and heat-sink is necessary.

It may also charged using a 3.6V power source and a resistor.

LiFePO4 6V/12V/24V battery pack can just use a lead acid charger unless it's out-of-balance.

\$\endgroup\$
2
\$\begingroup\$

Don't use a TP4056 for charging LiFePO4 batteries; it won't stop charging until about 4.2 V has been reached and while some LiFePO4 batteries will probably handle that without exploding, it could damage them and will shorten their cycle life (the number of times they can be charged and discharged without noticeable deterioration/capacity loss).

The maximum charging voltage for LiFePO4 batteries is about 3.65 V; they are less nervous about higher voltages than other Li-based batteries, but that is no reason to abuse them, or take risks.

We can't do product recommendations here, but you could search for LiFePO4 charger IC to find an IC suited for your purpose.

\$\endgroup\$
0
\$\begingroup\$

I've tried to charge my prism-cell LiFePo4 with smartphone charger using dc-dc buck converter to 3.6 volt, and it works. I suggest set the output voltage to about 3.34 volt so when the battery voltage is 3.34v, it will automatically terminate (at least with in my case).

Hi @SamGibson. I'll answer here, as It is too long for comment section:

My case: I'm using Aukey 54W smartphone charger. Using cheap dc-dc buck (XL6009), gives about 7watt current. I use it to charge my 23Ah prism-cell. So, the charging is <1C in my case == safe.

About my answers, as far as I know, smartphone chargers is just using CC, about ~5 volt with variable current. Cheap dc-dc buck will scale down the volt to 3.34 and the current usually to 2.1A, around 7 watt (using Buck Boost XL6009) or less. It should be quite safe to charge using this method, provided we know dc-dc buck converter output and maximum charging current (we can buy converter with configurable output voltage and current). Nothing wrong will happen when we charge like that, as LFP charger, too, will use CC to charge to around ~95% (~3.34v), and continue with CV to charge to 100%.

Me? I don't want to charge to 100%. So CC is fine. As for terminate charging, when input = output, will terminate automatically in my case. Tried that multiple times.

A few sources. We can googling for others if the info here is not enough:

  1. https://www.powerstream.com/LLLF.htm#:~:text=Because%20an%20overvoltage%20can%20be,batteries%20are%20safely%20force%20charged;
  2. https://battlebornbatteries.com/charging-battleborn-lifepo4-batteries/;
  3. https://www.power-sonic.com/blog/how-to-charge-lithium-iron-phosphate-lifepo4-batteries/#:~:text=Float%20charging%20is%20only%20required,any%20battery%20without%20causing%20damage.
  4. What are the problems with LiFePo4 float charging? How should I charge them?
\$\endgroup\$
5
  • 1
    \$\begingroup\$ Person that give minus point: Could you give a reason why? Did I do something wrong? How good your knowledge about LiFePo4? You can share here for us to know. \$\endgroup\$
    – tonny
    Commented Nov 12, 2020 at 15:27
  • 2
    \$\begingroup\$ tonny - Hi, It wasn't my downvote, but personally I disagree with the plan in your answer - perhaps the downvoter disagreed so much that they downvoted? The correct charging profile for LiIon, LiPo and LiFePO4 involves a current-limited initial CC phase, then CV, then the CV terminates when the charge current has dropped to a specified value. Your answer doesn't mention any of that, nor is it clear how your charging terminates. Using a CV source as you describe, could exceed the rated CC current, and has no mechanism to detect when the charge current drops at the end of the CV phase. True? \$\endgroup\$
    – SamGibson ♦
    Commented Nov 12, 2020 at 16:09
  • 1
    \$\begingroup\$ tonny - Hi, Please note that I don't care about this topic. I just tried to help you by replying why someone may have downvoted you. I don't agree about some of your update (e.g. a smartphone "charger" is not CC; you say that termination occurs automatically "when input = output" but that doesn't agree with all the LiFePO4 battery datasheets I have read, which specify a cut-off current when charging should be stopped; etc.). Your answer seems to describe what worked for you. That's fine on a forum; but on SE, answers must address the OP's question, not just what works for you. I'll stop here. \$\endgroup\$
    – SamGibson ♦
    Commented Nov 12, 2020 at 18:00
  • \$\begingroup\$ @SamGibson. Noted, and thanks for your input. I'll research further about this. From dozens videos, papers and articles that I read, none use smarphone charger, but a few use scaled solar panel to charge LFP . I've 3 different cell brand with different Ah, 2 different buck converter, and a few smartphone charger. Will try my method with the other 2. Me replying here, of course with the intent to help the OP. I usually just read. And I have no problem with down-voters too, as long as they give explanations, what is wrong with my answer. I'm still learning. \$\endgroup\$
    – tonny
    Commented Nov 13, 2020 at 7:31
  • \$\begingroup\$ @SamGibson. I've appended my sources. In source #4 You could read hclarkx post. It's similar with my finding. No charging will occur when input = output. As for my smartphone charger, it's universal charger using IC. When charging li-ion smartphone, it use CC CV. But when I'm driving Microcontroller or LED, it act like using CC. For charging my LFP, cause maybe bacause I use dc-dc buck, the charger see it as something like microcontroller. Meaning, it uses CC. \$\endgroup\$
    – tonny
    Commented Nov 13, 2020 at 8:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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