You often find salvaged phone batteries in cheap imported products. It makes sense to reuse them in a less demanding application once their capacity has dropped a bit. Some of those products rely on the batteries internal protection circuit to prevent overcharging when simple USB or solar chargers are used.
I've used them in projects like this too, but I always double check that there's protection there and that it's working.
I do this by connecting the battery to my bench power supply and setting the voltage fro about 4.5V with a 500mA current limit. The voltage measured across the battery should gradually increase to between 4.2V and 4.5V whereupon the current will suddenly drop to zero as the cell protection kicks in. If the voltage keeps rising above 4.3V then there may not be a protection chip in use.
The battery I show in this video is the first of this type that I've tested that has not had a full protection PCB despite having the usual gold flashed PCB contacts.

16 thoughts on “Unprotected phone battery copies.”
  1. Avataaar/Circle Created with python_avatars Martin Clemesha says:

    Maybe 4 years ago, but I still enjoy this type of format Clive. Useful reminder, and gives an understanding of the basics. Good to know the charging characteristics for using a bench power supply for charging.

  2. Avataaar/Circle Created with python_avatars MɅNU says:

    I wonder if I could replace old Samsung battery's pack with a new one (albeit a different sized pack) and use the protection circuit from the original battery. Would this is possible? if yes, is that even a viable option to DIY replace batteries for old phones that even 3rd party parts are not being made.

  3. Avataaar/Circle Created with python_avatars JPAG0806 says:

    Thanks for this videp👍.
    I see always 3 cupper connections on these batteries: +, ~, and connection 3: what is the function of this??

  4. Avataaar/Circle Created with python_avatars 那個誰SOMEone says:

    I bought one from china for 2.5 USD, and to my surprise, it does have protection circuit, I guess some of them do care about quality, but still, thank you for your warning. I only disassemble one of them, there is still a chance that I was lucky to pick up the right one.

  5. Avataaar/Circle Created with python_avatars electroumit says:

    Sticking the Li-ion battery behind the solar panel is not a very good idea. In the sun, its temperature can reach 70 degrees Celsius. Thanks. We love your videos.

  6. Avataaar/Circle Created with python_avatars Peter Sage says:

    I've just tested 3 batteries from phones I've previously recycled. The two Alcatel batteries have short circuit protection; the battery from a TCL Raven does not. (I only buy phones with removable batteries ever since I had a phone with a soldered-in battery die because it drank water in through the charge port from a damp pocket in a rainstorm.) Just goes to show that even a fairly known brand of phone can have unprotected batteries.
    Curious and concerned, I quickly tested the battery in my LG Rebel, and it happily does have protection.

  7. Avataaar/Circle Created with python_avatars UsernameNotDefined says:

    BS-5Crap

  8. Avataaar/Circle Created with python_avatars Charlie Chavez says:

    can I use this board to charge 18650 battery?

  9. Avataaar/Circle Created with python_avatars 987inuyasha says:

    I bought a BL-4U (3.7V) battery for my Nokia 515 how if it has IC built in?
    It came without packaging.

  10. Avataaar/Circle Created with python_avatars ⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻⸻ says:

    dont phones also have a protection on them aswell

  11. Avataaar/Circle Created with python_avatars Felenov says:

    Nokia batteries. Used them in many projects. I always made them easy to remove and put it in a Nokia or into the charging station I made. Very handy. No time for charging? Just change the battery over

  12. Avataaar/Circle Created with python_avatars Hyper Hektor says:

    why dont you just buy TP4056 for charging your Lithium Batteries? just 19-40cent per PCB
    i use them also for Nokia batteries and also for 18650 types.

  13. Avataaar/Circle Created with python_avatars Peter Feerick says:

    Now really Clive… real men don't need protection, let alone double protection 😛

  14. Avataaar/Circle Created with python_avatars Ivan Adriel Marchetto says:

    ahhaha I found out the same a long time ago, since then i save the protection circuits from dead litium batteries to use them in other bateries without it, to make more "safer" projects hahahha XD

  15. Avataaar/Circle Created with python_avatars crapcbm says:

    Do you know a safe source for a E61i battery?
    My batterie (original from … 2007?) now begin to get fat … so throw it in the battery bin.
    But you don't know where to buy a genuine / safe replacement …
    On my 9210 I bough a cheap one … the blown up and I believe if I did not see it, it would been burning…
    so a big risk today for old phones

  16. Avataaar/Circle Created with python_avatars david vanhorn says:

    The body diodes are present except in very specialized mosfets.

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