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Cheap Lithium Ion Chargers - Safe?

Discussion in 'General Electronics Discussion' started by SLRist, Jun 12, 2012.

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  1. SLRist

    SLRist

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    Jun 12, 2012
    Hello.

    I purchased two cheap ($15) Lithium Ion chargers from Amazon to recharge the battery for my Canon camcorder. These chargers are sold under several different brands and are very popular. The top-plate shown here is removable and plates for other types of batteries can presumably be substituted, though mine only has one for Canon camcorder batteries:

    [​IMG]

    Having read a little on the potential dangers of charging Li-Ion batteries (mine is a Canon BP-819) I was a little concerned that the cheap charger may be relying on the built-in safety electronics of the Li-Ion battery to cut charge rather than implementing anything particularly sophisticated. I'm also a little concerned that it might not take account of the variable charging demands depending on the starting voltage.

    To see exactly how sophisticated the charger was, I too it apart (I needed to have to it with a saw, as it was sealed closed at the factory). The image below shows what I found.

    Now my experience with electronics may be a bit limited, but I don't see how you can configure any kind of sophisticated charging and monitoring routines with an opto-isolator and a dc-dc converter chip. Am I wrong?

    Apart from the risk of explosion or fire, what is this likely to do to the life of my batteries? Is it always best to buy the charger made by the manufacturer, or are they no better? Are there more sophisticated universal Li-Ion chargers which can be purchased?

    Many thanks!

    [​IMG]
     
  2. BobK

    BobK

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    Jan 5, 2010
    Lithium batteries are actually one of the easier kinds to charge. You use a constant current unit it reaches some voltage then swich to constant voltage until the current drops to zero. This could be enough circuitry to do that.

    Bob
     
  3. CocaCola

    CocaCola

    3,635
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    Apr 7, 2012
    I use cheap Asian chargers like that for all my lithium batteries, and I have never had an issue... I have one on my desk right now that always has a backup cell phone battery in it that I can swap out on the fly, the battery sits on the charger 24/7 and never even gets warm or shows any significant signs of excessive wear...
     
  4. SLRist

    SLRist

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    Jun 12, 2012
    Thanks. Do you know if charging stops automatically when it hits full charge? The LED on the device extinguishes, but I couldn't think of an easy way to check. I read that it's really bad for their lifespan to 'trickle charge' them.
     
  5. CocaCola

    CocaCola

    3,635
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    Apr 7, 2012
    That is really a loaded question, but in general yes I would assume that in most cases the charging stops... The fact that the LED goes off, but if you remove and re-inserted it the LEDs comes back on would lead me to believe that it has some basic logic in there monitoring the battery and turning the charging on/off...
     
  6. SLRist

    SLRist

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    Jun 12, 2012
    I guess I could tape a thermocouple to the battery case and see if its temperature drops to ambient after the charge light goes out.
     
  7. BobK

    BobK

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    Jan 5, 2010
    If you really want to know, put an ammeter in the circuit.

    Bob
     
  8. SLRist

    SLRist

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    Jun 12, 2012
    Ah yes - I didn't think of that - I was thinking of voltages!
     
  9. weird_dave

    weird_dave

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    May 9, 2012
    It used to be the that Lithium Ion cells had battery protection circuitry built into the cell package, anyone know if that's still the case?
     
  10. BobK

    BobK

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    Jan 5, 2010
    I believe the batteries sold to consumers do typically have this protection.

    Bob
     
  11. khankll

    khankll

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    Feb 6, 2011
    these are pretty basic and good chargers..

    i have opened many nokia chargers they also have same two chips opto coupler and the motrolla chip..

    i have the cheapest cell phone universal charger .. which can charge any cell phone..
    i also had same concerns as urs so i decided to get a check on it..
    as an empty battery bl5c was inserted it started chargng it at a constant current of 300ma then as the voltage climbed past the 4 volts the current was reduced to 100-15 ma and at battery voltage at 4.17 it stoped.. so i think they are good and practical.. i also pryed the battery's protection circuit apart and i connected bare bl5c batter with charger through wires and it still charged it to 4.17 volts and then stoped..

    i then charged a 18650 cell protected in it got it charged to 4.17 ... charged unprotected still same results..

    so in my opinion they aree trustworthy.. and believe me charging liion is the simplest of all.. charging stops when battery terminal voltatge reaches 4.17-4.2 volts... in contrast nimh/nic charging is very very complicated..


    all liion lipolymer use same charging procedure.. and all lion lpoly batteries are same only difference is physicasl shae.. some wil be cylinderical other prismatric some physically small other fat or tall.. only if u could get the contacts of battery connected to chargers proper contacts u are fit to charge it.. in any liion lipoly charger.. i have een doing so fo some 3 years ..
     
    Last edited: Jun 14, 2012
  12. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    All bets are off if you get no-name or faked name ones on Ebay from the cheap Asian suppliers, make sure they are reputable sellers don't go for the bottom of the barrel...
     
  13. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,500
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    Jan 21, 2010
    Some do, I expect some of the cheaper ones do not.

    It's easy to tell with bare cells. For built up batteries it's harder, and using individual protected cells is apparently not a good idea.
     
  14. celiadeng

    celiadeng

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    Jul 3, 2012
    Generally, most of the Lithium Ion has the automatic intelligent protection functions such as over-charge, over discharge, overload, short circuit, lightning protection functions.Maybe you can come to Mobile Power Mall and pick some one in high quality.It won't come across this problem here.
     
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