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Thread: Syma LiPo management

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    Junior Member bmscott's Avatar
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    Default Syma LiPo management

    Recently I bought a used Syma X5c with many spares/etc on eBay. I got it flying - briefly, anyway - and for the $15 I paid, I wasn't even expecting that much!

    I've got about a dozen batteries and two of those little black USB-to-5x batt chargers. Half the batteries are puffy and I put them to one side for proper disposal right away. The rest - well I don't know if the chargers are even working, the lights are either all on or all off, or flickering, but bear no relation to how many batteries are plugged in.

    The batts measure mostly in the upper-3v range, some change after being on the charger awhile and others don't, but even one I got over 4v won't start the drone (it's stuck in fast-blink mode). The one that did work, ran the drone for about 2 minutes. For all I know the whole thing could have been on the shelf for a year and it was the last battery that had held any charge, and the chargers aren't really working. Or, all the batteries could be used up - it's clearly seen a lot of hard use.

    Is there a way to properly test these batteries? I can look up charging specs and charge them with my bench supply, then - put a resistor in circuit and watch the voltage drop, maybe? Is there a simpler way? I have a USB-to-battery charge cable for my Syma X26 but it won't fit the X5 battery plugs, so all I have for now is those little junky 5-battery chargers, which weigh nothing and seem flimsy anyway. Hard to tell if they're doing anything!



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    Quote Originally Posted by bmscott View Post
    ..,..Is there a way to properly test these batteries? I can look up charging specs and charge them with my bench supply, then - put a resistor in circuit and watch the voltage drop, maybe? Is there a simpler way?
    That is the (extremely simple and effective) procedure I would use.

    Goodness me! How much simpler can you get?

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    Junior Member bmscott's Avatar
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    Quote Originally Posted by tristen View Post
    That is the (extremely simple and effective) procedure I would use.

    Goodness me! How much simpler can you get?
    Well given that I'd have to go dig out some power resistors and clear space to set things up, and if I do it wrong I could blow up the battery, plus I don't really know what results to expect (I can dust off my old P=IR skills to guess what level resistor to use, but then what kind of voltage drop is normal?) I was kinda hoping there was a battery load tester out there - ideally, one cheaper than those for SLA batteries. Or better yet, a better way to bypass the possibly-dodgy chargers without waiting for something to arrive via mail order (the two nearest hobby shops don't stock Syma parts), if only to rule them out as the cause.

    The 'simple' procedure will likely take me a week or three to get around to and half a day of spelunking through my crap, as my tools and parts area has become a junkyard crammed into a tiny room... but I take your point.

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    I use one of these, charges, discharges, measure actual cell capacity, does 1S to 6S lipo packs (does NiMH and other battery types as well ;



    You'd need hack together your own battery connection (or buy one ) ...I actually just opened the small USB charger housing and use those connections on the PCB.

    Sounds like your lipo cells are stuffed, they don't like being stored anyway but should be charged to 60% capacity if you need store them for any length of time.

    Nominal cell voltage is 3.7volts, fully charged will be 4.2volts. They can be discharged to as low as 3volts but most flight controllers shutdown if voltage drops under 3.5volts or so (depends on brand/model).

    Lipo cells for RC models have high current discharge capability, expressed as their 'C' rating ...ie; for x5c the cell needs to be rated 20C or better. There was (and probably still is) heaps of cheap batteries on ebay for these & others, sold as being 20C types but were closer to 10C in reality -- if you try to pull 20amps out of a battery only designed to deliver 10amps, bad things happen (pack 'puffing' is an example). They also have a maximum charge rate that varies from brand to brand as well, and likewise a cell only designed to accept 1.5amps of charge, will go really bad (puff, burn or explode) if you try charging it at 5amps. Those small USB chargers only deliver about .5amp at best. There'd be more than a good chance you're looking at dubious quality batteries.

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    Quote Originally Posted by tristen View Post
    That is the (extremely simple and effective) procedure I would use.

    Goodness me! How much simpler can you get?
    For charging lipo cells, you need a constant current source & regulated voltage ... 'on the spot' circuit, charge curves, explanation;



    A search for 'simple lithium-ion battery charger circuit' will get the hits OP is after.

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    You're full of excuses!

    As my mother used to say to me as a child..."Would you like me to wipe it for you too?"

    Now, having got that off my chest...

    You need to bear in mind that there are several types of "lithium" batteries and all types require a specialized charging method, although a "simple" method, such as you have referred to, will work with certain provisos.

    There are special chargers for lithium-based batteries.

    If charged inappropriately, lithium batteries can ignite. Yes, it's happened to me when I first started experimenting with lithium polymer (LiPo) batteries as I was curious to see "how far I could go".

    But...I took appropriate precautions to make sure that the batteries were placed on a non-ignitable surface such as brick, concrete or asbestos, and that they were well-away from anything inflammable or otherwise vulnerable, e.g. body parts...particularly eyes.

    I used a variable voltage, variable current-limiting power supply set appropriately.

    You have failed, like many other newcomers to the forum, to provide ALL relevant information...i.e. what markings (if any) are on the batteries. Such detail would allow members to advise you more accurately.

    Having said all that, there is plenty of on-line information available and within easy reach to you.

    I suggest that you start at .

    Please read the reference I have provided and then return with your questions if you require any further advice.

    And, please keep us informed of your progress. We ARE interested.

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    Junior Member bmscott's Avatar
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    Quote Originally Posted by tristen View Post
    You're full of excuses!
    So let me get this straight - I ask around to see if I'm overlooking a solution simpler than my first guess, you respond that my guess is already simple enough, I explain why it isn't (my time has value, to me if to nobody else), and now I've - disappointed you somehow...?!

    Quote Originally Posted by tristen View Post
    You have failed, like many other newcomers to the forum, to provide ALL relevant information...i.e. what markings (if any) are on the batteries.
    What's relevant is they're LiPo batteries from a Syma drone in unknown condition. If the markings on the batteries can help you provide anything more specific, it's beyond me as to how. I'm not asking about charging voltages or rates - I'm familiar with Battery University.

    Quote Originally Posted by wotnot View Post
    I use one of these, charges, discharges, measure actual cell capacity, does 1S to 6S lipo packs (does NiMH and other battery types as well ;

    THANK YOU - a very helpful, pertinent answer. I had no idea they could be had so cheap (I realize this is not the finest quality example of its category, of course) Definitely worth considering.

    Quote Originally Posted by wotnot View Post
    There'd be more than a good chance you're looking at dubious quality batteries.
    I'm aware of this, but hoping not - the batteries are packaged identically to others I've bought (for other models of drone) direct from Syma. Also the MicroSD card in the camera had footage of lengthy flights. I suspect they're just very, very well-used (why even have 10+ batteries for a $30 drone anyway?!) and if I can find one that gives me 3-5 minutes I'll be happy for now.

    Quote Originally Posted by wotnot View Post
    For charging lipo cells, you need a constant current source & regulated voltage ... 'on the spot' circuit, charge curves, explanation;
    Thanks - that also looks helpful and pertinent. I really just need to try charging each one once - if it holds anything more than a trivial charge, I'll invest in better chargers. If not, then I'll sideline this whole project until I have an actual use for this, as I have other (far smaller) camera drones.

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