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  1. #1
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    How to overcharge a lipo

    Title says it all, i have slash and 2 lipos, i DONT WANT TO OVERCHARGE them, but how do u do that anyways ? i have a hyperion charger and it stops when the charging is complete, how do i over charge the battery if it stops automatically ?

    i assume 3s 5000mah lipo should have 12.6**v when its fully charged right ?
    and 2s should be 8.4**v when its fully charged ?

  2. #2
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    It may have to do with the 'rate' at which your charge the LiPo's, charging above the correct amps will surely over charge the batteries but not necessarily put them over voltage. Too much to fast is not too good!

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    This is a weird thread
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  4. #4
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    I think u can't
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  5. #5
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    You can over charge a lipo with a charger not in lipo mode or not lipo compatible.

    For charging amps, IMHO, you can damage the packs by charging too fast the same way as discharging too heavily by drawing too many amps. Most packs can do 1-2c charging just fine.

  6. #6
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    Quote Originally Posted by kwitty View Post
    It may have to do with the 'rate' at which your charge the LiPo's, charging above the correct amps will surely over charge the batteries but not necessarily put them over voltage. Too much to fast is not too good!
    kwitty is correct, overcharging is more about the rate of current (amps) than voltage, since a good LiPo charger will stop at 4.2v per cell. The SPC LiPos I have are rated at up to a charge rate of 2 coulombs (C). 1C = 1A/1000mAh, so my 5000mAh battery can charge at up to 10A. At 8.4V * 10A, this is 84W of power.

    ProgressiveRC.com has a nice charge rate calculator tool:
    http://www.progressiverc.com/chargingdemand

    The important thing, though, is check your battery manufacturer's recommendation on maximum charge rate, in coulombs to determine the maximum safe rate of current or amps to charge at.
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  7. #7
    RC Turnbuckle Jr. rag6's Avatar
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    You have a good charger, so it prob wont ever screw up, but you can. Your charger is prob capable of high charge rates. Check the batteries paperwork to see what the maximum charge rate is. It will say 1c or 2c (some even say much higher).

    If it is 1c max charge rate, then a 5000 mah pack should not be charged higher than 5 amps. A 5400 mah pack should not be charged above 5.4 amps.

    If it is 2c max, then a 5000 should not be charged above 10 amps, and a 5400 not above 10.8 amps.

    Thing is, if you have 2 packs then you really dont need over 2c. At 1c any lipo battery takes about 65 min to balance charge. At 2c around 35 min... Just about the time it takes to drain a 5000 mah pack. So with 2 packs, you can be charging 1 and running the other and pretty much have unlimited bashing 8*)
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  8. #8
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    and thats what i do, charging time never bothered me before, i dont care if its going to charge 30 minutes or 1:30 hour, i dont want the BLOWUP happen again in my room haha, so over charge is happening because of amperage, i use SPC and charge at 1c rate, so i guess i should be fine.

  9. #9
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    Yep, Agriganosa. You should have no problems at 1C with SPC. I've learned the most important thing I've done wrong is to leave a battery fully charged or fully discharged for more than a week. I have one pack that only has 80% of its original capacity because I didnt charge/discharge to a storage level of around I think 40% capacity (check mfr instructions). It still runs well, just not as well as it used to and I prob could have avoided that.
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  10. #10
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    Quote Originally Posted by Agriganosa View Post
    Title says it all, i have slash and 2 lipos, i DONT WANT TO OVERCHARGE them, but how do u do that anyways ? i have a hyperion charger and it stops when the charging is complete, how do i over charge the battery if it stops automatically ?

    i assume 3s 5000mah lipo should have 12.6**v when its fully charged right ?
    and 2s should be 8.4**v when its fully charged ?
    You already have some replies but none with the most important info. Voltages for lipo are not similar with other batteries
    Your "assume" is aready wrong 2s lipo will get you 7.2 volts and 3s lipo 11.1V
    good luck, get yourself a proper charger and you wil not overcharge your lipo's
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  11. #11
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    haha thats what battery will give out or OUTPUT which is yes each cell is going to be at 3.7v, but charges all the way to 4.2, and its normal, i called SPC they say that input should be at 4.2v for each cell. I am not wrong, or if i still is tell me

  12. #12
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    Quote Originally Posted by Agriganosa View Post
    haha thats what battery will give out or OUTPUT which is yes each cell is going to be at 3.7v, but charges all the way to 4.2, and its normal, i called SPC they say that input should be at 4.2v for each cell. I am not wrong, or if i still is tell me
    Short answer: U R right. He is wrong.

    Long answer:
    A fully charged 2S will read 8.4V and 3S 12.6V. Similar for NiMh, a 6-cell battery with nominal voltage of 7.2V will read about 8.4V fully charged and 7-cell NiMh nominal voltage is 8.4V but fully charged is about 9.6V. All batteries have voltage drop as they discharge, regardless of chemistry.

    Biggest difference with LiPo is its power flow output, measured as current in amps, remains relatively steady from when the pack is fresh until the voltage cutoff shuts it off at 3.4V per cell, so 6.8V for 2S or 10.2V for 3S. Current flow drops off much more rapidly as the voltage drops with NiMh on the other hand. That's why LiPos are more fun to use - you have full power from start to finish instead of continually diminishing power.
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  13. #13
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    Quote Originally Posted by Agriganosa View Post
    haha thats what battery will give out or OUTPUT which is yes each cell is going to be at 3.7v, but charges all the way to 4.2, and its normal, i called .... they say that input should be at 4.2v for each cell. I am not wrong, or if i still is tell me
    I am not sure what you are trying to say??

    A LiPo cell is completely empty at 3.0 volts, fully charged is 4.2 volts, nominal (resting) is 3.7 volts.
    Quote Originally Posted by OlorinTharkun View Post
    Short answer: U R right. He is wrong.

    Long answer:
    A fully charged 2S will read 8.4V and 3S 12.6V. Similar for NiMh, a 6-cell battery with nominal voltage of 7.2V will read about 8.4V fully charged and 7-cell NiMh nominal voltage is 8.4V but fully charged is about 9.6V. All batteries have voltage drop as they discharge, regardless of chemistry.

    Biggest difference with LiPo is its power flow output, measured as current in amps, remains relatively steady from when the pack is fresh until the voltage cutoff shuts it off at 3.4V per cell, so 6.8V for 2S or 10.2V for 3S. Current flow drops off much more rapidly as the voltage drops with NiMh on the other hand. That's why LiPos are more fun to use - you have full power from start to finish instead of continually diminishing power.
    A LiPo battery pack sees continually dropping voltage under load as does every other type of battery pack while under load. With voltage drop comes a potential power drop. Current day Nimh cells and packs perform so poorly as to be nearly worthless. Some Nimh cells and packs from 3 and 4 years ago would perform on par with many of today's 5000mAh/30C packs.

  14. #14
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    hmm hyperion charger eh there is a tvc that you can adjust i think you can get it up to 3v per cell(not certian)

    and the hyperion does a 20a charge rate at 90w ac and 150w dc

  15. #15
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    Quote Originally Posted by Jakey View Post

    A LiPo battery pack sees continually dropping voltage under load as does every other type of battery pack while under load.

    Are you getting tired of saying that yet?


    I honestly don't know where the whole "lipo runs the same all the way til LVC" theory comes from. I rarely ever hit LVC with any of my cars because they get too slow to clear all the big jumps long before that point.

  16. #16
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    Quote Originally Posted by harry697 View Post
    Are you getting tired of saying that yet?
    You have no idea.

  17. #17
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    Quote Originally Posted by harry697 View Post
    Are you getting tired of saying that yet?


    I honestly don't know where the whole "lipo runs the same all the way til LVC" theory comes from. I rarely ever hit LVC with any of my cars because they get too slow to clear all the big jumps long before that point.
    I tested fulyl charged lipo on my slash and it ran 65mph with 31/76 mph, right before lvd turned on i got 63 mph, so yes it does hold same power until it hits lvd, thats personally for me, idk about your lipo packs

  18. #18
    RC Turnbuckle Jr. harry697's Avatar
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    Quote Originally Posted by Agriganosa View Post
    I tested fulyl charged lipo on my slash and it ran 65mph with 31/76 mph, right before lvd turned on i got 63 mph, so yes it does hold same power until it hits lvd, thats personally for me, idk about your lipo packs
    How do you figure it holds the same voltage until it hits LVD? Take your fully charged lipo (4.2 per cell) and run it for 5-10 minutes. Then take a reading at your balance tab. Does it still say 4.2 per cell? Then go run it for another 5-10 minutes and check voltage again. Does it say 4.2 per cell then? There's no possible way your pack holds the same voltage through the entire cycle.

    I generally shut my cars down once I can't clear the big double. Voltage is usually 3.6-3.75 per cell. Granted, the pack recovers a little by the time I get the body off and check it, but it hasn't tripped the LVD, but it's also way slower than when I started the run.

  19. #19
    RC Turnbuckle Jr. Emaxx2.0's Avatar
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    Oh boy. Lipos do not hold full power until LVC. What a lipo does is hold it's voltage better under a load. It a slow process but the power is not the same.
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  20. #20
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    Sorry about the full power mistake. Compared to a lousy NiMh I spent $ on b4 the LiPo keeps _much_ more power until the end of the run.

    Of course it drops off towards the end, but I usually still have plenty of power to pull wheelies until almost LVC.

    Since I only bash, no racing or speed runs, I probably don't notice as much as some of the more experienced fellas.
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