Setbacks and Batteries

Well, after playing more with the IMU, the roll gyro has stopped working! I performed a visual inspection of the breakout board, and didn't see any shorts or signs of arcing. I reworked all the solder joints, making sure none of them had come disconnected. Finally, I removed the gyro daughter board from the IMU and tested it on its own, still no luck. The self-test function also is not returning anything, so I think it's stuffed.What a pain in the ass! Just as I was starting to get somewhere with the Kalman. Fortunately Sparkfun have offered to take a look at it and see if they can figure out what's wrong (and perhaps replace it!), as at the moment I can't afford buying any new sensors ($30 shipping every time is a killer!). If I have to buy a new one, I guess I'll have to wait until I have enough cash for a GPS unit, magnetometer and TTL->USB board as well so I don't get nailed for shipping twice.In the mean-time, I ordered some LiPo batteries for super cheap off ebay (E-Fly 2S, 900mAh, 15C), 3x batteries for $10! And only $10 shipping (from Hong Kong). I know what you're thinking.. never buy cheap & nasty batteries, but this is a low-budget project. I'm hoping these batteries will replace the 8.4V 650mAh NiMH batteries that my helicopter has been flying off, and that the weight saving will give me a bit more leeway with my autopilot payload. The only thing that I am concerned about, is that if these LiPos have built-in under-voltage protection (ie. switch off after reaching 3V per cell). Is that standard on all LiPos these days? Being a no-name brand, I couldn't find any specs on the batteries themselves..If I can sort that out, hopefully I can blow the dust and cobwebs of the heli and get some flights going this weekend to re-balance the helicopter and trim it right up.
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  • Developer
    Use cheap batteries with a good balance charger, but good batteries may last longer. Check out Hyperion's new Hybrid RS Nano Technology,
    I have a friend who flys a large 10 cell 4500mha pack in a T-Rex 700, He reports that these packs just get warm during a hard flight 110°F, while others pack got very warm 138°F , These can charge at 5C rate and stay cool... I have one Hyperion Nano Tech 1300mha pack for my BlueStik UAV it is working great...
  • Developer
    I had problems with 1st generation Walkera helicopter batteries and chargers several years ago. . Their poor protection devices limit output current and may cause over charging...

    These old batteries were 3 cells 1800mah with 18v charger that the protection board regulation to +12.6v when the protection board fails 18v is applied causing over charge and battery failure , lucky no fire....
    I have many cheaper batteries that perform well, Proper charging with balancer and only discharge to 80% will keep battery healthy...

    I have 2 factory batteries with these circuits running in a new 7"LCD HDTV monitor by Haier, 2200mah 7.4v this pack is current limited for this device. Since it is new and has a internal charger I will trust far so good.
  • I never have had troubles with HobbyKing batteries... I watch them closely upon the first charge, but that's about the only precaution I take.
  • Admin

    The LiPo low voltage cutoff is usually programmed in the ESC. I do not know of any LiPos with built in low voltage cutoff. You might check to see if the ESC in heli can be programmed for a low voltage cutoff. However, you do not want to be in the air when the ESC cuts off the battery power to the motor!

  • Moderator
    Unless its all you can afford, just don't fly them for as long as you would have the others and always balance charge the.
  • Never buy cheap & nasty batteries!
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