Syma Forum

A battery charged to 4.2V is still good.  I have replaced batteries as early as 300 minutes of flight time.  These motors fail fairly quickly as well.  I had to replace one motor at +300 (Motor B) and another at +450 minutes (Motor A) of flight.   The failure of lower rotor/Motor A (Black) is harder to detect during its death throes as the rotors continue to spin mostly because of the lower rotor blade interaction with the upper rotors blades.  When my heli's start to do the floor hover thing I first check the battery.  I then check the integrity of the drive shaft-rotor grips.  There should be no play in the shaft-grip connections.  I have large and shedding dogs; hair can really foul up those gears.  The gears should mesh.  Sometimes one of those little secondary drive gears drop down.  They need to be popped back up into position.  There are a lot of "How To" videos here that are very helpful for DIY repairs.  When I replace motors or batteries I leave a lot of the former part's wires intact to make reconnection easier.  It does contribute to a bird's nest of wires, but part replacement is much easier to accomplish.  I also recommend soldering those wire to wire connections.  A more secureconnection than just awire wrap and tape connection (Please do not look under the cowling on a couple of my S107's ).

Good Luck.

Thank you for the reply.

I installed a plug on the battery wires so that I could swap out batteries easily.

The wires run under the heli and I used velcro to attach the battery to the underside.

I took the gear box completely apart and removed the two motors.

I tested the motors without a load and found out that the black one was bad.

I took the black motor apart to see what the problem was and found that one of the brushes had broke off.

I found another syma s107g on CraigsList that was broken for sale $10 and bought it.

I was able to fix the heli and off and flying we are again.

Our dogs hate it but they cant reach it.