amps/motor burnout

[scottyb]

newbie here. i have a 13 turn motor in my tc3 all just 3 weeks old. today my motor crapped out on me. lhs said running 3300 batteries combined with that motor, that if i extend runtime the amps will drop and burn out the mototr. i was running about 20-25 minutes on a battery and he said that was causing the amps to drop, maybe not the voltage, and was burning the motor. sound right to you guys? if so, how do you know when to change battery? in the 20-25 minute runtime the speed doesn't really drop, so can't use that as an indicator-

[chevy camaro]

get rid of that 13 and get a 19 double that 13 is for low end power not top end trust me it will be much faster with a 19. Thats what all the local racers run . a newbe came to race with a 12 turn and he started 2 and ended in last. one of the racers handed him an old 19 he wasnt using and he finished in 3. so with that in mind choose a diffrent motor MIKE:)

[ElectricThunder]

What do you mean a 13 turn is low end power? When you say power do you mean torque? If so, higher turns definitely have more torque, but lower turns have more power, or watts. But anyways, does the motor get hot at all? Try gearing differently, as this will give varying amperage loads on the motor. With a 13 turn motor, there's no way in heck you should be getting 20-25 minutes of run time. At most, 15 maybe. :eek:

[chevy camaro]

and check the timing. yea i ment torque .If it has adjustable timing set it at zero degrese if you advance it to much you will burn up the brushes and com .Same if it is retared to much all you want to go at the most it 25 degreese ether way

[highroller]

Modified generally those in the 6-14 turn area used for racing were made to run for only 5 minutes. Depending on the type of motor you have there could be several things contributing to motor problems. 1. spring tension is usually inadaquate the springs motor came with may be too light - most use Purple springs with motors producing over 28, 000rpm 2. gearing may be off for the motor and amount of runtime you are getting - adjustments need to be made for the type of motor used, and sometime minor adjustments to gearing need to be adjusted further for using different turns or winds, changes in timing all to allow motor to run cooler. 3. timing may also be needed to offset the power a little, less timing would reduce the rpm range, reducing the amp draw but allow motor to run a little cooler 4. maintenance issue - most will only run a modified for 3 battery packs, sometimes after each pack (4 or 5 min heat) then check and perform maintenance as needed - in your cases you are running almost 5 heats. So if you are getting up to 25min of runtime you subjected motor to more wear than most racers see in one heat - I've worn out one set of brushes, almost destroyed a comm with a 13turn triple after one 4min heat because springs were too light, and timing was set too high.
As motor wears or something goes wrong the amp draws goes up it hardly ever goes down as the person explained.

[highroller]

The true power concerning modified is they all develop close to the same watts (HP) but the actual rpm (acceleration) levels and torque (pulling power) changes a bit depending on the turns or winds or size of wire that a motor builder uses. Usually a motor with less turns or winds (less wire) produces higher rpms ranges, less torque while a motor with more wire (higher turns, more winds) produce less rpms and higher torque. While a 10 turn double and a 13 turn double would reach the same 55mph speeds in the same vehicle, the 10turn double would be more ideal in certain instances.
It's abiltiy to accelerate quicker, allowing it to reach that 55pmh range than the 13x2 but the undersired result may be lesser runtime (run into problems dumping), on a track or surface with less than ideal traction you may not be able to use the full benefits of motor power - that low end power (hard acceleration) may cause tires to break loose. Then you may get two motors both being 13x2 but one using a smaller quage wire - the one using smaller quage wire due to armature being lighter should accelerate quicker than the one with heavier or larger wire.

Since the motor used, power range changes the gearing needs to be changed to suit the motor expected power output. Switching from a 13x2 to a 11x2 may require you go down 1 or even 2 pinion teeth to suit the change in the differences in motor power. Even changing the timing generally requires a change in gearing as well - you want motor to continue to run strong, cooler without sacrificing performance or increasing wear.

[scottyb]

thanks everyone-interesting replies