Amp draw question?????

[Toiffel]

After cutting the comms on my motors I use my Pulsar 2 motor run in function to break in the new brushes and so on. But I've noticed that the amp draw for each motor is different, the same for modified and stock motors, sometimes I have high readings 13amp others low 5 amp (run in set at 3v) also noticed that sometimes the motors with lower amp draw have better performance than the high readings.

What exactly does the amp draw mean??? should I judge my motors by this number??? or is it just a reference??? and if so for what????

Thanks for all the help....

[TEM]

You can use it for reference. I use CE chargers and here are my typical findings for typical stock and 19t for touring car use. My freshly done up stock motors pull from 9 to 11amps at 3 volts no load. After a couple runs, the same motor would pull around 6 amps at 3 volts no load. The 6 amp motor is still relatively fast on the track(no the amp draw is not directly proportionally to the performance), however, a small change in performance. If you are counting tenths between you and the guy next to you, yes there is a difference, especially on a large track. As for the 19T motors, the C2's behave like the stock motors in terms of no load current draw. I just started playing with Peak Dynastys, my T35's say amps too high when I try them at 3 volts. At 2 volts I'm getting around 13amps draw with a new motor thats just done up the "regular" way. Back on the track, they have not been proven to be much faster than my C2's despite the high no load current draw. But this current draw data can be used to evaluate how much a motor has changed. All I can say is if it's drawing too little amps, it's "probably" too slow(compared to same kind of motor, of course), and we're talking 3 amp at 3 volt stock motors!

[Grizzbob]

Right, there are too many factors that influence amp draw on a motor, that you really can't use that alone as a performance indicator, it could mean anything from the motor starting to make the kind of power you want to just dealing with more internal friction than normal(or higher electrical resistance than normal), so I wouldn't worry about it too much(unless it affects how the motor runs in the car)..... :cool:

[highroller]

Agreed, amp draw is not always related to how well the motor might perform but might reveal some problems that are going on with it. Usually you found that reading between 7-9 amps are the ideal area, while higher rates seem to have a direct relation to how motor performs on track. Those in the middle tend to have power start to end, while the higher amp draws run strong at the start but seem to fall off in the middle to end, those on the low side run strong forever but don't have the punch or top end.
As brush wear in or start to overlap the comm or changes in comm diameter from truing may cause slight increases or decreases in amp draw. What helps sometimes to bring amp draw back inline is filing or reshaping the brush, some file the leading and trailing edge at an 35 degree angle some are also trying to cut the trailing edge (.001) to reduce amp draw. Others are finding going back to a light spring tension, reduces some of the amp draw.
With amp draw it can be a relative method of what might be an okay motor, as long as the same testing technique is used as far a voltage settings. Some use a 1volt setting with fan attached, others use other voltage settings with or without a fan. Just like in dyno testing, the higher numbers doesn't always compare to actual track results - the idea is to get similar motors close to the same numbers as the best performing motor whose numbers might actually be lower.

[Toiffel]

thanks for the info guys