Originally Posted by jr dragster
I am going to build an electric jr. dragster for my daughter....... Please give me your ideas on motor size,controller and battery.
Hi jr dr,
You might be able to find some example systems and build info searching in the bikes forum here. It seems like a lot of kart builds end up there as well. Here is a parts list for a kart kit (just for example). http://store.kta-ev.com/Go%20Kart%20...%20(Basic).pdf
I personally would not use a PM motor (like the Mars) (and please call the electric motor a motor, not an engine). The Mars motor may be a good product, but I have seen too many PM motor parts laying on the drag strip and race track to recommend them. Stick with a series wound DC motor for great starting torque and durability. I think you should look at the 6.6 inch diameter motor. A bit heavier, but commonly available, and can provide good performance at low voltage to start and take increased voltage system as you upgrade.
With that in mind, you may wish to find a controller which will accommodate a wide range in battery voltage. WRT the batteries, this application requires power more than a large energy stored. Small Ampere hour (Ah) AGM Pb-Acid 12V batteries will work and not cost an arm & leg. Hawkers or Genesis brand are good. Lithium would be best, high C rate jobs, like A123 or Headway. Maybe even rob some Dewalt tools. You can get into the info forum here and read about energy, watt hours and Ah and such and figure out the number of runs per charge. Most such racers charger inbetween passes. You get the most power from a freshly charged and warm battery.
I think you will benefit from starting modest and working your way up in performance, meaning system voltage and power. Your mistakes will be less costly and you'll get it on the track sooner