[jr dragster]

I am going to build an electric jr. dragster for my daughter who is 10 years old.Last year was her first year racing with a stock 5 hp Briggs with a best run of 15.77 at 40 mph in the 8 th mile.We would like to run in the 10's to 60 mph(she wants to go faster),the car weighs 285 lbs without the driver,I have not yet pulled out the Briggs -thinking it will weigh 240 with out the engine-we must stay under 400 lbs.There is more info at Nedra.com. Now for a newbie question-in knowing weight will be an issue can i get power out of a 24/36volt or 48 or do I need 72. There are some Mars motor on Ebay with controller for under $1000.00-good buy???Do I need a progammable controller? How many runs do you think we would get out of batteries before re-charge?I think I will use a DC motor.I would like to do this for around $1500-$2000 if possible.Will post some pics asap.Thanks for any advice.I own a bodyshop and have a friend who is a machinist and another who is an electrician so we can fabricate most of the parts if needed. Please give me your ideas on motor size,controller and battery.
Thank you!

[major]

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

Good luck.

major

[jr dragster]

pulled out ice .jr weighs 225 .how do you post pics my pics all say failed when i go to download

[jr dragster]

ev drives has a d&d es-10e-33 motor, 500 amp controller 36- 48 volt kit for$ 1091 its kit #5. Kit 9 has a d&d es-15-6 motor 450 amp controller 72 volt kit for $1293.with kit would you recommend to get the jr in the 10s in the 1/8 mile?? could you run the #5 kit at 48 volts then later run it at 72,or would it fry the controller?thanks for your ideas.

[Harold in CR]

Where you located ?? There are 2 FREE motors listed in the Classifieds, if YOU or someone you know, could pick them up. See Forklift motors, in Classifieds.

[jr dragster]

im in canada a little far to pick up .lol

Convert your photos to .jpg format if they are not yet and be sure they are not huge. 100k or so should be just fine. Much larger the server balks. No need to clog up the server with photos that are too large. Use your camera to get nice photos then reduce them in size. Then try again.

Pete

[Yabert]

My D&D ES-15-6 from my motorcycle is to sold: http://www.diyelectriccar.com/forums...ric-48239.html
This motor put my 340 lbs DRZ (+160 me) from 0 to 50 mph in 6 sec. But the motor only put watt to the ground.... the power come from headway batteries.

The alltrax 72v 450A controller is really good and greatly configurable.

[jr dragster]

does anyone know the weight of alltrax axe 7245 controller?? The d&d weighs 62 pounds,i found 12 volt 22amp hr batteries that weigh 13 pounds each about $60.00 each .car weighs 225 batteries 6 x 13= 78 d&d 62 ,so im at 365 pounds so far have to stay under 400. so will the controller,wiring ,solenoid weigh less than 35 pounds or do i have to lighten the car some how. thanks

[Jimdear2]

Originally Posted by jr dragster

does anyone know the weight of alltrax axe 7245 controller?? The d&d weighs 62 pounds,i found 12 volt 22amp hr batteries that weigh 13 pounds each about $60.00 each .car weighs 225 batteries 6 x 13= 78 d&d 62 ,so im at 365 pounds so far have to stay under 400. so will the controller,wiring ,solenoid weigh less than 35 pounds or do i have to lighten the car some how. thanks

Go to the Alltrax site. If the info you need is not on their pages go to to the "Contact Us" page. They answer promptly.

http://www.alltraxinc.com/

Depending on length and guage of cable you are going to be close on the weight.

I have been running a small pulling tractor. Weight was/is a problem for us as well. Finally went to Headway batteries. We now have a (Edit change this to 99 pound from 65) pound battery that can produce over 100 (EDIT change this to hp from kW) for over 30 seconds. Check with some of the others like Yabert that have gone this route. Slightly more expensive then the lead you are looking at, but you will probably end up there anyway.

Jim