# Super Ghetto controller for cheap autocross car?



## onegreenev (May 18, 2012)

Now just imagine this as an AutoCross/Dragster


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## Batterypoweredtoad (Feb 5, 2008)

Lol-I have a good imagination.  

I can make it handle, I just need to make it go...........for very short periods of time.


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## tricklecharge (Oct 8, 2013)

I once saw an EV "controller" that consisted of a block of wood (probably like a 2x6 standing vertically). In the block of wood was a series of perhaps 8 flat headed bolts that followed the swing arc of a lever. Each bolt would complete the circuit to one battery in the pack so at lever position one the lever would direct connect the motor X volts at what ever amps the battery could produce, Lever position 2 would add another battery for 2X volts, lever position 3 would add a 3rd battery, directly connected to the motor for 3X volts, etc until at the final lever position all the batteries in the pack were directly connected to the motor. Ghetto, cheap, dangerous but it DID work.

-tricklecharge


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## onegreenev (May 18, 2012)

Yes, I know that switch. If you use a switch like that you need to hook it up correctly and it will take a bunch of contactors but remember that your contactors will be switched on and off under loads most of the time. Not high but under loads and it will kill them. If not connected properly you will unbalance your pack a whole bunch. You need to have your pack sized so you can divide it equally by how many switching zones you have. 

Lets use a 72 volt 12volt flooded batteries for your pack. You want low speed and high speed. A simple two speed controller. So when you are in low you don't just want to take out power from 3 batteries. You want it to take out from all 6 equally. So you need to have a switching setup that will connect all 6 batteries to provide 36 volts. Then when you switch into high speed that switch will need to put all the cells back into series for 72 volts. That way all the cells are drained equally but the switching box becomes quite complex as you add in different speeds. If you don't mind having batteries out of balance all the time you could just switch in different batteries and when in high all are connected. Still a rather complex setup. There is no Current Control and there is no smooth transition between speeds. It is all on or all off. All the time. 

Get a good controller and stick with a single size pack. Easy to charge and you have smooth transitions and you have all out if you need as well. Even for a little box like that you really should have a decent controller. 

Pete


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## Batterypoweredtoad (Feb 5, 2008)

I am severely limited by budget. The cap is $2013 and I already have around $1000 in the battery and $350 in purchase price. I need to fit tires, wheels, suspension, a race seat, bodywork, AND a decently performing controller in the remaining budget. I could barely squeeze in an open revolt if I sell off some parts but 500 amps will only give me about 50 ft lbs of torque which will give me pretty leisurely acceleration. Anyone have a good source for ribbon nichrome resistor wire. I'm considering a 3 speed resistor controller like an old golf cart.


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## onegreenev (May 18, 2012)

Well the motor you have is not meant to be a race motor. If you want fast you need voltage. If you want grunt you need amperage. I would say that 500 amps would give you lots more than 50 lb-ft of torque. How are you figuring you only get 50? To make a race vehicle you need to put in motors and controllers and batteries that will give you what you need. Stock stuff won't do much. Add in a couple extra batteries and you still have a stock little motor and I am quite sure that little motor is NOT pulling 500 amps under full load even with the stock controller setup. Its a covered golf cart. What are you expecting out of this? 

I have a nice three wheeled Cushmann Truckster all electric with the original conversion still installed and working. It uses a two speed switch and uses nichrome strips. Those suckers get super hot. Tiny motor too. I would not expect much from that little thing no matter what. I do however have a nice replacement motor and controller. Not sure it would make a good race vehicle but might be better than what you have. $250 plus shipping.

Too bad its been sitting idle for the past 4 years. Should be right fun when I get to it.


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## Batterypoweredtoad (Feb 5, 2008)

Tom Keenan put his helwig carbon brushed Alltrax 450 amp powered citicar on a dyno. http://www.evalbum.com/popupimg.php?12870. I will have helwig brushes and I will vent and probably fan cool my motor to help it survive. I will be pushing 90+ volts of a123's so I can carry the amps to quite a bit higher rpm's than his 72 volt lead acid setup.

Edit: looks like that dyno was at the stock voltage and likely pre-helwig or Alltrax.


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