# Cheap controller



## smellycat (Jun 25, 2008)

Hello , great site, I have a forklift motor, I have a vw, What is the cheapest controller I can get? Is there a site with giant potentiometers, I once saw how to do battery switching with diodes and relays going from series to paralell. ANy ideas? SCe


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## Guest (Jun 25, 2008)

Too little information. Kelly makes a cheap controller. Don't bother with contactor style speed control. If you have a series motor there are plenty of controllers with in most budgets. 72 volts minimum. What motor and what VW are you going to install it into? Big pot's? Why when small ones work fine. They are proven. 

: )


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## smellycat (Jun 25, 2008)

I have a 
Manville electric motor
The spec plate only says
part no 2809545
volt 36/48

I dont see any more info, and the web does not show what HP tha partno represents

THe motor case is about 18 inches high and 8 inches around

I emailed manville to see if they had any data on it.

It does not have a drive shaft, some kind of splinned shaft fits into it

I am guessing its a series wound 5-8 hp. SC


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## TheSGC (Nov 15, 2007)

Currently there are great deals on eBay for Curtis 36-48 volt controllers and they even have an excellent deal on a Curtic 72 volt controller. They are for series wound motors tho. 

If you want some really sweet insight to a forklift EV on a small budget, check out Project Forkenswift. http://www.evalbum.com/1146


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## Twilly (Jan 22, 2008)

Look into old golf carts if you want to do a resistor system... Although you will be wasting the majority of your power in heat. Another way is to go with a 48 volt controller, and a bypass... both of these ideas sacrafice range


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## smellycat (Jun 25, 2008)

I found this stamped on the case 8304B, No luck in web search on it.

I hooked a 12 volt battery to it and it spins, so that is good. I have had it for 2 -3years and today was the first test. 

Any ideas on getting a splined shaft to fit inside this motor? It also mounts on a platform and not from the front were the shaft comes out

What if i just have a circuit breaker and I goose 48 volts on/ off to operate it? kidding. but what would that damage? SC


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## Twilly (Jan 22, 2008)

Grainger has lots of different splined shafts, that is where I got my stuff to make my adapter...


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## ww321q (Mar 28, 2008)

Twilly said:


> Grainger has lots of different splined shafts, that is where I got my stuff to make my adapter...


Do you remember what Grainger has it listed under ? I can't seem to find it . Thanks J.W.


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## smellycat (Jun 25, 2008)

Yep lots of couplings in granger but not alot of splined shafts , SC


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## Twilly (Jan 22, 2008)

Smelly is right, I just looked, I needed a coupling... Try looking at a local farm store, they usually have a variety of shafts...


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## smellycat (Jun 25, 2008)

Can you tell how many HP a motor is buy how much it weighs? or its case dimensions? SC


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## Guest (Jun 29, 2008)

No and no.


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## deweysautoart (Jun 29, 2008)

on the couplers you can check with national oil well or macmaster carr


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## ga2500ev (Apr 20, 2008)

smellycat said:


> Hello , great site, I have a forklift motor, I have a vw, What is the cheapest controller I can get? Is there a site with giant potentiometers, I once saw how to do battery switching with diodes and relays going from series to paralell. ANy ideas? SCe


Commercial controllers for EV quality voltages (96V-168V) are not cheap.

Resistors are a no go. The amount of power that you'd lose in heat will completely kill your range.

The switching controller that you refer too is called a rectactor controller. There are a couple of threads discussing them. I have a post somewhere here detailing how a cost effective (under $400 total) rectactor could be put together using surplus diodes and MOSFET transistors for switches instead of contactors (which run about $120 each and you'd need at least 5 of them).

But honestly it seems that a DIY PWM controller is the only feasible option. There is a 25+ page thread here in the Tech section talking about homemade controllers. No one has posted back with any results.

The most logical cheap controller would be to build a PWM controller using a single IGBT module for the power switch. IGBT modules such as this one:

*http://tinyurl.com/3gbz2a

*are routinely sold on Ebay for about $50. It has its problems because it'll drop between 2 and 3V upwards of 400A, which means that at times the controller will have to dissapate upwards of 1200W of heat, with a cut into the range.

But it is cheap. It can be driven by a simple 555 timer based PWM circuit such as this one:

http://www.dprg.org/tutorials/2005-11a/index.html

Note that you'll need a much stiffer driver for the IGBT gate to get clean edges.

But simple and cheap is possible.

ga2500ev


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## smellycat (Jun 25, 2008)

Wow GA2500ev. Thats a great setup, and the price is super, Since I lack an Occ scope clean edges won't be a problem, cause I cant see them. I'll enter a work order at work and an get an electrican to explain it to me, then maybe build for me. Maybe I can buy that 555 timer , I have a radio shack leaning kit that has one in it SC


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## ww321q (Mar 28, 2008)

ga2500ev







What I was wondering (being I know almost nothing about electronics)If you are using a IGBT as a switch , why the PWM circuit ? Can't a simpler circuit do ? And isn't the heat that is produced partly from high frequency switching ? thanks J.W.


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## ga2500ev (Apr 20, 2008)

ww321q said:


> ga2500ev
> 
> 
> 
> ...


The PWM circuit gives you speed control. Without it the only options you have are full on and full off for the motor.

All controllers are about speed control. And all PWM controllers are about controlling the ratio of on time to off time for the switch.



> Can't a simpler circuit do ? And isn't the heat that is produced partly from high frequency switching ? thanks J.W.



The switching frequency does also contribute to the heat issue. But with IGBTs you get the voltage drop (and hence the heat dissapation) even if the IGBT is fully on. Generally pure MOSFETs will produce significantly less heat when fully on. There will still be some switching power losses with the MOSFET switch too, but it'll be much less than the IGBT.

The problem with MOSFETs is getting high voltage, high current parts for a reasonable price.

So despite their flaws, IGBT are the champ of cheap.

ga2500ev


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## ww321q (Mar 28, 2008)

I was thinking of using one as you would a contactor . And yes it would be full on . amps limited by rpm . I have a Curtis 1209b-640 72 volt 400 amp . I was thinking of using IGBTs as contactors to switch from a lower voltage controller to a higher voltage bypassing the controller that is only rated at the lower voltage . Or you could use it at the same voltage but a higher amperage then the controller allows "TURBO" for going up an on ramp or around someone. J.W.


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