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Author Topic: Starting a golf cart using Arduino (EZ-Go) - powering a LARGE DC motor  (Read 1586 times)
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Israel
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Hello all!

I have an EZ-Go electric Golf Cart which I would like to "start" using an Arduino.
The golf cart has 6 batteries of 6v which is 36v total.
It has a key switch with starts the motor.

I would like to trigger the motor ON or OFF using an Arduino's output. for now it's going to be a button but later it's going to be some remote control so I won't have to put the key inside the key switch and can start it by triggering remotely.
I want to connect the circuit in parallel to the existing key switch so I can still start it with the key.

I DON'T need to control the speed or drive the motor from the Arduino for it's been done using the "gas" pedal.
I just want to trigger it - ON or OFF.

I'm not sure whether all the load of the DC motor is running thorough the wires going to the key switch, but considering it does, I need to find the right circuit.
I have TIP142 mosfets at home which are 100v and 10A.
If all the load is running through that key switch I guess that on full load the current will be more than 10A.
Considering that, I could also order irf540 or irfz44 from ebay...
I would like it to be opto-isolated so it won't risk my Arduino board and be maximum safe both for my Arduino and my golf cart.

I found this PCB but first of all it's 4 circuits which is kind of an overkill for that and second of all the circuit is a little blurry to me:
what are the X1-1 and X1-2?
What is Vpp?
are the Grounds of the circuits connected?
I also have 4n25 at home. Is it good enough instead of the 4n35?

http://arduino-direct.com/sunshop/index.php?l=product_detail&p=60
http://arduino-info.wikispaces.com/Brick-4ChannelPowerFetSwitch

There's also this circuit (which is different):
http://arduino.cc/forum/index.php/topic,20358.0.html

On the other end, there's this guy who connected it directly from the Arduino's output.
http://arduino.cc/forum/index.php/topic,70150.30.html

So as you can see I'm a bit confused.

I would like your advice people about which circuit should I use to do that.
Could you please provide schematics for the circuit because I'm not very good with electronics...
Does someone knows if the full load of the golf cart is running through the key switch (I think the battery's charge display is serially connected with the key switch but I'm not sure. I'm also not sure if that means anything).

Could I use power supply from the golf cart's battery to power the Arduino and the mosfet circuit?

If someone did build this kind of circuit and can advice it will be great!!!

Thank you all in advance!
Golan
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I think you are over confusing the situation. If I understand you correctly, the easiest way would be to simply wire a relay parallel to the key switch. The key switch does not switch a lot of current, so practically any small relay would do the trick. This way you would have an OR switch. The cart would be powered if the key was on, or the arduino turned on the relay.
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Could I use power supply from the golf cart's battery to power the Arduino
yes
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Look at the size of wires on the batteries and the size of the wires on the key switch. This will quickly confirm the switch is a low voltage, low current path.

The key doesn't start (or run) the motor. It simply enables it to function.
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Israel
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Thank you very much!

But considering the key switch is connected to the battery charge meter showing batteries status, doesn't it mean it is connected directly to the Batteries?



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Only to one terminal of the battery, and that's if the meter is connected directly across the battery.  In all probability the meter will show zero when the key is off, in which case the key feeds the meter as well as the control system.
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But considering the key switch is connected to the battery charge meter showing batteries status, doesn't it mean it is connected directly to the Batteries?

It may be, but the current that runs the motor doesn't flow through the key switch or the charge meter.
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Israel
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please read the replies...
does this mean that the key switch does have 36v?

http://www.buggiesgonewild.com/electric-ezgo/32942-wiring-diagram-3-position-key-switch.html

and there's also this one:
http://www.buggiesgonewild.com/electric-ezgo/24030-ezgo-3-position-key-switch-wiring-diagram.html

if that means it has 36v, then again, I need something to switch it...
any help with the circuit will be much helpful!!!
« Last Edit: November 23, 2011, 04:07:34 am by Golan Gabay » Logged

Israel
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http://www.buggiesgonewild.com/electric-ezgo/36473-test-ez-go-key-switch.html

as far as I understand, it does hold 36v...
can someone please provide a circuit using the TIP142 mosfet (or irf540/irfz44) that can control this switching digitally using an Arduino?

Thanks!
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Israel
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Does anyone have any idea?
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The TIP142 is not a MOSFET, but a Darlington Transistor.  It would probably work, but the IR parts may be better for you.

Study http://www.electronics-tutorials.ws/transistor/tran_7.html

Without ALL of the details about your golf cart and what you want to do, we can't just give you a circuit diagram.  You need to know how much current is going through the switch.  If it is under 33A, the IRF540n will work.  I can't imagine that all the motor current goes through the switch, but I don't know.
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Very unlikely for large amounts of current to go through the key switch, what if you were to touch the metallic part with the key on? It'd hurt. Somewhat.
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Israel
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I posted a thread here:
http://www.buggiesgonewild.com/electric-ezgo/57280-key-switch-voltage-current.html

and the people there tell me it's low current, it's starting the circuit that moves the solenoid according to the pedal press... or that's what I understood...  smiley-confuse

does it help to tell which circuit suits for that?

is a regular relay good for that?
I have a relay that can hold up to 30v and 10A but considering the current there is low (let's say 2-3A) will it be enough? or becuase it's a 30v relay it will probably burn?
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