# Dc contactor

Thread Starter

#### Williesiddons

Joined Mar 26, 2022
9
I have a motor powered by 5 x 12volt 18 amp batteries, it has a dc contactor in the circuit and a controller for the throttle, would someone please be able to draw me a diagram of how the circuit should be along with fuses and resistors?

also if the contactor could be broken, what contactor should i but to replace this one, picture to follow

#### Reloadron

Joined Jan 15, 2015
6,712
I want to believe you mean 18 AH (Amp Hour) batteries. Next you do not mention if the batteries are in series (5 * 12 = 60 volts) or parallel which would be 18 AH * 5 = 90 AH battery 12 volts. As to a circuit drawing or schematic there is likely a dozen ways to control a motor speed. You do not even mention the motor application? Less much more information there is no answer to your questions.

Ron

Thread Starter

#### Williesiddons

Joined Mar 26, 2022
9
I want to believe you mean 18 AH (Amp Hour) batteries. Next you do not mention if the batteries are in series (5 * 12 = 60 volts) or parallel which would be 18 AH * 5 = 90 AH battery 12 volts. As to a circuit drawing or schematic there is likely a dozen ways to control a motor speed. You do not even mention the motor application? Less much more information there is no answer to your questions.

Ron
The batteries are in series and are powering a go kart, at the moment it the negative heads from battery straight into a controller then off to the motor and the positive heads from the battery to a contactor, then the positive from the controller heads to the contactor too and then off to their motor, the throttle is connected to the controller but this doesn’t seem to work

#### Reloadron

Joined Jan 15, 2015
6,712
So the contactor is switching about 60 volts. I am not sure of the contactor coil voltage. Also not sure of the motor's current? Less a good manual with a schematic it's hard to say what the control circuit looks like. When power is applied to the contactor coil there should be a pronounced audible click sound.

Ron

Thread Starter

#### Williesiddons

Joined Mar 26, 2022
9
So the contactor is switching about 60 volts. I am not sure of the contactor coil voltage. Also not sure of the motor's current? Less a good manual with a schematic it's hard to say what the control circuit looks like. When power is applied to the contactor coil there should be a pronounced audible click sound.

Ron
Do u know where I could get a new dc contactor from that would be adequate for 64 volts or have an image of what I need

#### MaxHeadRoom

Joined Jul 18, 2013
25,469
Automotive starter relay?
Good for 100amps.

#### Dodgydave

Joined Jun 22, 2012
10,366
This is how I would wire it, any automotive solenoid/starter will work.

Thread Starter

#### Williesiddons

Joined Mar 26, 2022
9

#### MaxHeadRoom

Joined Jul 18, 2013
25,469
One for each circuit normally
Automotive wreckers are a cheap source.

#### Dodgydave

Joined Jun 22, 2012
10,366
Would u use two contractors then
One will work easily, but if you prefer to put one on the negative terminal is ok.

#### Reloadron

Joined Jan 15, 2015
6,712
Would u use two contractors then
I would just use a single contactor for high side (+) switching. As mentioned an automotive starter solenoid (contactor) is a good choice.

Ron

#### Reloadron

Joined Jan 15, 2015
6,712
Depends, they make two types of those solenoids, continuous and momentary use. Most starter solenoids in a car are for momentary use. And now that I think of it do they even use them now days?
https://www.elreg.com/blog/continuo...ter-solenoids-why-they-arent-interchangeable/
That would be true. Good point, I always thought as them as intermittent or continuous duty. Continuous duty being for example an electric bike or golf carts for a few examples. Now that I think about it I really don't know what cars use these days?

Ron

#### MaxHeadRoom

Joined Jul 18, 2013
25,469
Most auto's now have the solenoid internal to the starter.
The service manual often says, 'not serviceable'!

#### shortbus

Joined Sep 30, 2009
9,446
Most auto's now have the solenoid internal to the starter.
The service manual often says, 'not serviceable'!
Yeah, the Ford and Chrysler cars used the solenoid switch because they used a inertial type Bendix drive on the starters, one that pulled the starter gear in on the movement of the motor shaft. Where GM used the starter solenoid built on to the motor to engage the gear by a lever and power to the motor when the ignition called for it.