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How to Modify Differential Steering Vehicle

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Sling

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Got a quick question which I imagine probably won't be too difficult for the experienced people out there...

I'm trying to build a differentially steered vehicle and I'm working off some instructions for a model, but I'm also using my own design for most of it.

My problem is that in the instructions, there are two battery packs (of 2 batteries) for the motors, one for left and one for right. But the way I have built my vehicle, I've used one battery pack of 4 batteries for both motors.

So how can I connect the motors so that the voltage and current would have the same effect as two battery packs?

If in parallel, then the current would be weakened (?), and if in series, the first motor connected would have to be on for the second motor to receive current.

Terrible mspaint pic attached for illustration!
 

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BTW a "battery" is a group of "cells". So in the instructions the battery pack contained two cells but the battery pack you are using contains 4 cells. Just a terminology thing. It gets confusing when you start saying something like "I have a battery made of 4 batteries".

Just have two + wire and two - wires splitting off from the battery. One + and one - for each motor. It's like having two engines run off of one fuel tank by splitting the fuel line. This is called wiring two motors in parallel with each other to the battery pack. This way, the current drawn by each motor from the battery will be independent of the other motor. It would also allow you to independently control the motors to turn the robot.

If connected in series, the motor performance is now dependent on each other since the same current must flow through both and since the heavily loaded motor drop more voltage across it, it will produce more power while the more lightly loaded motor produces less power. Not good when you want the two motors to be doing different things (like differential steering). It's only good for limited situations where the motors are always moving the robot in the same direction where you want to limit power to the more lightly loaded motor.
 
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There is no stearing function in what you have posted. It will probably go in a big circle, the radius depending on how well the motors and batteries are matched. Perfectly matched for an infinite radious circle, also know as a straight line.
 
It gets confusing when you start saying something like "I have a battery made of 4 batteries".

That's why I didn't say that - I said that I had a battery pack made of 4 batteries. If you look in the dictionary you will find that this is correct terminology. Apologies if you found this confusing. 'Pack'.

I take your point that connecting them in parallel should be ok though. I wanted to check and I'm grateful you could confirm that.

There is no stearing function in what you have posted. It will probably go in a big circle, the radius depending on how well the motors and batteries are matched. Perfectly matched for an infinite radious circle, also know as a straight line.

I was only showing the parts relevant to the question. :) Thank you for taking the time to post though.
 
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