Throttle Pot

[Night Train]

I'm posting this here to get a wider knowledge base but it can be moved to the Defender forum if/when suitable, Thanks.

I came across this Defender throttle pot while looking for one for my electric tractor project.

Does any one know what the potentiometer on it reads?

I really would like one that is a 5k linear pot over the travel of the pedal but I don;t want to spend £££ on buying a proper electric car one.

Thank you.

[FridgeFreezer]

So none of the 50-odd 5k pots RS components list for under a fiver are any good?

[dirtyninety]

Or from Maplin or Rapid

and sometimes Google is your friend

[Night Train]

I am currently using an audio electronics linear slider pot but, like your standard electronics pot, it isn't really rugged enough for automotive use, dirt, oils, grease, etc and have too large a sweep angle or stroke. They also tend not to last long enough due to not being designed for as many cycles as a throttle on a vehicle.

The Defender one has a pedal attached which makes life easier too as it would save me making one for the tractor.

[simonr]

Would you like a defender pedal to play with? I have one under my bench.

I used a Vauxhall throttle pot which is intended to be cable operated which clearly works quite well and was only £20 on eBay.

Si

[Night Train]

Cheers Simon, That would be good. Thank you.

How do you want to sort it out?

Any thoughts as to its resistance?

I'll check out Ebay for Vauxhall ones. I know the MR2 TPS is 6k so I will try that one too. I want to save that one for the car though as it is also cable operated.

Have you seen the video of the tractor in action on the DIY elec car forum?

[TSD]

If you are using a pot, as a pot, does it really matter much what its total resistance is? Or are you feeding it from a resistive source, or into a low impedance load?

[simonr]

TSD's right - for most speed controllers it doesn't matter. I'm pretty sure the Land Rover ones are 5k, as are the Vauxhall ones.

Si

[Night Train]

If you are using a pot, as a pot, does it really matter much what its total resistance is? Or are you feeding it from a resistive source, or into a low impedance load?

The controller has two wires that are connected to each end of the pot track so that there is 5k between them, The wiper is then connected to one end of the track so that the resistance between the two wires ranges from 0 to 5k.

I have been setting up and testing with a 10k pot and it just has a huge dead spot at one end with all the action somewhere in the middle onwards.

I have a throttle body from a Toyota MR2 that is 6k which I will try but I would need to then have a cable on it too. The Defender pedal makes things really easy if it is the right resistance. I would then use one on all my electric projects.

[TSD]

Sounds like they've 'padded' the pot circuit to set the control range - put extra resistors at one end or other of the pot (or both) to set the range of the control signal. As a thought, you can probably still use a pot with higher resistance by adding a fixed parallel resistance to bring the overall back to 5k. It depends on the internal circuit though, no way to tell without trying it.