The Homebrew Electric Car Saga - Escort EV Installment 3

[DanFrederiksen]

wow that's 60$ I wouldn't try to save.

[hipofalcon]

@DanFrederiksen - you are right. Shortly after the fact, I ended up buying a commercial potbox, as this one became a bit intermittent. Unfortunately, after a year, so did the commercial one. For $60 they are a sorry idea for throttle control. I hope these improve over time. You need to "pump" them a few times prior to switching on the controller or it tends to get a bit jumpy when you first accelerate - pain in the ass.... Ken.

[3gd16]

Instea of using that pot box would it be better to use the engine throttle body that has a TPS (Throtttle Position Sensor) that measures 0 to 5 ohms

[hipofalcon]

@3gd16 - I am not sure if it would be easy to use this, but anything is possible! The problem with the commercial controllers is that they are designed to use the 5K to 0 resistance for throttle input. Modification of the controller (or the TPS) would be required and I am not that familiar with these items to attempt it. Thanks for the comment - Ken.

[Sohave]

Well that beats my 65 USD comercial potbox. regarding the concern of the pot failing. most comercial potboxes has a switch that turns of the contactor when no preasure is applyed to the pedal. it is just a cheap microswitch that is activated at the no preasure position. With such a feature, which i belive Curtis has, you dont have to worry about the pot failing.

[hipofalcon]

@Sohave - they (Curtis) have both the type with the switches (at each end to prevent over-throttle at the top end too), or the type that has no switches. Most EV folks use the one without the switches. I think the ones with these switches were primarily designed for golf cart use to save the batteries - no power applied while the pedal is off, and prevented the "racers" from tearing up the greens on the course. Ken.

[uly875]

I'd strongly discourage you from using a single channel pot for a safety critical situation like this. These physical pots wear, and can result in you suddenly getting 100% or 0%. Ideally you would use a dual channel non-brush pot (hall effect style).

At the very least use a dual channel pot, and have the sensing circuitry confirm that the sum of the outputs from both pot tracks is always equal.

[hipofalcon]

While I appreciate the concern about the type of pot, you may want to take a look at a PB-6 potbox from Curtis. It is exactly what you have deemed a safety hazard - a brushed pot, Mind you it is sectioned down to provide only a portion to give the proper travel, but a brush-type pot all the same - no Hall-Effect or other magic. If Curtis thinks that these are OK and sell them as a component with their controllers, who am I to dispute it? Ken.

[labidus74]

I like it