Initial EV Throttle response is too sudden, add a component ?

[raamonkhan]

Hi All ,

How can i change the initial acceleration on this EV tricycle's throttle, from standing still to its first movement is a big jump forward.
The tricycle has a low and normal speed, but the initial acceleration on both speeds are the same . . .is there a way to restrict the initial voltage/current that goes through the 0-5V potentiometer (5k Ohm) ?

Can i add a "capacitor/resistor/other component" to the 5k-Ohm potentiometer in order to decrease the quick acceleration when the throttle is barely twisted.

I want the tricycle to slowly /accelerate/creep a bit first, before ramping up the speed.
It is difficult to manoeuvre the bike slowly when driving in confined spaces.
It jumps forward immediately even when the throttle is very slowly turned. . . barely start to twist it.
The speed stays the same if the the throttle is held in the same place.

We bought it brand new, to move compost and plants around in a garden on the farm,
but it is very difficult to manoeuvre the tricycle slowly through small pathways and past curving flower-beds as the slightest twist of the throttle shoots the tricycle quickly forward,
although you then move at a slow speed if the throttle is barely twisted.


This is what i could find in the manual that came with the TailG Tricycle:

TailG
Model:TL1500DZH-5A

Here is what the throttle and potentiometer looks like below.
I hope this helps.
Thank you in advance !

 

[amberwolf]

How can i change the initial acceleration on this EV tricycle's throttle, from standing still to its first movement is a big jump forward.
The tricycle has a low and normal speed, but the initial acceleration on both speeds are the same . . .is there a way to restrict the initial voltage/current that goes through the 0-5V potentiometer (5k Ohm) ?

Can i add a "capacitor/resistor/other component" to the 5k-Ohm potentiometer in order to decrease the quick acceleration when the throttle is barely twisted.

Yes, you can create a "Low Pass RC Filter" like this:
https://www.electronics-tutorials.ws/filter/filter_2.html
by using a resistor and a capacitor. You'd disconnect the throttle signal wire from the controller. Connect that to one end of the resistor. The other end of the resistor connects to where the throttle signal wire went at the controller. The capacitor connects to that same point, and to throttle/controller ground.

The values would need to be experimented with, but you could start with 10kohm and 1uF. If you use a potentiometer instead of a resistor (using just one end pin and the center pin, leaving the other end pin not connected), you can just adjust experimentally until it does what you want.


However, if the controller responds to even the tiniest bit of throttle with the same jumpy sudden power, then the ramping wont' change that. The controller itself may need to have it's behavior changed. If it's not programmable (most aren't) then it would probably have to be replaced to change it.


But first:

One of your images shows a potentiometer for a mobility scooter, which uses a long double ended lever for control, and stays in the middlewhen not touching it. The other shows a standard "ebike" throttle. Which one are you actually using? (If you're using both, can you post the exact wiring you're using?)

I ask because they operate in different ways, since the "ebike" throttle is almost certainly a hall-type throttle, that outputs a signal that starts around 1v or so, and goes up to only around 3-4v.

The scooter potentiometer creates a signal that starts at about 0v and goes up to about 5v but this design stays at about 2.5v (half of WOT) when not touching it.

The controller is going to be designed to work with one of those, and not the other. It may operate with either, but the behavior is different. If it's made for a pot throttle, then the hall throttle would make it run the motor all the time, and never shut off. If it's made for a hall throttle, a pot would normally not make it run until the pot was turned some fair part of it's rotation, this design would make it start at about half power when not touching it, and never turn off. Neither one should cause what you see; that's more likely to be a controller behavior issue, but knowing which throttle is being used and which controller expects may help to work out a solution.

Many controllers have a label on them that show the voltage range they expect on the throttle (not all of them do).



Another way to fix the whole problem is with a programmable controller using Torque (Current) throttle control, instead of Speed throttle control (which is what you present controller almost certainly uses). Most of them also let you set the throttle response range, so they work with either pots or halls.

Then you are controlling the amount of power with the throttle, rather than the speed, and you can apply very tiny amounts of power depending on how programmable the controller is and how you set it up.

Given the wiring diagram posted, the motor (incorrectly listed as "gradient" on the diagram) is probably a three-phase sensored brushless motor (three thick wires for power phases, and five thin wires for hall signals and their 5v/ground power supply).

 

[AussieRider]

As Amberwolf has pointed out, you have 2 pics of different throttles, hall effect twistgrip & mobility scooter "wig wag" pot & with most controllers, you can't swap one for the other. The wig wag is spring loaded to mid way, or 2.5k. If your trike has a cable twist grip running to a potentiometer, you could swap the linear pot for a log pot such as used for volume controls. Log pots have a small change for the initial movement. Let's chuck some bullshit figures out that might make it clearer. A log pot with 150 degrees of turn. The first 10 deg gives 10 ohms change. The next 10 deg adds 15 ohms for a total of 25 ohms,, next 10, 20 ohms for total 45 ohms & so on until near the full throttle end a 10 deg turn gives a 100 ohm change or more.

Hope this makes sense mate.

 

[raamonkhan]

Thank you AussieRider and AmberWolf for your input and response.

The seller of the tricycle EV had sent me that AliExpress picture (for a mobility scooter ?),
i couldnt figure out why he sent that, as it does not look like the physical throttle(from the green TailG tricycle) i have in my hand.

I really appreciate the feedback , i will try the resistor/capacitor idea first to see what happens with the pull-away of the tricycle.

Thank you so much !