Re: [EVDL] Potbox flaking - where to get a new pot?
Hello Cor,
To add a idle circuit to my 5K pot, I just added another 5K pot in series
with the existing accelerator circuit going to either pin out #6 or #7 on a
Zilla.
Use a on dash 1 pole switch that is wire in parallel with the idle pot. In
the on position, it shunts out the idle pot which connects the existing pot
in normal operating control.
Turning the switch in the off position, the idle pot adds the require
resistance to bring up the motor to about 400-500 rpm.
When I first start up, the idle pot has to be shunt out, because the motor
controller must see no resistance input for the controller to start up.
As soon as the controller starts up, I may turn off idle circuit which puts
in normal control during my drive and if I am doing a lot quick stop and go
where the transmission oil pressure does not drop off too much.
If the EV has a long stop and before I start up again, I will turn on the
idle circuit to give me a soft start.
On long constant drives that may require letting up on the accelerator at
times or down hill runs, I found it is best to keep the idle circuit off so
there is no battery power being use. I found with the idle circuit on all
the time down hill runs, the EV may use about 3.8 ah per mile while if the
idle circuit is off, it will be about 3.3 ah per mile.
I bought the 5K pot from EV Parts, which is a the same 5K pot for the
existing accelerator control.
I was thinking of getting another 5K pot and using a 2 pole double throw 3
position switch, so if the normal operating pot went out while you was
driving, I can switch out the existing pot with the standby pot which can be
control using a paddle switch that is mounted on the steering column just
behind the steering wheel.
The paddle switches are normally use in some cars to control the shifting of
a transmission with just the flick of a finger.
Roland
----- Original Message -----
From: "Cor van de Water" <xxx@xxx.xxx>
To: "Electric Vehicle Discussion List" <xxx@xxx.xxx.edu>
Sent: Wednesday, June 27, 2012 1:51 AM
Subject: [EVDL] Potbox flaking - where to get a new pot?
> I had my potbox open tonight to see why my accelerator is
> acting so weird.
> I believe that my pot is bad (though I still need to put a
> meter on it to verify) but I did get my answer as to why
> my controller is always complaining about accelerator input
> voltage being too high.
> Remember that I have an automatic transmission, so the
> controller must idle the motor when I release the accelerator
> and to do this the designer did not modify the resistance of
> the pot itself, but used the pedal-up microswitch to switch
> between the pot output and a trim resistor.
> So, the trim resistor gives the idle speed of the motor,
> while the pot gives the input as soon as the accelerator
> is depressed.
> There is only one little problem - the switch breaks before
> makes, so there is a short period where the accelerator input
> is completely open. And that causes a controller error
> "Accelerator input voltage too high during run mode" because
> the open circuit will go to 5V or thereabout and the
> controller will fault as soon as it sees more than 3.7V
> Another issue that I have found very annoying is that as
> soon as I depress the accelerator a little bit, the
> controller will suddenly give more than halfopen throttle
> input, there is nothing between idle and halfopen.
> I have the idea that the throttle pot is misaligned or
> broken, causing it to jump from zero to halfopen or
> because the microswitch overrules the pot in the low
> settings, the lower half of the range is masked out
> by the microswitch in "pedal up" position.
> So, I will need to re-align this and measure the pot for
> correct and linear increase of resistance.
> What I probably end up doing is modifying the circuit so
> that the pot is always in the circuit, but has a small
> series resistance added to the bottom which will elevate
> the minimum slightly, then have the microswitch add the
> circuit for the idle which will essentially be a fixed and
> a trim resistor to also give a low RPM signal and connect
> that signal also to the output of the pot, this will allow
> for a smooth transistion while still allowing trimming
> the idle running of the motor and also avoiding a broken
> pot to race the motor.
> Just in case my pot is bad - where to get a new one?
>
> Cor van de Water
> Chief Scientist
> Proxim Wireless Corporation http://www.proxim.com
> Email: xxx@xxx.xxx Private: http://www.cvandewater.com
> Skype: cor_van_de_water XoIP: +31877841130
> Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203
>
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