Paul & Sabrina's Cheap EV Conversion

[ev59rag]

Paul, another question? sorry for too many. I test drove my car last night, well it did not work....

Did you use your ignition key to turn on your contactor?

if yes where did you connect it? what line did you use. I tried the wire from starter but did not work. Checked how much amps the contactor is drawing... not much, just 1.5 amps.... Check if there is power, yes there is power. Hmmm where else can I hook this up?

If not? then did you just add a manual toggle switch to just turn it on and off?

Thanks.

[MPaulHolmes]

I had no idea what the heck I was doing, so with my $1.99 digital volt meter from Harbor Freight, I checked all those wires in the trunk. I tested their voltage when the key was turned off, and when the key was turned on. Then I just picked one of the wires that was 0v before, and 12v after. I ran that to one of the contactor wires, then attached the other wire to the 12v battery ground.

Possibilities: Have you tested the contactor with a 12v input with a switch, or even just touching the 2 wires to + and - of a 12v battery? Did you hear a click? Some contactors won't turn on without like 24v or even higher.

Oh the mystery of it all! With a HUGE project like this, there is no such thing as too many questions! Now the debugging begins! This is my favorite part!

By the way, it's not supposed to work the first time. It's tradition!

-Paul

[ev59rag]

Ok Ill do that later....

But what about reverse? Is it suppose to be that fast? How did you fix yours? thats a scary reverse speed.

Cesar

[MPaulHolmes]

I didn't have a reversing contactor. I just used the transmission's reverse. So basically, I just did the pre-charge resistor, turned the key, which made a loud click (contactor closed), and then drive in forward or reverse or whatever I want. Do you still have a way to shift into reverse?

[ev59rag]

I did the same... just use the reverse transmission... but its too fast for me i guess... Getting used to i guess. thanks for the input.

[MPaulHolmes]

Part of it might be your controller? ON various settings, reverse is too fast, and other throttle settings (on the homemade one) it doesn't feel too bad. When throttle proportional to pwmDuty, I would say that reverse feels WAY too fast. Maybe that's what Altrax did? It's the easy way out. hehe. Only like 2 lines of code compared to maybe 100 lines of code to take torque into account with the throttle.

[slurryguy]

Hey Paul,

My thought kinda crosses between two threads, so I'll post it here since you're kinda discussing the topic here already. Sorta.

The issue about reverse speed control.

In your Open Source Controller, you have talked about creating different driving modes. An economy mode... Maximum blood draining G-Force inducing mode... Granny Valet mode... etc.

What about a "reverse" mode? Would it be fairly simple to steal an input signal from a car's backup lights and use that to trigger a reverse mode that fits most anyone's foot when they are backing up? The only question I have is ability of the circuitry to handle more input signals.

There... I did what I've razzed others for doing. Trying to add features before the foundation of the controller is finished. Bad form on my part... So feel free to toss this in the "pointless ideas for people to consider on a future revision" bin.

[ev59rag]

Here are my thoughts.

Im going to put another potentiometer in series with the one on pot box. Then I will adjust it in such a way that my reverse will crawl. Now how to turn it on (while reversing) or off (while forwarding). Im thinking of putting a relay to short it (forward) and open it (reverse) and tapping the reverse light to power the relay.

does this make sense?

[slurryguy]

It makes a lot of sense if your controller produces zero current to the motor when the potentiometer is minimum ohms.

It sounds dangerous if your controller produces maximum current when your potentiometer is minimum ohms.


I encourage you to verify which way your particular controller "swings" if you get the meaning of my drift.


The general concept is a good idea if implemented appropriately for the way your controller is designed.

[MPaulHolmes]

Hey slurryguy! Reverse on mine with the current throttle setting is nice and smooth, so I don't think it's necessary to have a separate setting for reverse. If I couldn't have gotten it under control, then I would definitely used your idea!

Want to hear a funny story? Today, I accidentally multiplied the throttle by 16 in the program, so when I barely touched the accelerator, the car was jerking all over the place. I went flying out of the driveway, and almost into a neighbor's apple tree! Don't tell Sabrina, though. hehe. I had the bright idea to increase throttle resolution by multiplying by 16, doing some stuff, and then changing it back. Well, I forgot to change it back! The good news is that I have now thoroughly tested the hardware overcurrent shutoff! hehe. It saved my bacon.