Hybrid PWM/Contactor controller turbo-boost

[Voltswagon]

Did you ever run the turbo again? I have a 120V vw bug and was considering doing something similar to kick it up to 144v.

[bennelson]

I only ever really made a couple of runs with the "Turbo" button.

I was talking to somebody the other day, and it came up in the conversation.

The big issue is that you have NO SPEED CONTROL WHAT-SO-EVER when you directly connect a motor to a bunch of batteries.

It's just a matter of what speed you are doing and which gear you are in while you hit the turbo. I was working on a single long, straight stretch of road with a higher speed limit than the 72V Metro could do.

You are FAR better off with just a higher voltage PWM DC motor controller.
I didn't have one of those, and am just a little crazy, and had the parts to make the turbo-by-pass, so what the heck!

It was fun, but never was built into any sort of final design.

[bennelson]

Also, you need to charge the additional batteries separately, because they will get used a different amount from the rest.

[Voltswagon]

How did your system function on disconnect? How many amps would you be pulling after reaching top speed and how much arcing occured on disconnect? Were any plasma monsters sighted?

I would plan to use mine when in the front of the traffic pack, so clear road ahead, running up to 35 mph or so in 2nd at 120V (I top out at 45 in 2nd) then throwing in some turbo power to get up to around 55.

I also envision this as a possible chance to use a mad scientist switch for something awesome.

[bennelson]

My system worked fine after disconnecting.

As for arcing when disconnecting - I'm not sure about that. The reversing contactor was up under the hood where I couldn't see it.

Rigging up a light and under-hood video camera would be able to tell the answer to that one.

I'm also not sure exactly what happens, due to magnetism, when you break that large current with that contactor. Is there back emf or high voltage that really needs to be looked at? I'm not sure. I just took a basic electronics class and now know just enough to at least know what to think about.

Again, with any contactor system, you do need to make sure that the contactor is rated for the type of current you are dealing with, and that you have redundant systems to be able to shut down the vehicle in an emergency situation.

You might also need to figure something out so that the capacitors in the PWM controller stay charged while in "Tubo-Mode" so that there isn't a sudden in-rush of current to them when you switch back to the controller.