Re: [EVDL] controller
Alan asked:
> My VW Bug conversion is completed with the exception of
> the controller which I have been waiting for since April.
> Is there any way I can run this car temporarily without a
> controller. 20 6v flooded lead acid batteries and warp 9 motor.
Sure, you may use the layout that some use for "Turbo",
a bypass-contactor that connects the motor directly to the
batteries once the potbox hits "pedal to the metal".
You can even keep this configuration after you installed
your controller, just in case it ever does not work, you
still have an emergency way of moving the vehicle.
NOTE that using this bypass-contactor is hard on the
contactor and it is not an efficient way of driving at
lower speeds, nor is it comfortable, but for an emergency
it is a great insurance policy.
Also note that since you should have a normal main contactor
AND a bypass-contactor, that you get to keep all safety
against a welded contact in the bypass-contactor, because
the main contactor (which only opens and closes at no load)
will be able to break the circuit. This is important!
There are many ways to make the drive more smooth than
the crude on/off control, see the many schematics for
contactor controllers with intermediate voltages and
even with a series resistor (piece of stainless rod) to
reduce the current surge (and resulting acceleration)
when you first engage a new "gear" (voltage level).
See the EVDL archives.
But now you are approaching the cost and complexity of
installing a controller, so I think that the emergency
setup of a single bypass-contactor and a microswitch
in the potbox signalling "pedal down" may be all you need.
If doing it fancy, add another microswitch for a second
contactor, at a potbox level just before the last stop,
to first switch the resistor between battery and motor,
before shorting motor directly to the batteries.
NOTE: resistor will get hot if used for more than a
few seconds, but since it mainly serves to avoid the
initial jolt of full-power from standstill, it should
typically not be used much, you should drive it as if
you only had the on/off control that I see many drivers
use these days....
Again - this is not going to be good for range, but it
is a great way to build some security into your car
that you can move it out of the way as long as your
batteries have charge and your motor still works...
Success,
Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email:
[email protected] Private: http://www.cvandewater.com
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