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Re: Timing, Inductance & Bypass, oh my

Mark,

See inserted comments........

--- Mark Hanson <[email protected]> wrote:

> Hi Jeff etc,
>
> I measured the overall motor inductance amr + field
> with my B&K LCR meter.
> I found that adding an additional 150uH doubled my
> acceleration rate from a
> dead stop *independent* of the timing test. I
> always use a bypass (and
> engage start) contactor that shorts the control
> *and* the chokes when fully
> depressed so the batteries are connected *directly*
> to the motor for best
> efficiency. The trick is to set the fully mashed
> position at the nominal
> speed your going, for me it's 60mph in 3rd gear at
> 96V. Yes field weakening
> is a thought but would it be more efficient than
> just shifting into 4th
> gear?

It might be. Sounds like you're an experiment type of
guy. Install field weakening contactor and resistor
with an independent control switch. Record battery
amps and speed in 3rd with field weakening and compare
to 4th without.

>
> The best thing to do is *test* your acceleration and
> operating RPM's
> performance at neutral and then at an advanced
> timing setting. That way
> you'll know for sure (like me).
>
> In general it appears from testing and general
> consensus for lowly commuters
> operating around 96V or below that neutral is best
> overall since RPM's
> aren't that high <4k rpm's.

Well your motor started with 4.5 degree advance. So
it was never on neutral, was it?

The MTC motor was designed for 96 volts. The 4.5
degree shift was put there to get acceptable
commutation at 96 volts. Commutation at neutral
wasn't all that great.

Regards,

Jeff


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