Re: (ET) how does the late model I5 speed control work?

[Charlie <medievalist gmail com>]

Chris, if you look at the schematic for the late model E20s and I5s,
you'll see that the 2AH relay's coil is in parallel with the traction
motor armature.  As explained here by other people more knowledgeable
than me, when you floor the accelerator on the tractor *****with stock
batteries****** the juice available to the 2AH coil is insufficient to
close the relay and thus the 2A contactor will not drop the toaster
completely out of the circuit.  The traction motor is sucking up
everything the lead-acid golf cart batteries can give.

When I floor the accelerator on my 100% as-built-by-OEM late model
I-5, it most definitely does not go to full field, full armature.

When I press the CC button while the tractor is in the first speed, it
most definitely drops out the second half of the toaster, and the
tractor surges forward.  Incidentally, on the original schematics for
my I5, the button is marked "CC/PP".

It seems to me that your non-stock batteries are probably delivering
so many watts that the circuit is not behaving as designed.

--Charlie

On Wed, Sep 5, 2012 at 8:56 PM, The CZ Unit <cz alembic crystel com> wrote:
> Ok, I went out and floored it on my E20. Good wiring, newer disconnect, 
> all
> power wires were cleaned and assembled, BB600 cells, fully charged.
>
> It goes right to full power, full field. You can hear the motor whine, it
> does not go into field weakening until the tractor is well underway and
> stable. Battery volts are in the middle of the meter, so it's not low
> powering out at the battery. All contactors engaged.
>
> Now the E20 has two differences from the E15: First the motor pulley is
> smaller so you get more power with less speed. Which can be made up for 
> by
> the additional speeds. Second, the motor does have a compensation coil on
> the field that is *in series* with the armature. Thus under high power 
> draws
> in forward it helps to strengthen the field and reduce the potential amp
> draw at the armature. I don't know/don't think the E15 has this.
>
> That might be the whine, the secondary field is limiting armature 
> current.
> The drawback to this is that in reverse the tractor will pull way *MORE*
> current since the field is reversed and is acting against the natural 
> field
> circuit. Ergo progressive field weakening. However since the high speeds 
> are
> locked out in reverse this is only weird when going backwards up a hill 
> in
> D2.
>
> Anyway, the E15 motor is much more jerky, I guess this is the lack of
> compensating field and larger pulley. Which would explain why they put 
> that
> whole speed reduction thing in. The E12 has a similar motor so they put 
> in
> the centri clutch.
>
>
> Chris
>
>
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