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

[Charlie <medievalist gmail com>]

In my previous message, when I said "floor the accelerator" I meant
from a dead stop.  Sorry about the lack of precision!

--Charlie


On Thu, Sep 6, 2012 at 11:36 AM, Charlie <medievalist gmail com> wrote:
> 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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