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Discussion Starter · #1 ·
From: "Roger Daisley"

>>I am converting my John Deere L111 Riding Lawn Mower from ICE to
all-electric.
1) It must operate very much like it originally did, <<

I'll assume you don't mind it being quieter . not needing to be
started just turned on , will you miss storing the gas, what about
not charging the oil and air filter.
The last thing I'd want is for my EV to operate like it originally did. :)

>2) Because of above, I believe it is best to stick with the hydrostatic
transaxle, even recognizing the inherent losses. I think I can live with
that. The hydrostat is very simple to operate, with no gear shifting or
switching to go from forward to reverse.>

Probable best to use whats there , don't change to many things .

>At this point, I plan on using equipment on hand:
> Advanced DC motor 140-22-4001A
> Curtis 1204X-4407 (24-36 VDC) Not 100% sure about this one.
> Six 6-volt Golf Cart Batteries ... not yet acquired. (operate at 36 V)

Golf cart batteries would not be my choice , If you are pulling 100
amps ( kind of the max continues for GC bats) from a 36v pack you are
talking about 3.6 wk or about 4 hp . If your grass is not long this
might be ok , are you planning or cutting of 1 hour ? some kind of
AGM battery would let you pull more amp giving more power , and you
less run time but that may be the trade off . Also AGM's won't leak
from bouncing around.


QUESTION TWO: The hydrostatic transaxle should operate at around 3000 rpm,
continuously. Obviously, the DC motor speed could vary from runaway over
speed, with no load to some undetermined lower speed under heavy load. Is
there a controller, or some other way, to control the motor speed,
regardless of load, to around 3000 rpm, say +/- 200-300 rpm within limits of
the power available, of course. There is a multi-bladed cooling fan that is
between the motor and transaxle. (I have a piece of reflective tape on one
blade to use with my optical digital tachometer.)

I had a plan for a governor for my electric mower that I never got to
try , having something that would set the rpm would have been nice
but a plane out 5k pot worked well enough of me . The basic idea was
to use a small permanent magnet motor like the ones found in many toys
and have it turn from the mower motor . PM motors when used as
generators will change there voltage out put as rpm gos up or down .
So now you have something that will sense rpm and give a voltage to
show this change. Next we use that voltage to back off the controller.
My controller needed a 0 to 5 k so I was going to drive a opto couple
with the out put of the PM motor and have the opto coupler pull the
wiper wire to ground when rpm got to high. Would have taken some
experimenting with different resistors to fine turn it .
Steve Clunn

--
Tomorrows Ride TODAY !
Visit our shop web page at: www.Greenshedconversions.com

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Discussion Starter · #2 ·
On 17 Mar 2011 at 1:49, Steve Clunn wrote:

> Golf cart batteries would not be my choice ...

Hundreds of GE Elec-trac riders and tractors do fine with flooded batteries.
The plastic liners in the battery boxes do help keep the nasty stuff from
rotting the steel, however.

Unless that hydrostatic transaxle really sucks power from the motor, I don't
see any need for AGM batteries. While I've heard of peaks in the 350-400
amp range on ETs, my low power gel batteries are good for maybe 200a without
sagging, and I've never noticed excessive voltage sag.

I think golf car batteries would be an entirely acceptable and cost
effective choice for the OP. Just make sure the battery boxes are well
coated or lined to prevent corrosion.

David Roden - Akron, Ohio, USA
EVDL Administrator

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Discussion Starter · #3 ·
Easy, use a shunt motor. No controller is needed, just a contactor switch. A
shunt motor automatically works hard to maintain a key rpm, it'll draw current
if below key rpm and regen if above.




________________________________
From: Steve Clunn <[email protected]>
To: [email protected]
Sent: Wed, March 16, 2011 11:49:56 PM
Subject: [EVDL] Need A Little Help From My Friends: Tractor Project To:

... Is
there a controller, or some other way, to control the motor speed,
regardless of load, to around 3000 rpm, say +/- 200-300 rpm within limits of
the power available, of course. ...



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