Re: [EVDL] EV driver's ed: accelerating for max. range vs. best time
The reason that I monitor motor ampere, is that I do not want the motor
ampere go above the continuous ampere rating that is set by the manufacture
while driving a long distance or going up a very long hill.
A Warp 9 motor has a continuous amp rating of 199 amps while my battery
ampere may be 50 amps. Thinking that I could pull 100 battery amp
continuous or more will result in a a motor ampere of 350 to 400 amps.
My GE-11 motor also has a internal fan, external blower and has a continuous
amp ratting of 175 amps. Never had a motor amp meter on this motor, and I
was pulling 180 battery amp everyday.
I wanted to order a Zilla 1k for my EV and Otmar said to install a motor amp
meter, to check out the motor ampere, to see if a Zilla 1k will do it for my
7000 lb EV. So I did, and found that while I was pulling 180 to 200 battery
amp while driving at 60 mph or more, I was pulling 600 or more motor amps.
This cause one of the large motor bars in the field connections to melted.
So this is why I watch the motor ampere, more than the battery ampere. I
use a large 3 inch motor amp meter that is next to the speedometer which is
as important as the tachometer.
Roland
----- Original Message -----
From: "Cor van de Water" <
[email protected]>
To: "Electric Vehicle Discussion List" <
[email protected]>
Sent: Monday, October 15, 2007 10:54 PM
Subject: Re: [EVDL] EV driver's ed: accelerating for max. range vs. best
time
No, measure current in your battery feed.
Motor current has no relation to energy consumed.
Only reason to measure motor current is when it
maxes out your controller, typically when driving
in too high gear, so you will find this easily
by checking acceleration in different gears,
for example check 0 - 10 MPH times; 10 - 20 times
20 - 30 times and so on, in different gears to get
a feel where your motor can draw optimal power
from the controller without current or voltage
limiting (or back-EMF driving the current down,
which will be real evident from the battery amps
falling off with full throttle or even the RPM
limiter engaging).
The rule of thumb is actually quite simple:
Use the highest gear that still gives you
acceptable acceleration and you will never be
lugging your motor at too high current, you
only need to either do the math on your motor
revs or rely on the rev limiter (if installed)
to stop revving the motor beyond a certain
speed, dependent on the gear. You probably best
keep a list with max speeds per gear or place
red dots on your speedometer with the gear nrs
written on them, at the speed where the motor
redlines, for example
25 = red (1) dot
45 = red (2) dot
65 = red (3) dot
80 = red (4) dot
Cor van de Water
Systems Architect
Proxim Wireless Corporation http://www.proxim.com
Email:
[email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM:
[email protected]
Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
Fax: +1 408 731 3675 eFAX: +31-87-784-1130
Second Life: www.secondlife.com/?u=3b42cb3f4ae249319edb487991c30acb
-----Original Message-----
From:
[email protected] [mailto:
[email protected]] On Behalf
Of Roy LeMeur
Sent: Monday, October 15, 2007 8:18 PM
To: EVDL EVDL
Subject: Re: [EVDL] EV driver's ed: accelerating for max. range vs. best
time
Roland Wiench wrote:
> To find out the best rpm in each gear, drive the EV in that one gear
> and record rpm, mph, battery ampere, battery voltage and if you can
> the motor ampere and motor voltage. Repeat this test in each gear.
>
> There will be certain rpm that the ampere will stable or even drop.
This is so easy, no math or formulas needed. Simply place your shunt and
accurate ammeter in the controller to motor loop.
Drive vehicle, observe amp draw, speedometer, and road incline, and...
before you know it, you will know right where the sweet spots are in any
gear and, before you know it, it will become instinctual.
Sorta like using a vacuum gauge to determine fuel economy.
Roy
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