Re: [EVDL] Almost got stuck today on 22+ deg incline
OK, I was right - that short steep slope on the way back was
indeed steeper than anything else. Google Earth shows it as
a 30 ft increase over 55 ft (9 meters in 17 meters distance)
so that would be a 33% slope.
Of course it is possible that the road construction has
flattened some of that extreme height variation, so unless
you measure incline on the spot, it is hard to know what the
exact amount is if it varies.
Oh and that 36V Worx lawnmower?
Its motor (and brushes) look brand new, there is a magnet
on the top of the axle with a Hall effect sensor next to it
which leads to a controller that has a high and low setting
(Power and Silent) and there is a large hole burned in the
bottom and side of the controller....
(It looks like the motor wire was not attached properly,
overheated because the insulation is molten and then caused
the controller to burn.
The motor actually delivers voltage when you turn it by hand,
positive one way and negative the other, so it is PM.
Anybody seriously interested in a 36V motor, probably 500+W
maybe even 1hp from the 19" cordless mower, I believe it is
a WG788, it has a good blade attached and good bearings - I
could feel no play.
Since the 36V removable battery was indeed removed and lost
by the previous owner, I did not pay much for it.
I am contemplating putting 10 series Lithium battery pack in
and wire the motor directly to the batteries.
Will be a hard start, otherwise I will need to buy a scooter
controller for a 36V brushed motor and see if I can interface
the hall sensor to it, wire up high and low setting and
verify that it has current limiting....
Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: xxx@xxx.xxx Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203
-----Original Message-----
From: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On
Behalf Of Cor van de Water
Sent: Monday, June 25, 2012 11:28 PM
To: Electric Vehicle Discussion List
Subject: [EVDL] Almost got stuck today on 22+ deg incline
Someone told me that they were really nearby me so I could easily come
over and look at the 36V battery mower he had for sale. I agreed and
then looked up the address.
Indeed the distance was not too much but I got a first indication of a
not-so-easy drive when I noticed that it was in the foothills. Sometimes
roads can still be pretty easy and flat there, but more often they are
not.
So, I set out to drive there and by the time that I was facing the road
straight up the foothills I was feeling sorry for my little pickup
truck. With a screaming controller and ever slower inching upwards, I
finally made it up the 800ft or so hill. I had a little fear about
getting stuck there because I noticed on the way over that hill that the
rear side had wat seemed to be an even steeper slope and it was preceded
by a sharp 90deg turn, so no way to "run up" the hill.
Indeed I had to again inch up that slope again on my way back but it was
a short stretch and the controller had recovered, so I had more juice at
hand to make it. Phew!
I checked Google Earth and measured a short distance of the road where I
remembered my truck inching upwards and found that it increased 6 meters
in height (20ft) in 16 meters distance (50ft). That is more than 22 deg
slope. No wonder that the truck slowed to a crawl and only the fact that
the torque converter kept going to multiply the feeble torque from my
motor, allowed me to get up the hill.
The controller reported a transistor overtemp event which did not
surprise me at all, but this caused the current to be reduced right at
that critical moment.
Apparently the controller did consume more than I expected from the
batteries during that steep climb, because on the way back the voltmeter
started dropping faster and faster until one mile from home it suddenly
disappeared in the left corner where I never see it unless the car is
off.
Oh oh.
Reduced the current draw (I was still on the freeway but doing only 40
MPH by now and climbing a large overpass so I slowly started losing
speed but kept going as good as I could - the sign for the exit - only a
few more yards, at approx 35 MPH and with the voltmeter ever dipping
further below 90 I finally turned off the freeway and could give the
batteries a little rest while waiting for the light.
Carefully drove the last half mile home, luckily it is all
25 MPH residential streets so I got home and plugged the truck
immediately in to take a loooong drink from the juice bar and refill the
20 flooded 6V batteries.
Getting almost stuck 3 times today, not something I prefer to repeat.
The guy that I visited mentioned that he regularly had people with
underpowered cars that called him they were unable to make it to him. He
had a new Prius in his driveway, so that alone proves that the Prius is
not an underpowered car (as if I did not know that already, but you
still hear some people getting all upset about Prius' being
underpowered...)
Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: xxx@xxx.xxx Private: http://www.cvandewater.com
Skype: cor_van_de_water XoIP: +31877841130
Tel: +1 408 383 7626 Tel: +91 (040)23117400 x203
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