Thanks for the thoughts Damon,
It's a true mini-bike - the old school kind you see in Northern
Hydraulics. I probably look pretty stupid on it - though some might say
I look pretty stupid off it too ;-)
I suspect the controller too. It did get pretty warm with just a little
running around. I can pull a contactor out of one of the 'spare'
ElecTracs and try that. I went all out and put a voltmeter and ammeter
on the bike as I wanted to learn as much as I could about what it takes
to power an EM. The batteries are new, but they could have a factory
defect. The first motor performed about the same (before it died) as the
replacement, so it's not the motor -unless there is something about this
particular motor I don't understand. The old - "It's not what you don't
know, it's what you know that ain't so".
I'll report back after trying a more direct control approach.
- SteveS
damon henry wrote:
Well, there are only three possibilities. It's the motor, the
batteries, or the controller. How mini is the mini-bike? I have a
small scooter/mini bike that came with a bad controller. I ditched
the controller and installed a single contactor. Now I just switch in
either 24 or 36 volts worth of batteries. Even with me on it it will
do at least 15 mph at 36 volts and I am North of 250 pounds. I have
not counted the teeth on the gears so I'm not sure what the ratio is
set at, but everything about your setup sounds heavier duty then what
I am talking about. I would try hooking some batteries straight
across the motor. If you can, start with 12 volts then try 24 volts.
Just use a pair of jumper cables and don't ride very far. 36 volts is
starting to push it a little high for the jumper cable approach, but
if you have a decent contactor laying around you can also try 36
volts. A clamp on ammeter would be great if you have one, then you
can see how much current you are drawing. A voltmeter across the
batteries will also give you useful information.
A 750 watt controller sounds like plenty to tool around on a minibike,
but it is the easiest thing to take out of the loop, so I would start
there. I would expect you to be able to do at least 20 mph on 36
volts on your minibike, but you may find that the motor needs a lot
more current then the 20 amps or so your controller can provide.
damon
From: SteveS <[EMAIL PROTECTED]>
Reply-To: ElectricMotorcycles <[email protected]>
To: ElectricMotorcycles <[email protected]>
Subject: [ElectricMotorcycles] mini-bike performance
Date: Sat, 23 Jun 2007 15:04:50 -0400
Or lack thereof.
The volume of emails lately on the list served as a good kick in the
can for my mini-bike project. I finally wired it up and tried it out.
It was not a great experience.
The power was very low and then the motor shed part of one magnet.
Luckily I had another motor and put it and tried again. Still not
working well. On flat ground I can get it to move along maybe 3-4 MPH
after helping it start up. If I start on a downhill I can get the
speed up to 5-7 MPH but it bogs down on any uphill slope.
Here's what I have.
Mini-bike frame with 11" rear tire.
Motor gear 12 teeth, rear gear 64 teeth
~1HP 36V large mower deck motor from an Elec-Trak
3 12V-18AH SLAs in series
36V 750W controller from a scooter store
If I calculate right at 5MPH I should be turning about 800RPM. Maybe
I need a higher gear ratio? The motor is probably designed to run at
a constant speed since it's from a mower deck. Could that be the
problem? Or am I just asking too much from too little? On the flat it
was pulling about 20A or so.Voltage stayed pretty steady. Batteries
are new and freshly charged. It is a pretty heavy setup with the
motor, batteries (and me!).
I didn't expect too much, but I thought it would move along.
- SteveS
_________________________________________________________________
Like puzzles? Play free games & earn great prizes. Play Clink now.
http://club.live.com/clink.aspx?icid=clink_hotmailtextlink2
