# [EVDL] old lawnmower motor for bike conversion



## EVDL List (Jul 27, 2007)

Happy HOWLoween all,

A while back I scrapped an old black and decker corded electric mower. I only kept the motor, switch and cord. I have been trying to find some info on it online with no luck except that I can get a new replacement for about 140 bucks (DeWalt part 242238-01). I am wondering if I could put together an electric bike conversion. I have no idea of it's specs. It is 110 volt AC supply but is a permenant magnet brushed motor. It has an old Motorola bridge rectifyer (SDA 10206, can't find online either) on it along with a large resistor (I think). I have no idea what speed it runs at, and really have limited experience on what the rectifyer does to the input voltage. I read up on them a bit online but couldn't find if the DC voltage would be 110 or not. Anyway I would run it on 24-36 volts and find a controller (not run right off the pack). Probably run a chain off the left side of the rear wheel using a disc brake hub on the bike, with the motor on a rack above. I don't !
know if the thing will have enough guts or at what speed it runs. Any Ideas?
Thanks
Kelly

PS Lots of great info flies about on this list, I have learned much. I haven't posted much unless I have something that is helpful, unfortunatly that is rarely to do with the EV aspects of the cars, but mechanical stuff. I just want to thank you all for the education.
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## EVDL List (Jul 27, 2007)

The motor is a PM DC motor. I don't recall the gadget you mention in 
addition to the bridge rectifier, it's been a few years since I had one 
apart, but I'm pretty sure I don't recall it having a resistor. 

One more consideration is that mower motors live a rough life. You'll 
probably want to at least change the output shaft bearing. New brushes 
would be a good idea, too.

David Roden - Akron, Ohio, USA
EVDL Administrator

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General EVDL support: http://evdl.org/help/
Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
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## EVDL List (Jul 27, 2007)

Good advice on the bearing and brushes and they are pretty east to 
find it seems. What I called a resistor may actually be a capacitor. I 
admit to knowing little of electronics yet, but in my reading it looks 
like they are used to even out the voltage spikes from the rectifier. 
It is four or so inches long, and has a square brownish body. It is 
marked 5 ohm 10% 20W. The ohms symbol made me think resistor. As it is 
sounding, it may not be a good candidate for the bike, I may play with 
it anyway, I just can't bring myself to chuck it.

Thanks Dave,

Kelly Hales

Sent from my iPhone

On Oct 31, 2008, at 11:43 PM, "EVDL Administrator" <[email protected]> 


> wrote:
> 
> > The motor is a PM DC motor. I don't recall the gadget you mention in
> > addition to the bridge rectifier, it's been a few years since I had
> ...


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## EVDL List (Jul 27, 2007)

So perm mag motors aren't the best for this job. The limited specs I 
have seen say it is an 8 amp motor. I don't know if it has enough 
power for a bike. I was thinking ICE mowers are like 2-3 HP. If it 
will only put out a third of that I still have one. Can a perm mag 
take PWM? Guess I need to read up some more. I want to play it 
somewhere, can't do a wind generator here.


Kelly Hales

Sent from my iPhone

On Oct 31, 2008, at 10:53 PM, James Massey <[email protected]> 


> wrote:
> 
> > At 04:20 PM 1/11/08, Kelly
> 
> ...


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## EVDL List (Jul 27, 2007)

That most definitely *is* a resistor.
It will likely allow a slow start (half power switch?)
or protect the motor in case of a start while stalled.

Much better motors for e-bikes are slow running motors,
typically these motors have many poles and the diameter
is large compared to the length.
Still then you need a large reduction, as Lawrence
found out when he was lugging his motor on his
home-built bike and was burning it up until he went
to an extreme large ratio (I think it was 10:1) with
a rear wheel sprocket the size of half the wheel and
motor sprocket about the smallest he could find.
Memory is spotty but I recall comething like 300
and 30 teeth sprockets.

Most e-bike kits have lower gearing but depend on
a slow running motor to achieve the right speed
without burning it up.

Hope this helps,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040) 23117400x109 XoIP: +31877841130

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Kelly Hales
Sent: Saturday, November 01, 2008 11:06 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] old lawnmower motor for bike conversion

Good advice on the bearing and brushes and they are pretty east to find
it seems. What I called a resistor may actually be a capacitor. I admit
to knowing little of electronics yet, but in my reading it looks like
they are used to even out the voltage spikes from the rectifier. 
It is four or so inches long, and has a square brownish body. It is
marked 5 ohm 10% 20W. The ohms symbol made me think resistor. As it is
sounding, it may not be a good candidate for the bike, I may play with
it anyway, I just can't bring myself to chuck it.

Thanks Dave,

Kelly Hales

Sent from my iPhone

On Oct 31, 2008, at 11:43 PM, "EVDL Administrator" <[email protected]>


> wrote:
> 
> > The motor is a PM DC motor. I don't recall the gadget you mention in
> > addition to the bridge rectifier, it's been a few years since I had
> ...


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## EVDL List (Jul 27, 2007)

> On 1 Nov 2008 at 10:35, Kelly Hales wrote:
> 
> > 5 ohm 10% 20W. The ohms symbol made me think resistor.
> 
> ...


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## EVDL List (Jul 27, 2007)

Yup I figured the resistor and rectifier would be removed. The thing 
was used when I bought it and I've had it for 10 years or so. Don't 
have grass anymore. Not at all a high end unit. I'll have to see how 
it works on a couple 12 volters. I knew I would have to gear it down.

Kelly Hales

Sent from my iPhone

On Nov 1, 2008, at 1:16 PM, "EVDL Administrator" <[email protected]> 


> wrote:
> 
> > On 1 Nov 2008 at 10:35, Kelly Hales
> 
> ...


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