# a random thought



## major (Apr 4, 2008)

anand.ssukhi said:


> i have been thinking abt hybridizing a bike. my idea here is
> use 1 or 2 of car/truck starter motors to power the bike when extra torque is required
> iam not expecting much here just 30secs to 1 min at a time. and these motors shall be using alternate batteries.
> also iam thinking of applying regen somhow to reuse the energy while braking.
> ...


Here is a recent thread you might find interesting. http://www.diyelectriccar.com/forums/showthread.php?t=50111


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## anand.ssukhi (Jul 23, 2009)

thanks but the ending was not much encouraging
and actually my idea is a bit diffrent.
i wud be using the motor for what it is designed. i.e give short bursts of power just imagine like nox but less in magnitude.
and wud rewire the wiring somehow to get the regen effect.
i know the powering stuff wud work but wud it work effeciently is the question.
help!!


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## DavidDymaxion (Dec 1, 2008)

Many starters don't have ball bearings, they have sleeve bearings. They have no cooling. Your owner's manual will warn you to not crank for more than about 30 seconds so you don't overheat them. Heat is the enemy, that's a sign they are not very efficient. They are designed to take hundreds of Amps. That's OK when you start for a couple of seconds, but with Peukert's effects it's bad use of your battery -- it's better to do less current for longer periods. The final nail in the coffin is they are heavy.

One data point that illustrates the point: I went through several OEM starters. I then went to a racing starter with ball bearings. The car turns over much faster and this starter has lasted much longer.

I've read most folks use car fan motors, which are designed to run for longer periods of time and are more efficient.

Still not convinced? Try to turn a car starter by hand, then try to turn a car fan motor.


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## SimonRafferty (Apr 13, 2009)

My very first EV was an electric bike which used a Land Rover starter motor and an old car battery. It wasn't brilliant - but it worked OK

Like you, I only needed it for a short duration, in my case to to conquer a monster steep hill!

I subsequently found that not all starter motors are series wound - some, Ford I think, are PMDC which would be easier to wire for regenerative braking.

As has been mentioned, bearings are the biggest problem - but so long as you can disconnect the motor from the wheels and only use it for short durations - it's not a problem.

I used an old funnel to cast a concrete cone on to the end of the motor shaft. I arranged the cone to drive on to my rear wheel such that I could move the motor and cone from side to side to vary the gear ratio.

This limited the current draw and enabled it to deliver a decent top speed.

It was brilliant as a first project and taught me loads - so don't be discouraged! It lead to some much better engineered solutions - but you have to start somewhere!

Si


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## anand.ssukhi (Jul 23, 2009)

@ david
that peukert effect is a real monster just eats up the battery.
but i will be using li-ion its peukert constant is less and it wont be much costly as i wont need much.
and abt the bearing problem i sill have to search a starter with bearings.
and also iam not very sure abt the fan in terms of torque help me out on this

@ simon
thanks for the encouragement!!
i will think about an arrangement to disengage the motor when not in use.
please can u share the details of ur project


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## SimonRafferty (Apr 13, 2009)

anand.ssukhi said:


> @ david
> please can u share the details of ur project


What would you like to know. It was quite a long time ago but I'll do my best!

Si


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## anand.ssukhi (Jul 23, 2009)

How did u used to control the speed of motor.
I have a truck ac blower motor also any idea how much torque it gives cause i can run it for long duration
it says 24 v dc is abt 15 cm long and 8 cm dia
and weighs abt 2 kg


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## SimonRafferty (Apr 13, 2009)

On that bike, I didn't control the motor speed at all - I just used a contactor to switch it on and off (in fact it was the original starter solenoid).

That was the point of making a continuously variable transmission. Like you, I had no idea what torque the motor produced so but it didn't matter as I could pick the right ratio for the conditions.

Why don't you measure the stall torque? Just use a pair of mole-grips to grip the shaft. Put the motor body in a vice. Connect a spring balance to the end of the mole grips and fire up the motor. Record the max reading on the balance.

If the attachment point of the balance is D inches from the centre of rotation and the max reading in Lbs is M, The torque in FtLbs is:
T = D/12 x M

Starter motors seem to produce 20 to 40 FtLbs on the whole - so choose your spring balance accordingly. I have one which reads 0 to 100Lbs that came from eBay for weighing your luggage.

Si


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## anand.ssukhi (Jul 23, 2009)

That is a gud technique.
That made me remember the way we used to measure actual motor torque back in college


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## anand.ssukhi (Jul 23, 2009)

I did some study and found out that it would be really difficult to make the starter motor do regen!!
now iam thinking on reverse lines
i have a 3 phase 24 v alternator rated 100 amps
i know that it can be converted to motor (3 phase ac) but it wud be complex.
so please help me in doing so.

my basic requirment as a motor is not control over speed just the maximum and effecient torque.


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## Guest (Dec 17, 2010)

Old vehicles use DC generators rather than alternators and they have bearings on both ends and can be used for regen on a light weight bike. They are used as generators and could be powered and used as a motor. I have powered my old VW generator and it spins real nice at 24 volts. Real fast. It did not want to self start but with a slight nudge it just jumped to life. There are others that are larger and I am sure some that are smaller but use a generator rather than a starter or messing with an alternator. Find an old VW generator (12v) and give it a try. It has a shaft on both ends. From a Type III it will only have a shaft on one end. Get the ones from a Beetle. Double ended shafts. They are small and could be over volted to get you the speed you want. They are designed to run as generators at very good rpms too. So you get high rpm, regen, and bearings on both ends and a durable little motor. You do need to find a way to cool the motor. They have no internal fan but I figured that they would do well like at 24 volts and be happy. Can't hurt to give one a spin to see if it will provide the speed and power you need. They must be built durable to be used as a generator. 

Pete 

It's just a thought for you to ponder.


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## anand.ssukhi (Jul 23, 2009)

thanks gottdi,
i dont have many volks wagons or beetles here, all i get is honda, suzuki, tata and many more indian companies.
but i will go and have a look in some scrap yards for a dc generator i think i shall get some old truck or jeep generator.

also as i have an alternator i was just thinking of making it work as ac is more effecient.
opening and altering the alternator wiring is not a big deal here, all i need is a converter (dc to 3 phase ac)


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## Guest (Dec 17, 2010)

If you use the Alternator you still need a controller. Remember that AC is more expensive for parts but it would be better than DC as it will give you the best regen possible and best of all no brushes or commutator to deal with. 

Pete 

Yes the Jeep or old Truck or old Tractor Generator may just do the job. You could even use a contactor switch too with low voltage and have a blast.


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## anand.ssukhi (Jul 23, 2009)

i will go and find such a generator.

regarding the alternator i wanted to know that how much diffrence would it make 

short circuiting the feild/excitation windings in order to make it a induction motor or
giving it a dc supply in order to make synchronus motor


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## anand.ssukhi (Jul 23, 2009)

and regarding the parts for ac just help me if iam missing out any parts

alternator/ motor (i have )
rectifier (i have )
dc to 3 ph ac converter
battery
contactor


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## Guest (Dec 18, 2010)

I'm not the one to ask about powering any AC drive. 

Others will pipe in. 

Pete


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