Lister Engine Forum

Lister Engines => Original Lister Cs Engines => Topic started by: dieselspanner on March 13, 2018, 06:50:57 PM

Title: Lister (oid) Dynastart
Post by: dieselspanner on March 13, 2018, 06:50:57 PM
So, back to the sordid subject of engineering!

There I was bumbling around on Youtube and I ran across this........

A clip of a car alternator being used as a prime mover for a go cart, it must have some grunt to hit around 40 kph...

As is well documented on here, my knowledge of things electronical is somewhere on the sc an side of non existant and I ain't much better at things electrical either, I can copy and repair but innovation ain't me.

So, would it be possible / practical to use a 90 amp or so alternator to start a CS and then run as a alternator to charge the start battery (s) on either 12 or 24 volts?

I went on to read that most applications use a variable speed controller, of which there are umpteen on Ebay, however, it would appear that a simple controller, using 3 Hall Effect switches should suffice to power up at a given speed.

Looking at an alternator with a pulley for a serpentine belt that, been kicking around my shed for a while it would be running around 9/1 driving directly on to a 22" flywheel.

Has it been done, is it practical, do circuit diagrams for the 'speed controller'  already exist, ect, or have I beaten Elon Musk to the punch?

All answers (and any amount of derision!) appreciated.

Cheers Stef

Title: Re: Lister (oid) Dynastart
Post by: BruceM on March 13, 2018, 09:18:21 PM
While it would be possible to use the alternator as both motor and alternator, I have not seen the circuitry to do the switch over dynamically but it could be done...crudely with some DC contactors/relays or better designed into and in addition to the 3 phase motor controller.  But note that you won't be getting 1500 watts of motor power if running the alternator motor on only 12VDC.  It makes sense to do it for lightweight, high efficiency vehicles (something American's seem to have no interest in at present) as it would save the weight of the starter and cost of the toothed flywheel.  It would normally require external diodes, which I think is the coffin nail; they need a lot of cooling so putting them in the alternator case for forced air fan cooling made more sense. 

For our home DIY generators it's easier with DC starter/charger units since they use a brushed DC motor which is already inherently a DC generator and thus no electronics required. A few guys have done this and I found one unit for sale for $100 US.  I think this would be my choice if starting over for a dedicated generator unit.

I was interested in doing a ST-3 generator/starter since I have 120VDC to drive it with, but the pathetic state of ST single phase head quality offends me so much that I won't develop anything for it. 

Thanks for the video link, it was fun watching that claw pole starter being abused as a 1500 watt motor on 48V. The smart and handy young man who did it and the video has a promising future.

Title: Re: Lister (oid) Dynastart
Post by: glort on March 14, 2018, 03:18:38 AM

Once again, De ja vu.
I was only watching that vid and some others by the same guy a few nights back. As I sit here there is a 3 phase  controller sitting beside me  with a bunch of other components I have ordered in waiting to be thrown at this very idea of a motor from an alt.
I'm thinking it could be very easy to make an All wheel drive Vehicle for around the property by putting one alt on each wheel and having the benifit of max torque at 0 revs instead of a geared down IC engine that had gob of torque for pulling shurbs but was so slow took 20 min to get them up the back to the pile to be chipped or cut up. Of course one could put in a gearbox but that's not as easy as a direct drive to a wheel and some wiring.

I have also noticed the ventilation blowers in Subaru's and no doubt other makes, are also 3 phase DC  now and I am waiting to get some of them and run them up on the ESC I have. these motors can be quite powerful and useful with the fan removed and coupled to other loads.

While in my limited knowledge and zero experience so far, I can't see why one could not make a starter/ generator out of an alt. I am more thinking along the lines of why would you want to though?  I can see additional components like relays and large diodes being needed to basically isolate one function from the other. As one needs to remove the diodes to convert the alt to a motor but to retain the brush pack which is notmally a single unit, the first thing that would be required for dual operation is a replacement diode pack . Not a big Deal, one can get a 100A 3 phase rectifier off fleabay for about $15 but it is more wiring, components and heat sinking to be done.

To me apart from the aspect of doing it, it would be far simpler and maybe even cheaper just to use another unmolested alternator for the generation side.  In stationary use, space is rarely a problem  and having a separate alt also gives a degree of backup in that if something goes wrong with the starter, you can still hand crank and make power.
That said, if one were planning on using an external controller so they could use the 12V alt to make 24 or 48V, then the complication may be lessened by what had to be done anyway.

If we look at the mentioned 90A alt as a starter, we can work out the theoretical power.
90A @ say 14.5V = 1305w / 746 =  1.75 Hp.
I would be thinking myself that the real power after inefficiency's and limitations is more likely to be around 1 to 1.25 HP.  That may struggle to spin up a Lister especially with the added rotational mass and drag of a generator coupled to the thing.  I don't know what the original start o matic was rated at as a motor but I'm sure several here do and it would be interesting to see the comparison in what they put out.
In any case, If one weren't enough would could do 2 alts in parallel.

For my thinking, the question is not if you can make a motor generator which is a definite Yes, it's " Is it worthwhile doing it?"
Title: Re: Lister (oid) Dynastart
Post by: dieselspanner on March 14, 2018, 05:00:23 PM
Hi Bruce,

It was the you guy's enthusiasm that made me think there might be something in it all.

I wasn't thinking of anything too technical, see the bit above about my level of knowledge!, more like mounting the alternator 'as is' and then supplying the power 'in between' the diode pack and the stator with something like a 3 phase relay to switch it and a control circuit with a rotor mounted between the alternator and the pulley with the 'doings' in a box elsewhere. Playing to the strength of generation rather than starting.

Given Glorts calculation on 14 volts could a 24 volt start system be used in the same way as the original 'Startomatic'?

Cheers Stef

Title: Re: Lister (oid) Dynastart
Post by: ajaffa1 on March 14, 2018, 11:09:52 PM
My ST2 SOM requires 24 volt and specifies 118 amps for cold cranking, if that helps.
Title: Re: Lister (oid) Dynastart
Post by: glort on March 15, 2018, 12:21:04 AM
My ST2 SOM requires 24 volt and specifies 118 amps for cold cranking, if that helps.

24V (28 actually) x 118A= 3304W / 746 ( watts to HP) = 4.42 Hp.

Significantly more than the alt would do... or even 2 of them... or 3....  :-[

Starter has 3/4 the grunt of the engine!  :o
Title: Re: Lister (oid) Dynastart
Post by: BruceM on March 15, 2018, 12:36:42 AM
When I was first working out the cranking power needed for my 6/1  I started with a vee belt and small pulley on a Gast 3AM air motor, which is about 1 HP max rated; it was gutless and barely adequate.  The 4AM is rated 1.7HP and has plenty of power for starting with a rubber roller of 2.5" OD.  Air motors have moderate starting torque so you should be able to do a lower HP in electric.  I'm think you'd do fine with a 1.5 hp induction motor, for example. 

No reason you couldn't experiment away if you can get the parts cheap enough to give it a whirl.

Title: Re: Lister (oid) Dynastart
Post by: ajaffa1 on March 15, 2018, 05:41:19 AM
Thinking back, I remember seeing a video on YouTube where a guy had rigged up an air powered starter with a small compressor and tank that charged up when the engine was running. Ozlisteroids I think. It was a very impressive system.
Title: Re: Lister (oid) Dynastart
Post by: glort on March 15, 2018, 05:56:17 AM

Wasn't Bennylovesdiesels was It? I think he had an automatic start system with an air motor as well.
Title: Re: Lister (oid) Dynastart
Post by: ajaffa1 on March 15, 2018, 06:08:42 AM
yes I think you might be right, I`ll check it out.
Title: Re: Lister (oid) Dynastart
Post by: ajaffa1 on March 15, 2018, 06:13:24 AM
check this out