[Woodsmith]

Originally Posted by Qer

About the mechanical motor control, drop that idea. It's one thing to run a few Volts and Watts through a tube for fun and quite different when you start to get into SERIOUS power. Get a cheap Curtis on E-bay instead.

I probably will do but the playing is a good learning curve that cost nothing and it does show me in a very physical sense how PWM works and where the limiations are.

As I get the components together I will see what I can afford to buy and what I can afford the time to experiment with. Good controllers are expensive but if a kit of bits or a comprehensive design plan was available I could then have a shopping list of electronic components to buy and assemble.

However, I would still be interested in seeing how a properly built mechanical controller with carbon brush contacts would cope with more power and where its limitations were. If nothing else it would make a good college teaching aid to demonstrait PWM at a base level.

[OHM]

I still think not everyone in poorer countries or with limited
budgets can aim for expensive and non self-servicing controllers.
This is an interest of mine as I still believe Lead acid batteries
can work in the right setup for a 40-60 mile range vehicle that
has lower technology and efficiency but easy to be locally repaired.
If a modern controller fails you end up waiting weeks of months
for repairs or replacements and with an old controller you could
be back on the road with a little sandpaper or hands on with the
right knowledge and care.

I wouldnt mind seeing a perfected mechanical controller.
I did ask someone to make a contactor controller for me
based on his perfected design but has used my funds to
build something totally different from his original design
calling it an all-in-one prototype which I never requested.

Hopefully someone succeeds in a mechanical controller that
can help the poor to economical electrical transportation.
If such a controller is available online for others to build there
could be more EVs out there instead of polluting clunkers.

[Qer]

Originally Posted by OHM

I still think not everyone in poorer countries or with limited
budgets can aim for expensive and non self-servicing controllers.

The price is much because controllers are built more or less by hand and in small series. The price for the components also keeps dropping so that, in combination with a (hopefully) raising demand, should affect the price in a good way.

Originally Posted by OHM

If a modern controller fails you end up waiting weeks of months for repairs or replacements and with an old controller you could be back on the road with a little sandpaper or hands on with the right knowledge and care.

On the other hand, controllers shouldn't fail. If you do a good design that's well tested it shouldn't break more than any other core part in the car. There's literally tons of controllers out in the industry and they're quite reliable and well-proven by now. And, of course, why we see weeks or months now is because demands is bigger than supply. If people are gonna use EV's for every day's use these parts has to be on the shelf, just like any other spare part for a car.

A mechanical controller will fail more often because they will wear down. Also, to get a PWM of 8 kHz means the bar has to spin with 480000 rpm! At 6000 rpm you will get 100 Hz which will probably mean a rather jerky ride plus that it will put quite some strain on batteries (you can't get a cap pack for that frequency), motor, drive train etc, not to mention it's a dumb controller that can't react smoothly on over current etc so people are likely to burn things up (like the motor).

Forget about it. A mechanical controller is definitely nothing but a DIY-toy today.

[OHM]

With NSK type bearings as the only expensive part can they help with the speed issue?
Some NSK bearings are rated at 5000hrs of continuous use at 50,000rpm.
How big does the copper bar have to be for ideal operation?

[Woodsmith]

There are a number of issues around controllers both in terms of cost, reliability and kindness to the motor and battery pack.

My gut feelings is that anything electro-mechanical, no matter how it is made will have some reliability issues. Even electric motors will require brush replacement and commutator cleaning to maintain its best performance.
reliability comes from being one or the other but not really both. I reckon that an electronic controller that is looked after will require no maintenence or repair. The sealed bearings in a motor will, likewise, also require almost no maintenence or repair if they are not over stressed.
Where the two meet, electricity and mecanical movement, there will be a constant need for servicing and inspection.
That will be the case for a speed controller whether it is made from a rotating cylinder or a set of contactors.

The advantage I can see in the mechanical controller does lie in very low cost and ease or repair in use.
For the time being if I was to be in a position where I wanted to have a failsafe I would have a mechanical speed controller and a box of spares but that is only because of the cost of carrying a whole spare electronic controller for lack of testing equipiment for repairing one. Also it is because I can repair just about anything mechanical and nothing electronic. An electronics person may dispute the ease of repair I speak of because of their own expertise.

However, a well made and modular, sealed, electronic controller would probably never fail. And if it is made as two or three sealed units then that would make any repair or adaptation easier and potentially cheaper. This does lead to it becoming a throwaway device with the corresponding waste of resources.

There are no easy answers.
If an electronic controller was to only cost $200 all in as a standardised part that required a standard pot input and had a rated output and a standard display output that worked on a standard display screen then things would be great. That will come in time if manufacturers were to standardise their interfaces and had sufficient market to bring the price down.

In the meantime mechanical is a great learning tool that may find itself in an experimantal off road fun/development vehicle. If I were to 'perfect' it then it might get on the road, I would like that. But the investment may not be economically viable as I really do want, not only reliability but, ease of use. I don't want to spend all my commuting time fussing over my speed controller, I want to take it for granted. I am not sure I can afford that right now though, but equally I am not sure I can afford not to if I want to have a reliable motor and a lithium battery pack.

I feel that the investment in components has to be matched. It would be a waste of money to have the best of one thing and a bodge on another except in the development stage.

[Woodsmith]

Originally Posted by OHM

With NSK type bearings as the only expensive part can they help with the speed issue?
Some NSK bearings are rated at 5000hrs of continuous use at 50,000rpm.
How big does the copper bar have to be for ideal operation?

Cross posted.
There wouldn't be an ideal really, just big compromise. The bearing would never be the problem any more then they would be on the vehicle drive motor. The problem would lie in the moving parts of the system. From what I have seen in my simple test rig and from my experience of electric motor repairs it is the moving brush that would be the main issue. If the brush stayed still then the wear on the copper would be low, as it is on a motor commutator, as it would bed in. It is the constant and irregular speed change movement that causes uneven wear on the brush and copper. That leads to greater arcing that accelerates the wear.

I servicable controller would require a quick replacement copper cylinder and brush set. The rest of the system would be fine.

[OHM]

thats what I was looking at, Id be happy to change the points, sparkplugs and adjust the timing so to speak once in a while knowing that I can. This is better than a Curtis, Electrosystem, Warpcore or whatever affordable modern controller would be if it had to be shipped back over oceans for a replacement or repair.

Surely an understatement to someone in a third world country running some kind of tuk tuk EV or goatless cart.

The commutacar and ev1 did it with contactor controllers, not the most efficient way but more reliably than most EVs out there.

[Qer]

Originally Posted by OHM

...but more reliably than most EVs out there.

You probably should say "...but more reliable than most DIY-EVs out there."

As far as I know, for example RAV4-EV is considered a rather reliable car and some of those has been on the road for over 10 years without popping the controller. And, of course, the whole industry has moved from contactors to transistors to get more reliable controllers, not less.

Finally, electromechanics isn't cheap as well. It quickly adds up when you start to put it all together.

[Woodsmith]

Shall we shift the reliability and usefullness of electronic vs electro-mechanical controllers to the thread in the controllers forum?

I am interested in the discussion but I don't want it to be the dominant factor here. I see it as a good learning curve, as I have said, and there are pros and cons on both sides. I will err on the side of a mechanical system being easy for me to repair but I also believe that a well made and encapsulated electronic controller would probably not need any repair at all but costs more at the moment.




In the meantime....

I went out with an ex girlfriend today, no no, nothing funny going on. She has been thinking of trading in her car for something larger. Also her son now has a replacement car for his one which is no longer running. It means that, if I play this right (again no funny business), I might have the choice of a 1997 VW Polo 1.4 or a 2000 Nissan Micra 1.0 to convert.
The Polo is a little battered and needs a bit of body work to make it look good but it is a non runner and so scrap value on a good day.
The Micra is a fantastic runner and in excellent condition with only a tiny area of corrosion just begining underneath so still has a fair trade in value.

I don't know if either would be suitable for what I want but at least I know both cars are honest and not messed about with.

Any thoughts about these options would be good. I will check the garage to see if there are any existing conversions of these.

Cheers,
Alfred

[OHM]

Glad to hear you will persist this logical route Alfred.
You never know what could come of experimentation.

On the Polo vs Micra front.
The Polo would be easier to convert as they have the same box
as the Golf which kits should be available for, but apart from that
they are not as well put together as the Micra in quality.
The Polos trim age ungracefully making it look tatty faster.
The gearbox are known to be full of gremlins.
Electronics are not far off the Lucas days.

I would check for the Micra clubs to see if someone has done an
conversion to EV if going the micra route.
The Micra has classic well rounded lines, should be lighter than the Polo as a glider,
In japan they are collectables so after market parts are plentiful.
Electronics are excellent and the body alignment of the panels is superior
to the Polo. Its also a preferred Micra model over the newer ones in Japanese
Micra forums due to its lines and overall package.
Aerodynamics should be superior also.

However it depends if you have access to a cvt or manual version of the Micra?
I keep thinking what would be of a cvt mated to an industrial engine with a simple
controller that runs at it optimun rpm range thanks to the cvt.