Chip

iTrader: (3)

Anyone know a cheap (ie secondhand) source of such a thing?

What do they get used in?

And what sort of voltage do I need?



Its for an electric car project a mate of mine wants to do and I said would give him a hand with.

AlexF

jesus thats a big motor!

100kw is 136 metric HP!

LINCOLN

iTrader: (1)

Old cnc spindle motors where and some still are dc - 100kw is massive though and probably hard to find. Think they are normally 180vdc and most where brushed and not permanent magnet so need excitation.

Chip

iTrader: (3)

Yeah im aware its a big motor, but bear in mind its to replace an engine!
50kg or so in weight im expecting, and was thinking it would probably need to be 400V or so, and be about 12" in diameter and a similar length (so similar size to an engine without sump or head)

Its old industrial uses im thinking of, rather than having to buy new.

like for example maybe an electric overhead winch in a shipyard for lifting heavy steel or something like that

AlexF

NOt a motor but you might be interested:

http://homepage.ntlworld.com/electric.mini/index.html

Isaac.Hunt

IIRC, Fanuc GE Make 100kw spindle motors. I dread to think how much one would cost though. I remember last time one of our 20hp/15kw Haas spindle motors was replaced, it cost around Ł7,000.

Chip

iTrader: (3)

By the way, im talking 100Kw peak output, not continuous rating, the sort of motor im thinking of would only be rated by suppliers to 30kw continuous use probably.

Here is the sort of thing Ive got in mind, maybe a little bigger than this:
http://www.electro-vehicles.eu/shop/...p?ProdId=ADC01

That one has a 5 min rating of 40KW, so about half the size im after, but TBH as it will peak at 80KW and I will only need it for perhaps a quarter of a minute at a time, that could be enough, would prefer bigger though.

Chip

iTrader: (3)

Aha, here's the kiddy:

http://www.electro-vehicles.eu/shop/...t=0&path=47,61

That would be fucking spot on, 43hp one hour rating at 72V, but capable of more than double that.


Trouble is, i was hoping to pay a few hundred secondhand, not a few grand new

ECU Monitor Enthusiast

iTrader: (1)

Chip,

Try a milk float...LOL

In an ideal world a motor is cheapest when drive at the same voltage as the power source as there is no voltage conversion power loss.

The way car manufactures do it is to use a higher voltage motor and use a frequency/voltage inverter circuit to control the speed and power delivery requirements.
You need to do this other wise you will struggle to control the power of a big motor using a potentiometer directly and it may make a bit of heat..LOL

Its not going to be cheap even bodging it !


Good luck, sounds an interesting project

Mark_w

http://cgi.ebay.co.uk/1958-co-op-ori...3A1%7C294%3A50

Chip

iTrader: (3)

What sort of power is milkfloat battery rated for continuous use, and what can it peak at for a few seconds?

Chip

iTrader: (3)

It doesnt need speed control at all for this application, its just a case of hitting it with all the current at once flat out, its ONLY for drag racing, its not going to be used to drive normally etc.
So 12 * 12v motorcycle batteries in line = 144v nominal, and thats only a weight of around 40kg
Thats based on 10ah 3.2kg batteries
I doubt they can handle the current draw, but will do to test it initially.

So for this particular application, with the throttle just being on/off it means I dont have to worry about the ineffiency of speed controller etc.

AlexF

What batteries are you thinking of?

wirralphil

Try some scrap metal merchants.

Chip

iTrader: (3)

Alex, I was looking at motorbike batteries initially, the downside to these is they only have about 180CCA where as I probably need double that, but I could always double them up, although that would mean 24 batterys, but even thts not horrific at 3kg a pop

Chip

iTrader: (3)

The problem with scrap merchants is they tend not to have technical data about the motors and stuff, but yeah might be worth a look

Chip

iTrader: (3)

PS

Alex, mini start motor external solenoids can handle a couple of hundred amps, are 12v operated and are very compact, so was thinking of using those as an on off switch.

AlexF

hmm I'd of thought higher CCA car batteries would be better....

Unless your desperate for the voltage!

Alex

Chip

iTrader: (3)

Yep the voltage is really important, needs to be 140V or so at a miminum, potentially more than that depending on the motor I end up with.

Dont need very much capacity, quite happy if it only runs for 30 seconds before needing a recharge.

zvhrst

CNC spindel is prob the most common to get hold of, but the main promlem is the 3 phase (415v)

i have a spare high weimer lift motor (like a 4 post ramp for HGV vehicles) but again its 3 phase (415v)

as for power, thought about truck batterys? high amp out, but they are ridiculasly heavy... but its one or other i suppose unless u get expensive dry cell batterys.

what about an old laith?(sp) what motors were they rated at? but again i suspect a 100KW motor will be all 3 phase??

Chip

iTrader: (3)

I guess I could get 3 motors of 30KW each, and connect them all to the input shaft of the box.

Kind of like this (these are only 3kw starter motors, but this is just turning a supercharger)

Chip

iTrader: (3)

3 phase AC is relatively hard to achieve in a car, and truck batteries would be no use at all, I need high voltage and they are only 24V for loads of weight, could have 10 motorbike batteries connecte together for 120V for the same weight as one 24V truck battery!

AlexF

Its not so much the current capacity as the cehmical-electrical conversion rate - bike batteries are not design for rapid discharge, hence the low CCA, light weight and small size.

Over heat them and they'll buckel the plates and short.

Alex

zvhrst

i know what you mean about truck batterys was jus a sujestion cause there hight amp output

what about runing say 2 starter motors on each wheel, so 4 wheels drive ??

danneth

this might help abitchip

http://www.control.com/thread/1026205217

http://www.diyelectriccar.com/forums...tor-23878.html

AlexF

Then you would need serious speed controllers to sync each motor.

Chip

iTrader: (3)

As per my post above mate, no speed control needed, just on or off for this specific application.

Lorry starter motors are 24v yeah?
Wonder what KW output they would be at 48V or 60V instead?

zvhrst

yeh but say 8 comercial starter motors would cost less than one 100KW DC motor imo

zvhrst

i'll have one knocking about in the garage so i'll have a look now for ya,

alistairolsen

Chip, unlike you not to have done a load of reading....

You might not need speed control per se, but you will need a soft start of some form! The torque output of an electric motor used as you describe would break things, wheelie or wheelspin. Youneed to ramp the power in gradually (talkingless than a second but vital all the same)

Chip

iTrader: (3)

No I dont, I want to hit it instantly with full torque, its easiest if you consider it as if I have essentially endless grip for this application basically mate.

Chip

iTrader: (3)

Been looking and 24v lorry start motors seem to go up to about 9kw, are cheap, and are a sensible size for fitting several of them in place on an engine.
So seems reasonable in principle

Thats their continuous safe rating at 24V, so what I need to do is figure out a way of testing their peak output at 48-60V or similar.

I guess the easiest way to do that, is to test the starter in a scrap car at 24V withthe car in gear and see what happens to it as what happens to a 12v car starter at 12v is likely to be indicative of what happens to a lorry starter at 48v, ie wether it will catch fire or not!

zvhrst

right had a scrounge and also been on phone to my mechanic/electrition who works on my coaches

ive got kicking about 2 starters
1 is a Delco 40MT 24v from an 18litre cummins engine
and a
Butech MS1 24v from a 12litre B12r volvo

right both these starters are obv 24v, the KW rating does not apply to them, there AMP rated and these 2 types inperticular are as follows
off load amps would consume 50amps to turn them

on load depends on how much load, but basically these will be ok at taking (or using) up to 7000 amps each on load,

but basically once the car is moving the load isnt as great as the initial set off and my sparky rekons for a VERY short time could be made to take double the 7k amps so an initial 14k amps then obviously the load will reduce if needed, now the idea you wanting to 1/4 mile it is really a low target period, so i told him this and basically he says for what your wanting to do jus wack as many amps through as you can coz all it will do is burn motor out lol

now onto amps etc. i said about bike batterys and he said it wouldnt work, you will need HIGH amp batterys and the more the better.

so looks like only optioon for that is really dry cell batterys and link them together for max AMPS

hope this helps and sounds like a cool project

he also recomends tho, doing it RWD on a beam axle and bolt starters to a frame underneath all linked to a flywheel of which you would need to figure out wat gear ratio you wanted

Chip

iTrader: (3)

zvhrst, thats really interesting info, you seem to be forgetting with the amps thing though, that I want to run them at much higher voltage than normal, so at 60V they would take far less amps for the same power output.

zvhrst

yeh upping the voltage will increase the AMPS you have, but no matter how many batterys you have, a batter will only give off as many amps as its made to do. trying to make a little 30amp battery kick out 100amp by runing silly voltage will amke the batterys short and explode.

am not sue on a way round this other than a capacitor of somesort maybe ??

Chip

iTrader: (3)

No you are missing the point a little mate.
If you put more volts into the starter, it will make more power for the same number of amps.
So for example if I used say 8 bike batteries to drive one starter motor, I would wire them in pairs that were in parrellel, each battery can do 180amps, so each pair would do 360amps.
I would then put the 4 pairs in series, which would give me 360amps at 48v.

Thats just an example, might be that I used 12 batteries for 540amps at 48v or whatever.

Chip

iTrader: (3)

PS

100kw = 100,000 VA
So at 48V I would need 2000A roughly to achieve my target power
So if I had 4 starter motors running at 48V with 500A, that would give me the power I wanted potentially, if they can handle that, which I have no idea at all if they could or not yet.

zvhrst

right i get ya now,

i thought you was on about making a link of batterys to make 24v but linking more than 2 in pairs...

yeh your way could work... altho how many batterys are been planed on having?

theres going to be some serious weight

zvhrst

they would handle 500a each quite well, a 12 litre coach drags 750 amps to start at 20v

orionmojo

iTrader: (1)

Aston Welding might be able to help you. They do all my dads stuff on his trucks, chassis repairs, press work, ram maintenance and machining etc. they're an "old skool" metalshop of three very talented and skilled blokes. I've no idea if they can help you, but they get their hands on all kinds of winches and motors and the like as payment for jobs and stuff.

Maybe of use. i'll bet if they dont have one they'll know someone who does.

http://www.yell.com/listings/DoFindL...elding/Welders