Alternator to BLDC motor conversion

[barbender]

This is interesting, even more so than Southside's sense of humor😁 I feel that owing to the fact that I also have a very odd sense of humor (or maybe just overactive) he tends to get me at every chance. I can't leave a crumb on the ground without that sucker jumping right on it😂
 
 I'm always open to better, smarter and more efficient ways of doing things. And Don, I don't think you're completely off base, sometimes folks do try to pile on when alternative energy is brought up. Sometimes I fear we could walk right past a brilliant solution because we are so used to resisting things being crammed down our throats. 

 I like electric things. The level that cordless tools have attained is absolutely incredible, IMO. Who here, on a remote jobsite would ever use one of those chainsaw head powered drills versus one of the new cordless drills that outperform even corded units? Not me! 

 Anyways, I'm just trying to give a insight to my perspective. For my part, I'll try to keep a better eye on if folks are coming on too strong when others are trying to have an honest discussion. 

 

[Don P]

Well, I've watched about 8 hours of utubes on rebuilding priuses while on What did I just do exile. And I'm throttled for 3 more weeks  :D. There's about 10 million hybrids out there, the electric motors have around 125 ft-lbs of torque but after the gear reductions they are in the 1200 ft-lb range. That got my gears turning.

[mudfarmer]

cellular connection? I just switched from tracfone prepaid to vzw contract because they actually accept my weird cell modem now and got 3x the data for the same price. sorry for everyone on the forum for the increased # of posts :D

[Al_Smith]

I thought of another option depending on what you want the end results to be .A Ford long shaft starter which has been used for a number of devices requiring battery power .Relatively inexpensive ,reversible if you need it to be .Not heavy relative to a golf cart motor and powerful ..I've used them twice .One a front mounted winch on a CJ jeep that was brand new in 1964 and a starter using a vee belt to start the pony motor for Caterpillar D4 circa 1943 .I myself was brand new in1948 .

[Don P]

I've been told, at some point in the mists of time, to never crank a starter motor for more than about half a minute because they will overheat? That and I've rarely had a battery that would hold up to cranking for much more than that anyway. A good amount of power but they suck the juice. I think even on the dump trailer which is starter motor over hydraulic it is up in about that time.

We're on satellite, but broadband will be here any day now, or so they've been saying for the past 20+
 years.

[Ianab]

I was curious at what point the smoke escapes the controller. No not that way  .  I looked up the MOSFET transistors that are doing the switching for the DC to 3 phase. They are rated to 100 volts, 180 amps and can dissipate 370 watts. There are 6 in the little controller I have, 3 pair of 2. I see the 5kw controllers have 18-24. The rest of the components and board I don't know about, the traces themselves are printed circuit so not much capacity. I've seen where some people have overlaid them with copper and solder to make for larger current carrying ability to those transistors that are producing the 3ph. I think the chips are timing, feedback, low current.

MOSFETs are interesting devices. 
Basically think of them as a switch that can either be on or off, controlled by the voltage applied to the gate terminal. But unlike a "conventional" transistor the gate is insulated from the other terminals. The only current flowing is some "leakage", which is almost too small to matter. Because they work in either on or off mode, they don't dissipate a lot of heat, except at the instant they are actually switching, as they transition between insulator and conductor. 

This means the control circuitry is relatively light duty / low current stuff, and the system only needs heavy conductors / thick wires and PCB traces around the main MOSFETs. 

I'm more familiar with them from the computer side of things, which are almost totally MOSFET based, from the mains power regulation, down to the actual logic and memory circuits. In the power regulation side they are switched on and off at high frequency to regulate the voltage. (inductors and capacitors then smooth the voltage to the downstream devices). But when you consider a modern CPU chip may dissipate 100W or more, and runs at ~1.5 volts, you realise there is almost 100 Amps flowing into that chip. The CPU chips themselves are now crazy high transistor counts, the M2 Apple chips are up to 134,000,000,000 transistors now. So the power used per MOSFET in there is tiny, and they only really draw current as they switch on or off. Just there are so many of them, and they switch so fast, that the chips still get HOT.

But it's all the same MOSFET technology that's running a battery drill, electric chainsaw, golf cart or Tesla. 

[Al_Smith]

When I wore the clothes of a younger man specically the bell bottom blues of the US navy I was a technician on nuke subs .I was well versed for the time period .However fast forward 50 years and I have to review theory today .It's still there I just have to find it again .It's the old use it or lose it thing .I've got a lot of books plus the internet ,I'll find it some where .

[Ianab]

About 40 years ago when I was learning electronics at Tech. We actually built our own (kitset) computers at the time. It was a level above the course we were actually doing. We only had to actually make a linear regulated bench power supply to pass. But a couple of us had already done that at High School. The computers we built had a similar power supply arrangement, horribly inefficient linear powers regulators.  If you needed 5V for the chips. and your PSU was making 9V AC, then they just wasted the extra watts and needed a heatsink, as 1/2 the power was wasted  by the regulator. 

My first job was actually servicing video arcade machines. Common fault was shorted capacitors, same a a common fault in modern electronics. Before the days of thermal cameras I would just connect a serious bench supply to the board, set it to 5V and as many amps as it wanted. The short usually smoked in a few seconds. 

Faulty capacitors is still a likely failure point for modern electronics.  

[Al_Smith]

Again the application or use is what has to be considered before adapting something not really designed for what the end results to be determined .A starter motor compaired to a DC servo motor is apples to oranges .Might work for a while until all the smoke leaks out .Could an alternater become a small DC motor? Sure it could but it would be a lot more simple just to find a motor made for the application .However that would not provide the challenge of redesigning something  which speaking only for myself have tried for decades to reinvent the wheel . 
I say go for it Edison didn't get the light bulb on the first try and in fact wasn't the first one .Just took credit for it .If not we'd be in the dark with kerosene lamps and candles .

[Joe Hillmann]

I thought of another option depending on what you want the end results to be .A Ford long shaft starter which has been used for a number of devices requiring battery power .Relatively inexpensive ,reversible if you need it to be .Not heavy relative to a golf cart motor and powerful ..I've used them twice .One a front mounted winch on a CJ jeep that was brand new in 1964 and a starter using a vee belt to start the pony motor for Caterpillar D4 circa 1943 .I myself was brand new in1948 .

What is special about that starter?
Bearings instead of bushings?
Doesnt get ridiculously hot when run continuously?
Something else?
I have tried to use starters for projects before.   They get very hot very quick so I never did anymore than basic testing.