Whoa, a perpetual motion machine under every hood!!! Once you get it started it goes on with no energy input.
The gasoline is the input, seriously how the hell do you think a gas generator works? You guys astound me. I guess you have never push started a car before.
No you astound the members here that have knowledge of how electrical circuits operate... Anyway whats push starting a vehicle to spin the engine fast enough to create enough RPM so the alt can supply voltage to use the starter??? Engine will be running long before the alt is supplying enough current to MAYBE make the starter click... Not much doubt most of us have push started their cars but you'll never get it started without some voltage to excite the alternator... Yes a almost dead battery will usually be enough, but it isn't happening without a battery... Secondly it must be a std transmission vehicle because all modern automatics rely on the front pump to supply hydraulic pressure to engage the clutches/bands... A automatic vehicle from the early 60s & older with a generator can be push started without a battery, most also had a rear pump in the transmission to operate the hydraulics so if you could get speed up to around 30 MPH they'd start... Defiantly not going to push start it by hand...
You can excite an alternator without a battery, the only thing the battery is for is reference for the voltage regulator. Self-exciting alternators would still excite if they weren't connected to the battery, there just would be no voltage reference point to activate the regulator so it would output an un-regulated voltage. I only spent 1 summer working in alternator repair though maybe I don't remember as much about them as I think I do. Also, I know that you can start the stock starter on a 74 302 and a 71 200 spin the engine enough to start it on less than 100 amps because I've done it. Once the engine is running battery is superfluous, it's only function is reference for the VR and storing electricity for your next start-up. If we didn't use batteries we would just use Hand Cranks like they used to, or I guess you guys have never seen that before either.
Tell us how you excite an alternator without any voltage present to do so ? Those two examples you gave us (the 74 302 and the 200 six) could likely have had FMX transmissions, which had rear pumps allowing them to be push started. That 1 year (probly less as it was a summer job, making it 2-3 months at best) and the fog of the years past since then have obviously clouded your judgement here. If you truly want us to believe you, then go out and actually do what you say is true. We will all happily tune in to You-tube to witness it happening. Or just go down to your local parts house that has a machine to test alternators and grab on off the shelf, hook it up and spin it without energizing it. I can guarantee you there will be no voltage (or amperage)registered on the meter when you do so. If you DO find something registering, let us know what the numbers are.
It wasn't a summer job it was one of the places I interned at getting my EE. Sorry guys, the whole point of this was that the battery listed was sufficient, and it is. Just because you don't understand simple electrical circuits don't expect me to waste a bunch of time explaining magnetic field theories to you. The alternator is an electrical generator, it will generate whether or not it is hooked up to the Voltage Regulator. Basically the principle behind 1 wire alternators. They supply the voltage to the car, and the battery, and self-reference for the VR. There are ways to simulate a battery being there without one if you wanted a system without a battery. I am not advocating that because it's dumb, but I have started many many cars off the voltage generator on my test bench and it cannot output more than 100 amps. Just read this - http://auto.howstuffworks.com/alternator.htm and this - http://alternatorparts.com/what_is_a_self_exciting_alternator.htm Then explain to me exactly why we have a battery in the car other than to conveniently power the starter. If you just want to power the starter get as small a battery as you can get. Me I like listening to the stereo and having lots of lights, so I use a big enough battery to do that. I also just figured out how to prove this to you guys. Start you car, unhook the battery, then turn the key to the starting position, the starter will crank and you will hear that sound that says omg I just engaged my starter with the engine running. Also I've never owned a car with an FMX transmission. I don't argue with hardly anyone about anything car related, I've been an industrial mechanic since I was 10 working for my dad in his plastics plant, but that does not directly translate to cars except that I understand the components and how to turn a wrench. Oh and I'm an electrical engineer so I went to school to learn all about magnetic field theory and how to make 3, 6 whatever phase you want generators.
So, it's up to you now to prove you're right and we're wrong. Just saying it's so, doesn't mean it is.
You're just a wealth of bad info... If you want to try that go ahead, but it's a good way to damage the starter and/or ring-gear/flexplate, plus all you'll prove is the starter would extend the drive gear... With the engine running, it will spin the starter if the drive extends... If you really want to prove that works you'll need two vehicles, start first and remove battery cable then attach jumpers to second vehicle also with no battery connected... BTW when you blow up a alternator or worse, don't blame me... It's very possible to destroy the control modules(computers, PCM, BCM etc) in modern vehicles, they won't tolerate alternator voltage spikes that occur when the alternator is disconnected from the battery...
Well i just wasted 5 mins i could have spent dreaming about a Maverick that i'll never get done. Speechless, just friggin speechless.
[nomedia="http://www.youtube.com/watch?v=287qd4uI7-E"]Perpetual motion machines (hypothetical ) - YouTube[/nomedia]
I'm not advocating actually doing any of that, but it proves a point you know it's possible. I'm still trying to figure out your issues with my saying 65 amps will start it when someone else says 70 or 80 amps will start it. It's like you only read my post out of the entire thread and freaked out because I stated some things that are true conditions. It's kinda ridiculous.
It's called "load dump". Never disconnect the battery from a running engine, the voltage spikes can be 10X the alternator output voltage. The rest of the car won't like it. The battery also smooths the rectified alternator output, think of it the same as a large filter capacitor in a power supply. As far as the small battery in the OP goes, depends on the mechanical load provided by the engine. A heat soaked high compression engine might need over 200 amps, especially with these old inefficient starters with no gear reduction.
Disconnecting the battery on a Ford used to be the easiest way to tell if the alternator was working. Never had anything bad happen from doing it.
Yes the battery is the reference for the voltage supply, and most modern vehicles have dampers and filters to deal with it because it's a very real occurence for battery cables to become broken or come off on occassion sometimes while driving. It's still very possible for those to fail. But if they failed every time someone went too hard over a speed bump and bounced a battery cable off it would be an issue. It is still not something to do, but I've seen it suggested as a method for testing an alternator as baddad says above
