[Dan53]

I understand that given current technology we couldn't charge the batteries as we drive because any alternator powered by the batteries couldn't provide the same amount of energy back to them, that's fine. But I was suggesting that one set of batteries powers not only the motor but also, through whatever means, an alternator or series of alternators, that charges another set of batteries, and you may switch between the two sets when one gets low. When Set A gets down to maybe 80% you can switch over to Set B, which have been charging all the while, to run the motor, while Set A becomes dormant and gets charged up. True that maybe it would take too long to charge each set, meaning that Set A might become dead before Set B is fully charged, and I admittedly don't know that. Obviously it would depend on the batteries you were using as well. Batteries that charge rather quickly would be necessary. This idea seems too simple to not have been tried before, so I can assume that it must not work, but I heard that there are batteries in design that will charge in about 5 minutes, and this seems possible with them. You might say that with batteries that charge so quickly, what does it even matter if they charge themselves while driving? I guess I agree, other than that it would just raise technology to a new level if we could pull it off, whether it's totally necessary or not.

Dan

[mattW]

How long it takes to charge a battery just depends on how much power you are putting in, which is how fast you are draining the other battery. Splitting the pack in 2 wouldn't make any difference to the net energy of they system- if you pour water from one cup to another you still have the same amount of water... And you always spill some whenever you transfer it... It the same for batteries.

[Dan53]

Yeah, I guess you're right.

How many revolutions per minute would an alternator have to spin to put out about 100 volts? Anybody know? Forgive me if this was answered already.

ICE's may have 6 volt or 12 volt generators/alternators, even 24. But they all spin at about 1,000rpms at idle. I can't speak for everything, but on a Beetle the 6 volt and 12 volt generators even use basically the same size pulleys and belt as well. I'm just thinking about this, no real point.

Dan

[dfwheelman]

alternators always put out the same voltage (whatever their rating, 12v 24v etc) ,its the amps that go up with more RPM, due to the built in voltage regulators and bridge rectifiers

[Manntis]

Originally Posted by dfwheelman

alternators always put out the same voltage (whatever their rating, 12v 24v etc) ,its the amps that go up with more RPM, due to the built in voltage regulators and bridge rectifiers

unless you have a weak alternator that drops a few volts at low RPM

[dfwheelman]

That sounds like a generator, not an alternator.....my VW generator would output varying volt values but alternator is supposed to be 11 - 13.7 volts.

I was thinking about using this on my next project

[Dan53]

So here's a generator head that puts out enough energy to charge a battery set for an EV and it spins at about 3600-3700rpm. Is everyone in agreement on this? Forgive my ignorance, but how many RPM's might we expect a wind turbine mounted to a car to put out? I know this has been discussed, but I'm just wondering.

Dan

[dfwheelman]

Originally Posted by Dan53

So here's a generator head that puts out enough energy to charge a battery set for an EV and it spins at about 3600-3700rpm. Is everyone in agreement on this? Forgive my ignorance, but how many RPM's might we expect a wind turbine mounted to a car to put out? I know this has been discussed, but I'm just wondering.

Dan

wind turbine on a car...im still chuckling about that idea.

the overall BEST idea is a series hybrid using a Biodiesel engine driving a heavy duty alternator... that generator only puts out 21 amps, a heavy duty alternator can put out 300 amps. even a truck alternator puts out a hefty amperage. Then it depends on how much you want to work for your fuel.

the plans i have says "75 mpg hybrid car"

Cheers,
Mark

[Dan53]

Can you show us an example of such an alternator? How many rpms would it have to spin to efficiently charge the batteries? It seems that if you're going to go through the trouble of locating a suitable fuel for a Biodiesel engine, then your car might as well be fully Biodiesel. It would be supremely cheaper than an electric car powered by a small Biodiesel. 75mpg is great, of course, but my 10+ year old stock Jetta gets about 40.

Dan

[weelliott]

I didn't post the thing abotu the Biodiesel car above, but I'll comment on it. The attraction of making a car that uses a generator running on Biodiesel versus a car running on bioodiesel with no electric motors involved in the system is efficiency. A generator can be made to run at the most efficient speed and load for that particular diesel engine. Whereas a diesel driving the wheels is not always running at the most efficient speed, it is running while the car is not moving, and is always a larger engine than would be needed if the car were set up as a series hybrid.

Even though diesels can run at efficiencies around 40 percent, that is only realized at certain engine speeds and loads. The diesel running the generator can be optimized to those conditions. The diesel in a car driving the wheels is subjected to many different conditions where it is not running most efficiently.

I don't have the time to go on and on about how series hybrid cars can be super efficient if they have an appropriately sized engine hooked to a generator and electric motor. There is plenty of information on the internet about it. It is actually how diesel electric locomotives work. They are the most efficient form of land based transportation there is.