OT-Automobile alternator rotation direction

1.I don't think the drill would get you any significant output. The diameter of the drill chuck is only 1 1/2" or so. The vehicle's crankshast pulley is a LOT bigger and the car engine would have to be running at 400 or 500 rpms or so to do the job. Maybe the use for the duct tape is to wrap around the chuck until it gets big enough to do the job. But I think that would take several rolls.

1. If I was in that situation, I'd consider taking the alternator (or something else in the vacinity) apart to get a diode. Then I'd slow the generator down a lot and use it to directly, (now outputing a much lower voltage, half wave rectified) charge the battery. The duct tape could be used to keep me from getting zapped. I think.

3.On the other hand, depending on the weather and the voltage the of battery pack in the "radio" one might be able to use its batteries to trickle charge the car for one start. If the "radio" was one of those contractors models, it might take a 12, 18 or even higher voltage plug in battery pack.

4.Okay---- Here it is: The "radio" has a built in charger for it's own battery. Just plug the thing in to the generator, and with a little judicious rewiring, use that charger to bring the car's battery back to life. Pour the olive oil out around the car, so wild animals will slip and fall down before they can attack you while you are getting things going.

Pete Stanaitis

Assuming a fair sized drill, 1/2 hp = 373 watts. 13.6v nominal charging =

373/13.6 = 27A No figuring conversion efficiency at each level.

Yup, that drill is going to be a bit warm and the arm sore. Maybe the olive oil is to lube the bushings in the cheap walmart drill you are using. ;)

Wes

And the battery voltage at this point is ..? At some point the curves cross. But when?

Unplugging the field makes the load nil. Once the engine is going, plug it back in. It will go to full field excitation, and provide as much current as it can at idle.... and engine load.

A former poster on this group.... Told a tale of parking his car Many miles into the wilderness, and leaving on foot for several months. Upon his return, the battery would be dead, and a few ( 50?) miles from any passing help. What he used was an old propane tank, and AIR (80's style smog) pump, and some lines.

He'd fill the old propane tank with water, throw it on the fire, and the line ran to the old AIR pump, which was rigged to run backwards and act as a "turbine" spinning the alternaor and charging the battery to allow his escape in the fall.

That was his story. It was Just crazy enough to work.. Maybe.

Whatever you want to believe is fine by me. I hope you don't miss that hand too much.

You could also disassemble the alternator and wire the AC from the gas powered generator to two of the phases of the three phase bridge in the alternator and use that to charge the battery. The alternator with no load can produce 120 VAC 3 phase, so the diode bridge should be rated to handle that much voltage.

Or perhaps the generator may even have a battery start in which case it will have DC to charge its own battery and that could be wired to the car's battery as well -- assuming that both are 12V batteries.

Enjoy, DoN.

On Tue, 05 May 2009 18:03:49 -0400, the infamous Wes scrawled the following:

Nah, it's likely for the massage of your arms when you're done with all this funky apeshit stuff.

Either that or as a, um, lube to amuse yourself while you wait for the battery to charge.

-- The scientific theory I like best is that the rings of Saturn are composed entirely of lost airline luggage. --Mark Russell

I thought the newer alternator diodes were Schottky and have a lower reverse voltage?

[snip]

You don't actually have to take the alternator apart to use its diodes. Just remove the alternator output terminal and connect the generator AC output in series with the alternator positive output stud and the wire leading to the battery. Then, as you suggested, throttle the generator down to reduce its output voltage.

Too many conversion and mechanical losses in spinning the 18V drill to spin the alternator to turn it back into 12V DC. You will start out with 2.5 AH in the drill battery and if you're lucky get 1 AH into the car batery.

Plus, you would have to leave the car ignition key on to excite the alternator, and all the power you transfer would get sucked up by the car ECU and other stuff that would be turned on at the same time. Even the dome light could make the difference betwen Go and No Go.

You would be MUCH better off wiring one 18V drill battery straight to the car battery, and let the car battery take a surface charge. Then hook up a second drill battery and try starting the engine with the two batteries in parallel.

And as to the rotation question - the only difference is the fan, and the set the brushes take. Corvairs turn their alternators "backwards" from the usual, so they require a reverse fan or they don't live long.

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Agreed - Just crazy enough that it might work.

But the efficiency would be abysmnal, AFAICT those were carbon-vane pumps and weren't very efficient going forward, reverse would probably be worse.

Now an air drill motor, that has far better possibilities...

And as has been brought up, there has to be enough power left in the battery to excite the field windings on the rotor. Or the alternator won't start alternating - chancing enough residualk magnetism after several months of sitting is asking a lot.

If he thought far enough head to disconnect the battery when he left the car, and the battery was in good shape, it's possible.

If he left in a hurry, he's screwed - "several months" and the battery will be dead just from the clock and memory drains. Even 5 to

10 milliamps will kill a battery if you let the car sit over two months - one month is about the limit without a trickle charger or disconnecting the battery.

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373/13.6 = 27A

It's a 120V drill, and you've got a generator to run it.

What "18V" drill? The problem was stated with a 120VAC drill....

I think you'll kill the alternator diodes very quickly with this stunt. What do you think their PIV rating is?

And then WTH will you do?

If you insist; then disconnect the battery from the car, and run a wire to the positive terminal from the generator. The battery can withstand short overvoltages far better than anything else in the car. Watch out for ground loops.

That sounded great but they didn't specify the type of drill.

Wes

I think you nailed it. I used to have a converter wired into my 66 plymouth's alternator that allowed me to run 110v electric tools.

Backwards should work also. I'm assuming a voltage regulator that modulates the field to control output.

Wes

Umm, "rustic", "cozy", "quaint", "charming"... Oh hell, you're right - "disgusting".

Joe

How do you like this cabin?

Funny, I've left vehicles sit all winter and they start in the spring. Left them sit all summer and started them in the fall too. No trickle charger connected.