i tried starting the Z a min ago and the battery is dead. I have no jumper cables, and no battery charger. I already tried calling people, but no luck.

So lets say i were to take the alt belt off, and turn the alternator with a drill for a few minutes. Assuming the ignition was in the on position, would this charge the battery? It seems like it would to me....

Eric

 

Sounds like a good way to burn up a drill.

 

hmmm, didn't seem to work. I ran the drill on it for two minutes and it didn't gain any charge. owell, it was just a stupid thought

Eric

 

i believe the alternator needs 12 volts to excite its field windings.

 

It doesn't need 12v, but it needs some voltage.

If it did happen to work, it'll cause what's known as "alternator death". If you get a new or rebuilt alternator, you'll see a warning note in the box to have the battery fully charged before you operate the alternator. That's because you shouldn't use the alternator to charge a dead battery - it'll burn it out.

 

Assuming you had enough surface charge left in the battery to generate a field you would have to spin it a LONG, LONG time. 5.7 is right you can possibly damage the alt. Whatever you think remeber this, the alt is not a battery charger. If a battery is sufficiently discharged the alt will never bring it up. Nothing will substitute for a trickle charge. An alt only charges until it brings the terminal voltage up to a point determined by the voltage regulator. It will not for lack of a better word restore a battery's capacity. The reason they tell you to charge the battery with a new alt is to reduce overheating of the rectifier and regulator IC. A very low battery will force the alt to run wide open for a time determined by the state of discharge and the battery's overall condition causing high heat. The regulator IC has a thermistor incorporated inside it to prevent this but it is not worth taking the chance.

 

A car alternator is not the perfect device for charging a lead acid batt, due to the fact it's a constant voltage type charger.
They tend to charge the batt too quickly at first, then as the voltage rises, they decrease their output to the point they are charging too slow; taking forever to completely charge the batt.

Charging the batt is the secondary function of the alternator.
Maintaining system voltage its' primary purpose.

However, a decent quality alternator (i.e. not an Autozone special), shouldn't be damaged by charging a low batt, assuming the batt isn't shorted. Actually, the batt is more likely to be damaged due to the high charge rate.

A safer, more complete, more efficient method is constant current charging.
I made a portable batt charger from an old 70 amp GM alternator and a 5 horse Briggs&Stratton eng. It was built to re-charge a huge (850 amp/hr@20hr rate) forklift batt. Used it for 3 years and it still works like a champ. I did have to make my own adjustable voltage, adjustable current field regulator so I could charge with a constant current.
I've run that thing for hours at a time and the alternator would only be warm to the touch.

BTW; the 5 hp eng is working pretty hard to maintain 60 amps!
Cant see how a low hp motor like a drill is going to do much at all.

 

1 HP = about 746 watts IIRC

60 amps @ 14.2 VDC = 850 watts

850 watts = about 1¼ HP, once you take into account the inevitable inefficiency of these things

Hmmmmm..... got a 1¼ HP continuous duty drill???

Good idea in principle, but not so good in practice. Gotta give the guy credit for trying to think his way out of a jam though, without taking anything off of his car that would decrease its value, or cutting any wires.

 

thanks for all the info guys, lot of stuff in here i didn't know about before. I knew the alternator was mostly used to maintain the charge on the battery, but i figured it had to have some kind of charging value. For the record the battery did have some voltage (according to the factory guage it had about 8 volts, but i don't trust that a whole lot.).

i'm just shocked no one called me a dumbass

Eric

 

dumbass ( feel better now?) Ha Ha