sharp21

My mother left her lights on the other day & had to get AMA to give her a boost. The guy mentioned that she should put it onto a charger because when you drain the system it also drains the charge from the alternator & this will not recharge by just running the engine.
Is that the case? My wife left my keys clicked over while on vacation & killed my battery...
S.

RSWORDS

the charge in the altenator... LOL

Jump it and drive it around a while.

BC847

That fella must have been around for a while as it's been my understanding that back when automobiles ran generators, it may have been necessary to flash the windings so as to impose a residual magnetic field, thus getting the generator started (if you will).

sharp21

Yeah I thought it was suspect, but perhaps there was some kind of capacitor in there...
S.

ppiggppenn

charging with a charger is not a bad idea since your alternator can overheat doing a full charge on a dead battery. Driving it around as RSWORDS says will cool the alternator with ram air during the charge.

rustbucket

It will be a lot easier,on both the battery, and alternator if you use a battery charger on slow charge, because the battery is more likely to take a a full charge again. I was allways told, the alternator, isn't to charge the battery, but to maintain the battery and run all of the accesorys.

Billut

"Stole" the following from a car site for general info.:

"The alternator is there for one thing and that is to convert the mechanical energy into an alternating current. How it works is the belt of the engine drives the shaft of the alternator. In doing so, the electricity is produced from the machines mechanical energy. After this takes place, the power begins to be channeled. With all of this said and done, the electricity is used to recharge the battery as well as power the vehicle’s electrical system. "

BearKiller

Everything I read says to NOT charge a dead battery with the alternator; BUT, what are you gonna do, leave the vehicle sitting stranded wherever it may be, take out the battery, and slow-charge it over-night ???

There are very few vehicles on the road that haven't been "jump-started" several times in their life; usually with no issues whatsoever.

I will say this, though, it seems to drastically quicken the demise of any battery to be run way down; it seems that from that point on the battery just won't have the staying power it once had and it will lay down at the first convenience.

Jim Lane

Geez just think of the poor batteries that I have jump-started, I will always connect the cables and then run my engine at a fast idle for a few minuets before I have them start their engine so they are not starting off my alternator.

You are also supposed to disconnect the battery before you connect it to the charger, the battery acts as a buffer and will filter out and dirty voltage that could destroy sensitive electronics.

I cannot tell you how many alternators I have replaced when old timers had flashed their generator by arcing the BATT to the Field terminal of the regulator only they didn’t have a generator any more.

I still overhear older guys at the auto parts asking how to flash their generator.

However most military Gensets have a Flash Switch to manually flash the field even though they have 12 wire alternators on them.

Generators produce current opposite of an Alternator

On Alternators the magnetism is created in the Rotor while the current is produced in the 3 phase windings of the Stator and then rectified into Direct Current by the diodes. The brushes only carry the current to the rotor through the slip rings.

On a Generator the field creates the magnetism and the Armature produces the heavy current and passes through the brushes, which reverse the polarity many times per revolution through the segments in the commentator.

When you overloaded a generator it would spit lead, as the solder would melt from the heat where the windings were soldered to the commutator, destroying the generator.

What were we talking about?

ofcmarc

Someone was wondering about self-exciting alternators.........

BearKiller

That tin-foil hat you were talking about must have slipped over his eyes.


I don't think Jim has anything to worry about when jump-starting mere passenger engines off of his alternator.

When my first one to arrive came in yesterday on the OverNite Express truck and we fork-lifted the pallet onto the ground, it was stamped on the back side "Property of Wolf Creek Dam Power Generation Dept." and has lift-rings forged on the casing.

Looking at that thing beside the stock Nippon Denso is like comparing a grizzly-bear to a Beagle pup.

Jim Lane

How many did you finally buy?
Jim

04ctd

exactly.

think if the battery had a gauge on it....
it was zero...
then you hooked up the jumper cables..
it was 50%
then you cranked the car, and drained the battery.
it was 20%
then you drove around: AC, radio, power windows, seats, locks
it was 50%
then you park it, and drive it at night: lights, AC, radio, heated seats
40%

basically, the alternator makes barely enough voltage to maintain an even keel, it's not designed to fully power the needs of the vehicle, and fully recharge the battery.

to even fully charge the battery off the alternator takes a LONG time, (think hours on the highway) because 50% of the alternator's output is going to your accessories: ECM, PCM, AC, Digital dash, ABS...

most alternators need to be over 1500 RPM to charge, so idling in traffic, your battery is actually draining.
and how many don't set in trafffic

so yes, any time you kill the battery, you need to charge it over nite.
it's just good preventive maintenance.

most folks get in a vicious cycle of replacing the battery, the alternator, the battery, the alternator....
because they wore out the alternator trying to charge the battert.

BearKiller

In a real life situation, in 99% of cases, the battery being "jumped" is not "DEAD", but only slightly below the voltage required to work the starter.

I almost always check battery voltage with my digital meter, prior to adding the jumper-cables, and also after the engine is running, again no jumper-cables connected.

In almost all occassions, the battery voltage is around 11.5-volts when it is too weak to operate the starter.

Once "jumped" and running, providing the charging system is not at fault, after maybe three minutes at idle, you can shut the engine OFF and battery voltage will be around 12.4-volts or so; and usually, the battery is HOT enough to start the engine on it's own.

I guess if one turned ON the lights and left it until the lights completely went out, it could be considered "DEAD", but there will still probably be six or seven volts present.

BearKiller

In my possession is one 140-amp unit.

Paid for (before ^^^that^^^ one) and not yet received is a 160-amp unit.

Currently in negotiations is another 160-amp unit.

My aim is to actually install these identical-case units on the three most often driven trucks and have at least one complete ready-to-run spare unit carried in my truck for emergencies.

I am buying all of them identical, regardless of amp-rating.


My only concern in retrofitting these to the trucks is there is a bunch of coolant tubes and hoses close behind the alternator on the wife's I/C automatic engine that will probably interfere and have to be thought around.




I tell you what, if size is any measuring stick, expecting the stock alternator to keep up with a 555-Leece-Neville is sort of like expecting a fat pony to do a big mules work; he might get it done, but he is gonna have to press the collar.