Possible Bad Alternator

I thought I had heard that too. Although I don't know why it would.

GA. I've got a test meter.

If anyone else looks at this thread and can shed some insight as to why this is no longer an acceptable practice, I'd be interested in knowing the answer.

Thanks

My uninformed opinion is that it's the voltage spike that runs through the system when you re-attach the battery lead. If the alternator is charging, you'll cause a 60 AMP surge in the system, till the alternator settles down and regulates it's output.

That's only a WAG.

I'm not going to attempt it, but my old practice was to cut the engine off, remove the negative, then replace the positive first, followed by the negative. Not to put the positive back on with the engine running.

It seems like I've heard something along the lines of, 'just taking the battery out of the loop can cause damage'. Now I want to know.

Go forth, Grasshopper, and learn.

Hey Mark, alternators normally run 13.8 to 14.2 volts with the engine running and under load, head lights and AC on, that's measured across the battery. If you have 14.5 volts like what Lyn suggested, you should be good to go. Anything above that will indicates the regulator is bad and will eventually fry the battery. And anything below 13.8 won't charge the battery sufficiency to maintain it. Low voltage could be caused by a bad diode in the alternator. You can PM me if you want, I used to specialize in auto electrics years ago, but still keep up with whats going with the new stuff. DJ

Thanks dj,

No reason to PM..................unless you want to cuss at me. After the last few days I feel like I have PMS.

I haven't used the meter yet. The little one is sleeping over at my my wife's brother's and his wife's house for the weekend, so I'm pushing the party envelope.

I liked the old method of checking alternators. Is it safe to go old school?

LMAO!!, TOAST ONE FOR ME!! And with the new electronics's on board, the spike you'd get when reconnecting the battery back up is like what Lyn said, I wouldn't try it for fear of killing the ECM. It's safer to check the alternator's out-put across the battery terminals with the engine running. Used to be easy to check for a bad diode in the alternator with a test light connected between one battery terminal and the corresponding cable, with the engine not running, the test light would dimly glow if there was a bad diode. But with the newer cars with the on board computer that draw current with the ignition off, can't be a trusted, now days, you have too isolate the alternator to check the diodes, or take it off and have tested at a parts store. Anyhow, let me know if I can be any help to you.

Enjoy the Party, wish I was there!!

Low voltage could also be due to worn brushes.

Codey

Have a question for you! So I am having kind of the same problem but this is the whole story. When my van is in an idle state it will start to die but as soon as I start giving it gas it stays running but as soon as I let off the gas and let it idle a little bit it will die. Then I have had the battery and altinator tested and they have said its fine and they told me to change thenpcm so I did and its still doing the same thing. I have also noticed if I charge the battery with a charger I can drive the car for a little while before it starts acting up and doing these things. Do you happen to have any suggestions at all I am thinking may the altinator is going out I would really appreciate the help!!!

Thank you

Josh

Hi Josh, not having the van in front of me, it's hard to say. What year is it? I have have seen similar problems with late models, don't know if it caused by inferior wire but they seem to develop high resistance between the alternator's battery terminal and where it connects to the battery. The easy way to check this is with a digital voltmeter connected in parallel between the alternator battery terminal and the battery. If the meter shows anything more than .03 volts difference, replace the wire between the alt. and the battery. What I usually do is install a new, (at least 8 gauge wire & fused) parallel to the existing wire and tie strap securely it to the existing wire harness.

So far everyone hasn't had anymore problems.

Dan

Assuming no squeaking from the V-Belt or equivalent, not correctly tightened.... get that fixed first!!!

Put a voltmeter across the battery and watch the voltage.

After starting the engine, the voltage may be down, but even with just tickover, a good modern alternator should "hold its own", eg. the voltage should not drop further. It should increase slowly usually.

If up around say 1800 RPM, the voltage should increase a lot faster.....

If the voltage increases VERY rapidly, but also drops at tickover, the battery needs first to be tested. (Though I feel its probably OK!)

If thats OK, then the alternator needs testing (at a different shop of course!!)

Bad connections will often get VERY HOT, a cold wet finger and great care are helpful.....

I tend to think that the alternator is weak when reading from your description.....it might even just be bad alternator brushes.....though these are not always easy to either find/purchase or install......a quality replacement (with guarantee) is usually the best idea....

Regards.

I think it is still OK

You've lost me here. How does pulling the positive terminal while the car is running check the alternator?

Codey

It goes like this, if the alternator is charging, there will still be voltage to the ignition coil, and the engine will continue to run. But if the alternator is not charging, the engine will die.

OK thanks, I didn't think of that. But I wouldn't try it, I've also read thou shalt not disconnect the battery with the engine running.

And it might not work. The first car I had with an alternator, in 1974-ish, the charge warning light came on, weakly. I had to swot up on alternators to fix it, and for 2 - 3 weeks it ran like that. Turned out to be worn brushes, but the battery didn't go flat (not enough to give a starting problem) so I suspect the battery lead test wouldn't have stopped the engine.

Codey

Disconnecting the battery on running motor will cause a spike in the rectifier on the alternator. While the diodes are somewhat robust and high current they are low (in comparison) voltage types. Also the regulator will suffer too..

If you are in car battery maintenance mode it may pay you to clean the "coral" growth on the battery terminals, first by pouring boiling hot water over them, to wash away the "acid salt" build up. Then disconnect them from the battery, and wire brush them so that they're shiny. Reassemble and apply a thin film of petroleum jelly, that will slow down the corrosion process till next time.

If your battery is a conventional non maintenance free type you might want to check and top up the electrolyte. Use only deionised water or at a pinch filtered rain water to top up the battery. Using tap water is a no no as the additives the municipalities add to it to make it "potable" don't behave nice in the average car battery.

Using a voltmeter(multimeter) check to see if your getting better than 13.8volts but not more than 14.4volts at the battery terminals with the engine running for at least 1 minute. (assuming the alternator light is extinguished) you can load test by turning on the headlights and measuring the voltage at the battery, should not dip below 13.5 volts at idle and go up to the previously measured voltage when the engine RPMs are around 2000rpm. Always allow a little time to provide for settling of the results.

If the alternator is failing it won't provide adequate charging under load.

Oh one other thing to check, is the drive belt for the alternator tight enough? a loose drive belt will not allow the alternator to be driven hard enough to provide a suitable charge. If you have a single serpentine belt driving all the accessories, it shouldn't be an issue unless it is very worn/stretched.

A quick check I use is to put a screwdriver end near the end bearing cap of the alternator when the engine is running. If you feel a magnetic force, chances that the alternator is working, because there is a field. Usually when an alternator doesn't work, it is due to the lack of field. I have never had a diode go, but have replaced brushes and voltage regulators occasionally. Of course you must remember that it is a Dodge.

Vic

Good call. I have had alternators with bad diodes on rare occasions, but mostly if the field current is there, it is charging. So, if there is a magnetic pull at the rear alternator bearing it should be good, but, if no magnetic field, it is bad, or bad wiring to it.

All I have to add to this is that it's my understanding that whenever you replace a battery in a car, that the negative always goes on last. Or else you can spike the computer or something.

As the Fonz would say, " exactamundo! ". GA GA. I was hoping someone would speak on safety - a car battery can easily cause third degree burns, even known to have melted Snap On brand quality wrenches! Not to mention blinding you.

The voltage spikes can occur at any time while you have the battery disconnected with the vehicle running, and could damage the powertrain control module. The pcm controls the field of the alternator by means of the small green wire connected to the alternator by grounding to energize the field. If you hook the lead of your test light to the positive terminal of the battery , and then touch this green wire with the other end with the vehicle running, if it lights, then you would know the field circuit is good and the pcm is trying to regulate. If it doesn't light, you could momentarily ground the green wire to full field the alternator, and check the voltage output with your voltmeter hooked to the big terminal on the altewrnator to see if it's charging. In the event the pcm isn't doing it's job, I have wired in an older chrysler voltage regulator with success. It's easy to do and a lot cheaper than a new pcm. Let me know if you need directions or a schematic.

You will instantly fry your electronics!!!

I drive a 72 New Yorker. It's the 1st yir they had electronic ignition and they had electronic voltage regulatorz for several yirz. I wuz going to swich batteryz with another car and my starter wuz going bad, so I didnt want to stop the enjin and possibly get stranded. The second I got the battery terminal off, the enjin died. I proceeded to swich the batteryz, but it woudnt start even tho the starter wuz cranking.

Lucky for me, the guy whoz place I wuz at had sum spare electronics. Later I learned that the voltage regulaor will interpret a detached battery cable az low voltage and run amok trying to increase it.

Maybe its different in your newer Chrysler, but it coud be expensive to find out for sure.

One other tidbit for you. In the late 80's I was involved in the development of active noise cancellation systems for cars/trucks/planes/headphones, etc. (We had a twin engine Beech airplane in the shop for a year)

We had numerous vehicles on loan from the "big" 3, among others. All the Chrysler Corp. alternators in vehicles we installed our systems in could not keep the batteries charged. Our system consumed about as much power as an aftermarket sound system.

After starting the engine, monitor the voltage across the battery terminals, it should creep up to more than 14.2 and less than 14.6 as the alternator charges the battery back up.....it may take a few minutes or more, depending upon just how low the battery was before starting.......

Even in the old days (60s, 70's, 80's) pulling a battery lead was not a good idea:

1. Sparks around a charging battery can make bad boom.

2. Spike can easily exceed the alternator diodes' ability to cope, and ruin a perfectly good alternator.

3. Even back then, other things (radios) could suffer from spikes.

Then as now, using a voltmeter is the simplest check. It used to be that the regulator would cut out at something close to 14.5 volts. If the battery was low when you did the test, the alternator might not have been able to get the system voltage up to 14.5, but if you could get 13.5 or so, that was a sign that the alternator was charging. (The real test had to be done with a good, fully-charged battery.)

Now, however, it is a new world. My Honda often sits at 12.8 volts, and never gets up to 14.5 under any condition. The alternator cuts out completely for periods of time. (Always has, since new, and always will.) So now, you need to know what the actual charge profile is suppose to be, because even charging is likely to be under control of the ECM, etc.

But certainly, if with the engine running the battery voltage is 12 volts or less, the alternator is not doing its job (and might, or might not, have failed).

Back in 1975 or so, I taught auto mechanics. Even back then we would never pull the battery lead when the engine was running.

In the 70's, I had an alternator pack up, when the engine was running and the fan belt broke (which was turning the alternator!!).....

You can do three easy tricks:

1. Use the pos term of the battery and the pos term of the alternator and measure the voltage there with a changing load (lights, heater and AC). You can determine the resitance of the wire by using R = pL/A where p is the resistivity of copper and L is the length and A is the cross secional area of the conductor. You can determine amps this way.

2. A scope on the batter AC coupled and look at the waveform. It should be 3 phase sine wave. I missing wave means a bad diode.

3. Measure the voltage across the battery under a changing load. It should be about 13.8 or so.

Hello.If you would like to keep things simple:Turn headlamps on for 15 minutes,a good battery will handle the load.While you are waiting disconnect field terminal wire from alternator.After the 15 minutes , start the engine and take note of the brightness of the headlamps.While watching the headlamps reconnect the field terminal of the alternator,the headlamps should be brighter as the alternator increases the voltage.I agree with the previous posts as to "not" be disconnecting the battery with the engine running.Try to see the battery as the ballast for the electrical/electronic systems.Good Luck.

Besides the problem of voltage spikes, the Motorola alternators used by AMC in the late 60s and early 70s did not have a circuit designed to limit voltage when there was no battery in place. When these cars were run without a battery in place, the voltage would be able to clime up to about 75 volts if the engine was running on the fast idle speed of the choke. If this circuit was to be damaged by the voltage spike on a current vehicle, the amount of damaged equipment on today's cars would total it.

Please no not do that.

Thanks all for the good advice. I guess I just got lucky back in the old days by pulling the positive. Of course, it's not something that comes up very often.

With all of the electronics these days, they've taken the basic IC engine and turned it all into something most of us can't work on.

I'll use the test meter today. If it's not showing it charging, the parts store does a free check also, which will confirm it. I like the screwdriver idea too to check for field. I'll probably skip that one in this case though, due to the fact that the engine compartment is real tight and with my luck, I'd get my hand caught in a moving belt or something.

One person mentioned boiling water to clean terminals. I use warm water in a small container with about a tablespoon or a little more of baking soda. It pretty much cuts out a lot of the wire brushing. The corrosion just bubbles off.

I don't think changing out the alternator is too tough. We'll see how much stuff needs to be removed to get to it.

I'll get into it today and post my findings here.

Thanks again.

Pepsi or Coke cleans terminals. Works on chrome too.

Doh!!!!!! I completely forgot that I had this handy little unit in my boat for just this purpose. Anyway, they're cheap and they work well. Just plug into accessory port. The top picture is with car off (12.62). The bottom is with car running (13.96).

This is a new battery, so it looks like the charging system is okay. Now I think I have starter problems or a bad connection to the starter. It really bogs down while trying to start..............which is what started my quest.

A web search indicates that the starter solenoid is probably sticking. I wonder if those can still be bought separately?

Charging looks OK.

What are the symptoms? You've clearly managed to start it, to take the bottom photo.

Does it have a separate solenoid? They're only on inertia-type starters (I'm fairly sure) but mostly nowadays starters are pre-engaged.

I would definitely start by cleaning all the connections before parting with any cash.

Codey

That is too low, it should be over 14.2 volts.....I now suspect worn brushes are the problem.....

This means they (the brushes) are sparking and will destroy the commutator before long.....

When you cosider where the voltage is being measured (at the cigarette lighter) then yes this is an acceptable value, you will only see 14.3volts directly at the battery terminals. By the time the electrons get through the vehicle electrics to the cigarette lighter they're just a little tired...........

The only really correct place to test is on the battery terminals.

Checking anywhere else is possibly invalid.

If a reasonable quality high impedance meter (a DVM for example) is used, it should actually reflect the same voltage as seen at the battery unless wiring problems are present, or there are more sockets in parallel with some form of unit plugged into them and drawing current.

If a problem is noted at the socket, then a comparison must be made on the battery itself using a known good volt meter to first find out whether it is comparable or not, is there a problem or not.

The load that a modern DVM presents when measuring a voltage is really, really tiny and should not cause a volt drop through the wiring.....so the voltages that he measured are almost definitely out of tolerance or the meter he is using is either defective or uncalibrated.

A modern DVM should present a load of 10 Meg Ohms or higher when measuring voltages. Assuming 10 Meg Ohms and using Ohm's Law, the following is true:-

I = V/R = 13 volts/ 10,000,000 Ohms = a current of 0.0000013 amps!!

If the wiring has a resistance of say 1 Ohm, then the voltage dropped will be:-

V= R x I = 1 x 0.0000013 = 0.0000013 volts drop over a piece of connecting wire with a resistance of 1 Ohm....a reasonable figure as such sockets are designed to be able to supply 8 - 15 amps.....

This voltage drop will not effect the reading of a good meter in the slightest.

So in the case in question, the OP should get hold of a good meter and measure over the battery to see where his problem lies.....

Hi Andy,

I took the posts above regarding voltages under consideration. This mornings readings on my little plug in tester were taken when the engine was cold and at very low RPMs.

I checked with it again this afternoon and the readings were about the same, however, if I hit the gas a little and accelerated the engine, the readings went up to about 14.3.

For right now, everything is behaving normally. It fires right up and runs fine, which it wasn't doing before changing the starter. Starting was a problem.

I'm not going to say for sure that I don't have a secondary problem. But if it starts fine and runs fine, I'm done for the moment. With 250,000 on it, it's not going to get too much of my time or money.

Good to hear.

14.3v is just in the good ball park, keep an eye on it in the future....

Best of luck.

Can't agree with that. Acceptable voltage range varies a bit with manufacturer, but some quote minimum 13.7 volt. 13.96 should be OK.

Also an alternator does not have a commutator, only slip-rings. That's one reason they last longer than dynamo brushes - less abrasion and only see field current, not output current. (as I'm sure you knew )

Codey

I have not seen any vehicles where such voltages are considered normal, but I have not seen all vehicles either.

But, that voltage will never charge a battery fully either, something over 70% or so, when generally 100% charge would be considered normal...........which makes it very suspect for me personally.....

The voltages I generally measure for a good condition alternator and battery with a running motor and no other major loads, is between 14.2 and 14.4 volts, generally the higher one......

If you look here:-

http://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery#Measuring_the_charge_level

You will find a single line that tells it all:-

Typical (daily) charging: 14.2 V to 14.5 V (depending on manufacturer's recommendation)

I trust this helps a little......

That does help Andy.

It actually ties in with my theory that the old starter/solenoid was binding up and pulling too much charge from the battery, trying to start the engine.

I think I'm in good shape now. I'm glad I didn't toast a new battery in the process.

Thanks.

Well done, stay healthy.

Interesting article in Wiki, but it doesn't support your statement about voltage. It shows 100% charge at 12.7 volt. Just checked in a Haynes manual and it says 13.5 - 14.6 volt. Last time I checked mine (at the battery, with a high-resistance digital meter) it was 13.9, and has never shown a sign of low charge. Post #18 suggests 12.8 volt is enough, and the Wiki graph seems to agree.

You didn't mention commutator - have I convinced you an alternator doesn't have one?

Slip rings still need very occasional brush replacement, if left too long, the sparking from worn brushes will damage the slip rings and ruin the alternator. Some models are worse than others....

Sparking at the brushes can also damage other equipment in the vehicle, or cause computer type equipment (MCU for example) to error....as well as reducing the charge level on the battery.....

Quite agree, I wasn't saying brushes on sliprings don't wear out, just that they last longer than on a commutator.

The early Lucas alternators in the "worse than others...." category. These had face-type sliprings, outboard of the rear bearing, one brush just off the axis, the other at about 12mm radius. So the outer one wore faster, typically lasted ~ 80000 miles in my experience. The good news was you could swap them and do another 50000. That was practical as in those days it wasn't several hours work to remove the alternator!

I believe Lucas use conventional sliprings on later models, which should last better. My current one (not Lucas) has done 126000 miles with no problem.

My longest lasting one was 380,000 KMs on a Mitsubishi....but it had ruined the slip rings, so I still had to buy a new one! It was expensive as it also had the vacuum pump for the brake servo mounted on it......

I had to work on a Bearing truck with an alternator-vacuum pump combination. That job sucked.

A flooded cell battery generates (stores) 2.2 volts per cell 13.2 total. It must be charged at voltage higher than this. When you test the battery, you fully charge it (zero current flow) and then let it sit disconnected for several hrs to remove the surface charge. The voltage will settle to 12.7 with a specific gravity of 1.265.

Try this link: www.batterystuff.com/tutorial_battery.html. More info than you will probably ever need.

Mini Van? I understand your reluctance to open the hood. You probably solved your problem(s) (corrosion and 12 years of funk) when you moved some wires. Time to dedicate a weekend with a wire brush and anti corrosion compound.

There have been some really good posts on this thread.

Well, yes, but it says 12.7 volt at 100% charge, same as in the Wiki link Andy Germany posted. I still think alternator regulator setting 13.5 - 14.6 volt is fine in practice.

What's this about a Minivan? Must have been a different post.

It's a mini van..................from the OP.

I don't care how wimpy it is. It's the closest thing to the Star Trek space shuttle I could find. The front seating area is huge. I love it.

My next project is reattaching the headliner that keeps draping itself over my head every time I open the window.

Winning!

spraymat?

That stuff doesn't work.

I'm thinking hot glue gun or recycling some old paint with a roller. That might be illegal now though. I'll check with my local citizen compliance office tomorrow..............................I mean Monday. Unless it's a holiday.

Carefully remove the headliner being sure to get no wrinkles in it. Then take a perfectly clean garbage can and throw it away. There should be some illegals in your area working out of the back of an old Dodge van doing them for under $100.

Nope, problem is the thin foam backing is crumbling....the only non-ugly fix is take it down, clean off any crud that remains and properly glue new material up to a clean sound backing (usually by spraying both sides with a proper spay contact cement, letting dry then putting up to bond)

Which trust me isn't as easy as it sounds.

You can't glue a material that is in the middle of biodegrading. (well you can try, but its still not going to work)

how about

take Bob's suggestion, rip out the headliner, scrape away the crumbly foam

& use

http://compare.ebay.com/like/390350976521?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar

can't be any worse

I don't know......you could staple it up into place......assuming its a hardboard backing.....man is that ever butt ugly and I saw LOTS of cars like that in the laste 70's or early 80's. Still see them like that from time to time.

The plus side is ugly inhances the antitheft features. Few self respecting theives will steal a butt ugly car when there are nicer ones around.

Painting it Pink and sprinkling glitter over it before it dries helps too. You could leave the keys in it and find it when you came back.

Lyn-Door Industries had cornered the market on Popiel spray on hair. They are now selling it as an instant mohair headliner kit.

www.youtube.com/watch?v=2GeF7A05zQ8

If I rip out the headliner and scrape away the crumbly foam.....................I'm done.

Same thing happened in my truck, and I did roll a coat of paint on the foam just to hold it in place. It kept falling on me...............looked like I had gray dandruff.

Actually I meant pink with sprinkle glitter from those kids shops on the OUTSIDE of the van. Your pre-teen daughter would love it, and the thieves wouldn't go near it. Even with the keys in the ignition.

Hello.I agree,Battery/Charging OK.Now if you can hook your meter to the positive terminal (large/heavy)on the starter while cranking (under Load),you can determine if it has sufficient voltage or not when comparing to reading at battery under load.I use .5 volt maximum voltage drop between battery and starter.Good Luck.

I've been looking at some Dodge forums and it seems like a sticky solenoid is a pretty common problem. With 250,000 miles on it, a new battery, and a good charging system, I'm off to the parts store. $115 US for a rebuilt starter. Naturally, a solenoid can't be bought separately.

Oh joy!!!! It's also a nasty, gunky mess under there......................guess I'll get some engine cleaner too.

Thanks. I'll post results here.

STOP. You are smart enough to test before you spend your money. Have you cleaned all of the battery terminals till shiny bare metal to shiny bare metal? Have you checked the ground strap-cable on the engine? Have you tried to tighten the nut holding the battery cable to the starter solenoid? Any and all of the above will give you the results you show.

depending on how much you use the van, you could just take the starter apart & polish the contacts up a bit

If you do need to go to a starter, try using this as a comparison price for the vendor in your area to compete against.

Hey guys,

Just posting to the thread rather than individually.

Yes- the first thing I tried was cleaning all contacts, battery terminals, etc.

Also installed a brand new battery, which I didn't have to pay for since it was still under free replacement warranty.

My test meter is just a cheap general use meter, and didn't have the scale to read accurately across the terminals.

After all of the above, it was still really bogging down when trying to start.

This is my primary vehicle, so I didn't have a lot of time to carry out a lot of tests, or do a tear down of the old starter.

I checked a few places, and they didn't have a starter in stock, so I went with the one for $115.............lifetime warranty.

Now the good news................I got lucky! I just got the new starter installed, and it fires right up.............no bogging down. Granted, it was an educated guess, based on what I already new, the posts I got here, and poking around some Dodge forums. Like I said, I got lucky. I'd be bumming out right now if it was still acting the same.

Thanks for everyone's input. I'm off to return the core. My guess is that the old sticking starter/solenoid was pulling so many amps that it killed the old battery.............discharging it faster than the alternator could charge it back up between starts.

PS- Working on newer vehicles sucks.

Glad to hear it's fixed!! And having to work on any car old or new, still sucks

After all this work be sure to put that core money towards some fine scotch or brandy or better yet tequila good use.

Just a couple of things:

The "cable disconnect" seemed to be a "generator test" rather than an alternator test. The alternator needs a magnetic field from a battery to work.

It's important when jumping a car to connect to the block of the engine of the jumped car for two reasons:

1. Less resistance

2. Possible sparks away from battery.

Now I did jump my car an unusual way once. I disconnected the _ terminal and then jumped the car to the + battery clip. Then I tightened the (+) battery clip. The battery had such poor series resistance, that it was unable to be paralleled with another battery. Safety is paramount here.

I guess "generator" might be more accurate, but in automotive lingo it seems like it's been called an alternator for a long time.

During the course of the thread I found this site. It's kind of interesting to go through. I don't know about anybody else, but the amount of stuff that I once knew and have forgotten is getting fairly substantial.

The alternator needs a magnetic field from a battery to work.

Are you sure about that? I was thinking that the alternator ran via a belt from the engine, which creates the magnetic field, turns it into DC voltage and feeds the battery and other things.

Sure. The alternator is composed of a rotor which is magnetized by the voltage regulator (varies current into rotor). This is in lieu of permanent magnets which a generator has on the stationary side.

The stator is a 3 phase AC generator that is rectified into DC.

A standby generator typically has an auxiliary winding that will generate some electricity to "jump start" the magnetic process until the main windings take over.

I was thinking this way. You are also correct.

From the link:

Field current supply is provided from two different sources - from the alternator itself, via the diode trio, and from the battery, via the alternator warning lamp. When you first get in the car and turn the key on, the engine is not running and the alternator is not spinning. At this time, the voltage/current source for the field current is from the battery, through the ignition switch, and through the warning lamp. After the engine is started, and the alternator is up to speed, the output of the diode trio is fed back to the regulator, and serves as a source of current for the field current. At this time, the alternator is self sustaining, and the battery is no longer needed to power the automobiles electrical system WARNING!!! This is theoretical only - in actual practice, the voltage surges resulting from disconnecting the battery can seriously damage the regulator circuitry. All alternator manufacturers strongly advise NOT doing this! This test will not prove the functionality of the alternator anyway, as the engine may still run with a weak alternator output.

I didn't find this until today.

Just the other day when I stopped my 99 ford truck, I noticed all power was gone & the truck wouldn't restart

the positive terminal had popped off the battery

the little wool washer had kept it from fully seating, so it wouldn't get tight

it ran fine with no battery what so ever, which sticks a stake in the heart of the notion that a battery is required for the alternator to make power [at least on a ford]

I think that because the engine was actually running and the alternator was producing power, THAT allowed the alternator to keep producing power......

The battery power is just needed to "kick-start" the alternator, nothing more.....

Zackly!

The battery is only required to set everything in motion.

Probably no damage done either. I still won't be pulling the positive to check the alternator, (anymore). It's old school and shade tree mechanic stuff, but I never saw anything bad happen from doing it.

I'd be scared to try it on a new car.

It only needs the battery to start charging (as others have said). After that you can remove the charge warning light bulb (see my #60) or remove the battery if you want to risk it. Clearly in your case you got away with it.

With a dynamo you can tow-start the car without a battery, if the engine turns fast enough to close the cut-out points (> about 1000rpm) and keep the revs up after starting. You can't do that with an alternator.

Yes, it does. A dynamo retains enough magnetic field to produce a small voltage, which is fed via the (closed) regulator contacts to the field winding, and it bootstraps itself up. An alternator usually doesn't, and the initial field current is provided via the charge warning light bulb. You can see how if you check the wiring diagram. So if the bulb blows you lose charge. When I first read about this I was sceptical and couldn't see why the alternator rotor doesn't retain magnetism like a dynamo stator, both made of iron. So I did a test and the book was right. Maybe some alternators some time self-excite, but you can't rely on it.

Codey

He is right, it has a wound rotor that is fed from the battery via a couple of slip rings. This is the "magnet" to generate AC power, which is converted into DC by a small bank of diodes.

There is a regulator circuit that tries to maintain about 14.4 volts to the battery and car, so recharging the battery.....the difference in voltage between the battery and the alternator causes a higher current to flow when the battery is low. When the battery is full, the current drops to a small amount just to maintain the charge. All automatically.

It sounds to me like none of you know what the heck you're talking about.

So, I think this would be the perfect group to ask, how can a sticking/sticky starter solenoid cause the starter to drag? Or draw more current?

Stolen from another sight:

1. Binding of starter armature as a result of worn bushing
2. Oil too thick (viscosity too high) for weather conditions
3. Shorted or grounded starter windings (inside starter) or cables
4. Tight or seized engine
5. Shorted started motor (usually caused by fault with the field coils or armature - which is inside the starter)

A little credit should be given to, " I have a feeling". The new battery should have turned the starter normally. It didn't. Due to my propensity to over think things, I figured that possibly the new battery had lost it's charge while sitting on the shelf, so I couldn't eliminate the alternator possibility.

Once it was determined that the new battery was fully charged, being the impatient fool that I am, I bought the starter.

That's not to say that I've never thrown good money after bad...................I've done it plenty of times. I'm glad this wasn't one of them.

None of which has anything to do with the solenoid.

Next.

A solenoid won't cause the starter to drag. Based on what I've learned during the course of this thread, the starter motor itself was probably at fault. The solenoid was engaging the starter motor, I believe it was the starter motor itself that was binding.

This is also based in the hindsight of knowing that all is fine now.

Don't push it. My brain is like an old computer...............every time I learn something new, I have to delete something else from the hard drive. RAM is almost nonexistent.

Your brain is like an old computer? Cry me a river!

My brain is like a slide rule. No memory at all, and only one operation at a time.

Touche'..............good one!!

I wasn't going to open Pandora's Box myself, but seeing as you are braver, lets see what the answers are like!!

Maybe we get another good laugh!!

Lyn,

Think about what conditions would have to be present w/ a sticky solenoid. 1. Dirty Contacts. 2. Worn Contacts 3. Same as 1 and 2 for the coil/solenoid/plunger 4. Age/ Use/ Moisture/ Corrosion/ Wear all of which will cause a voltage drop. The PROOF would be to measure the Vd as the starter was cranking and it wouldn't hurt to observe the amperage at the same instant. Compare to specs. I FIRMLY believe this because it adheres to Ohm's law and I have had this exact experience, both automotive and in Hvac/R (Potential, Curent and Solenoid Relays).

DrFreon

I don't think it's worth debating.

My point was that once the solenoid contacts make, power will be supplied to the starter motor, which I believe to be the weak link here. If sufficient resistance is present to underpower the starter, the contacts will fry themselves very quickly.

But, you're the expert, I'm not.

Absolutely untrue. Making is not current flow. This can be proven, even to the opinionated.

Whatever. I concede. You are right, I am wrong.

It's just lots of experience, Lyn.

I kinda have to agree with you. I always hate it when people, things don't follow the rules (laws) and theories that suppose to govern them

How could a solenoid cause a dragging (or slow turning ) starter? Connections. Remember that the solenoid is connected to the battery by a bolt on cable. Also the voltage to the motor is transfered by another bolt on cable. What happens to those connections as the resistance grows from being loose?

The fender mounted solenoids that Ford used for so many years were the only ones that never seemed to come loose. JMHO.