Technical Battery removed while running

The presets on the old AM radios are mechanical ****ons, and the timing and mixture are controlled by springs and holes...no worries about disconnecting the battery.

 

I used to live about an hour from Va. Beach, once while spending the day at the beach my car (off topic 455 Hurst/Olds) wouldn't start, battery was shot, I got a jump and drove it back to Ft. Eustis without issues. So from my experience yes it'll run and no this wasn't my first experience of doing it, although this was definitely the longest drive.

 

I’ve took the battery out many times with the engine running in older vehicles. Wouldn’t try it on one of these new computer controlled monstrosity vehicles. Friend changed batteries on his Caddy, AC quit working. Carried it to the dealer, they did some mumbo jumbo pushing ****ons on the radio, AC started working! All that **** is wired together somehow, you have to bury a chicken head on a full moon night behind the barn and then go say three Hail Mary’s under a dead persimmon tree to make that **** work yourself! Or just get a good shop manual and follow the instructions.....

 

You just need the proper tools.

I reprogram modern stuff frequently. It is not hard.

 

You must have missed the last sentence.....

 

After driving twenty miles down a logging road in my old mini truck this fall, I opened the hood to find not one, but both battery terminals completely off the battery. The washboard road apparently shook the darn things right off, but it kept running fine. I only found the problem when I tried to restart the truck to park it a bit better.

I had just put the battery in and got this old beater running a few days before, I guess I forgot to tighten the terminal bolts.

 

Generators have residual magnetism in the pole shoes. You can push start a generator equipped with a dead battery.

With and alternator you have a problem, you need a little current in the field to get the alternator to start charging. It doesn't take much, but you are pretty much dead in the water with a totally dead battery.

 

I'm old enough to remember when Chrysler did that take out the battery and drive several hundred miles cross country (In a Valiant I believe) to show that their alternator could operate the car without a battery and ever since guys have thought that was how you checked to see if your alternator was working. Over the past 60 years I have lost track of how many guys said that was how you could check one.
Truthfully I never tried it as I never saw or had the need.

 

I have heard about the disconnect the positive battery cable to see if the alternator is putting out many years ago , infact some of the old motor manuals tell you to do that as a test.
I have done it myself many times, it doesn't give you a reading but its a cut and dry way to see if your alternator is working.
Another way is to put a screw driver against the rear bearing cover of the alternator, if its charging the screw driver will stick , magnetic, and if its not charging the screw driver will not stick, non magnetic.
Hey its back yard , but its away to get a quick answer if you haven't got any test equipment handy.

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I see alot of references to electronics being fryed .
On a alternator charging system yes you do have a greater chance at cooking something than you do on a generator charging system....but traditionally speaking...and remembering the fact that this is a site for traditional hot rods and customs pre-1965 , and a alternator charging system was first offered in a U.S production car in 1960 ,a Plymouth Valiant with a slant 6 engine, I believe alot of the hot rods and customs of the times were still running generators for there charging systems and very limited on electronics .
The big thing to remember about the old generator charging systems is polarizing the voltage regulator each time that the battery , generator or regulator is replaced or just disconnected for any reason or amount of time.
Of course every one knows about polarizing a voltage regulator , and how to do it....right ?


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You're polarizing the generator, not the regulator. Generally speaking, the only time a generator needs to be polarized is when it's removed or replaced. What you're doing is briefly 'magnetizing' the field poles (establishing which is positive and which is negative), and the residual magnetism that leaves behind in the iron pole piece is enough to allow the generator to charge correctly and is generally enough to allow a push-start with a dead-flat battery. This residual is very weak and handling it with any bumps or shocks can cause the residual to dissipate.

Alternators produce AC power and won't magnetize a iron core in use which is why they have to have a outside source of current to work.

 

Through the years I've disconnect a lot of batteries while a vehicle was running and moved the battery into a different vehicle. I've not ever had a problem, but I wouldn't even consider doing it with the headlights turned on. Headlights draw a lot of amps, I wouldn't want to take a chance making that much draw without a battery in the ride.

I can tell you a good battery can run a car about a 1/2 hour pulling the headlights after an alternator quits charging, or 2-3 hours without the headlights and all the other accessories off. Gene

 

The problem with removing the positive cable with the engine running is that the voltage is no longer stabilized by the battery. It can be hard on the diodes.

Checking for magnetism will tell you that the field circuit is energized, but it won't tell you if the alternator is charging. If you lose the diodes the field circuit can be fine, but the alternator will not charge.

 

I didn't. You said shop manual.

 

We have always called this a hot swap in shops around here. I've probably done it 100 times or so...never had an issue...though it's always been a concern.

 

It would be very interesting if someone could hook an oscilloscope to positive and negative and disconnect the battery to show us exactly how stable the voltage will be. Preferably both generator and alternator, but either would be very nice.

 

Yeah, I did. Figured it would give the correct method to do it. Anything I'm not sure of, I try to locate factory info for it if I plan on doing it myself. A missed step. no matter how simple or easy, can screw up the works. The way I look at it, the more info you obtain, the better result you end up with if you follow directions.

 

In the dealerships I worked as a tech for 11 years we did it a lot when replacing batteries. In order to avoid losing radio pre-sets and other modern car issues . The manufacturers always said not to do it however in a busy Atlanta metro dealer I'd guess we did no less than 40 batteries a week with no issues...... No one (customer or dealership ) wants to pay you for writing down all the radio station pre-sets or replacing cigarette lighter fuses and or seeing why they are blown in turn preventing the memory saver devices from working correctly so this was our method. May sound petty but techs gotta earn a living We didn't show up at our customers offices and ask them to do their jobs for free.

Of course dealership politics are another matter and the reason I decided to change careers. I enjoyed the actual mechanical work, but that became secondary.

 

Nope, this is incorrect. The battery can be disconnected and reconnected as often as you want, you can also replace the regulator as often as you want.

Heck, you could even remove the generator from the engine as often as you want (don't drop it!) disconnect it, put it in another car even. Very common misconception.

It's actually the generator that is polarized, not the regulator. This polarization business is performed at the regulator, which is why the confusion I expect. It doesn't hurt anything to polarize a generator, unless it is done incorrectly,. Unfortunately this is extremely common because there are different types of generators, the way the field is grounded.

 

A nearby lightning strike can do it, or if it has sat for a looong time, or getting knocked around as you mention. The book sez a generator only needs polarization if it has been dis***embled and the pole shoes replaced.

I've never needed to do it just removing and reinstalling the generator itself.

It won't hurt anything to polarize, but ... so many people use the wrong method to burn up voltage regulator contacts or relays by shorting stuff out, it is a bad practice .. in practice.