It has to do with the chemistry of the battery, how it accepts a charge, and the output of the alternator.
A battery needs 1.2 volts more than its open circuit voltage to charge. If you apply more current than the battery is willing to accept the voltage starts to spike. The alternator doesn’t care if you want more voltage. But the battery and the rest of the car does. Too much voltage is a very bad thing from a battery longevity point of view.
Batteries are funny things. how much current they will accept on charge is partially a function of just how they were discharged. If you left your headlights on, then the next morning your battery will take a much higher current than if you left your car parked for 3 months and now the battery is flat. In the first case a 20 amp charge rate is probably no problem. If you tried that in the second case, the voltage would probably spike to 16+ volts, at which point the control units may start to shut down to protect themselves against over voltage.
Simply put, if the battery won’t take easily take a charge, the alternator won’t supply one.
The bottom line is unless you know the charging rate tables for your exact alternator use a battery charger to charge a battery. Use the alternator to keep it charged.
I remember lugging the battery a block and a hafl (fortunately) to get it recharged. At least it has a carrying strap.
It must weigh about thirty pounds! Is the presence of lead cells in the battery what makes it so heavy? I would think that the advent of nickel-cadmium technology would supplant lead-acid batteries–or can’t NiCd batteries produce enough power?
I doubt they could produce the power at anywhere near the cost. You can get a metric buttload of amps from a car battery for $60. Which is what a replacement battery for my DeWalt drill costs. My drill battery has nowhere near the power of a car battery.
I guess not. I understand that a battery, which must crank the engine, has an output of as much as 14 amps (all right, a Triple-A tow truck), but at 12 volts it’s hardly dangerous. The old-fashioned “coil,” or its modern successor, whatever that is, augments the voltage to 30,000 or more, but the amperage is very small–all you need to generate a spark in a combustion chamber. All the same, I try to kieep my bare fingers away from live connection points in the car–even when it’s not running.
The battery in your car can produce way more than 14 amps. Batteries are rated in cold cranking amps. A fair sized car battery is 600 cold cranking amps. That means at 0 degrees F that battery can produce 600 amps for 30 seconds and still have 7.2V left in it at the end of the test. When you consider the fact that chemical reactions slow down when the temp drops, a car battery at normal temps can supply a mind boggling amount of amps.
Once the car is started the battery is pretty much out of the picture, the electrical needs of the car are supplied by the alternator. So the secondary ignition voltages of 30,000 V or more really isn’t part of the discussion of how much power a battery puts out.
Remember too that, if IIRC, 95% of your natural insulation is your skin. Be very careful of open cuts and wounds with blood.
I believed the instructor when he said that if you cut each index finger and touched a fully charged car battery that the current flow thorough you body from finger - through the chest - to the other finger would kill you. ( blood seems to carry current just fine )
Rings also can cause some nasty surprises.
YMMV
I had noted that 60-cycle house current (AC) can set up ventricular fibrillation–that is, the heart starts quivering like a blob of Jello and doesn’t pump blood. How effective the DC current common in a car–say, the headlight, radio, or horn circuits, might be to deliver a potent electric shock I dion’t know, and I am not particularly interested in finding out. Or, “a harp is pretty, but it’s hard to play.”–Soupy Sales. :D.
After some wangling, I was able to arrange financing to get the damn alternator replaced.
First, I took the battery to a nearby service station to get a “trickle charge,” which would supply enough electrical power to start the car and run it the mile-and-a-half to the garage. When the work was done I drove the car on some short errands, and then went home, and let it set a while–about two to three hours. Perhaps not surprisingly, it wouldn’t start–I got the familiar click/rattling sound instead of cranking.
After a while a neighbor loaned me a battery charger that runs on house current, and let the battery sit there for eight hours. That was Wednesday; the car sat unused Thursday and yesterday about noon I drove back to the garage and talked to the mechanic. I suggested I drive 20 miles on surface streets, then come back and have him test the battery. So I did the 20 miles of driving (so the alternator would bring the battetry up to snuff), and returned to the garage. The mechanic hooked the car up to the testing machine and, sure enough, it seems to be fully charged.
At this point I’d like to have a clearer idea of how much driving is necessary to “build up” a battery if, for example, I’ve just been given a jump-start…
Maybe related?
My car, a '98 Honda Accord, has recently picked up the habit of not starting early in the morning when it’s very cold. It happens intermittently, and usually will not start a couple times, then the third to tenth try it kicks on with no issue whatsoever. It doesn’t whine and the engine doesn’t turn over. There’s possibly a click(?), but not a loud one like with my old car when it had issues. Just [turn key-nothing] [turn key-nothing] [turn key-nothing] [turn key-nothing] [turn key-vroom!].
Finally I couldn’t get it to start at all, so I called my mechanic. From a description of the symptoms he thought it was a starter issue rather than a battery issue. The electrical system works just fine, and when the engine won’t start the dash lights stay on, steady with no flickering. He had me try to start it in neutral, too, same story.
I had it towed to my mechanic’s shop. It gets there and he calls me back reporting that it started just fine for him, that his starter guy took the starter out, did some mechanic-y things, put it back, and they couldn’t find a problem. He tried leaving it out on the street overnight to see if the cold would make it not start, which it did for him the next morning (not start). He called me back and said they still couldn’t find anything wrong with the starter and also couldn’t make it not start again, so they were going to try replacing a widget in the starter and hopefully that would help, but because it was an intermittent issue, it’s hard to say if what they’re doing is going to solve the problem.
Any suggestions?
Sometimes I wonder whether batteries should be better insulated than they are.
About two weeks ago, I took the car to get a Smog Check (Per California law, this has to be done every two years, as a condition of renewing registration). It was bad enough that the car failed (The catalytic converter has worn out), but when I tried to start the car to drive it out of the service bay it wouldn’t start again! A mechanic from the shop next door checked it out and said the battery is shot. So, he gave it enough of a charge for me to drive homne; I bought a new battery at Sears a few days ago. (Yes, it does start now.)
Alternator, battery, battery cables, starter relay, starter, flywheel–all have been replaced. The only other components of the ignition system, so far as I know, are the ignition switch and the other wires connected to the starter relay.
This is turning into the thread that will not die, and the car that will not start.
Well, I hope you’re only half right.
Ford’s tend to have lots of electrical problems, for whatever reason. My advice, if you can afford it, is to ditch the car and get something else, because when Ford’s start developing electrical problems, they just keep on having problems. If you can’t afford it, and the problem continues, get yourself a factory service manual (don’t bother with Haynes/Chilton unless you can’t find the factory manual) google and eBay searches should turn them up fairly cheaply, and start looking at the various electrical grounds as that’s probably where the problem is.
If you’ve got a decent mechanic, who understands the problem, he might be able to jerry rig a good solution to the problem if it looks like you’re going to have to replace the wiring harness.
Good Lord…if that is what I think it is a wiring harness would cost me an arm and a leg. :eek:
In the interest of disputing blanket statements, I’m going to have to dispute this. I have had 5 Fords, my family has had a dozen or more, and the only persistent electrical problem I’ve had is a negative ground issue with my 95 F-150.
Quite possibly. An aftermarket job would be cheaper than a dealer item, but still probably more than you want to spend unless you’re attached to the car. Most likely, I’d say that it was a bad ground, and even if it’s not, you could probably get away with just splicing in new sections.
control-z, you and your family would be in the minority, based on everything I’ve experienced and heard. I’ve owned 3 Fords, my brother’s owned at least 3, all the coworkers I’ve known who’ve had Fords, have all had electrical problems of one kind or another. Mind you, I’ve had electrical problems with many of the non-Ford cars I’ve owned, so it’s not like they were limited to Fords, but the Ford’s have either been newer than the non-Ford’s or have had more severe problems than the non-Fords. My beef with Fords is that the problems have been so severe that they’ve reduced the cars to scrap, while with the non-Fords, all I’ve lost is something like the radio.
Most recently, I bought a new battery at Sears and within a week the car went back to its habit of not starting. I called the Auto Club again; I told the tow driver what was happening, and how many things I’d replaced. He suggested I have a mechanic check the battery’s subsidiary connections with a voltmeter, as he got the engine started with the powerful engine of his truck. I drove over to my mechanic’s garage. As it turns out, the voltage regulator has gone haywire and was really screwing up the operation of the alternator, the battery, the battery cables, the starter relay, and the starter motor…
Interesting. My dad’s 1995 Mustang has very similar symptoms to your T-Bird. I think he has taken it to and from the mechanic about 10 times, and has had them tow it several. They recently found a loose connection from the battery to the starter, which they fixed, but I hear tell it died again a few days ago…
I’ve been concerned about that myself–especially since a couple of days ago, the car did it again–it wouldn’t start.
I borrowed a charger from a neighbor, and hooked it up to the battery between 9 p.m. and 5 a.m. the other night. After daylight came, I drove the car around for 20 miles. Yesterday evening I drove to South Torrance and back–no problems. I did discover a broken bulb in the trunk lid, and replaced it; before I headed home I tried the trunk lid and opened it after dark before starting the engine–the light went on; the engine started with an eager roar. And it started this morning when I took it to a mechanic I know, to have it checked out.
(My current suspicion is that the light in the “center compartment” between the front seats, which stays on even when the ignition is off, is involved. I’ve had trouble for years wth that light, but I removed the bulb because it tended to stay lighted when the ignition was off–the lid was out of shape and not holding shut and keeping the light off, like a refrigerator door not closing properly so that the light inside stays on. and was likely the cause of the constant drain on the battery. So I took the car back to the mechanic today to have him check it out.)