I Think my Alternator is Bad? Help Plz.

thanks i will look in to the wiring and take a multimeter to it.

Again I state: "The last person that touched it screwed it up." It is my #1 rule of auto repair.

Good answer though.

Its entirely possible you have a slow drain in your electrical system. The battery gets run down further than it should while sitting and then the alternator has to put out its maximum output for much longer and more often than in typical running conditions. That will lead to much shorter alternator life. Many of the alternators built from the mid 1980's and newer have very short peak power time ratings. Many of the old ones could support full rated amp draw for many minutes to near continuous duty. Many of the newer ones cant do it for more than a minute without damage on some vehicles. Simply giving someone who has a dead battery a boost charge can kill some of them now.

If you can check your amps draw from the battery while everything is off. The only thing drawing power should be the memory keep alive systems and they are typical in the few milliamps range. If its much higher than that something is drawing power when it shouldn't be. If no larger parasitic drains are found and the charging system is in fact putting out the correct voltage and amperage when the alternator does work it may be that you simply need a bigger alternator.

Us northerners are well known for burning up stock sized alternators in the winter due to longer cranking times and more electrical loads. Whenever I replace an alternator for my friends and family I always put in the largest one that will fit. That usually means a stock 70 amp unit gets a 100 amp replacement one or a stock 100 amp gets a 140 amp replacement. This typically solves any burn up problems and often safely allows a larger than stock battery to be used as well. At -30 F our vehicles need all the starting and charging help they can get!

thanks for your input. that is a good idea for putting in a bigger alternator. but if i do and keep the battery i have. will it cuz any problems? i don't know the amp that the Alternator does. but upping it sound like a good idea. because it get pretty cold here in Winter-peg, in winter. if i also up size the battery will it hurt the computer components in my car? and also will this effect my belt size if i up the Alternator? meaning a bigger belt? i also have an immobilizer in the car and it have an led light that flash's when the car is off. but i think led don't use that much power. but i thought i might want to mention it.

but the Alternator i am have problems with happen in the summer. but i think upgrading to that sound good for a no problem winter. cuz who like working on there car in -40 C.

It shouldn't be a problem. Many aftermarket devices draw high current and typically most people just add the bigger alternator to make up for it. Changing batteries by a size by a range or two wont affect anything.

The additional power draw on the drive belts is small enough that with good belts you will unlikely ever have any more problems than you do now.

Depending on what style of alternator your vehicle uses you may even find that they have the exact same case but its internally how they are different in order to produce the extra power.

Depending on how much bigger you go it will reach a point where you will have to add a second wire between the alternators output post and the main electrical point the system connects at near the battery. The auto parts store will be able to tell you if you will need it or not. If so its usually just a length of heavy gauge wire with the right ends crimped on it and they can make for you if needed.

Upping either battery size or alternator should not cause any problems at all, it will just work better. Make sure that when the engine wobbles, it will not hit anything, that goes for both.....

To check an alternator take a digital voltmeter and connect it across the battery to measure the volts. Start the engine and run it, you should see the battery voltage climb slowly to about 14.4 volts. More is bad. Less than 14.2 volts with a running engine (if it is not or stopping charging) shows either a bad battery (very seldom, bad batteries seemingly charge too quickly generally....) or a bad alternator....I bet the alternator is bad.....

Revving the engine should speed up the charging rate, 2000 RPM will be enough for a good output.....

To check for a slow discharge, switch off engine completely, take off the plus pole of the battery, connect an ammeter between the battery plus and the plus cable, you should only see the power/current for say the clock....a few milliamps or so. More is generally very suspect.

Take a look at a car that runs with no problems to get an idea what you need to see.....

Best of luck.

its just the brushes

If you tested the alternator and tension in the battery terminals seem to be charging, then take the car to someone that has a battery tester - not more than a variable resistor that measures your battery tension under a determined current draw. A battery that is apparently working fine right after charge most of the time can sometimes show its deffect under load only. If you have the battery for like more than three years or have just replaced it, it is a good potential cause of the failure.

Just check it out before changing the alternator, I think changing the battery for a good one would be more effective and less expensive.

Lets keep this simple, remove your positive battery cable or both while the car is running if it dies it is your alt, if not go look at the battery.

That was a good test when we all had generators. Did you know that Motorola alternators when run with no battery load can exceed 100 volts. How many voltage sensitive devices do you think that will destroy? A simple voltmeter will tell you what you need to know. The voltmeter attached to the battery when starting will also test your battery.

Bad connection or bad ground. with a car that vintage in Winterpeg it likely is something like that. Check the ground on the car and give the terminals a really good cleaning with a wire brush. It also could be a loose belt on the alternator, if it is not spinning fast enough while the engine is running it won'r charge the battery.

thanks for the info everyone, i should be working on my car early next week. and i think i am going to go for a bigger alternator. again thanks

Take it to Sears. They'll check out your electrical system.

Heed BobC ., one of quickest ways to fry an Alt. or elec. system is to disconnect a Batt. terminal while the engine is running.

If your Alt. had stopped charging while you were driving , you would have seen an indicator lamp light up on your dash board to warn you . All cars have this indicator.

If your car is old enough to have a gauge only , you would see the gauge needle go into the red , especially at idle.

Being an older car there is a chance that the Alt. warning lamp is burnt out , to check this simply turn the key to on ( not start ) and check all the warning lights to see if they all work.

I suspect that you have a different problem other than a bad Alt.

"If your Alt. had stopped charging while you were driving , you would have seen an indicator lamp light up on your dash board to warn you . All cars have this indicator." At least some older cars actually used the indicator lamp as part of the charging circuit (in a feedback loop, I think); failure of the voltage regulator would NOT light the bulb. Specifically, I know that this was the case with the 1987 - 1989 VW GTi 16 valve, and very likely with many others. When LEDs replaced bulbs, the circuit got redesigned, but I fell victim to this "no warning" warning light a couple of times back when those cars were my daily drivers. Usually, the first thing I noticed was that the fuel level appeared to be dropping fast (after the battery voltage dropped below the set value of the little tab-mount regulator that was part of the instrument cluster wiring). A few miles later the car would shut down, so a wacko gauge reading was my clue to find the first available exit.

One "minor" point, the red light indication from an alternator is a "pseudo" indication only....it can stay off and the alternator is still not charging!! It is not really 100%....

In the old Dynamo days, it was a more "real" indication.....the lamp was placed between the dynamo output and the battery "+", when the dynamo gave no output, it was effectively ground, so the lamp lighted. When it gave output, the lamp was between battery + and dynamo + which meant it was out.....

Just my 2 cents worth......

Using a Digital Voltmeter, check voltage with engine running.Should be 13.8 to 14 volts.

If not, check alternator belt for proper tension.If still below 13 volts,probably the regulator has gone bad inside the alternator.Replace regulator and brushes if you are handy with tools, if not remove alternator, take to an Auto Zone, and they will verify condition of alternator.

To test battery, check voltage when cranking over the engine.If it drops more than 25%, a cell is probably gone in battery.If the battery has caps, use an electrolyte tester to determine condition of cells.Instructions usually come with the tester.

Be certain all ground wires are clean and solidly connected,as well as the posts and cables on the battery.

Good luck.

A car battery if below about 14.4 volts, should show an increasing voltage with the engine running. More than about 14.5 could indicated over charging.

A battery with one or more cells defective will show less than 12 volts (assuming all other cells in good condition), but also a discharged battery will show a similar voltage, so this is not a good check.....

Once a battery reaches say 14 volts with the motor running, turn motor off and monitor voltage, if a cell is bad, it will quickly drop to below 12 volts again.....

The best test is a battery load tester......most good car shops have one......

Best wishes.