I just gotta know. Fella on this board claims it does. I can't figure out any way the two could be related.
Since all of the alternators that I've encountered are grounded through the mounting bolts, how does one "unground" one?
Depends on how the ground is . Lets discuss a couple posibilitys : Lets assume that you alternator isnt grounded well and has a partial ground. The partial ground would allow a voltage drop to the circuit. Some alternators apply voltage to a ground field ( rotor) and others apply ground to the field to control the rotor field current. If the voltage regulator was seeing a low voltage ( due to a bad ground) then the regualtor would ask for more laod to try to supply proper charging voltage, resulting in a high load all the time , decreasing belt life. After teaching these charging circuits for 20 plus years i could argue both sides of the fence depending on the actual field circuits. A bad ground wouldnt have to be external either , it could be a burnt shunt lead inside the alternator. The answer is YES it could !!
Paint it nice and pretty and not reinstall allof the body and chassis grounds. Not make sure that the main ground wire from the battery is making a solid ground.
Ok, a real question here, I like to think I am kind of sharp on auto electric stuff, so I want to learn. How will the alternator "load up" enough to wear the belt if it has a bad ground? A bad ground would not allow for a complete circuit for charging would it? if not, then it could not "load up" right? I guess a bad ground might get hot and load up and create a load in created heat through resistance?
If the ground is intermittent the load would cycle too frequently therby setting up harmonics in the belt,possibly causing premature failure. How`s that for a WAG?
In the event it lost ground from the mount, it would hunt for a ground. Use a volt meter with one lead on the alternator housing and one lead on the negative post of the battery. Any measured voltage should be minimal. Ideally zero. But I have never seen one take out a belt if it had a missing ground. Just my two cents.
A weak ground is a resistance the same as any other load. The regulator reads this resistance and builds current to overcome the resistance and bring the battery voltage up to approximately 13.8 volts. This is no different than putting any other load on the charging system. As the load grows, the alternator attempts to meet the potential. this load puts more load on the belt than friction can overcome, the belt stretches and begins to slip on the pulley, leading to catastrophic failure.
I've had ground problem on a 63 vette once, and I understand the increase in output and wear on belt , but in my case the overcharging of the battery and fumes from the overcharged mad me sick while driving long before belt wear had a chance to show any damage, but I'm sure it didn't do the belt any good. But neither does the fan belts like a high amp alt & dual amp stereo system. Roger
In this situation, the battery is not overcharged. The resistance brings down the voltage that the battery sees. The alternator is straining to overcome the weak ground which the alternator sees as load.
But, this resistance (energy) would HAVE to be converted to heat, it wont just disappear to the ethier..... right? If I am right, enough heat to destroy a belt ain't going to be un-noticed.
in my opinion the only way an alternator can ruin a belt is if the bearings locked up. let's say an alternator is putting out 14 volts at 100 amps , that's 1400 watts. one horsepower is 750 watts so it takes 1.866 horsepower to turn the alternator. that can't be a big strain on any belt how am i wrong? what did i overlook?
I agree with you 36-3window. Let's think this through. A bad ground is only a step removed from an open circuit which means no current flow and therefore no load. Load on an alternater is a function of demand by the electrical system as a whole, as is the power generated. If there is a high resistance at the earth then, thinking it through with ohms law, that translates to a very low current flow. As it may well be generating maximum voltage at say, 14.5 V ,then because of the diminished current flow, the overall power generated is lower the load is lower. I see no harm being done to the belt in this situation. Further, I do say yes to bad bearings causing belt damage.
Define "Bad" alternator. Bad bearings in the alternator? Definately. If there is a bad winding inside that causes the alternator load to increase/decrease the load affecting the tension on the belt? Possibly.
Positive or "ground", either is a circuit completion or incompletion, however a poor circuit tells a voltage regulator that the battery is low and in turn it charges "full field" as it is called causing a great deal of load on the belt as well as heat in the unit decreasing clearances from the stator to the windings. We have had this problem several times, primarily on boats, "artificial" grounds exposed to moisture, leading to low amp circuits. Think about it a starter with poor connections on the cable can cause all kinds of problems. We have had several folsk over the years whom did such a great job of painting componets that would not work due to ground circuits not completing.
I understand the idea of extra load and bad grounds but I can't see it causing a belt to be destroyed in the week or two mentioned in the previous post Ebbsspeed refers to. Maybe we are talking a 20,000 mile life as opposed to 30,000? I'm curious because I'm having a voltage gauge issue that I'm 99.9% sure is the gauge but this thread and the previous one have me wondering just a little.
I had said no as usually a bad bearing or belt that isn't quiet adjusted correctly will be the cause of premature belt wear. On rods with relocated alternators I have seen a couple (including my own) where the setup although looking great and fitting the confines of the engine compartment didn't allow for enough adjustment on the belt or didn't give the belt enough contact with the pulley allowing it to slip. A poor ground due to one reason or another may cause the alternator to charge harder because the regulator misreads the demand and sets the charging rate higher than needed. I think a bigger problem may be caused by running an alternator with minimal amp rating on a system with a high demand. This would be the 35 amp alternator in a car with power accessories, big sound system, air and high powered headlights or one or more of the above. It would be charging full tilt almost all the time to keep up with the demand.
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