Starting and charging systems: The Basics

Starting and charging system

Starting and charging systems are probably the most mis- conceived systems in the automotive world today. Many a well intending next door neighbor, all across the nation, has lent an experienced hand, and seemingly helpful advice “That sounds like yer alternator”. Fact is though, starting and charging systems can’t be diagnosed by symptoms. They have to be diagnosed with a voltmeter. Here’s why:

 

It’s actually not just possible, but fairly common, for two identical cars to have two identical electrical symptoms, yet have two different causes for those symptoms. So you have two cars doing the exact same thing, but for two different reasons. Therefore, NO ONE can tell you for sure, what’s wrong with your car by talking to you. They can really only make a guess.

Our job is to take the guess work out of the starting and charging systems.

 

1. The single most common absolute wrong doing, in starting and charging systems, is the act of taking the negative battery cable off, to see if the car stalls as a method of checking the alternator. This has all the intellect of shooting yourself in the foot to see if your gun works. A simple voltmeter must be present to know if you have a bad alternator. We don’t really know when this horrible practice got started, but it  never was a good idea…not even back in the days of the old fashioned generator. Here’s why:

It’s called counter EMF. It means counter electromotive force. When you take the negative battery cable off, the regulator senses low voltage, because there is zero voltage on the sense circuit. So the voltage regulator does its job and goes wide open amps. The system’s internal voltage, without a battery to stabilize everything will climb sometimes to 24-30 volts DC, at all the amps that the alternator will do. That exposes all the electrical components on the entire vehicle to more voltage than it was ever intended for. And still the real damage is yet to come.

Counter EMF (the equivalent of a silent electrical explosion) occurs when you put the negative battery cable back on the battery. This monstrous backlash will ruin any electrical component in its path: Lights, sensors, switches, gauges, but the most common thing is also the most expensive thing: your onboard or drivability computer. The ensuing expenses can be catastrophic. A voltmeter only cost $6.00.

Often times for illustrative purposes, plumbing and pipes provide an easy and accurate way to explain electrical properties. Imagine yourself in an old house with old plumbing. Probably the pipes are not secured to the wall studs every 18 inches like they might be in a modern structure. You’re in an upstairs bathroom and you turn on both hot and cold bath faucets full blast. Run the water for a minute, then suddenly, turn off both faucets. The pipes groan and shake. If done often, this could even cause a rupture.

The water, rushing through the pipes develops a force. Then, when you suddenly shut the water off, the pressure has no where to go, so it causes a backlash and the force must be absorbed into the pipes. That’s why they shake and shudder. This is counter EMF with water. When you take the negative battery cable off a starting and charging system, the alternator surges to full capacity. Electrical force is rushing towards the battery cable. Then, when you put the cable back on, the power is instantly stopped and backlashes into the rest of the system.

 

2. The second most popular cardinal sin with starting and charging systems is installing an alternator without charging the battery.  “It’s a brand new alternator, let it charge up the battery.” Are the words of an idiot. No starting and charging system should ever, under any circumstances, no matter who says what, be subjected to an alternator install, without a generous battery charge first. Even if you don’t have a charger, take the battery out, take it to a local part store or repair shop, and have the battery charged for a nominal fee. Whatever it costs, it’s got to be cheaper than installing the alternator again, 2 months down the road.

Once, a very stupid person went to the hospital for open heart surgery. Due to the extremely high technical capabilities of our modern day medical facilities, the operation was a complete success. As the patient lay in his recovery bed, he suddenly jumped up, jogged outside the building and ran around the block 4 times. After being severely scolded by his physician, his only defense was “ C’mon Doc, it’s a brand new heart.”

No….Many people return to a rigorous, fulfilling lifestyle, after major surgery. The key is a gradual, sensible ramp to the end goal, for optimum results. The same with your new alternator. Never make it over work, right out of the gate. After the chip in the voltage regulator has been subjected to a reasonable break in period, it is more ready for a rigorous work out. Periods of normal thermo-cycle are needed to provide a break in period, so that the regulator can achieve an optimum life expectancy. Periods of abnormal thermal cycle, during the break in period, are suicidal to the chip in the voltage regulator.

3. This is why it’s so important to assess your battery’s age, when installing a new alternator. A battery that is starting to fail will ruin your alternator. Batteries don’t just suddenly quit working. They gradually get weaker and weaker, which is sometimes unknown to the car owner. It is during this failure period that the starting and charging system goes through the most torture.  If the starter and alternator are old, they receive their last rights. If the starting and charging systems are new, their life expectancy will be severely shortened. Today’s fuel injection systems and permanent magnet starters can crank a car with as low as 100 amps. A 500 CCA battery could crank your car over repeatedly if it was ½ bad. (250 CCA). Can you see why you shouldn’t think your battery is fine, just because you haven’t had a problem cranking?

A battery that is used regularly should last 3-4 years. A battery that is not used regularly (stored for the winter) will normally last 2-3 years. In other words, if you have a labor intensive alternator replacement, think really hard about replacing the alternator and the battery simultaneously. If you have an alternator that is easy to get to, possibly your financial situation would dictate a risk. Remember though, at some point, as the battery begins to fail, the driver never realizes, the starting and charging system does.

↑ Back to Top