Starting Charging system basics

[mentalbreakdown00]

Ok, To first diagnose a starting/ charging system you need to understand the basics of the two systems. Let's start with Volts, Ohms, and Amperes. First a voltage is the amount of electrical pressure exerted onto a circuit(imagine the water pressure in you water hose). Now Ohms would be the resistance to that flow, for example the nozzle on the end of the hose. Last but not least the amps is the amount of flow itself. Now a hose with 40 psi and no nozzle has a lot of flow and no pressure, where as a 1/16th inch hole at the end of the same hose would result in a lot of pressure and little flow. Next well talk batteries. It is a chemical storage device that uses dissimilar chemicals or metals to create a voltage, and automotive voltage is 12.6 volts. You have 6 cells inside the battery making 2.1 volts each. Now you have a battery cable leading to one side of you starter relay, this cable has to be big enough to handle the amperage of the vehicle plus some on both pos and neg. of the battery. Now you have another cable out of the other side of the starter realy to the starter. I will stop at that and explaing the relay for the moment. A relay is a device that uses a lower current to control a larger current. Therefore you can use a low amperage from the ignition switch to control the greater current that the starter needs. So to control the relay when the key is turned to start 12 volts and a very low amperage it sent to thi relay via the smaller wire on the relay and it pulls a contact together inside the relay making contact between the battery wire and the wire to the starter making the starter turn. Now the last part of the staring system is the ground wire, which needs to be as big or bigger than your main battery cable to handle all the amperage in the vehicle. Now on to the charging system, which uses the ground and pos cables and the relay in a lot of cases. An altenator is an electro mechanical device that actually produces a AC current, but is turned to DC for use in vehicle by three diodes which are electrical one way check valves. Now earlier we discussed that automotive batteries are 12.6 volts, so to charge one an alternator must produce at least 13 volts to charge a battery, but not go higher than 15 volts in order to avoid damage to electrical control units. To avoid this there is a regulator that controls the amount of current sent to the windings to control the voltage. Now if you have a bad ground an altenator will tend to under charge, but is not always the case. If you have a broken battery cable between the battery and altenator the alt itself will put out as much as it can (i've seen 75 volts), but it won't charge the battery. Now that you have a basic understading of the systems, and if Mr. Jim Oaks allows me to I will do a write up on how to diagnose, what voltage drops are, etc. Hope this helps someone, or can get saved, and edited and whatnot.

 

[AllanD]

I'll simplify much further.

Electricity has to have a way in (a "Goes inta")
and a place to get out (a Goes outa")

if on either side the contact is dirty, corroded or simply loose
you will be just as shit-outa-luck as you'd be if the thing you
want operating is actually dead instead of "apparrently dead".

THE first step in ANY electrical diagnosis is clean EVERYTHING.
wire brush and anti-corrosion paste.

And old saying is "Do the stupid shit first"

"Stupid shit" in this case being the "thing" you overlook
during your long diagnostic proceedure that would have corrected the problem without 99% of the brain sweat you just expended.

In other words after you check EVERYTHING ELSE it's the thing that you find and say "**** me, I'm a total idiot, I shoulda checked that first..."

Simple rule? clean ALL the grounds first >90% of the time it's your problem anyway...


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[RobbieD]

if on either side the contact is dirty, corroded or simply loose
you will be just as shit-outa-luck as you'd be if the thing you
want operating is actually dead instead of "apparrently dead".AD

Technically, sir, you are perfectly describing the a "Goes to shit" condition. Well done!

 

[AllanD]

Bigger wires don't necissarily make things operate better than a wire that's "sufficient"

BTW, on the Original post above?

One suggestion... a concept that you missed in school:

Paragraph breaks.

Try them.

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[mn_smokeater]

Simple rule? clean ALL the grounds first >90% of the time it's your problem anyway...


AD

thats been over 99% of my issues iv ever had and added your words of wisdom to my siggy

 

[AllanD]

Hey, I worked in the Military and Medical Electronic industries and before that I was fixing stuff for friends from Junior HS on and frankly with electronics stuff the FIRST thing you look for (other than a cloud of smoke) is a bad solder joint.

And on audio equipment the next thing you look for is a leaky electrolytic capacitor.

BTW, that cloud of smoke is MAGIC SMOKE.
It takes a skilled technician days to properly re-infuse the right ammount of
coffee steam, cigar smoke and solder flux fumes into a device to make it
work again.

But always check for the simple stuff first before you start washing
everything in brain sweat.

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[mentalbreakdown00]

Hey allan chill man. I was trying to do a write up on starting charging system basics, but I am no writer, was going to do some editing later when I get a chance. I don't have any writing software on this work comp so had to save it here. Was going to get into corrosion, voltage drops, etc. Also I was not saying a bigger cable is better, was saying that the cables need to be sufficiently large enough to handle all the amperage, but you should err on the side of one size bigger. Thanks for the support, was gonna try to do this to help some people because there are so many posts on these sorts of subjects thought it could help someone.

 

[Will]

Well, you have to expect criticism if you post something like that in an open forum. A 600-word block of text is like the maze in the Sunday paper--after the first couple of turns it's on to The Wizard of ID. People need it simple so they can use it.

If you want to do an article that will help people diagnose charging/starting systems make it simple and include pictures that show people where to probe and what to expect when they probe it.

By simple I mean--after you are done, go back through and read it. If it doesn't directly relate to troubleshooting, erase it.

For an explanation of the basics of electricity, you aren't going to beat wikipedia so it's a waste of time. That's why I suggest a Ranger specific article on troubleshooting with pictures. Where it's neccessary, tell people what the object does.

For instance, you have a picture of a starting relay. You tell people that this dirty bugger lets you control a lot of current with a little bity switch. And when your buddy keys the switch you should register 12V here and 12V here.

You show a picture of a ground wire. That's when you can describe the problems with a corroded ground. People will understand what you mean.

With a well thought out article--meaning you state a specific goal and then accomplish it--I'm sure Jim would use it.

 

[mentalbreakdown00]

Thank you will, that's what I was after. Constructive critisism. I will do this exact thing when I get a moment then and re-do this article to a ranger based diag and trouble shooting thing.

 

[graff104]

I didn't make it through reading the whole article. Probably because of the paragraph breaks making it hard on me, but from the 10 or so lines i did learn quite a bit. I never was certain on the difference between ohms amps and volts. I guess you learn something new everyday!

 

[mentalbreakdown00]

Well graff, help me explain this i'm an auto tech, not a good writer.

 

[Legend]

Since you're writing about electrical / battery problems, please let me throw in a cautionary note....

A fully charged typical 12 volt truck battery contains roughly the same energy as 14 to 16 sticks of dynamite. While 12 volts isn't enough voltage to hurt you, there are several ways to get injured.

1) The starting motor takes a lot of power to spin the engine and the battery cables are large enough to carry the huge current required. I saw a guy get his wrist watch band between the hot wire and ground on a tractor. It instantly heated the watch band red hot and cut through his wrist clear to the bones all the way around. As they were hauling him off to the hospital, he acted like it was hurting a lot.

2) When a battery is being charged it gives off a small amount of hydrogen gas. Normally this isn't enough to be a problem, however when a battery is being overcharged it gives off a much larger amount of hydrogen. Hydrogen is very light and will dissipate quickly, but if the battery is in a fairly confined space or conditions are just right, the gas can easily accumulate to an explosive level.

Usually the gas catches fire and rapidly burns up the vent hose or follows the path back to the inside of the battery and blows up like a bomb. I saw this happen to a friend of mine and the battery blew up right in his face. He was wearing glasses so it kept it out of his eyes a little. We rushed him into the kitchen and put his face under the faucet and flushed his face and eyes for an hour or so and he was lucky enough to not have any permanent damage.

This leads to a tip about jump starting vehicles....

FIRST - Connect the hot wire to the battery of the vehicle being started.
SECOND - Connect the hot wire to the battery of the jumping vehicle.
THIRD - Connect the ground wire to the battery of the vehicle being started.
FOURTH - Connect the ground wire NOT TO THE JUMPING VEHICLE BATTERY, but to an exposed unpainted metal, well away from the battery, such as a chrome bumper or the frame. Then, if there is a spark, this is when and where it will occur and be less likely to explode or start a fire in the engine compartment.

The real trick with safety is to identify and be aware of any hazards. When you're playing with batteries, electricity and gasoline all in the same area, there are plenty of opportunities for things to go badly. Just be careful and think about what you are going to do, before doing it.

 

[Bob Ayers]

This is a good one, already done with diagrams:


http://www.bcae1.com/charging.htm

 

[tpking]

1) The starting motor takes a lot of power to spin the engine and the battery cables are large enough to carry the huge current required. I saw a guy get his wrist watch band between the hot wire and ground on a tractor. It instantly heated the watch band red hot and cut through his wrist clear to the bones all the way around. As they were hauling him off to the hospital, he acted like it was hurting a lot.

i had a friend that was holding onto a wrench tightening the hot wire and hit the fender somehow and grounded it out and melted his wedding ring all the way around his finger.. nasty scare left..