Electricity is the life blood of the automobile. This has always been the case as nearly all gasoline internal combustion engines use electricity to ignite the fuel. Today the total automobile is controlled and operated by electricity and electronic equipment.
This include fuel control, emission control, accessories such as the heater and air conditioning system, steering control, brakes, lights and many more. It is obvious that the charging system that provide this power is a very important system.
The charging system usually include a method to generate electricity and a battery to store the power. This sound pretty simple but it is no longer a simple system. The typical system consist of an alternator that is usually belt driven by the engine. The out put of this alternator must be regulated to control the voltage with in a specific range. The usual range is 12 volts to about 14.2 volts. If the voltage gets to high or too low electronic and electrical components will not work or they may be damaged.
Every alternator is controlled by some form of electronic regulator that controls the output of the alternator. In years past that was a regulator mounted to the vehicle independent of the alternator. A few years ago the regulator was moved into the alternator and the system was called internally regulated. A few manufactures decided that the electrical system should be interfaced with the computer network. Now most cars either control the charging system by computer or monitor it and set certain levels by using the engine control computer. Many systems reduce the alternator load during periods of hard acceleration.
Can I test and diagnose problems with my alternator? That depends upon the equipment that you have. A good multi meter will give a fair indication of the state of a charging system. If all that you have is a multi meter measure the voltage at the battery terminals before starting the engine. Then measure the voltage with the engine running at a fast idle. The resting voltage should be close to 12.6 volts and the operating voltage generally ranges 13.2 to 14.2 volts at the battery. You can also measure the output voltage at the alternator and it should measure with in 0.1 volts of the battery voltage. After measuring the voltage at a fast idle, turn on all of the accessories and the lights. The voltage should remain close to the same as at a fast idle (with in about 3 or 4 tenths of a volt).
A customer came in the other day and stated that one of the parts people at a national known auto parts store had told him that the only sure way to see if an alternator was working was to disconnect the negative battery cable and see if the engine continued to run, if it does the alternator is okay. DON’T EVER DISCONNECT A BATTERY CABLE IF THE ENGINE IS RUNNING.
Disconnecting a battery cable with the engine running will most likely damage your voltage regulator, engine management computer and other components. This could end up costing you thousands of dollars. For the same reason do not reverse the battery terminal when jump starting a car.
Can I change my own alternator? Yes if you have the correct tools. Get a good repair manual before you try to diagnose or change your alternator.
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Charles L. (Bud) Evans is an experience automotive repair technician specializing in the difficult to solve problems with 30 years of full and part time auto repair experience. His education and experience include a masters degree, a major in industrial technology, several years teaching industrial technology and auto repair and 15 years experience as a health physicist. Bud is the owner of Rattlesnake Mountain Enterprise, http//:http://www.ratmtent1.com./ Please visit our web site for free auto repair information.��������
Article Source: http://EzineArticles.com/?expert=Charles_Evans
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8 Users Responded in " Automotive Charging Systems "
Hey mate, great site! Some bloody useful tips here. I actually came here through your article about the turbo RA28 you worked on ages ago, and have been reading some of the other articles for the past 20 minutes or so, haha. Great resource for those of us less mechanically minded – I’ve always been about the design and style aspect of cars, though I know enough about the mechanics to get me by. So this is a useful site!
For what it’s worth – and I don’t know if this is important to you, though given their market share, it’s something to think about – your site doesn’t display too well in Firefox! The middle and far right column seem to get mashed into each other, really screws things up.
Anyway, cheers for the good reading!
- Van
http://grandJDM.com
Hey Van,
Thanks for your feedback. I urge anyone reading this to check out Van’s site, simply awesome if ‘old school’ cars are your thing.
Craig
Great site Craig. I thought it would be a great idea to have a section on how to replace the standard stereo a new car stereo on a Magna. Although I am not an expert on cars by any measure, I am excited at the prospect of doing something like that with my Magna.
Cheers and keep up the good work
Rony
Thanks for your comments Rony. I will see what I can arrange for the stereo swap article.
Hi Craig.
Just found this site when looking through the auto’s in blog catalog. I was looking for related sites to my own blog.
I like how you have focused on the details of alternators and their seperate components like the bridge rectifier (AC-DC) and voltage regulator. Nice guides.
Can anyone tell me how to tell if my vintage car is pos earth it had a new wiring loom years ago but the owner couldnt tell me if he had it changed someone said turn key if amp meter goes back wood its neg earth if it goes forward its pos earth does that sound right
[Thanks] Alot Of Information… Thankyou For Taking Your Time To “In Full Detail” explain The Operation Of The Alternator. There Should Be A Thanks Tab That Every Member Can Click On If They Found That Information Helpfull. Also Under ELECTRICAL: Can Members Post Usefull Information Like DIAGNOSTIC TROUBLE CODES and How To Read The Check Engine Light… Remap Of Ecu? I Have A Small Amount Of Information Including The Latest OBDII technology And Cheap Scan Tool Advice For “DIY Diagnostic Checks” That Can Save People Money And Extract There Own Codes. As A Automotive Technician Living In Australia I Find Australia Lacks.. Information On Aussie Built Cars When It Comes To ECU..
Overall A Great Website.. Keep It Up We Should Have More Mechanics Sharing There Knowledge.
A quick response to RU$$ELs comments on DIY diag checks/code reading.
engine management diagnostic work is in my humble opinion NOT a DIY task.
Using a scan tool is a task that should be carried out by a suitably trained and experienced technician,and the equipment required to complete this task safley and with a usefull outcome would i think be out of the practical reach of most DIY mechanics.Our diag equipment is worth somthing like $150,000 and we dont have it all by any means. Sure there are cheapo scan tools (SO CALLED)
avail all over the net, there are just as many horror stories to go with them.Modern vehicle management systems are far more than engine control,lets use airbags as an example.So you buy your $200 “obd reader”(as they are described),plug in and sit back in the drivers seat to “diag” your vehicle, after the code reader triggers the drivers side airbag and punches you into the boot , you may realise that $200 wasnt a cheap way of trying to locate the fault with your vehicle.(I use this example as it has occured more than once in australia)we wont even mention brake control equipment, steering etc etc
Back to vehicle diagnostics…..Code scanning a vehicle is a VERY small part of diagnostic work.
As a guide , i will describe a standard vehicle diag in my workshop.
1)engine compression test
2)engine vaccum reading
3)fuel pressure and flow rate test\fuel quality\vehicle on gas bench and read emissions(most important step as far as i am concerned.).
4)static and discharge battery test\alt charge rate\voltage drop across batt terms and grounds (body & engine)
5)code scan
6)scope ign
There is no point in scanning a vehicle that has a burned valve , a leaking inlet manifold, has a charge rate of 12.4v,has bad body grounds or the cat is glowing red hot on arrival etc etc.
Diagnostics is a start from the basics procedure.
We constantly have customers arrive at our workshop that have spent many thousands of $ on diagnostics and replacing ecu s afm s etc etc only to find that the vehicle needs a coil and leads ,or some rabit has cracked an insulator putting a set of plugs in…..
Im not sure why you find it hard to obtain info on ecu’s russel, we use autotech, boyces auto data ,electraspec and autodata, havent ever not been able to find somthing it costs but it is an essential tool, as important as a 10mm spanner.
As for mechanics sharing their knowledge, we have a saying in our workshop “why should i tell you in 5 minutes for nothing what it has taken me 25 years and thousands to learn”
Not trying to be a smart arse, please dont take it that way, but we all invest big money in equipment and training, we need to make a living and pay our bills, giving things away dosnt do that.
Regards,
Dave.
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