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Is it really the alternator?

Tuesday 23rd February 2016
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Is it really the alternator? Don’t do it twice, do it right!

We are continuously pointing out how far technology has advanced from the good old days of just a battery feed and warning light circuit on alternators.

We are now at a stage in the market where alternators are becoming a slave to the charging system. The charge rate is now in effect being controlled by the vehicle. This can be through ECU, engine control module, powertrain control module, etc.

With the task of testing the charging circuit becoming more difficult, the easy option is to simply replace the alternator, or is it?

Without carrying out the proper tests, investigating the reason for the failure of the original alternator and carrying out remedial work, you run the risk of repeated failure, premature failure of the replacement alternator or the replacement alternator does not work (does not cure the existing fault).

This is where comments such as; “I must be getting poor quality units", "it works fine then the light comes on after a while", "it’s still not charging", "it’s getting hot", or the good one, "I got one from the dealer and it's fine”. But, did they really get one from the dealer or has the old one gone back on the car?

There are really only two main reasons why an alternator needs replacing:

1. The alternator has come to the end of its life span
2. A vehicle fault has caused the alternator to fail prematurely

It is inevitable that if the original alternator has failed, and the cause was not accurately identified and corrected the replacement alternator will prematurely fail too.

With misdiagnosed faults being one of the most common issues we come across it is clear that faults are either being overlooked or not being rectified properly. The alternator has in some ways become a diagnostic tool, try one, try two, try three, it doesn’t mean that it will rectify your fault. In some cases, yes, the second or third alternator may work but this is usually down to the fact that the connection has been unplugged and reconnected so many times it has cleaned any contamination that may have been on the connection. Some alternator wiring functions with milliamps so it is more critical now to ensure that the connections are clean of any contamination. A surprising number of old core will be working when tested due to such faults as wiring issues.

It is more critical now than ever before to thoroughly inspect the wiring harness for breaks, contamination and corrosion to minimise the risk of fitting an alternator where it is not needed, saving you time and money.

"I’ve just fitted an alternator and it's getting red hot"

Another very common failure is due to excessive load/demand.

Often we receive calls to the nature of "I have just fitted an alternator and it's getting red hot". When the alternator is exerted to excessive load it has to over work to compensate for this abnormal load request. The most common source of this is due to poor battery condition or the incorrect type of battery. The battery is quiet often overlooked assuming that; "it’s quite new, it should be ok", "I’ve had it on charge for an hour, that will do", "I can jump start the car then let the alternator charge the battery" or even, "it’s a new battery". Regardless, the battery must be checked before fitting the alternator and ensure it is showing 12.6v. If the battery is not at its optimum charge rate the alternator will not function correctly. As many alternators are now controlled by the vehicle’s engine management system, the vehicle will demand more from the alternator to compensate for any discharge in the battery resulting in the alternator overcharging and damaging its internal components.

We provide vehicle specific technical information free via our website which will have information on faults which can result in alternator failure, but we cannot stop faults being overlooked in the hope of turning a job around quickly.

By spending a little time investigating the reason why the original alternator had failed in the first instance will save you time, money and your reputation in the long run.

‘Fit and Forget’ with our quality products and save yourself the repeated hassle by investigating the cause of failure and rectifying it before replacing the alternator.

You do not want to lose money or the warranty on the alternator by trying to save some time.

Finish your day knowing that you have completed the job without the risk of the same fault occurring again.