My Account Login | Register

Welcome

Enjoy quick and easy access to our Repco Rewards program and faster checkout.

Login Sign up
Account

Welcome

Enjoy quick and easy access to our Repco Rewards program and faster checkout.

Login Sign up
My Vehicle

Vehicle

Set my store
Cart

0
My Cart

No stores found - check that you entered a valid postcode or place name.

OEX Alternators

Charging your Battery and Powering your Accessories.

On a cold winter’s morning, or late at night, there is never a good time for your vehicle not to start when you turn the key in the ignition. The ‘click’ of a starter motor relay due to a low or flat battery may not be the fault of the battery at all and it can sometimes be diagnosed as a faulty alternator that is the cause of issues. The role of the alternator is to power not just your accessories but charge your battery to provide current to the starter motor and when this charge falls below the current required, your vehicle won’t start.

A faulty alternator on your vehicle can sometimes be hard to spot but in most instances, there will be warning signs alerting you to possible problems. Some of the examples of a faulty alternator could present as;

Warning lights on the dash – Displayed as either a battery symbol or “ALT” for alternator, this light may flicker or stay illuminated dependent on the amount of charge is being drained while the vehicle is running.
Dim or flickering headlights or dash lights – When an alternator is not producing the power required, one of the more pronounced ways to identify a faulty alternator is through the vehicle lights being dimmer than usual or only getting brighter as the engine revs are increased.
Trouble starting or a flat battery – Although your vehicle battery relies on the charge from the alternator to remain topped up, your battery will eventually run down if not receiving adequate charge from a functioning alternator. This is where it is important to correctly diagnose whether the battery or alternator is at fault.
Loose or slipping alternator or multi accessory belts – Drive belts should also be inspected and tightened to manufacturers specifications. A faulty or loose belt will reduce the performance of the alternator, especially when the alternator is under load.

What are the points to check for common charging problems?

Quite often alternators fail for reasons that are possibly caused by vehicle faults. If the faults in the vehicle are not repaired before the fitment of a new or rebuilt alternator, the new alternator may fail on fitment, or soon after leaving the workshop.

Check points for common charging problems

A defective battery could cause an alternator to work beyond its limit, this may cause the starter to be damaged due to overheating. Diodes could also fail in this situation.
Battery cables MUST always be connected. Disconnecting the battery from the alternator while the vehicle is running will cause damage to the diodes, and potentially electronics in the vehicle.
The warning lamp circuit should be checked, most vehicles require the warning lamp circuit to be working for the alternator to charge correctly.
A voltmeter is required to check voltage.
Corroded wires and poor connections could cause a voltage drop between the battery and the alternator. If a battery receives less voltage than that which is specified by the vehicle manufacturer (V(I)), the vehicle battery may fail prematurely.
There should be no more than 0.4V drop between the positive terminal of the battery, and the B+ terminal of the alternator (V(II)).
There should be no more than 0.4V drop between the negative terminal of the battery, and the body of the alternator (V(IV)). All Earth connections must be clean and tight.
If the alternator is fitted with an external sense wire, “system voltage” should be found at the sense connection of the alternator. There should be no more than 0.4V drop (V(III)).
Vehicles are now controlled by engine management systems, so a system scan may need to be carried out after any repairs or part replacement.

Note: Due to every vehicle having different cable sizes and lengths the above is a rough guide only.

Note:

The listed measurements are for a standard automotive system – 12 Volt
Caution is advised when checking later model vehicles as some manufacturers have included ECU interfacing with the alternator.
Incorrect testing could cause damage to the vehicles ECU or other electronics.
The vehicles service manual should be referred to for specific vehicle information.

The above “points to check” should be completed for every vehicle with a charging problem.

Once the above points have been viewed and repaired, if required, and the alternator is still not working correctly, then a replacement alternator should be sought. OEX offer the largest range of alternators to suit the Australian and New Zealand markets, this includes:

Passenger vehicles
Heavy duty
Light commercial
Agricultural
Marine

Working with the world’s leading brands, OEX design and enhance existing alternators to better suit the Australian and New Zealand market and the needs of auto electricians or home mechanics alike. Operating under ISO 9001 quality certifications means all OEX Alternators are constructed to the highest standards, meaning you have the peace of mind of reliability and durability when choosing OEX.

For nearly 25 years, OEX have employed stringent testing, engineering, and quality control procedures on their entire range of auto electrical products. Tested in some of the harshest terrains and unforgiving environments delivers you a product that keeps you on the road longer and all backed by superb after sales support and warranties.

By choosing OEX, your purchase of an OEX starter motor comes backed with a 3 year, 90,000km warranty on passenger vehicle applications. Please refer to website for full conditions.

Whether it be a replacement alternator, starter motor, or any product in the OEX range you can trust the quality and reliability of OEX for all your auto electrical solutions.