x

Alternator Diodes Blown – Inspection & Repair

What is an alternator diode?

The alternator’s rectifier assembly

The alternator is part of your vehicle’s charging system. Its purpose is to charge your vehicles battery to provide the necessary power to operate the starter motor, ignition and all of the electronic accessories in your car. It does this by providing your car battery with a constant charge and allowing it to stay full.

Your car’s alternator (used to be called a generator) will typically have up to six diodes. These are located on the alternators rectifier assembly. Electricity flows through the diodes, which convert the alternator’s AC output to DC (which is what the battery runs on). If the diodes do not function correctly, the alternator will not work. This will stop the battery from charging, resulting in your car possibly needing jump-starting.

 

What causes alternator diode problems?

Heat – As electricity passes through the alternator diodes, heat is produced. At low levels, this heat is not harmful. However, high levels of heat can cause the diode to burn out.

The more electricity that passes through the diode, the more heat it will produce. Using the radio, headlights, air-conditioning and other accessories can cause more heat to pass through the diode, putting it at risk of burning out over time.

Dry diode solder joints – in use the soldering around the alternator diodes expands and contracts with the heating and cooling of the vehicle engine and alternator. Overtime this can cause a dry soldering joint for the alternator diodes, preventing them from working / charging your car battery correctly.

Reversing the car battery terminals – if someone fits a new or recently charged battery to your vehicle and accidentally reverses your cars battery terminals, it may mean that some of your alternator diodes may take full battery current which can quickly destroy them.

The other slightly less common problem is when people jump start a completely flat vehicle battery and accidentally reverse the jumper leads. This can also cause hundreds of amps to flow through the alternator diodes in the forward biased direction, which will quickly destroy them.

 

 

Symptoms of a burnt out diode:

When the alternator stops working, the battery will stop being able to charge. This may cause the following things to happen:

  • The battery will become depleted, resulting in the car not being able to start.
  • The engine will begin to run rough, lack power and eventually stall and not start again.
  • The battery warning light will turn on, warning you that there is a problem with your alternator charging system
  • The headlights will become dim due to reduced battery voltage.

 

Alternator Diode Repair & Replacement in Hamilton

If one or more of your car’s alternator diodes fail, then the diode rectifier assembly will normally need to be replaced. At Grimmer Motors, we can perform an alternator diode rectifier replacement on your vehicle. This will allow the alternator to keep the battery charged.

At Grimmer Motors, our mechanics are experienced in all sorts of alternator and battery repairs. This allows us to quickly identify and repair battery/charging system issues.

For fast, quality alternator repair in Hamilton, contact Grimmer Motors today!

 

CONTACT US

Phone: 07 855 2037

Email: office@grimmermotors.co.nz

Address: 998 Heaphy Terrace, Fairfield, Hamilton

Providing reliable services for:

 

Japanese Cars:

Daihatsu
Honda
Isuzu
Kia
Lexus
Mazda
Mitsubishi
Nissan
Subaru
Suzuki
Toyota

 

American & Australian Cars:

Chevrolet
Chrysler
Dodge
Ford (US and Australian makes)
GM
Holden (US and Australian makes)
Jeep

 

European Cars:

Alfa Romeo
Audi
BMW
Citroen
Fiat
Jaguar
Land Rover
Mercedes
Peugeot
Porsche
Renault
Rover
Saab
Seat
Skoda
Vauxhall-Opel
Volkswagen
Volvo

 

Korean and Chinese Cars:

Daewoo
Chery
Foton
Geely
Great Wall
Haval
Hyundai
Kia
Ssangyong

Thousands of happy clients from:

Aberdeen
Ashmore
Beerescourt
Callum Brae
Chartwell
Chedworth Park
Claudelands
Crawshaw
Deanwell
Dinsdale
Temple View
Enderley
Fairfield
Fairview Downs
Whitiora
Te Kowhai
Thornton
Western Heights

Flagstaff
Forest Lake
Te Rapa
Nawton
Frankton
Glaisdale
Glenview
Grandview Heights
Hamilton Central
Hamilton North
Hamilton East
Hamilton West
Harrowfield
St James Park
St Petersburg
Somerset Heights

Huntington
Livingstone
Magellan Rise
Maeroa
Melville
Fitzroy
Pukete
St Andrews
Queenwood
Ruakura
Riverlea
Rotokauri
Rototuna
Silverdale
Hillcrest
Stonebridge

Morrinsville
Cambridge
Te Awamutu
Matamata
Te Kowhai
Raglan
Ngarawahia
Kihikihi
Ohinewai
Huntly
Taupiri
Gordonton
Horotiu
Ohaupo
Tirau
Putaruru
Otorohanga
Matangi