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Snowy90 L322

Member Since: 24 Aug 2015
Location: Surrey
Posts: 220

Battery Light Flashing and then staying on

Hi All

I have a battery light that comes on and off when driving but stays on at idle.

Battery is quite new about 1 year old and charges to 12.6v so i think thats fine.

However the alternator seems top be under charging at 11.9v so i have got a reading at 14v when i first tested but now it seems to always be at 11.9v

I'm pretty sure the alternator is fubar but i have heard of bad engine earths, so before i run out and change the alternator what should i check for?

Thanks in advance

Chris

20th Jul 2020 4:25pm

Brian Considine

Member Since: 15 Apr 2019
Location: Garlinge
Posts: 428

As a quick comparison test you could see what the readings are using a jump lead from a clean chunk of engine to the battery negative.

If you get higher voltage reading this could point you towards a defective engine earth. 2003 Range Rover Vogue TD6

20th Jul 2020 5:22pm

RR P38

Member Since: 12 Oct 2013
Location: Sydney
Posts: 215

2003 Range Rover Vogue 4.4 V8 Java Black

Almost certainly the alternator is on its way out
Get it checked ASAP or you will be stranded and or need a new battery as well as an alternator

20th Jul 2020 10:41pm

Snowy90 L322

Member Since: 24 Aug 2015
Location: Surrey
Posts: 220

Brian Considine wrote:
As a quick comparison test you could see what the readings are using a jump lead from a clean chunk of engine to the battery negative.

If you get higher voltage reading this could point you towards a defective engine earth.

Sounds a good idea, 99% certain it is the alternator but worth a check.

21st Jul 2020 8:55am

Snowy90 L322

Member Since: 24 Aug 2015
Location: Surrey
Posts: 220

RR P38 wrote:
Almost certainly the alternator is on its way out
Get it checked ASAP or you will be stranded and or need a new battery as well as an alternator

Thanks the car isnt going anywhere right now so will swap the alternator soon btw its done 155k miles so its done ok! Just strange that it seems to have gone quite quickly rather than slowly dropping voltage?

Also no strange sounds coming from it.

21st Jul 2020 8:57am

mercs600

Member Since: 19 Mar 2011
Location: North Yorkshire
Posts: 425

Just done this - 168k and it was the carbon brushes that were worn. Changed them myself and all back kicking out 14.1 v again. Initially was the same as yours at 11.5 volts.

21st Jul 2020 8:31pm

Snowy90 L322

Member Since: 24 Aug 2015
Location: Surrey
Posts: 220

I assume thats an alternator out job? Where did you get the brushes?

29th Jul 2020 1:37pm

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