Not joined yet? Register for free and enjoy features such as alerts, private messaging and viewing latest posts and topics.

Battery light on despite new alternator

Discuss problems you have had or are having with your Z4
Post Reply
User avatar
LeeMacca
Newbie
Newbie
Posts: 32
Joined: Sat Feb 23, 2013 8:19 pm

Battery light on despite new alternator

Post by LeeMacca » Sat Mar 02, 2019 11:17 am

Hi all!

So I have had an intermittent battery warning light for a while now so I changed the alternator for a reconditioned bosche one whilst I was fixing the oil filter housing gasket. Unfortunately I now have the intermittent battery warning light again! My diagnostics tool is reading 14v from the battery when the engine is on.

Anyone have any ideas what could still be causing this?

Cheers!

User avatar
cj10jeeper
Lifer
Lifer
Posts: 17846
Joined: Fri Jun 22, 2007 11:50 am
Location: Lichfield, England

Battery light on despite new alternator

Post by cj10jeeper » Sat Mar 02, 2019 11:41 am

Test the battery. It's always way more likely the problem than the alternator.
Check voltage after left overnight and I'd want to see around 12.6v and again when running and charging on or over the 14v
Jaguar F-Type 3.0 Supercharged V6 S, Stratus Grey, LSD, Active Exhaust, CF wheels, Performance brakes, Sports seats and mods ongoing
Gone but not forgotten Z4 3.0i SE Roadster ///M front, Red ///M leather seats, Aero sills

User avatar
LeeMacca
Newbie
Newbie
Posts: 32
Joined: Sat Feb 23, 2013 8:19 pm

Battery light on despite new alternator

Post by LeeMacca » Sat Mar 02, 2019 11:53 am

cj10jeeper wrote: Sat Mar 02, 2019 11:41 am Test the battery. It's always way more likely the problem than the alternator.
Check voltage after left overnight and I'd want to see around 12.6v and again when running and charging on or over the 14v
I haven't got a volt meter or anything but I just did a test using a cheapy diagnostics tool. In the image below the engine being started is on the right hand side, the line hovered around 13/14 for a minute or so after the engine was started then stayed at 14v comfortably until I turned on all the accessorises and lights etc then it seemed to drop down to 13v and stayed there until I turned off all the accessories. Could that be more likely battery based on that?
IMG_4734.jpg
IMG_4734.jpg (303.05 KiB) Viewed 312 times

User avatar
cj10jeeper
Lifer
Lifer
Posts: 17846
Joined: Fri Jun 22, 2007 11:50 am
Location: Lichfield, England

Battery light on despite new alternator

Post by cj10jeeper » Sat Mar 02, 2019 1:07 pm

Not a reliable test. Sorry
You need to test the battery after it’s stood for a few hours. That tells if it’s holding the charge. Halfords will test it for free if needed
Jaguar F-Type 3.0 Supercharged V6 S, Stratus Grey, LSD, Active Exhaust, CF wheels, Performance brakes, Sports seats and mods ongoing
Gone but not forgotten Z4 3.0i SE Roadster ///M front, Red ///M leather seats, Aero sills

Post Reply