Member Since: 11 Jan 2018
Location: Hull
Posts: 148
Battery light on but seemingly good alternator output
Hi,
The battery light illuminated on the dash today and stayed on. The radio went down to low power mode too.
Everything seems to be working fine.
When measuring the voltage across the battery with the engine running, I'm seeing about 13.5v and about 12.5v without the engine running.
The 5A fuse for the ALT circuit tests good too.
Has the battery light come on because the voltage from the alternator is under a certain threshold?
What do you think?
Alternator on it's way out?
Thanks!
15th Feb 2019 4:36 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8097
12.5v across the battery with the car “asleep”(brake light off) is very low, with engine running with battery as low as that should be over 15v for first 5 minutes or so dropping to 14.7+volts= alternator goosed It can when others can't,
It will when others won't,
It goes where others don't.
15th Feb 2019 4:50 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10363
think your alternator is broken
unless the light has fixed itself
15th Feb 2019 4:54 pm
jonathanrichards
Member Since: 11 Jan 2018
Location: Hull
Posts: 148
LOL!
15th Feb 2019 5:29 pm
jonathanrichards
Member Since: 11 Jan 2018
Location: Hull
Posts: 148
Well, that seems to clarify it then!
Denso alternator and viscous fan tools arriving in the morning.
15th Feb 2019 5:29 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8097
In the meantime disconnect the battery, alternators are notorious for taking batteries with them.It can when others can't,
It will when others won't,
It goes where others don't.
15th Feb 2019 6:05 pm
jonathanrichards
Member Since: 11 Jan 2018
Location: Hull
Posts: 148
Yes, already done that.
15th Feb 2019 6:22 pm
jonathanrichards
Member Since: 11 Jan 2018
Location: Hull
Posts: 148
Thanks to Advanced Factors for speedy weekend service and my new Denso alternator arrived and fitted.
A moderately sweary job as access is a bit limited to the right of the engine and it's quite low down. But with a ratchet ring spanner, it was soon replaced and the battery light went out soon after start up.
Voltage was measuring 14v with the engine running.
I bought some crazy viscous fan tools from a company called Flat Dog UK
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