I'd disconnect main battery and try charging it ... if it holds charge, it MAY just be low volts due to starting car and not getting charged by the alternator.
Risk in changing one and not the other is that it seems they designed these cars so these two components can take each other out, so a duff battery could kill a new alternator.
17th Dec 2019 12:14 pm
RogB
Member Since: 15 Jun 2018
Location: Mansfield
Posts: 1730
ive got one of those aux socket plug in voltmeters (I know not 100% accurate but hopefully a reasonable indicator)
nothing running - shows 12.5v-12.8v
on start up - drops to between 10.8v and 11.8v depending on if the auto climate kicks in (heated front/rear screens on, blower kicking in quite hard)
settles at around 14.5v -14.8v when running depending on whats switched on (seats, screens etc)
does this sound about right? I don't have stop/start or any other aux batteries as far im aware, just the main battery2011 D4 XS 305 MY12 - gone but not forgotten
17th Dec 2019 12:42 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8230
Yes!It can when others can't,
It will when others won't,
It goes where others don't.
17th Dec 2019 1:00 pm
Iceman08
Member Since: 22 Sep 2014
Location: Hereford
Posts: 2284
Thanks chaps
Is this okay for my D4?
17th Dec 2019 1:10 pm
RogB
Member Since: 15 Jun 2018
Location: Mansfield
Posts: 1730
M3DPO wrote:
Yes!
2011 D4 XS 305 MY12 - gone but not forgotten
17th Dec 2019 2:34 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8230
Iceman08 wrote:
Thanks chaps
Is this okay for my D4?
You need an AGM for a D4 3.0ltrIt can when others can't,
It will when others won't,
It goes where others don't.
17th Dec 2019 5:35 pm
robpenrose
Member Since: 12 Jan 2016
Location: Surrey / SW London
Posts: 2138
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