whats goosed - battery or alternator?

[edoh]

the story so far.... left lights on van overnight about a week ago... main battery under drivers seat flat in the morning - stuck on battery charger - started fine - been driving well all week - until tonight.. red battery light seems to be brighter than usual on switching on ignition? Van cut out a few times on the way home... more difficult to restart... put on the multimeter on 20v attached to main battery - at rest-ignition off - reading 13.10v (previously read 12.4 to 12.6) - with engine running reading 13.70v (previously read 14.4) - ? - whats up doc? battery? alternator?wiring?
work in the morning - so any replies/thoughts/comments/ gratefully received -
edoh

[rich broom]

20v is overcharged.
Alternator fault.

[Bigjcc55]

He put the multi meter in 20v I think? If the charging light is on it would suggest the alternator or wiring/earth.

[California Dreamin]

Based on that information:
Battery standing voltage of 13.10 volts is high but then that isn't unusual when measuring directly after charging....measure after an hour and I bet that has dropped to 12.7 - 12.8.
The charge voltage however, of just 13.7 volts is definitely on the low side and may need a new regulator brush pack.

Martin

[blacky]

Should charge in region of between 13.5 and 14.2 under load e.g. with headlights on. ( at a moderate rpm of course, not at idle.)
As Martin said reg brushes are often worn down causing this prob

[edoh]

thanks so much people -
recharging spare battery over night -
up early early to have another look at it all -
see what the battery light is doing on the dash -
leaning towards voltage regulator/alternator as the issue -
will keep you posted-
thanks again -

[edoh]

ok - so far this morning -
van starts up fine -
red battery light goes off on start up -
battery reads - 12.7v - with the ignition off
13.89v - with the engine running -
so far - so good?
alt reading still low?
as a fallback position -
(still think the alt might be dodgy)
checked for replacements on the gsf site -
http://s270.photobucket.com/user/arseyn ... 1.jpg.html" onclick="window.open(this.href);return false;
130 knacker + 50 back for the exchange -
BUT -
does the pulley arrangement look different to my current one?
http://s270.photobucket.com/user/arseyn ... 0.jpg.html" onclick="window.open(this.href);return false;
length of my current alt - 5ins to edge of fan - plus a further 3 ins to end of pulley -
would the wiring connections be similar/the same? current arrangement -
http://s270.photobucket.com/user/arseyn ... 3.jpg.html" onclick="window.open(this.href);return false;
also having a look at the gsf volt regulator -
http://s270.photobucket.com/user/arseyn ... 9.jpg.html" onclick="window.open(this.href);return false;
are these universal - or specific to a brand?
cant see a particular brand name on the alternator that's in at the moment?
plan is to - drive van into work see how it goes -
then call into a gsf branch pick up a volt regulator/alternator/depending on how the journey went -
worth checking to see if i have 12v at the end of the blue wire at the alt? - or - asume power must be getting to alt - if voltage moves up when engine running?
as always - would be grateful for any of your thoughts or comments -
edoh

[ghost123uk]

ok - so far this morning -
van starts up fine -
red battery light goes off on start up -
battery reads - 12.7v - with the ignition off
13.89v - with the engine running -
so far - so good?
alt reading still low?

Not low, those figures look like perfectly normal figures for a standard van with original equipment.

(Modern voltage regulators tend to be set higher than your measured 13.9 volts, often 14 or 14.5 volts, to cater for more modern battery designs).

[kevtherev]

Why replace the whole alternator...
the brush pack is the the consumable... big diffence in price

Those figures are fine

[edoh]

thanks for the reassurance gents -

van drove fine to work n back -
picked up a brush pack - just to have in the back pocket - just in case -
it's my daily drive - so - just has to work everyday!
T hanks again for all the useful comments -

[Cruz]

Based on that information:
Battery standing voltage of 13.10 volts is high but then that isn't unusual when measuring directly after charging....measure after an hour and I bet that has dropped to 12.7 - 12.8.
The charge voltage however, of just 13.7 volts is definitely on the low side and may need a new regulator brush pack.

Martin

I too only get 13.7 when driving. Alternator is only 2 years old. I suspect the 28 feet of 30 year old wiring is causing the drop.

[kevtherev]

Based on that information:
Battery standing voltage of 13.10 volts is high but then that isn't unusual when measuring directly after charging....measure after an hour and I bet that has dropped to 12.7 - 12.8.
The charge voltage however, of just 13.7 volts is definitely on the low side and may need a new regulator brush pack.

Martin

I too only get 13.7 when driving. Alternator is only 2 years old. I suspect the 28 feet of 30 year old wiring is causing the drop.

well it's thickness would be a hindrance at those distances.
It's all about girth in the voltage drop game.

Although not cheap, 8-10 mm copper cable is a coveted thing