Battery or alternator?

Brucey · **Posted:** Thu Nov 12, 2009 8:20 pm

Hi all, well here I am again with yet another problem. The voltmeter has been steadily dropping over the last week and eventually the car wouldn't even turn over. So off with the battery and then borrowed the neighbours battery charger which said maximum battery to charge was 70ah although my battery is 74ah but desperation prevaled and so decided to give it a go anyway. 14 hrs later and it showed as charged. Placed it back on the car and bingo it turned over 1st go, but it only shows as 12 on the dash and not 13 as it used to! It also drops when I put the lights on and after a half an hour drive it is now on 11. Now I should let you know that my rad fan is permanantly on and also my fan belt has been screeching for 10 mins after start up. Any ideas?
Thanks in advance. Andy Bruce.

Mas · **Posted:** Thu Nov 12, 2009 9:12 pm

Brucey , if you start the engine and put a volt meter accross the battery what rwading do you get on the voltmeter ? , a dodgy alternator will often show up here and give a big clue. Also what voltage does your battery show with a meter accross it " fully charged " but under no load .

Regards Mas

DavidL · **Joined:** Fri Mar 14, 2008 7:32 pm **Posts:** 457

Sounds like the battery to me. Sadly you get no warning with modern batteries. One day they are fine the next they aren't. You can charge them and to begin with they may start the car but it won't last.
At least it's the cheaper option.
David

Mas · **Posted:** Thu Nov 12, 2009 10:18 pm

From those symptoms he must still rule out the alternator or he could just ruin another battery ( and one he didnt need yet) could he not :wink:

DavidL · **Joined:** Fri Mar 14, 2008 7:32 pm **Posts:** 457

Certainly wise but I bet its the battery!
I've had a voltage regulator go and that was quite sudden. A good battery fully charged ought to last a bit longer than that. A friend of mine with a very vintage Alvis uses a Landy battery that doesn't get charged by the vehicle at all. Usually lasts a month or so between charges.

All the same check the obvious and see. As Mas says there is no point destroying 2 batteries.
Still think its the battery

Brucey · **Posted:** Fri Nov 13, 2009 12:23 am

Thanks for the replies, I should have also told you that the battery was only purchased in February. I suppose the good news is that it's guaranteed for 12 months so hopefully will get a straight swap. I'll take your advice though and test everything with a voltmeter. Going to put the thermo coupling on tomorrow and also tighten the fan belt. Hope it isn't too big a job :roll:

Thanks again. Andy Bruce.

Li Moo Bai · **Posted:** Fri Nov 13, 2009 8:44 am

The rad fan being permanently on won't be helping things..

That will probably just be the stat in the radiator and is an easy inexpensive job.

albi · **Posted:** Fri Nov 13, 2009 6:58 pm

just check that your glovebox light isnt coming on on its own. i taped my switch up so that is is permanantly off (this was after i changed the battery and discovered the glovebox light was at fault :oops:

) still, nice new battery now so thats one less thing to go wrong :wink:

Brucey · **Posted:** Fri Nov 13, 2009 11:49 pm

Well I changed the rad fan switch and fan belt and BINGO the needle on the dash is slap bang between 12v and 14v and not budging with everything on (lights, wipers, blowers and radio). AND NO MORE ANNOYING CONSTANT FAN NOISE! Needless to say were best friends again

Thanks for the advice everyone :wink:

Andy Bruce.

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Battery or alternator?

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