Alternator Problem , Not Charging Properly

[mista_khan]

Hi

ive noticed my car tries very hard to start first thing in the morning, then I noticed my alternator metre on the dash was below normal, using my cigarette lighter Battery tester, the alternator isn't even charging anything,

voltage at idle is 13.4v and when the fan in the engine turns on it goes to 13.6v and thats just with the engine on, which is still low,

so is it a case of the alternator is on its way out, or have I blown a fuse and worth checking out.

ive attached photos of the metre on the dash and the Battery tester thing.

cheers

[IHgs300]

The Battery meter looks ok to me, mine always hovered around 12-13v. The dash one is Battery voltage not charge voltage.

The rac tester could be at fault, if the alternator wasn't working the Battery wouldn't be charged, also engine speed would drop as more electrical items are switched on, until it eventually cuts out.

One of these is what i used,

http://www.ebay.co.uk/itm/Car-Battery-Alternator-Tester-6v-12v-6-Volt-12-Volt-High-Load-/201081182614?pt=UK_Diagnostic_Tools_Equipment&hash=item2ed15f5996

If you need a replacement alternator let me know.

[mista_khan]

hey man, could it be I need a new Battery as when the car is off, if I leave headlights on for few mins or play the cd player for say 5 mins, the cars Battery dies, and in the morning the car tries very hard and then turns over

,

also what I noticed today is when I turned on cd player, fans were on 2 and turned on headlights, the interior dash lights were hardly visible, including the lights for the fan and rear window de steamer.

[ROYT]

If you have 13+ volts showing with headlights or HRW on, the alternator is OK.

Sounds like you are right, new Battery needed!

[mista_khan]

okay just to confirm the voltage above was with everything off, will do another check tomorrow with headlights and HRW on and then with headlights, HRW and ac and cd player

with engie on whats the minimum voltage it should be regardless of anything being on or not?

[ROYT]

You need to have the lights or HRW or both on to test the alternator charges with the load these items put on it.

In other words it must still exceed 13 volts to keep the Battery charged.

If it does this and the Battery goes down rapidly, it is most likely failing.

Remember the alternator won't fully charge the Battery in 5 minutes,

Iif the car is not in regular use, charge the Battery fully with a trickle charger first, if it's still going down quickly bin it!

[mista_khan]

Hi

okay will do tomorrow, and by failing you mean Battery is failing after keeping HRW and Lights on and voltage stays above 13v?

and I do over 200 miles in my lexus atleast per week so that should be sufficient to charge it, I also don't have a subwoofer or anything car is standard except Xenon headlights which use less power then normal bulbs.

[ROYT]

Yes, if the alternator output is 13v or more with the items switched on then the alternator is still charging

under load.This is correct, if the Battery is still not holding charge it needs replacing.

You may have to increase engine revs above idle speed to check the output

[mista_khan]

Okay done the load test today with ac, and HRW, headlights and cd player on, the Battery level stayed above 13.2v and maxed at 13.6v with all those on so alternator is fine, and today my car has died 3 times, so now as a last resort ive put the Battery on charge, if this doesn't work it will be a new Battery but atleast we know alternators fine, its the Battery not holding charge.

[mista_khan]

Hi

ive gave the Battery 2 x 12 hour charges off main charges over 2 days,

now when it put it back in the lexus and turned engine on,

with everything off voltage was at 13.1v and with headlights, hrw and cd player on voltage hovered between 12.9v and 13.1v

[IHgs300]

Might be ok then, but if you find you need a new Battery, i have a 3wk old one with receipt from Halfords if you are interested.

Cost £110, £80 couriered.