Battery charged by alternator.

True to a point. An alternator will only charge up to about 80%.

i read that an alternator can only maintain the existing charge on a battery, so the solution for you must be to get a charger and slow charge your battery for around 10 hours for a full charge. it should be ok after that..

The message from PunkJack contains these words:

Then you read wrong. Many's the time I've recharged a flat battery by driving the car.

As for "only up to 80%" I'm inclined to suggest that in that case the rating of the battery is wrong and that the 80% should actually be considered full and charging with an external charger as capable of overcharging to 125% of rated capacity.

It's BS. Maintain 13.8V across a conventional lead acid for long enough & it will fully charge, the last 10% or so takes ages though.

An alternator will easily deliver sufficient voltage and will fully charge a battery unless the regulator has gone totally loopy, OR if something like an AGM battery has been fitted to a charging system expecting a flooded battery.

He is pulling on your c*ck boy.

Stubby Sekka.

This is something I have never come across before but apparently this information came from an Exide briefing to their retailers and it certainly amazed me. pete

Yes that is the obvious solution for me now. It is just that I never realised a charge from an alternator would not fully charge a battery that had not previously been fully charged by another method. Surely a battery would have been fully charged before it was sold or even before it left the factory! That would mean if it was bought slightly flat it could still be fully charged by the alternator! pete

I had always considered a battery could be fully charged using an alternator. However the advice I was given came from Exide the battery manufactures. pete

I believe the point Exide are making is that if a battery is not fully charged at sometime by a method other than an alternator it cannot be fully charged at any time after that merely by an alternator. This is all news to me but who am I to argue with battery manufacturers! pete

That was my original impression too. Now I am not as sure. pete

Well it's by someone from Wilco not Exide, and it's bollocks. Any car alternator will charge to about 14.7V which is sufficent voltage to get above the bulk and absorption phases and therefore will fully charge the battery.

No it didn't.

John

Isn't it like when you buy a mobile phone they say the battery must first be charged for 18 hours without interruption or your battery life will be diminished?

No.

Have a look at

An eight-month-old battery should be working fine. You may have other problems such as a faulty alternator or voltage-control device - both can be easily checked by a competent technician.

Not necessarily BS, as the chappie may be confusing the issue.

There is a problem with 'dry-charged' batteries being filled with acid and put straight into service. This will ensure that no more than eigthy percent of its capacity will ever be realised.

The correct method is to fill with acid and let stand, topping up any shortfall after an hour or so. The battery should then be charged at C/10 for something like five hours, ensuring the battery stays at ambient temperature, IIRC.

I've never seen 14.7 quoted as the maximum voltage from any car alternator. It's usually 14.4.

oh be fair, it was probably a salesman.