Will running the car in neutral with the engine running charge up the
battery? How long will it take to charge it/top it up on a vehicle
that has been standing?

"Dan Tanner" <DT> wrote in message
news:bk6gj159st3d50grd5fhcpa7c31h5gduic@4ax.com...

> Will running the car in neutral with the engine running charge up the
> battery? How long will it take to charge it/top it up on a vehicle
> that has been standing?


Marginal, at best, in my experience.

-- 
M Stewart
Milton Keynes, UK
http://www.megalith.freeserve.co.uk/oddimage.htm

"Dan Tanner" <DT> wrote in message 
news:bk6gj159st3d50grd5fhcpa7c31h5gduic@4ax.com...

> Will running the car in neutral with the engine running charge up the
> battery? How long will it take to charge it/top it up on a vehicle
> that has been standing?


Take it for a 20-30 minute run down a motorway. That'll do most of it.

I.

On Mon, 26 Sep 2005 16:58:06 +0100, Dan Tanner <DT> wrote:


>Will running the car in neutral with the engine running charge up the
>battery? How long will it take to charge it/top it up on a vehicle
>that has been standing?

 Just idling is not enough to charge a battery properly. You would need
to increase the revs to about 1500rpm, otherwise most of the current
generated is used up just keeping the spark going (and other "always-on"
elctrical stuff).
It doesn't do a battery any good to charge it too fast, which is why
battery chargers take several hours.

A car battery's capacity is rated in amp/hours. A small battery may have
a rating of 40AH, which means, in theory, it would take 40 hours to
charge with a 1amp current, 20 hours with 2 amps, etc. But although a
modern alternator will have a current rating in excess of 100 amps (for
running lamps, screeen heaters, etc), it won't charge a battery at that
rate, and to do so would wreck the battery.

The best option is to use a charger overnight, and next best is to take
it for a drive, out of town, in the daytime so that the lights aren't
needed. Running at a fast idle will work as you suggest, but it's not
very efficient.
-- 
Regards,  Chris    (Please take out my car to reply by email)     
----1961 Austin A40 Farina----1966 Triumph Herald Estate---
---1967 Riley Elf---1965 Hillman Minx---1969 Morris Minor--
-1972 Mini Clubman estate--1957 Standard 8--1979 Ford Capri
    ********** Please don't email in HTML! **********

The message 
from Dan Tanner <DT> contains these words:


> Will running the car in neutral with the engine running charge up the
> battery? 


Yes, slowly, but it's not a nice thing to do to the engine. Get a
battery charger.

-- 
Skipweasel.
In the beginning was the word.
And the word was Aardvark.

"Dan Tanner" <DT> wrote in message 
news:bk6gj159st3d50grd5fhcpa7c31h5gduic@4ax.com...

> Will running the car in neutral with the engine running charge up the
> battery? How long will it take to charge it/top it up on a vehicle
> that has been standing?


That is a very good question.  I hope someone with some real experience of 
this comes along with a factually based answer, not just a bunch of hearsay, 
guesswork and bollocks that these dongers have posted on this thread so far. 
:)

z

The message 
from Chris Bolus  contains these words:


>  Just idling is not enough to charge a battery properly. You would need
> to increase the revs to about 1500rpm, otherwise most of the current
> generated is used up just keeping the spark going (and other "always-on"
> elctrical stuff).


That was certainly true with dynamos, but all the alternator equipped
cars I've ever bothered to test have always provided considerable
charging current at idle. Not as much as at higher revs, but at least 10
amps beyond what the car was using.

-- 
Skipweasel.
In the beginning was the word.
And the word was Aardvark.

"zillah"  wrote in message
news:p9WZe.21177$ws4.7445@newsfe5-win.ntli.net...

>
> "Dan Tanner" <DT> wrote in message
> news:bk6gj159st3d50grd5fhcpa7c31h5gduic@4ax.com...
> > Will running the car in neutral with the engine running charge up the
> > battery? How long will it take to charge it/top it up on a vehicle
> > that has been standing?
>
> That is a very good question.  I hope someone with some real experience of
> this comes along with a factually based answer, not just a bunch of
hearsay,
> guesswork and bollocks that these dongers have posted on this thread so
far.
> :)


OK, try this simple test. Take a car with a flat (but good condition)
battery, jump or bump start it and leave it ticking over. In five minutes it
will be charged enough that you can stop the engine and the battery will
start it. This of course assumes that the alternator is ok etc, ie that the
flat battery was the only problem.

And yes, a battery charger would have been more efficient, and yes a 30
minute drive would give it  a nearer to full charge.

The answers to the 2 original questions are -

Yes,

and

It depends.


Steve