battery charging

<mrdarrett DeleteThis @gmail.com> wrote in message
news:c5bf0137-a047-4d8c-899d-9afef7afd3d6@r15g2000prd.googlegroups.com...
> So let's say I've got a discharged car battery. How long would one
> have to drive the car, for the alternator to fully charge it up?
>
when that happens to me-I drive roughly 10-20 miles on the freeway with no
lights or air..(I have used the air on low and it still charged up)
 >> Stay informed about: battery charging 

<johngdole RemoveThis @hotmail.com> wrote in message
news:b52f27a3-8d9f-4b90-be61-668a52bc2adf@v13g2000pro.googlegroups.com...
Given the rule-of-thumb below, a drained battery with 120 min reserve
capacity needs about 10 hours to charge. I guess that's using 2-stage
or 3-stage charging rates. Now there are 10 minute rapid chargers out
there, but I'm sure they generate a lot of heat (boils the
electrolyte) and is only meant for the occasional "charge-to-start",
which may not be "full charge".


http://www.batteryuniversity.com/partone-13.htm
The charge time of a sealed lead-acid battery is 12-16 hours (up to 36
hours for larger capacity batteries). With higher charge currents and
multi-stage charge methods, the charge time can be reduced to 10 hours
or less. Lead-acid cannot be fully charged as quickly as nickel or
lithium-based systems.

It takes about 5 times as long to recharge a lead-acid battery to the
same level as it does to discharge.




On Aug 22, 2:23 pm, mrdarr... RemoveThis @gmail.com wrote:
> So let's say I've got a discharged car battery. How long would one
> have to drive the car, for the alternator to fully charge it up?
>
> Michael

First question that I have is, how did the battery become discharged, and
how old is the battery?
 >> Stay informed about: battery charging 

On Aug 22, 4:23 pm, mrdarr... RemoveThis @gmail.com wrote:
> So let's say I've got a discharged car battery.  How long would one
> have to drive the car, for the alternator to fully charge it up?
>
> Michael

a 600 amp battery a 100 amp alternator or a 60a, go figure. What is
dead, 0v, 12v? 13.3 is full charge and you will run the blower lights
etc so use a real charger. So nobody can say.
 >> Stay informed about: battery charging 

That's what I originally thought. It turns out the alternator pretty
much generates 0 amp below 1000-1200 rpms (that's when the battery is
drained). It doesn't come near rated output until about 3000 rpms or
so, and most people don't reach that most of the time. With each
rebuilt alternator from NAPA you should get a test printout showing a
logarithmic-like output curve.

Only a small fraction of alternator output goes into the battery. If
the charge fuse in your Camry is 7.5 amps, you know the normal charge
rate is probably < 5 amps. I suppose you can put an ammeter there to
see the charging current at various rpms.

The newer Bosch & Delphi "high speed" high output alternators are
designed to generate in the low rpm ranges, so the output curves may
look different.



http://www.batteries-faq.com/activekb/questions.php?questionid=9
Will driving a car fully recharge a battery?

There are a number of factors affecting an alternator’s ability to
adequately charge a battery. The greatest factors are:

1) How much current (amps) from the alternator is diverted to the
battery to charge
2) How long the current is available (drive time)
3) Battery temperature
4) Battery age

Generally, running the engine at idle or short stop-and-go trips,
during bad weather at night, will not recharge the battery
effectively.





On Aug 23, 9:45 am, ransley <Mark_Rans....DeleteThis@yahoo.com> wrote:
> a 600 amp battery a 100 amp alternator or a 60a, go figure. What is
> dead, 0v, 12v? 13.3 is full charge and you will run the blower lights
> etc so use a real charger. So nobody can say.
 >> Stay informed about: battery charging 

Let's say you're driving 2000-3000 rpms on the highway (or lower
speeds with air and lights off) and get the 5amps diverted from the
alternator to charge the battery, then a 50 amp-hour drained battery
would take 50/5 = 10 hours to charge. Hey, that's what
http://www.batteryuniversity.com/partone-13.htm suggested.

The reserve capacity measures the minutes at 25 amp discharge rate
down to 10.5 volts. So a "drained battery" at 10.5 volts will take 10
hours at highway speeds to become fully charged.
That's a good excuse for me to get one of those Black & Decker 2/4/6
amp high frequency microprocessor controlled chargers. Never needed
it, for occasional use just in case of course.

http://www.blackanddecker.com/ProductGuide/Product-Details.aspx?ProductID=15575

I've also seen dealers use trickle charger on showroom cars similar
to:

http://www.blackanddecker.com/ProductGuide/Product-Details.aspx?ProductID=15572




On Aug 23, 11:42 am, johngd....TakeThisOut@hotmail.com wrote:
> Only a small fraction of alternator output goes into the battery. If
> the charge fuse in your Camry is 7.5 amps, you know the normal charge
> rate is probably < 5 amps. I suppose you can put an ammeter there to
> see the charging current at various rpms.
 >> Stay informed about: battery charging 

On Aug 23, 9:43 am, "mack" <macke... RemoveThis @dslextreme.com> wrote:
> <johngd... RemoveThis @hotmail.com> wrote in message
>
> news:b52f27a3-8d9f-4b90-be61-668a52bc2adf@v13g2000pro.googlegroups.com...
> Given the rule-of-thumb below, a drained battery with 120 min reserve
> capacity needs about 10 hours to charge. I guess that's using 2-stage
> or 3-stage charging rates. Now there are 10 minute rapid chargers out
> there, but I'm sure they generate a lot of heat (boils the
> electrolyte) and is only meant for the occasional "charge-to-start",
> which may not be "full charge".
>
> http://www.batteryuniversity.com/partone-13.htm
> The charge time of a sealed lead-acid battery is 12-16 hours (up to 36
> hours for larger capacity batteries). With higher charge currents and
> multi-stage charge methods, the charge time can be reduced to 10 hours
> or less. Lead-acid cannot be fully charged as quickly as nickel or
> lithium-based systems.
>
> It takes about 5 times as long to recharge a lead-acid battery to the
> same level as it does to discharge.
>
> On Aug 22, 2:23 pm, mrdarr... RemoveThis @gmail.com wrote:
>
> > So let's say I've got a discharged car battery. How long would one
> > have to drive the car, for the alternator to fully charge it up?
>
> > Michael
>
> First question that I have is, how did the battery become discharged, and
> how old is the battery?


Probably just from old age/~100F Sacramento summers. It came with the
'99 Camry I bought 2 years ago. I thought it was new (recently
replaced) when I got the car, but maybe I was mistaken.

I was under the impression that regular driving / alternator would
charge the battery, but I hadn't realized 1) the charging fuse is
rated for < 10 A, and 2) the alternator doesn't do diddly squat in the
<1200RPM range...

Thanks,

Michael
 >> Stay informed about: battery charging 

On Aug 23, 1:54 pm, johngd... RemoveThis @hotmail.com wrote:
> Let's say you're driving 2000-3000 rpms on the highway (or lower
> speeds with air and lights off) and get the 5amps diverted from the
> alternator to charge the battery, then a 50 amp-hour drained battery
> would take 50/5 = 10 hours to charge. Hey, that's whathttp://www.batteryuniversity.com/partone-13.htmsuggested.
>
> The reserve capacity measures the minutes at 25 amp discharge rate
> down to 10.5 volts. So a "drained battery" at 10.5 volts will take 10
> hours at highway speeds to become fully charged.
> That's a good excuse for me to get one of those Black & Decker 2/4/6
> amp high frequency microprocessor controlled chargers. Never needed
> it, for occasional use just in case of course.  
>
> http://www.blackanddecker.com/ProductGuide/Product-Details.aspx?Produ...
>
> I've also seen dealers use trickle charger on showroom cars similar
> to:
>
> http://www.blackanddecker.com/ProductGuide/Product-Details.aspx?Produ...
>
> On Aug 23, 11:42 am, johngd... RemoveThis @hotmail.com wrote:
>
>
>
> > Only a small fraction of alternator output goes into the battery. If
> > the charge fuse in your Camry is 7.5 amps, you know the normal charge
> > rate is probably < 5 amps. I suppose you can put an ammeter there to
> > see the charging current at various rpms.- Hide quoted text -
>
> - Show quoted text -

Battery U is a bit pesimistic in my view, alternators do charge at 6-
700 rpm, it might take 3-5a to run a car motor. Alternators are higher
power than years ago, easily twice as much. A charge fuse? I thought
full power could go to the battery, are you sure the 7.5 isnt the
motors fuse? But point is a battery charger is best on weak
batteries, you can burn out an alternator, it isnt designed for full
load continously.
 >> Stay informed about: battery charging 

mrdarr... RemoveThis @gmail.com wrote:
> I was under the impression that regular driving / alternator would
> charge the battery, but I hadn't realized 1) the charging fuse is
> rated for < 10 A, and 2) the alternator doesn't do diddly squat in the
> <1200RPM range...
===
My Owner's Manual shows a Type "A" alternator fuse rated at 7.5 A, and
also a Type "D" fuse rated at 100 A. I would suspect the 7 amp fuse is
for the charging light indicator circuit in the dash, where the 100
amp fuse may be a circuit breaker type carrying the load of the
alternator output.
While it is true higher engine speed is required for full output, it
is an exaggeration to say it is zero or nil at lower speeds - just not
up to the full rated output yet.
The alternator is designed to maintain battery charge. If for some
unusual reason the battery becomes overly discharged it is best to use
a dedicated battery charger over a longer period of time, remembering
that auto batteries are not designed to withstand repeated deep
discharge cycles. When the battery is discharged it is more likely to
form "sulfation" a crusty coating on the plates that inhibits fresh
acid from absorbing into the plates again during subsequent charging.
 >> Stay informed about: battery charging 

Daniel wrote:

> While it is true higher engine speed is required for full output, it
> is an exaggeration to say it is zero or nil at lower speeds

It's more than an exaggeration, it's simply incorrect. There is very
little current draw from the alternator when the vehicle is idling,
unless some heavy current draw accessories are on, such as the
headlights. The battery will charge, albeit more slowly than if the
alternator is running at a higher rpm.

Alas, just tried to start the 4Runner this morning, after several weeks
of only using the Camry, and it had a dead battery. At least Costco
doesn't hassle about pro-rated refunds.
 >> Stay informed about: battery charging 

On Aug 25, 12:41 pm, SMS <scharf.ste....TakeThisOut@geemail.com> wrote:
> Daniel wrote:
> > While it is true higher engine speed is required for full output, it
> > is an exaggeration to say it is zero or nil at lower speeds
>
> It's more than an exaggeration, it's simply incorrect. There is very
> little current draw from the alternator when the vehicle is idling,
> unless some heavy current draw accessories are on, such as the
> headlights. The battery will charge, albeit more slowly than if the
> alternator is running at a higher rpm.
>
> Alas, just tried to start the 4Runner this morning, after several weeks
> of only using the Camry, and it had a dead battery. At least Costco
> doesn't hassle about pro-rated refunds.

Generators used to not charge at idle, 600 rpm, alternators are more
efficent, at least my gen never charged at idle.
 >> Stay informed about: battery charging 

ransley wrote:

> Generators used to not charge at idle, 600 rpm, alternators are more
> efficent, at least my gen never charged at idle.

This may be true, but it's literally been decades since generators were
used on cars.
 >> Stay informed about: battery charging 

On Aug 25, 5:03 pm, SMS <scharf.ste....TakeThisOut@geemail.com> wrote:
> ransley wrote:
> > Generators used to not charge at idle, 600 rpm, alternators are more
> > efficent, at least my gen never charged at idle.
>
> This may be true, but it's literally been decades since generators were
> used on cars.

mine was a 54 Buick.
 >> Stay informed about: battery charging 

The following alternator output chart typifies the traditional
alternator outputs (not the newer high speed high output alternators),
as with test result page included with rebuilt alternators. There is a
reason why Toyota wants you to raise RPM to 2000 and only then check
the voltage > 13v.

If anyone ever comes across a different output curve that produces any
current below 1200 RPMs I'd certainly like to know.

"Alternator Output Graph:"
http://www.rpc.com.au/products/batteries/car-deepcycle/carfaq5.htm


On Aug 25, 10:32 am, Daniel <nospampls2....RemoveThis@yahoo.com> wrote:
> While it is true higher engine speed is required for full output, it
> is an exaggeration to say it is zero or nil at lower speeds - just not
> up to the full rated output yet.
 >> Stay informed about: battery charging