How long does it take to fully charge a battery?

 

Bronze Member
Username: Panamanian

Panama cityPanama

Post Number: 33
Registered: Aug-05
Let's say i have a totally discharged battery, and I my car full of gasoline. then I in my garage start the engine and leave it in neutral for minutes or hours...

how long would it be needed to fully charge a battery?
--------------------

Will it charge faster will driving (normal or fast), or only with the engine on and the car parked.

gracias
 

Bronze Member
Username: Thelonewolf

Post Number: 56
Registered: Jul-05
it will charge faster durring the day with the lights off driving around, it will take quite a while to charge fully, but if it is a fully discharged battery you might not be able to charge it.
 

Bronze Member
Username: Firlefanz

Post Number: 48
Registered: Jul-05
Hm..., if the battery is totally discharged (deep discharge) you cant start the engine without help.

And deep discharged battery wont charge in the car, youll need a charger like CTEK and even than its not garantueed that it will work.
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 8971
Registered: Dec-03
actually unless it's a deep cycle battery, if you run it to below about 10 volts, you've damaged the battery and it'll need to be replaced anyway. That's why people buy deep cycles.. since they aren't damaged by being run to low voltages like the average lead acid battery.

also as noted, you can't start the car without a battery.

another point would be that at idle, the alternator is 12 volts, so the battery isn't being charged.
The car has to be above about 900-1200 RPM so voltage goes up to 13.8 to 14.4 volts to create a forward bias across teh battery and put the battery into a charging state, so driving the car will charge the battery more quickly, yes.

all that aside, the charge rate is entirely dependant on the charging voltage of the alternator and the hysteresis curve of the battery itself. You'd need to get a spec sheet for your specific battery. Optima provides this data for theirs.

if you just have a "weak" battery from playing the stereo, and the car still starts, you'd want to run it for at least a good 30 minutes around town to get a charge on the battery sufficient to keep the car going later.
Personally I'd just stick the car battery on a trickle charger for 24 hours. That does the job too.
 

Amy S
Unregistered guest
On a related topic, with a new battery and an alternator that is on it's last legs, how long can I run my car?
 

Gold Member
Username: Carguy

Post Number: 3881
Registered: Nov-04
With a bad alternator, it can range from few hours to days. After that, you WILL have to replace both the new battery and the alternator.
So don't delay it.
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 9209
Registered: Dec-03
some cars won't run at all without a functional alternator,.. that is what supplies current to your ignition system, fuel injection, power steering and brakes, etc..
 

New member
Username: Vader

Post Number: 1
Registered: Sep-05
Can someone help me out with understanding the concept of car batteries and alternators.

I have specific questions based on specific information:

Car battery fully charged = 600 AH
Current Consumption during ignition = 300 AH
Alternater provides 140 amps @ 12volts @ 6500 rpm

After current consumption during ignition my car battery needs to supply current to a 272 Amp Load.

My questions are the following:

1) Will my alternator be able to charge the battery? Or will I drain my battery with the 272 Amp Load?

2) If my alternator is able to charge the battery with the 272 Amp Load how long will it take the battery to reach 600 AH again, will it ever?

3) If my alternator is unable to charge the battery because the 272 Amp Load is to much how long do I have until my 600 AH battery is completely drained.

Please help and inform me of any conceptual problem in my thoughts.
 

Platinum Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 10437
Registered: Dec-03
1: with engine running, your alternator needs to put out over 300A to handle 272A of system draw plus demends of the car itself.
battery just acts as a filter and stabilizer. alternator supplies the current in a running car.

2. depends on charging voltage (has to be over 12.5VDC) and current across teh battery, which determines the charge rate.

3. depends on combined amperage between the battery at it's present charge and alternator current.

what you want to know is all answered here:
http://www.wickedcases.com/caraudio/capacitors.html
http://www.wickedcases.com/caraudio/charging.html
http://www.betteraudio.com/geolemon/newmain/battcapalt/
http://www.bcae1.com/charging.htm
http://www.bcae1.com/chargin2.htm
http://www.wickedcases.com/caraudio/batteries.html
http://www.optimabatteries.com/
 

Bronze Member
Username: Gpz1100

Post Number: 65
Registered: Jul-05
Otis,

What are you running that has a nearly 3500 watt draw (272 * 13)?
 

New member
Username: Vader

Post Number: 3
Registered: Sep-05
Hi GPz1000,

The 272 amps was a typo. I meant 172. I came up with this number if all my basic/standard car manufacturer components were being used at the same time after the car was turned on. This is how I derived 172 Amps.

Air Conditioner 35 amps

Headlights (high beam) 20 amps

Exterior and interior
lights 5 amps

Ignition Coils 4 amps

Engine cooling fans 4 amps

Factory Radio 4 amps


Other electrical
components such as
(wipers, power windows,
sensors,diodes,relays,
actuators, etc.) 100 amps

Total Electrical Load
after ignition 172

It may not be this much but for what I am doing I would rather be over than under.

What I'm trying to figure out is if my alternator could only provide my car electrical system with 140 Amps and my total electrical components current consumption is more than what the alternator can provide how fast will I drain my battery? How do you calculate this?

GlassWolf provided me with some links but I dont see anything that entertains my question fully, I could be wrong, I will look again:-).

I welcome all comments, help, and especially criticisms.
 

Bronze Member
Username: Panamanian

Panama cityPanama

Post Number: 75
Registered: Aug-05
DONT even mention you will install a capacitator, because GLASSWOLF may slap you in your face, actually ISAAC was slapped by him.
INDEED.
 

Gold Member
Username: Carguy

Post Number: 4371
Registered: Nov-04
Did someone slap me when I wasn't looking?
 

Platinum Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 10509
Registered: Dec-03
heh
a capacitor is fine if you want it to decrease latency or act as a smoothing filter.. it just won't replace the purpose of an alternator.
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