Battery

[Lexxan]

Well i have a new truck/battery but I've let the battery die 3 times.. died & boosted it earlier.. i drove it about 30 minutes earlier today and it died again next time I went to start it. Is the battery toast because of dieing 3-4 times or do I just need to let it idle for a few hours to fully charge the thing??
Thanks

[msommers]

take it into Canadian tire. Get em to check it. Plus if it's good it's charged completely.

[mo_money2supe]

You could let it idle, but that just wastes gas. Charging it wouldn't be a bad idea, but that could take time. Just drive it around for awhile and let the alternator do its job; since your truck's new, and assuming your alternator is working the way that it's supposed to, it should fully charge the battery in under an hour (but obviously more than 30 mins).

[Speedy]

According to most manuals your not suppsed to charge a dead battery with the alternator, they only put out enough amperage to maintain a charged battery and supply the electrical needs of the vehicle.

I would suggest having it tested as stated above and if its fine buy a cheap battery charger and charge it overnight.

If that dosent fix it then maybe look at the vehicles electrical systems for a short or somthing that is draining it when the vehicle is off.

[soupey]

most alternators should still be able to handle the strain for a little bit, u just cant go drive around without a battery at all. i dont think your battery should die THAT quick tho, i mean whenever i drain my battery by accident when im working on my car i usually boost it and drive around the neighborhood and on the main road where i can rev a lil higher and go a bit faster....and im good...sooo i'd get ur alternator checked out to see if its still working properly.

[rc2002]

Idling won't do squat. At that engine speed, the alternator is not providing enough current to charge the battery properly. At highway speeds, your alternator will be generating enough electrical current to properly charge your battery.

If I were you I would invest in a battery charger for $50 at Canadian Tire. Charge the battery until it's full and see if you have the same problem. If the problem persists then you'll probably need a new battery.

[dave5473]

[QUOTE]Originally posted by richardchan2002
[B]Idling won't do squat. At that engine speed, the alternator is not providing enough current to charge the battery properly. At highway speeds, your alternator will be generating enough electrical current to properly charge your battery.



Alternator output depends on battery voltage. When the battery voltage drops the alternator output voltage goes up and charges the battery. Idle or highway speed the alternator will charge the battery.

[Speedy]

Alternator output depends on battery voltage. When the battery voltage drops the alternator output voltage goes up and charges the battery. Idle or highway speed the alternator will charge the battery.

That is exactly my point, if you try to draw to much amprage through the alternator you can damage it, they are simply not designed to charge a dead battery.

It will charge the battery but my point is that it can damage the alternater which is why its recommended to charge the battery with a battery charger.

Also you can in fact drive around with no battery, I dont know why you would but the battery acts as a storage device so you can start the vehicle when it is not running, once the vehicle is running it is supplied by the alternator in a stock vehicle (if a aftermarket winch or sound system drew more then the output of the alternator it will drain the battery)

I know this is overkill but I just hate seeing misinformation. I myself have boosted vehicles and then driven them while they charge, but only when I had to for time sakes otherwise I let them charge on a charger

[Whitetiger]

+1


Originally posted by richardchan2002
Idling won't do squat. At that engine speed, the alternator is not providing enough current to charge the battery properly. At highway speeds, your alternator will be generating enough electrical current to properly charge your battery.

If I were you I would invest in a battery charger for $50 at Canadian Tire. Charge the battery until it's full and see if you have the same problem. If the problem persists then you'll probably need a new battery.

[dave5473]

Originally posted by Speedy


That is exactly my point, if you try to draw to much amprage through the alternator you can damage it, they are simply not designed to charge a dead battery.

It will charge the battery but my point is that it can damage the alternater which is why its recommended to charge the battery with a battery charger.




As far as i know, alternators will only charge your battery at a metered rate which wont allow the alternator to charge at more than about 14.5 volts, which the alternator can and is designed to handle. The only way it will charge at a higher rate is if there is a short in the alternator and that wouldnt be caused by charging a dead battery.

Im not saying that it is the best way to charge your battery but I dont think it would damage your alternator.

[Speedy]

Originally posted by dave5473



As far as i know, alternators will only charge your battery at a metered rate which wont allow the alternator to charge at more than about 14.5 volts, which the alternator can and is designed to handle. The only way it will charge at a higher rate is if there is a short in the alternator and that wouldnt be caused by charging a dead battery.

Im not saying that it is the best way to charge your battery but I dont think it would damage your alternator.

True the voltage regulator should stop a alternator from producing more the 14.5 volts however I am talking about amperage which is load it is putting on the alternator.

A alternator charging a battery wont reach 14.5 volts until the battery is charged to at least 12.5 volts so by the time the voltage regulator kicks in the damage can be done.

here is a good site about battery myths...I learned a few things :clap:

http://www.carquest.com/partsBatteryFAQMyths.html#4

[andyg16]

The battery on my brothers 300zx was dead when it got here and everytime i wanted to start it id have to boost it, so one day i boosted it and drove around for a while 45mins to an hour and after that the battery stayed charged...might wanna try that :dunno:

[dave5473]

Im not understanding what you are saying.

The alternator will only go up to 14.5 V when the battery charge is low. With a charged battery alternator output should only be around 13.5, give or take a decimal point.

The current draw is directly related to the voltage (ohms law) and will only go up if the voltage increases or the resistance decreases (like a short in the alternator).

With a dead battery there is a lower amperage in the field current supply that the regulator uses to decide output voltage and it will raise the voltage until the current draw is higher and then the output voltage will drop to a normal level.

It does take a long time to charge a battery with the alternator but i still dont think it will wreck the alternator. maybe if it was always charging at full output over a long period of time but not to bring a battery back up to charge if it was drained.

[dave5473]

Or thats how i understand it anyways.

[Speedy]

as the battery level decreases it increases resistance which according to ohms law (amps = voltage over ohms) increases the amp draw on the alternator to a point where it is at or above the max rated output of the alternator causing damage.

[dave5473]

you have that backwards. when the resistance increases the amperage will decrease


12volts/2ohms = 6amps

12volts/6ohms(resistance increase) = 2 amps(current decease)

[Speedy]

What you are calculating is the output amperage of the battery so yes as the battery died its voltage would lower and the ohms would increase thus the output amperage would decrease as well.

What I am talking about is the load the dead battery would place on the charging system.

This explains it better and there is a graph.

http://www.uuhome.de/william.darden/carfaq9.htm#vehicle

[dave5473]

i see what you are getting at now. good website.