how car batteries recharge

[IronAnaconda]

I was wondering how car batteries recharge.. I already know when you turn your engine on your battery starts recharging.. does anyone how this works? If anyone can explain it with details that would be great, thanks.

[ezflow]

Basically, an alternator runs off your engine (with a belt/pulley) and puts out about 14Volts AC (alternating current) which is rectified to a DC voltage (since batteries are DC) and a regulator which allows a specific amount to the car battery. The load and condition of the battery determine how much charge it needs at a given time.

Older cars had generators which output DC (direct current) to the battery through a regulator. But generators are not very efficient at low engine speeds, especially with modern cars and all their electrical accessories and systems.

One thing that is overlooked is charging or trickle-charging your own batteries at home if they need it.Most cheap off the shelf chargers are very hard on batteries as they produce a lot of heat internally which breaks the battery down every time you use it. Some batteries, sometimes called 'appliance batteries' are provided to run separate systems on loaded luxury vehicles, like the high end Mercedes. These can be destroyed after just a couple of charges on typical units found in most home garages.

Here is a good article on battery charging. A bit technical. and here is the charger I keep in my garage (if needed).

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

http://www.ctek.com/us/MUS3300...s.asp

You can find these discounted on ebay.

Modified by ezflow at 9:08 AM 8/23/2006
Modified by ezflow at 9:09 AM 8/23/2006

[IronAnaconda]

sweeet thx a lot man thx for not posting a halfassed answer =) good info

[Q45tech]

The regulator doesn't sample the current it increments the voltage in tiny steps by controlling the field winding voltage.

Lead Acid batteries have a very specific output voltage vs temperature which tells you the exact state of charge [of the 6 in series 2.2 volt cells] = 13.2 volts.

[telcoman]

If you would like to observe the charging voltage, pick up a inexpensive digital voltmeter at Radio Shack for around $20. Observe the DC voltage between the positive & negative battery terminals with the car not running. You should observe 12.6v. Now start the engine and take another reading. you should observe around 14.4v which indicates the alternator is working. If the red idiot light ever lights up & you do not read 14.4v you either have a broken belt or a defective alternator.

[USsil80]

[QUOTE=Q45tech]The regulator doesn't sample the current it increments the voltage in tiny steps by controlling the field winding voltage.

QUOTE]

now now... sounding all technical .... wonder how many people actually know how a alternator works.... the diffrence between a brushed and brushless alternator....

[szh]

now now... sounding all technical .

That is Q45tech's forte! Keeping us interested in learning the technical details!

Z

[ezflow]

I think the man was looking for a basic answer, but more information is certainly better than less!