charging car battery

Hello,

how long would it take for the car's alternator to fully charge the battery? Assuming the alternator's output is 70amps and battery is

48ah?

Thanks.

Reply to
Brian Su
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It does not charge it at 70 amps! As soon as it tries the voltage comes up to the regulated 14.3 or whatever and then it only charges at a few amps.

And contrary to popular opinion a car alternator will never "fully" charge a car battery properly because that would require an equalisation charge and a lot of hours....

But basically an alternator charges it more if its more discharged and the current tapers off slowly as it charges. And it never quite gets there.

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Reply to
Burgerman

I havent a clue and you probably couldnt calculate it based on using an alternator without measuring current and voltage for at least part of the charging cycle because charging rate isnt constant, and the alternator probably wouldnt push 70amps though the battery at any point.

You can calculate the time if you use a fixed current battery charger though, but you would still have to measure start voltage of battery and probably specific gravity of it to determine how flat it was to start with, and then again at the end to know when it's fully charged.

Rather an anal question- haven't you got some left over turkey to be eating instead?!

Tim..

Reply to
Tim (Remove NOSPAM. Registry corupted, reformated HD and l

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