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Battery Charging

DebuGger

Apr 1, 2013
1
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Apr 1, 2013
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Imagine I have a 12V,24Ah battery that I need to charge using Solar.

I know that to charge a 12V battery, I need a voltage exceeding 12v. Ok thats fine.

What about the Ampere? and How can I find Amps of the batter from AmpereHour? by dividing it with 60?

And I do know more Ampere I apply, that fast would be the charging. So what would be the best ampere range to charge the battery I mentioned before? Is there a way I can calculate the time required to charge with all these datas known?


A newbie getting into the field. From a Mechanical and Web Development background. New to electrical and Electronics :)
 

john monks

Mar 9, 2012
693
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Mar 9, 2012
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693
Typically it's a small fraction of the Ah rating. This can be looked up on a datasheet for that battery. So what is the make and model of the battery you are using?
Short of that information can you tell me if this is a nicad, gell cell, or ni-mh?
 

GreenGiant

Feb 9, 2012
842
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Feb 9, 2012
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The Ah rating means that if you charge it with a full 24A it will be fully charged in about an hour.

You can use this to calculate how long it will take to charge at other currents as well, 12A would be 2 hours, 6A would be 4 hours, and so on.
 

JMW

Jan 30, 2012
90
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Jan 30, 2012
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Welcome to the forum. AH readings are sort of misleading. You might think you could draw 24 amps for one hr and you would be quite wrong. Typical times are 10 or 20 hrs, meaning you could draw 2.4 amps for 10 hrs or 1.2 for 20.
Charging rates also vary, usually you can charge a lead acid battery at 50% of its AH until it reaches 85% of capacity. This can be measured by observing the current flow vs voltage of the charger. The charge is then reduced to 10% of the AH until a 95% charge is reached and then 1% for the remaining 5%. This will ensure max battery life. If this isn't a concern, then all bets are off. The battery manufacturer will give you specific charging instructions and may possibly recommend a charger. Nicad, Li ion and NiMh, all have different parameters, but they share two things, as the battery heats up, they are approaching full charge and the current/voltage should be reduced. Over charging WILL result in battery failure, sometimes in a CATASTROPHIC manner.
 
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