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Battery Power Capability (C) Answered

I'm trying to understand a little bit more about batteries. I've learnt so far:

"Volts,  amps, and  watts measure electricity. Volts measure the “pressure” under which electricity flows. Amps measure the amount of electric current. Watts measure the amount of work done by a certain amount of current at a certain pressure or voltage."

Now I'm interested in knowing the maximum amount of energy you can draw from a battery at any one time.

I presume you can't instantly drain a batteries full energy capacity at any one time. I have read that:

"The way the power capability is measured is in C's. A C is the Amp-hour capacity divided by 1 hour. So the C of a 2Ah battery is 2A. The amount of current a battery 'likes' to have drawn from it is measured in C. The higher the C the more current you can draw from the battery without exhausting it prematurely. Lead acid batteries can have very high C values (10C or higher) , and lithium coin cells have very low ones (0.01C)"

Am I write in saying a 1.2V 1200mAh has a power capability of 1.2C? In which case I should only ever draw 1.2C or less to preserve the battery?

How do I increase this amount when using 2 batteries, if I wire two batteries together does the power capability increase to 2.4C for the above example batteries? If so do I have to wire them in parallel or series for this to work?

Thank you.

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steveastrouk
steveastrouk

9 years ago

You used to be taught about the property of a power source called its "Internal resistance", and how to measure it, and how to calculate it.

If you think about it its nature's way of preventing you from getting infinite amounts of power from a source.

The maximum safe discharge rate is a strong function of the shape and chemistry in the battery.

The capacity of a rechargeable cell is quoted after a 10 hour charge cycle, and assumes a discharge RATE = 10 hours. If you take that energy stored out faster, you will always find it is less than the nominal capacity.

Why do you think THAT happens ?

Steve