Looking for a good resource for Battery Calcs

[Flatliner]

Hi all,

I am looking for a good explanation of how to build a battery pack. Or more accurately how to calculate what the output voltage and the run time at that voltage will be.

If you could point me in the correct direction I would appreciate it.

Flatliner
aka Robert

[the gooch]

Check this site out http://www.powerstream.com/BPD.htm

[Doghouse]

Lets add to that the 2 important electrical formulas.

P=I*E Power (watts) = Inductance(amps)* Energy(volts)
E=I*R Energy(volts) = Inductance(amps)* Resistance(ohms)

With those two formulas, you can calculate the draw values for any circuit.
A 10 watt low voltage (12 volt) lamp draws...
10/12 = .83 amps. You now can look at the amp hour calculation to determine how long the battery will last.

[Flatliner]

Originally Posted by Doghouse

Lets add to that the 2 important electrical formulas.

P=I*E Power (watts) = Inductance(amps)* Energy(volts)
E=I*R Energy(volts) = Inductance(amps)* Resistance(ohms)

With those two formulas, you can calculate the draw values for any circuit.
A 10 watt low voltage (12 volt) lamp draws...
10/12 = .83 amps. You now can look at the amp hour calculation to determine how long the battery will last.

That is very helpful. Thanks for the formula.

Flatliner
aka Robert

[Dale]

You're quoting Ohm's Law, perhaps best written as:

E
----
I * R


Cover up the one you don't know and you have the formula to determine it from the other two.


Also note, I is current in amps, inductance is something else altogether.

The other formula to note is:

P = E * I

You can substite from Ohm's law the part you don't know and you get:

P = I^2 * R, E^2 / R, etc.

[Flatliner]

OK, deeper question from my non-electronic brain. Say my battery pack is rated for 10AH. This is figured with a discharge over 10h. How do I calculate it if the discharge is going to be over 2h? I know it will no longer be 10AH but what will it be?