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how to calculate AA battery percentage with known load current.

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anboli

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Dear All,
I having 4 AA battery with 1.5v 2300mAH. I have to connect 6 Leds to glow continously for longer life. so i made two arrangement, one type is all 6 LED's are connected parallely, and another type is serial and parallel combination.

1. All parallel connection consuming 40mA load current, My battery volt is from 6v starting and its start to drain upto 5.2V. For this, how long the battery life comes?
2. Serial and Parallel Connection, Consuming 20mA load current. My battery volt is from 6v starting and its getting drain upto 3.3v. For this, how long the battery life comes?

Please give an idea to calculate the battery life for both the configuration. If any having formula, please give it.

LED Configuration arrangement sample.jpg

regards,
Anboli
 

On your first case you draw less current but disconnect voltage is higher.

On the second case you draw more current but disconnect voltage is lower.

Since battery discharge curves are highly nonlinear, (and you did NOT tell us what type of batteries you are using) the only way I see to solve your problem is to actually test both configurations with a chronometer.
 

Hi,

connecting in series or in parallel won´t change power consumption.
There are only very tiny differences, like the loss in the wires. It will be slightely more in LED_parallel_operation due to higher current in the wires.

Klaus
 

I think having two LEDs in series in each string wastes much less current than a resistor for each LED. It is difficult to calculate because as the battery voltage drops then the current also drops.
But the LED current and their brightness will be almost the same when the battery is 5.2V as when it is 6V. The current and brightness will be much different when the battery is 3.3V as when it is 6V.
AA alkaline battery datasheets from Energizer show that the voltage of each cell drops fairly quickly from 1.6V when new to about 1.25V so four cells will drop quickly from 6.4V to about 5V.
 

Thanks for the reply, I couldnt clearly understand your replies.

And im using Duracell AA, LR6 Alkaline Battery.

Please tell me which configuration will take longer life?
And is there any calculation regards that?
And FYI, in both the configuation LED brightness remains same, and i tested. I couldnt calculate the life of the battery.
Please give any suggestion.
 

Hi

the answers are already given.

Please tell me which configuration will take longer life? --> none
And is there any calculation regards that? --> A x h = Ah
And FYI, in both the configuation LED brightness remains same, and i tested. I couldnt calculate the life of the battery.
Please give any suggestion. --> What suggestions?

Klaus
 

The calculations do not add correctly if the LED voltages are all the same.
 

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