adrian1906
Mechanical
- Oct 12, 2012
- 7
I'm helping my son with his science fair project to compare the useful lives of different batteries. I helped him build a data logger using an Arduino micro controller board which as 6 Analog Input channels (the board is powered via the host computer's USB port). Originally, the circuit was designed to handle 3 batteries (A0,A1) for battery 1, (A2,A3) for battery 2, and (A4,A5) for battery 3 and log the differentials with the negative terminals connected to A0,A2,and A4. Unfortunately, I was having difficulty getting reliable values for the voltage difference computed using the pseduo command: voltage =(AnalogRead(A1)-AnalogRead(A0)) * 5volts/1023 (5 volt reference on the 10 bit A/D converter).
So, in my desire to move along, I changed the circuit. I connected all of the battery negatives to the ground of the powered board and each + terminal to A0=>A5 (This configuration allows 6 batteries to be tested at once). Flashlight bulbs are being used to drain the batteries. Each bulb had one connection to ground and another to the Analog Input channel (via a breadboard). The data logger works. My son is happy. I'm happy that he's happy and even more delighted that understood what I did AND took a liking to it
(Still keeping my fingers crossed).
Nevertheless, I woke up this morning wondering if the intent of the tests was compromised. Since the bulbs and batteries are no longer independent (common grounds), is it possible that the battery capacities could be modified (ie, one battery pulling current from another)?
So, in my desire to move along, I changed the circuit. I connected all of the battery negatives to the ground of the powered board and each + terminal to A0=>A5 (This configuration allows 6 batteries to be tested at once). Flashlight bulbs are being used to drain the batteries. Each bulb had one connection to ground and another to the Analog Input channel (via a breadboard). The data logger works. My son is happy. I'm happy that he's happy and even more delighted that understood what I did AND took a liking to it
Nevertheless, I woke up this morning wondering if the intent of the tests was compromised. Since the bulbs and batteries are no longer independent (common grounds), is it possible that the battery capacities could be modified (ie, one battery pulling current from another)?