Working out battery requirements
September 9, 2010
I'm putting together a shopping list of parts for my second robot but I come from a programming background and my electronics knowledge is still in its infancy, so I'm not sure how to work out what batteries I need.
In my last robot I was able to power two lego motors and my Arduino from 8 x AA rechargeable batteries; but this was simply because the lego battery pack came in that configuration and I tried pluggin it into the Arduino and luckily it worked.
I'm now leaving the lego behind and want to run two of these motors:
And one of these servos:
Plus my Arduino board and a couple of Sharp IR sensors.
Now I think I'm supposed to be looking at the current supplied by the batteries, and the current drawn by the devices, is that right?
The motors say 40mA free run and 360mA stall - does this mean I have to use the larger value when I'm calculating?
The servo datasheet says 8mA IDLE and 150mA NO LOAD RUNNING - is this the same?
Can't seem to find any information on the Sharp IR or the Arduino, which now leads me to wonder if I've got all this wrong anyway?
The AA batteries I have state 2500mAh on them which I assume means mA per hour. They also have "7h - 500mA" in small, so does that mean they're 500mA batteries?
How do they work when you add them all together? Do 6 then produce 3000mA?
I feel even more confused now than before I started writing this post!
Any advice would be greatly received, or even just a pointer to somewhere I can read up more on what I'm trying to figure out.