Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: zabuza™ on March 03, 2010, 08:22:24 PM

Title: Batteries
Post by: zabuza™ on March 03, 2010, 08:22:24 PM
i wanna know how long a battery would last in say for example a normal line following robot, what do i have to take into specification.

i am confused as why do we work with power for motors and other equipment, how is this related to a battery
Title: Re: Batteries
Post by: SmAsH on March 03, 2010, 08:36:09 PM
Well, it depends on the battery, some will last 5 hours, some 5 minutes.
How long a battery lasts depends on its mAH rating, the more the longer it will last.

Power is voltage x current, that is how it is related to batteries, i don't completely understand your question, could you please explain it a bit better?
Title: Re: Batteries
Post by: nottoooily on March 04, 2010, 02:20:03 AM
A battery that says 2000mAh on the side will last roughly 20 hours if it's delivering 100mA continuously.

20 hrs * 100mA = 2000mAh = the amount of energy stored in the battery.

It'll usually perform worse if you draw more current, so this is kind of a best case. How much worse is more complicated, but you can easily test it with a resistor and a battery! I remember a technician who wanted to buy AA batteries for some gadget so he left several different brands draining and recorded the voltages on a multi-channel chart recorder, came out with pretty graphs that showed massive differences in lifetime.