measuring battery usage

Joe Fishback

I have a BOE-BOT that has alot of stuff added to it. The things that run off the main BOE are the BOE, (4) Parallax servos, "Gazbot" sensor·system that has·2 bump switches and a IR sensor, (3) Parallax "QTI" line sensors and a R/C radio receiver (50 mA). I am using a 1100 mAh NiMH 7.2 battery to run the main BOE. While the program runs fine, it will run only a little over 2 mins, then it starts to act up. Stop and recharge the battery and then it runs OK for another 2 mins. I thought the system would run longer with that battery.·My question is how do I make something to measure low mA usage while my robot is running? I tried using a digital multimeter, but it would not let the BOE run. I am quessing that the internal resistance of the meter is·to high to pass enough current at 5V. Does anybody have any ideas on how to figure out what is using the most current?


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······ Joe Fishback

-Robots are my friends-

Bean

Your meter you measure the current and it shouldn't make the BOE not run ???
You may have blown the fuse in your meter. Most meters have a seperate input jack for the red lead when measuring high currents. That seperate jack doesn't have a fuse so it should work if you use that jack.
Bean.

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m_fabio2

The way I would go about measuring the current would be to place a 1 ohm resistor in series with the battery, and measure the voltage on that resistor. Hook that mesurement up to a AD8031, hooked up to the stamp.