On board battery meter $1.48
RadioShack has an "Analog RC Car Battery Tester" on clearance for $1.48, it's usually $15 (what a profit they make!). See link here: www.radioshack.com/product/index.jsp?productId=2103163&cp=&pg=2&kw=rc+battery&parentPage=search
It can test 1.5V, 6V, 7.2V, 9V, and 9.6V. If you have any battery voltage other than the ones listed, you can create your own battery meter by simply substituting a different value resistor (if you open up the meter, you can see the resistors they use). Most likely, these different voltages should be suitable for most applications.
To modify it, all I did was remove the casing, and attach the meter's readout panel onto the circuit board (so it's more compact). I disconnected all the wires except the 6V one (that's for my battery). I also utilized the slide switch that's used to switch from 7.2V and 9.6V to make an "on/off" switch. I hooked up the power and ground wires permanently to my robot(on the plug where the battery plugs in), and use the modified switch to connect/disconnect the meter (so it doesn't slowly drain the battery, I suppose).
Here are some pictures:
The best part is not only do I know when my batteries are getting low, but I can also see the voltage drop on the battery during high current usage (when my robot lifts something).
It can test 1.5V, 6V, 7.2V, 9V, and 9.6V. If you have any battery voltage other than the ones listed, you can create your own battery meter by simply substituting a different value resistor (if you open up the meter, you can see the resistors they use). Most likely, these different voltages should be suitable for most applications.
To modify it, all I did was remove the casing, and attach the meter's readout panel onto the circuit board (so it's more compact). I disconnected all the wires except the 6V one (that's for my battery). I also utilized the slide switch that's used to switch from 7.2V and 9.6V to make an "on/off" switch. I hooked up the power and ground wires permanently to my robot(on the plug where the battery plugs in), and use the modified switch to connect/disconnect the meter (so it doesn't slowly drain the battery, I suppose).
Here are some pictures:
The best part is not only do I know when my batteries are getting low, but I can also see the voltage drop on the battery during high current usage (when my robot lifts something).
Comments
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Chris Savage
Parallax Tech Support
csavage@parallax.com
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Chris Savage
Parallax Tech Support
csavage@parallax.com