Roboticsin Schools

Basics of Power Supply

After you've fininshed making your bot, the next thing is to power it up. Now you can power up your bot with Batteries, SMPS, AC~DC adapters (basically anything that gives a DC output). Now some things to keep in mind :

AC~DC converters :

For these devices which take in AC power and give out DC power; the output current capacity of the power source should be more than the sum of the Stall Currents of all the individual motors put together in the bot. This is for the safety of the power source, else you might end blowing up your power source, if your motors stall. Stall current is basically the current that the motor sucks in when it is stalled.


Batteries :
Batteries are also good solutions to powering up your bot, the only disadvantage being that they get used up and have to be charged again (if its a rechargable one). On the contrary, using batteries increase the bot's freedom of movement.
Now how to know the output current capacity (output load) of a battery? Because its not mentioned in Amperes but in Ampere Hour.

Ampere hour of a battery is basically the

Current output x Time for which it can provide.


Now, a 5 Amp-Hr battery, can give out 5 ampere current for an hour (ideally). Also, it can give out 10 Amperes of current for 30 minutes; Or 20 Amperes of current for 15 minutes. The idea is, the charge capacity is constant, i.e. the Current x Time (in hours) product is a constant and that is the Amp-Hr rating.


Another thing to keep in mind is the Peak Discharge of the battery (if its mentioned). A 30C, 6 Amp-Hr battery means it can discharge a maximum of 30x6=180amperes of current at its peak at one go.

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