Powering a robot with a power supply?

We have a robot test bench to test motor controllers, sensors etc… every time we want to run something we just plug in a battery and burn through our supply of charged batteries. Is there any way to hook up a power supply or something else to plug our “robot” into the wall?

Technically yes, but if you’re going to have motors on this test bench, you would need a pretty beefy power supply (like one that is rated to provide upwards of 20A on the DC side) - if you are just going to run electronics (no motors, but watch the outputs on the motor controllers), you can get away with like a 3 amp power supply.

I would encourage you to hook up the power supply as if it were a batter (go through an Anderson-Pole and all the breakers that you would for a battery) for safety reasons (and make sure all connections are insulated).

You need a high current 12v DC Power Supply. A new lab bench PSU that can provide the amount of current a test bench would need is pretty expensive. A good alternative is an HP server Power Supply, modified for continuous output. You can get a 1200w one here, and follow this guide to get it to output power. That guide has a 560 ohm resistor between the 2 power on pins (33 and 36), which is not necessary. You can instead use a solid wire. A wire would mean the power supply starts up immediately when plugged into the wall. If you want to be able to turn it off and on, put a small switch between the terminals. It doesn’t pass current so any switch will work. If you dont want to drill into the power supply or solder directly to the terminals, they do make adapters with a switch and screw terminals.

I have a 750w version (the one used in the guise) for home use and it works great.

Good Luck,
David Fiel
Team 5401
Programming & Assembly

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^^ possible but not likely if you’re running motors.
Your team will have to figure out a battery charging strategy once you enter the drive practice phase anyway - do it now, and make this a non-issue.

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You have to be very careful running motors with a power supply. Unlike batteries, most power supplies are not designed to sink current, and motors and motor controllers can have significant back emf resulting in sourcing current back into the power supply. The safest but most expensive approach is to use a power supply designed for this, such as a 4-quadrant supply.

If you’re just running code and not motors, a 12V wall wart is enough to power a RoboRIO and sensors.

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Perhaps consider getting a larger deep cycle battery and a dedicated charger for it. It will likely be less expensive than a suitable power supply. But… If you really want to test motor performance under ‘real’ operating conditions, then it would make sense to use a real battery. That means that you’ll observe the same battery internal resistance and voltage drop that you would when running the real robot under similar conditions.

My best suggestion would to to take a few of your lower performing batteries, dedicate them to the test bench and practice runs, and purchase a few new batteries for the robot. You’ll save money, get new batteries, and have more realistic test conditions relative to purchasing a suitably sized power supply.

Jason

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If you are going to use a large power supply, you may want to oversize the power supply by 2 or 3 X. They generally have some sort of output overcurrent protection circuitry that will act in microseconds. The starting surge of a motor may activate the protection circuitry.

Does your team have old batteries that don’t hold their charge well? Those would be a candidate for such and application. You are in Oakville with many other teams around you. Perhaps some of them have old batteries they no longer want.

A variant of Jason’s suggestion would be to purchase the batteries used in burglar alarms. They have a smaller capacity but they should be easily available in a large urban area.

I have built computers for years and created a robot power supply from one of my computer power supplies. These PS put out 2 power levels, 12V and I think 5V (don’t recall now). So I combined all the 12V leads into one and fed it into an Andersen connector.
This is just for testing new panels and maybe programming using small motors for rotation etc., not full load work. Works very well and saves having to chase down batteries to test the basic electronics and many programming experiments. These have a circuit that goes to the mother board that you need to locate and ground to get it to power up. Google is your friend to find it and how to do it.