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Here's some updates and news from FIRST^® Tech Challenge.

In this week's blast: 

💻 Tech Tip of the Week

❤️ Bid For a Cause: 35 Years of FIRST^® Virtual Auction  

Tech Tip of the Week  

Welcome to the Tech Tip of the Week, where hopefully after reading you do not blow a fuse. Yup, you guessed it, today we are talking about fuses - more specifically, we are talking about the fuses on your Main Robot Battery. 

Every legal Main Robot Battery in FIRST Tech Challenge is required to have an in-line replaceable fuse on the battery, you will find the fuse housing on the red (positive) cable on your battery between the battery and the connector (the top lifts off, exposing the fuse). This fuse helps protect your battery and your electronics from prolonged or excessive over-current. The fuse used with all legal batteries is a 20A Automotive-Mini (ATM) blade-style fuse, and can be found in virtually every auto parts store. It has a yellow-colored housing which easily identifies it as a 20A fuse. If you find that your battery’s voltage suddenly drops to zero (when tested using a battery tester or multimeter) it’s probably because you’ve blown your battery’s in-line fuse.  

A fuse is a short span of specially designed electrical wire intended to carry electrical loads up to a specific amount of current. When the current loads exceed the rating, the wire within the fuse begins heating up - the more the load exceeds the rating, the hotter the wire will get. Eventually the wire will heat up so much it self-destructs and melts or burns up, breaking the circuit. This fuse-melting condition is often called "Blowing a Fuse;" which is when the fuse is destroyed and is no longer usable, but it protected the electronics in the circuit as its last selfless act. 

What causes a battery fuse to be blown? These are two of the most common reasons why a fuse can be blown: 

1. Overcurrent Conditions - The Robot has components (generally actuators, like servos and motors) that can pull a combined current that is more than the robot’s electrical circuit can safely carry. The main electrical power wires on a robot are required to be a minimum 18AWG, which can easily continuously carry up to 16A of current. When components pull a combined current far exceeding this limit, generating unsafe heat more than what the wires can tolerate (risking melting the wire insulation which could lead to short circuits and fire), the fuse blows to protect the circuit. The wire size and fuse limit has been carefully selected for the safety of the robot’s electrical system.

2. Short Circuits - Usually this happens if unshielded wires of opposite polarity touch each other in the robot’s electrical system, like when performing electrical maintenance on switches or wires (ALWAYS unplug the battery before performing any maintenance on a robot!). Other causes can be failed electronics and damaged components. This causes an extremely high current load to travel through the battery, instantly causing the fuse to blow. When replacing the connector on a battery, ALWAYS remove the fuse prior to performing any work - this protects the person doing the maintenance AND protects the fuse!

Always make sure your main battery fuse is replaced with the proper fuse (20A for FIRST Tech Challenge) and make sure you are always following all safety guidelines when working with your robot’s electrical system! 

Bid For a Cause: 35 Years of FIRST^® Virtual Auction

The deadline is approaching for your chance to bid on our virtual auction! Looking for a chance to join Dean Kamen and FIRST supporters at a Lobster Bake at his New Hampshire home? How about a tour of DEKA and lunch with Dean? What about a relaxing Tuscan getaway in Italy? Or bringing home exclusive FIRST memorabilia?

Check out the virtual auction and get your bids in by 11:59 p.m. ET on March 22, 2024. All proceeds support the FIRST mission and the future of FIRST programs.