Attention to detail and mindfulness is CRUCIAL for a stress free and fully capable electrical system. Troubleshooting electrical issues is one of the hardest parts of robotics. Do electrical right the first time and save a lot of time and sweat.
Always use Strain Relief Techniques to avoid putting strain on the actual electrical connection
Secure the connector with zip ties, double stick tape, or mechanical fastener
Secure the wire going into and out of the connector with some slack to avoid strain
Bottomline: the wire connection between connector and wire should not feel any strain if pulled on
Secure wires to moving mechanisms with enough slack in full range of motion
Create wire "rivers" to keep electronics neat and organized
Label wires to easily troubleshoot devices
Make an electrical diagram, especially the CAN network -- judges will ask many questions
AWG means American Wire Gauge -- the bigger the number, the smaller the wire
We use stranded wires, not solid -- connectors have different size limits based on type of wire
Wagos are our prefered lever style connectors that allow quick and convenient connections
221-612: 20-10 AWG wires for around 30A; strip wire 13mm -- use for thicker power wires like on Krakens and Spark Maxes
221-422 (Green): 24-12 AWG wires for around 20A; strip wire 11mm -- use for CAN wires
221-2401 (white inline): 18-12 AWG stranded wire for around 20A; strip wire 11mm -- general use for all other wires
221-2411 (clear inline): 18-14 AWG stranded wire for around 20A; strip wire 11mm -- general use for all other wires
Strip wires to proper length (11mm to 13mm depending on type of Wago) -- read side label of Wago to be sure
Do not overtwist wires to make it fit into Wago connectors
Do not allow "whiskers" in the connections -- these can touch other connections and cause brownouts or electrical noise
Do not allow wire insulation to be clamped in the connection (not an issue if you strip the wire to the right length)
Use Wago Strain Relief Carriers to secure the wago and the wires going in/out to avoid brownouts or mysterious and hard to find signal issues
Anderson Power Poles allow quick and convenient connections too
Anderson Powerpole Connectors | REV ION Brushless (revrobotics.com)
Requires proper sized connectors and proper crimping techniques
Always do appropriate wire tug test to ensure good connections
Always strip the wire to the proper length referencing manufacturer documentations
REV PDH:
High Current Wire: 12mm
Low Current Wire: 8mm
Main Electrical Input: 19mm
Wago Inline: 11mm
We use MK Battery ES17: MK Battery ES17-12 - 2 Pack - REV Robotics
Datasheet: MK Battery Datasheet
Sealed Lead Acid, 12V with internal resistance of 0.012 Ohms
13 lbs
Always check battery connections for loose connections -- these cause brownouts and mysterious robot behaviors
Always use Nordlock washer sets to connect the battery cable to the battery
Critical to prevent loosening of connection due to high vibrations
Much better than split washer in maintaining tight connection
Use two sets: one on the screw head side -- the other on the nylock nut side
Batteries are nominally 12V, meaning it will vary when fully charged
With no load, the battery can be 12.7 to 13.5V
Check battery charger for Volt readout -- when Amps read 0, then it's done recharging and is in maintenance mode
Voltage readout on driver station will differ from the readout on the PDH
Driverstation voltage should read above 12.5V to avoid potential brownouts in an intense match
If batteries are warm, let them cool for 15 minutes before charging
Never carry batteries by the cable
Track each use of batteries to ensure even rotation of batteries
Never drain a battery below 11 volts to avoid permanent performance degradation
Test batteries before every season to check internal resistance -- worn out batteries will have higher resistance that can cause brownouts in intense matches
As internal resistance increases, battery power output decreases and heat increases
Ideal internal resistance is less than 0.015 Ohms
Batteries with internal resistance greater than 0.020 Ohms should be retired
O-Reilly's Auto Stores will pay to recycle batteries, usually 2 batteries for approx. $5 in store credit
Insulate exposed metal connections with heat shrink to avoid accidental shorts
Electrical tape can be used but is not optimal
Silicon tape is the best alternative to heat shrink
Battery testing should be done regularly to avoid battery related issues at competition
CBA Tester is more extensive and can detect bad or failing batteries
Done on March 1 prior to first event
Done prior to state and world championships
Battery Beak is less extensive and takes less time, but it does not accurately identify bad batteries that should be pulled from competition
Done prior to an event, unless a CBA test was already done
NEW BATTERY PROCEDURES
Do CBA test
Label battery: Year purchased, team number, compeition or practice only
Print and attach battery usage tracker to ensure even cycling of batteries between matches
HOW TO USE THE COMPUTERIZED BATTERY ANALYZER (CBA):
Install computer software: Software for CBA II, CBA III, CBA IV, CBA V & CBA HR - West Mountain Radio
Connect the battery tester to your computer
Connect a fully charged battery to the battery tester
Click the "New Test File" Button
If you wish to add an additional test to an existing file chose "Append Test" instead.
In the New Test window do the following.
Select "Discharge" on the left
In the blue box on the right click the "Detect" button
For an FRC Battery fill in the following settings: Lead Acid, 13.2V, 6 Cells
Enter the Ah of the battery (Usually 18 for FRC batteries)
Enter a name for the battery at the top under "Test Name:" and label the battery with this name for future comparison
In the center of the screen set "Cutoff V:" (recommend using 10.5) - This is the voltage that the battery will be depleted to
In the center of the screen set "Test Amps:" (recommend 7.5) - This is the load that the tester will apply to the battery for the duration of the test.
This is the highest the tester can do on an FRC battery and will result in the fastest test.
Click "Start"
The test will now run for anywhere between a few minutes to a few hours
Do not move or touch the battery at all during the test
Pausing the test will result in a bad portion of data around the pause and is not recommended
When the test is complete a dialogue box will appear informing you of the result and the graph will be complete
Click "OK" and repeat the test for another battery.
HOW TO USE THE BATTERY BEAK
Beak User Manual (andymark.com)
Connect Beak to the battery
Hold button until screen lights up
Press again to start testing
No need to enter Battery Type Menu since default settings is set for our battery type
Default settings: Lead acid battery, 12V, 17-20Ah
Use to test voltage and internal resistance
Use to test circuit issues due to bad connections or crimps by replacing a motor with a battery beak connection
Allow batteries to "rest" 15 min after charge cycle, before testing or reading voltage levels in order to remove surface charge that affects accurate state of charge
CAN Bus Utilization can be found on the Driver Station in the DS Logs
Rule of Thumb: Never go over 80% or you start seeing issues from devices on the bus. Typically it’s under 60% depending on what devices are on the loop
CANIVORE: CTRE product that lowers utilization using CAN FD. CTRE products typically have higher utilization rates and this helps keep it down.
REV products do not and cannot benefit from CANIVORE.
Technique: Put CTRE products on the CANIVORE CAN loop (connects to rio using USB) and put everything else on the standard CAN loop (RIO to PDH loop)
You can also reduce CAN utilization with software also based on frames/signal by controlling the data rate.
Power
Green: Power is good
Amber: Brownout protection tripped, outputs disabled
Red: Power fault, check user rails for short circuit
Status
On while the controller is booting, then should turn off
2 blinks: Software error, reimage roboRIO
3 blinks: Safe Mode, restart roboRIO, reimage if not resolved
4 blinks: Software crashed twice without rebooting, reboot roboRIO, reimage if not resolved
Constant flash or stays solid on: Unrecoverable error
Radio
Not currently implemented
Comm
Off: No Communication
Red Solid: Communication with DS, but no user code running
Red Blinking: E-stop triggered
Green Solid: Good communications with DS
Mode
Off: Outputs disabled (robot in Disabled, brown-out, etc.)
Orange: Autonomous Enabled
Green: Teleop Enabled
Red: Test Enabled
The status LEDs on the VRM indicate the state of the two power supplies
Bright green: System Normal
Not lit or is dim: Output may be shorted or drawing too much current
5V LED Example:
Great video by Triple Helix (link)
NOTE: Do not use same VRM that the radio is on
LED parts and wiring instructions
⚠️Check direction of LED wiring. Power wires must transmit in the same direction as the arrow indicated on the LED strip [Wires → LED → LED → LED → LED]
⚠️No LED wires: solder PWM wires to appropriate contacts on LED strip
For silicone shielding: gently scrape away with knife until contacts completely exposed.
Find positive (red) and ground wire (white or black)
5V LEDs ONLY Positive and ground goes to VRM (Voltage Regulator Module) 2 AMP 5V PORT
12V LEDs ONLY Positive and ground goes to PDH (Power Distribution Hub) Use 20 amp fuse
Find signal wire(s) (Green, blue, purple, yellow, anything not black, red, or white)
For multiple signal wires: twist together or use triple wago
Connect signal wire(s) to WHITE WIRE on PWM cable
Find signal ground wire (Ground wire bundled with signal wire)
If absent: splice into power ground wire by twisting together or using triple wago
Connect signal ground wire to BLACK WIRE on PWM cable
Connect PWM cable to roborio PWM port (0-9). Inform programmers which port
WARNING: LEAVE RED PWM WIRE DISCONNECTED!
WARNING: MAKE SURE WIRES ARE SOLDERED ON THE RIGHT DIRECTION OF THE LEDs!
