Power Management & Brownout Issues

This is where I'm going to be posting all of my problems/findings/solutions for various power management issues.

## Reference Docs

[RoboRIO Manual (See p.7)](http://www.ni.com/pdf/manuals/374474a.pdf)
[WPIlib Brownout Info](http://wpilib.screenstepslive.com/s/4485/m/24166/l/289498-roborio-brownout-and-understanding-current-draw)
[CIM Datasheet](http://files.andymark.com/CIM-motor-curve.pdf)
[CIM Specs](http://motors.vex.com/vexpro-motors/cim-motor)
[miniCIM Specs](http://motors.vex.com/vexpro-motors/mini-cim-motor/)
[120A Breaker Datasheet](http://files.andymark.com/PDFs/am-0282_data_sheet.pdf)
[40A Breaker Datasheet](http://files.andymark.com/MX5SpecSheet.pdf)
[PDP Datasheet](https://www.ctr-electronics.com/PDP%20User's%20Guide.pdf)

#### Key Info

RoboRIO Brownout Voltage is **6.8v**
40A Breakers (at 80A overload or 200%) Trip Time is **1.5 to 3.9** seconds *(I'm not sure if Trip Time is how long that current must be applied to trip the breaker or if it's the time it takes it to reset)*
120A Breaker Time (at 300A or 250%) Time is **7.5 to 20 seconds** *(again, not sure what this "time" is)*
CIM stall current is **133 Amps**
miniCIM stall current is **89 Amps**

## Forum Posts

[CD 6 CIM Brownouts](https://www.chiefdelphi.com/forums/showthread.php?t=140796&highlight=brownout)
[CD Brownouts & Design](https://www.chiefdelphi.com/forums/showthread.php?t=137231)
[CD 4 CIM Brownout](https://www.chiefdelphi.com/forums/showthread.php?t=138910)
[CD 6 CIM Voltage Ramping](https://www.chiefdelphi.com/forums/showthread.php?p=1644452#post1644452)
[CD Whitepaper CIM Current Draw](https://www.chiefdelphi.com/media/papers/3276)

## Experimental Data

### Hammerhead

#### Driving Against Wall Test:

* Voltage dips below 6.8v
* RoboRIO cuts power to Sparks
* CIMs reach ~30A max, rare spikes to not quite 40A
* Total current draw ~180A max
* Breakers **do not** pop
* Communication **not** lost

### Ratchet (w/o miniCIMs)

#### Driving Against Wall Test:

* RoboRIO **not** cutting power to motor controllers (indicating voltage > 6.8v)
* DriverStation reporting "Brownout State" (indicating voltage < 6.8v)
* CIMs reach ~70A max
* Total current draw ~280A
* 40A breakers pop after ~2 seconds
* Comm **not** lost

#### Match Data:

* Voltage went below 7v only once, never below 6.8v
* Comm often lost for ~0.5 seconds
* 40A breakers popping occasionally

### Ratchet (w/ miniCIMs)

#### Match Data:

* Total current > 300A
* Main breaker popping after ~3 seconds

## Solutions

#### Mechanical

* Smaller Diameter Wheels
* Omniwheels
* Lower Friction/Traction Wheels
* Lower Gear Ratio *(or two-speed transmission)*

#### Electrical

* Check all Connections (both batter/PDP and to radio)

#### Programming

* Spark Voltage Ramp Rate
* Current Checking -> Limit Max Power to Spark
* Disable Compressor etc.

The issue contains RoboRIO, WPILib, breaker, motor, and experimental data references, but names no repository files, tests, or entry points. Review the linked hardware and WPILib documentation first, then define a bounded brownout investigation; the issue does not specify what change or acceptance criteria would constitute done.

Written by the indexing model from the issue text.