REV Driver Hub Tips

Started in the 2023-2024 season, Tech Tips are segments released in the FIRST Tech Challenge Team E-mail Blast. Sometimes the Tech Tips are included in whole in the email blast, but sometimes there is more content than is reasonable in the email blast so partial content is included in the blast with the rest of the content here.

This Tech Tip is a long one, filled with great REV Driver Hub tips. Most everything here can be found in REV’s Driver Hub Troubleshooting tips page, we’ve just annotated a few of these for the most common scenarios you’ll potentially experience with the REV Driver Hub. Understand that this Tech Tip is not meant to disparage the REV Driver Hub in any way - no device is perfect, but the REV Driver Hub can provide you trouble-free performance if you can understand its nuances and take a few additional steps to keep it running optimally.

Ten Driver Hub Tips

  1. Make sure your REV Driver Hub time/date is set correctly! This is the cause of a number of inspection nightmares and Robot Controller log file confusion, the first step should always be to check to make sure the Date/Time on the Driver Hub is set correctly. This is set through the normal Android System Settings by pulling down the Android Quick Settings pull-down twice, tapping the Gear Icon, selecting System, and then selecting “Date & Time”.

  2. USB wall chargers are all the same, right? Wrong. A/C-to-USB wall chargers can range drastically in power (measured in Watts) - the REV Driver Hub comes with an A/C-to-USB wall charger, and that is the recommended wall charger to use to charge the REV Driver Hub. Can you use another device to charge the REV Driver Hub? Maybe, but it’s best to stick to either the one that ships with the REV Driver Hub or a fully-charged USB Battery Pack like the Anker 10,000mA Power Bank which can keep a Driver Hub fully charged all day without ever needing to put the Driver Hub to sleep.

  3. Rechargeable Lithium batteries don’t necessarily work the same way that other batteries work, they all have a slightly different usable Voltage range. The REV Driver Hub needs to calibrate to the Voltage range of the internal lithium battery plugged into it, and to do that there’s a full calibration process that has to be followed for any new battery, along with a verification step. DO NOT simply “replace” a drained battery with a new charged one when it gets low, the new battery is NOT guaranteed to have the same calibration as the first and it is not guaranteed to perform optimally. If you’re having problems keeping the REV Driver Hub internal battery charged, consider a USB Battery Pack like the Anker 10,000mA Power Bank.

  4. Battery safety in any Lithium Battery system is paramount, and the REV Driver Hub has battery safety features that most teams will likely run into at least once. The most commonly experienced safety feature is the Battery Lockout system. If a REV Battery depletes to a level below its recommended safe level, or the battery is overcharged, the REV Driver Hub will enter lockout mode to protect the battery. In this mode, the REV Driver Hub will not power on when the battery button is held down. The process for recovering from Battery Lockout can take several minutes, but it’s better than the alternative. It’s not recommended to leave a REV Driver Hub on charge unattended for more than 8-10 hours, and definitely NOT for multiple days.

  5. When a user puts the REV Driver Hub to sleep, or if it goes to sleep on its own because the Driver Station App main screen is not actively running in the foreground, it goes to sleep pretty easily. However, when the REV Driver Hub returns from a sleep state, sometimes the Wi-Fi and the gamepads will not reload correctly or automatically; this requires you to unplug and replug the gamepads from the REV Driver Hub before you can use them again, or perform a hard reboot in order to bring Wi-Fi connectivity back. Many veteran teams use a fully-charged USB Battery Pack, like the Anker 10,000mA Power Bank, and leave the Driver Station App main screen running all day without putting the device to sleep.

  6. Keep the REV Driver Hub safe by using 3M Dual-Lock or hook-and-loop fasteners (like those sold by Velcro Brand) to mount the Driver Hub to a Driver Station Carrier. This prevents your REV Driver Hub from being placed on the floor (where team members may step on it) and prevents you from accidentally dropping the Driver Hub on the floor - dropping the Driver Hub is the #1 cause of all Driver Hub damage! Some teams have designed their own custom Driver Carriers, be creative and have fun!

  7. When the REV Driver Hub is not in use (not at competitions, not in use during practices) it should be turned OFF and have all sources of power disconnected. Do not put the Driver Hub to sleep, but actually turn it off - press the power button for 1-2 seconds and then use the drop-down menu to turn off the device. The Driver Hub uses power even in sleep mode, and that can lead to a dead battery and you may have to perform Battery Lockout Recovery before you can turn it back on.

  8. Sometimes teams may experience “random power loss” on the REV Driver Hub. This is usually due to a battery fitment issue within the battery box on the device (the battery momentarily stops making a connection with the power pins on the device), and can be mitigated using techniques from the REV Troubleshooting tips. Some teams have been known to operate their REV Driver Hubs without a battery inserted at all, and simply run the Driver Hub using a fully-charged USB Battery Pack, like the Anker 10,000mA Power Bank. The jury is still out on whether that’s a good idea, but worth considering if you’re having problems that you’re desperate to solve and REV Support is unable to help you resolve (because of time pressures) before your big event.

  9. Ensure your REV Driver Hub is fully updated. Firmware 1.2.0 solves a host of REV Driver Hub issues, and it makes sense to use the on-board updater (once connected to Wi-Fi) to perform all updates on the Driver Hub.

  10. This isn’t specifically a REV Driver Hub tip, but it’s a question we get asked all the time. Did you know that the Robot Wi-Fi network name (Robot Controller Name) and the Wi-Fi passwords can be managed straight from within the Driver Station app? With the Driver Station App connected via Wi-Fi to the Robot Controller, click on the three dots menu on the upper-right and select “Program and Manage”, then use the hamburger menu on the upper-left and select “Manage”. On this page you’ll find all of the same settings as you’d find on the webpage by logging in to the controller on a laptop!

Why Driver Hub Batteries Aren’t Interchangeable

The tips above cover the REV Driver Hub broadly, but we never really covered the batteries used in the Driver Hub themselves - and, of course, this topic was brought up in a team question. The question was, “Why aren’t batteries for the REV Driver Hub interchangeable?”

Well, that wasn’t the actual question, as the team didn’t know the question they SHOULD have been asking, but that was the root of the issue. The team in question had purchased an extra REV Driver Hub battery, charged it, and was using it as a spare. We’ve also heard anecdotes from teams who attended events where FTAs would also purchase spare batteries (or pull batteries from spare Driver Hubs) and let teams with depleted batteries use their charged batteries. However, in each case the teams noted that the spare battery never lasted as long as their “regular” batteries, often significantly shorter (half or less). The issue is actually not specific to the REV Driver Hub, but in the batteries themselves.

I noticed the same thing a few years ago when I owned a smartphone that had user-replaceable batteries. My phone battery stopped holding a charge, so I bought a battery online to replace it. However, I noticed that the replacement battery had a significantly lower “lifespan”, meaning it would go from full charge to near-dead in a shorter period of time versus the original battery. Over time the battery seemed to “last longer”, until after about a dozen charge cycles it was very close to the original battery’s performance. Did the battery get better, or did my phone adapt to the battery?

What I didn’t know was that minor variances in how batteries are manufactured, especially in lower-voltage Li-Ion batteries, can affect the voltage stability of the battery as it depletes (how the voltage of a battery changes as it’s used). In order to know how much battery power is left, the device needs to know the “charged” voltage, the “depleted” voltage, and generally needs to understand how the battery voltage changes from one extreme to the other. Unfortunately this isn’t linear, and differences in a battery’s specific internal resistance and other factors will cause each battery to have different behavior (this occurs in all batteries, but higher capacity batteries with low internal resistance tend to show this difference less). The REV Driver Hub performs a calibration phase as it charges a battery, and stores the battery charge characteristics - that helps it know how the battery should behave when it’s being depleted. In this way the Driver Hub “learns” how to interpret the battery it’s charging so that it can create an accurate charge profile for the battery as it’s used by the device.

When a team replaces the primary battery with a spare, the Driver Hub doesn’t necessarily know that this has happened, and can only apply the stored discharge characteristics for the primary battery to the new battery. Unfortunately this often leads to the device misinterpreting the battery and shutting down before the battery has fully depleted, or thinking there’s more battery left when there really isn’t. If the new battery is then charged, the Driver Hub will calibrate to the new battery, and changing the battery again will cause the Driver Hub to mischaracterize the original battery if replaced.

It is highly recommended that all teams use an external USB Battery Pack connected to the USB-C port on the Driver Hub to provide consistent power (use USB-A to USB-C cables only). The battery pack will sustain your Driver Hub and keep it from being additionally depleted by any high-power-drain gamepads (such as the Sony DualShock and Sony DualSense gamepads) that your team may be using.

Got any questions about the REV Driver Hub? Come start or join the conversation on the FTC Community Forums!