How can I purchase an additional dual mode virtual wall barrier for my Roomba 800?

Check your batteries , Cleen the sensor on the virtual unit

Support won't help you with this. They maximally try to ignore such questions since it raises the thought the robotic vacuums aren't working.

You can find a solution here: Roomba 650 and 770 and don't about your Roomba being a different model. They all work the same.

How Do Install Virtual Wall Batteries video

"The Charge Indicator Light is located immediately to the right of the power button on Roomba Red and Roomba (sage). On Roomba Discovery and Discovery SE, the Charge Indicator Light is incorporated into the power button. Please refer to the table below to determine what the Charge Indicator Light is telling you.

* Pulsing Amber - Charging
* Green - Fully Charged
* Amber - Partially Discharged
* Red - Almost Fully Discharged
* Flashing Red - Fully Discharged"
At the end of a cleaning mission, Roomba will tell you if it has successfully completed it's mission or not:

GREEN = MISSION COMPLETE

YELLOW = MISSION ABANDONED (Check robot's brushes, etc.)

YELLOW RED POWER BUTTON = BATTERY DEPLETED (Scheduler Models)

RED YELLOW POWER BUTTON = BATTERY DEPLETED (Discovery Models)
number of beeps after ?uh-oh? :

No beeps: A wheel is stuck or is not touching the ground. Pick up the robot, place it down securely on the floor and touch the clean button to restart the cycle.

1 beep: The main brushes cannot turn. Turn over Roomba and remove the brush guard by pushing the two yellow tabs. Remove the brushes, clear any obstructions, and replace them again.

2 beeps: The side brush cannot turn. Turn over Roomba. Look to see if something is wrapped around the side brush. Remove the side brush with a screw driver and check for string or hair that may be wrapped around it.

3 beeps: The vacuum cannot run Remove and empty Roomba?s bin.

4 beeps: A wheel motor cannot run Your Roomba may be stuck or something may be wrapped around a wheel. Look for something wrapped around the wheels. Push them in and out and make sure they turn easily.

5 beeps: The cliff sensors have failed or are blocked. Turn over Roomba and clear any debris that might be caught underneath the front bumper in the cliff sensors. You can also use compressed air to clean them out.

6 beeps: Wheel obstruction or robot attempting to drive over an obstacle. Turn over Roomba and remove any obstructions that prevent the wheels from seating all the way up into Roomba?s body. Also, remove any obstacles that Roomba could drive over.

7 or 8 beeps: Not applicable Roomba?s beep codes do not include 7 or 8 beeps. If you are getting an error with 7 or 8 beeps, try counting again or contact iRobot Customer Care.

9 beeps: Sensor error Please contact iRobot Customer Care.

10 beeps: Roomba is stuck Pick up Roomba and start it again somewhere else. Use a virtual wall or other barrier to keep Roomba away from the
place it got stuck.

Your Roomba may be experiencing an issue where the battery is deeply discharged and may need to charge longer than the standard 3 hours. (or 7 hours if you have a standard charger)

Even with the charging light showing green (this indicates a fully charged battery) the robot is still charging. If your Roomba exhibits behavior where it charges for a short time then runs for a short time you will need to do the following.

1. Plug the charger into Roomba (if you have a home base be sure to plug directly into Roomba instead of using the home base, this will ensure the robot's charging cycle is not interrupted.)

2. After the Roomba's charging indicator goes to solid green please keep the Roomba on the charger for an additional 72 hours. (3 days)

3. After the 72 hours (3 days) has passed, turn your Roomba on and begin a normal cleaning cycle. If this works successfully it may take several uses for the battery to get back up to the performance it once had.

If this does not correct the problem, please call customer support at 877-855-8593

Hello. Most likely, your rechargeable battery is on it's last legs and needs to be replaced. Joe

Hey'
This means Roomba is not registering obstacles. Roomba may be stuck in one place.
Roomba may be in extremely large room, try setting up virtual walls to create smaller area.
If Roomba is not in a large room, tap Roomba's bumper to confirm it is properly working.

Hope this helps
Avi

Reboot is probably not your solution. Your Roomba will react to invisible signals or 'interference' from other electrical appliances as well as the invisible wall boxes. You can clearly see how this happens when a Roomba gets near your computer or other device that is on. Also, the Roomba will go in circles when the dirt chamber is full or it thinks it's full. Try a thorough clean of all major parts including the brushes. Sometimes this activity will occur when the brushes get snarled on thread or carpet fibers.

To change the batteries you simply remove the door on the underside of the unit. It requires you to remove a single philips screw.

You may not believe this, but the new 500 series lighthouse virtual walls have both infrared and radio frequency communication. How they work and associate with the Roomba is pretty complicated. The best posting I've ever seen about how they work is here:
http://www.robotreviews.com/chat/viewtopic.php?f=1&t=11048

Check out that link to understand how the communication works.

If your Roomba is contained by the virtual walls, then you can assume the IR sensor on your Roomba us good....you should test that though. Then you might have to replace the "home base" which could have a bad IR transponder . New ones can be found for reasonable price at www.RoboticVacParts.com or you could order straight from iRobot for twice the price.

If the Roomba is not contained by the virtual walls, then the IR sensor on the Roomba is likely bad and you'll need to change the bumper on your Roomba. Again ....parts are available through ebay, or www.RoboticVacParts.com. Follow this link if you need it.
http://cgi.ebay.com/NEW-Roomba-500-series-white-bumper-510-530-532_W0QQitemZ270400281066QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3ef51cd9ea&_trksid=p4634.c0.m14.l1262&_trkparms=|301%3A1|293%3A1|294%3A30

Make sure your virtual wall batteries are fresh-- even if you're sure they are, try removing and replacing them just to reset the virtual wall.

Then reset your Roomba: hold down "spot" and "dock/demo" for about fifteen seconds. Release them and wait for the tune.

Recharge the Roomba and then try to run it. The virtual walls ought to respond at that point. If they don't, you might find that calling customer support may help.