Roomba should not be used on a UPS.

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Roomba should not be used on a UPS.

Postby RTC » August 24th, 2018, 2:38 am

I encountered problems after moving my Roomba to a different location and plugging the Home Base into a UPS that was in the room. Intermittently the Roomba could not see the Home Base, causing it to fail to return home.

I spent a lot of time verifying that the problem only happened on the UPS, never the wall. Since then I have kept it plugged into the surge suppressor outlets of the UPS and experienced no further problems.

On contacting iRobot (7/30/2018), their support people said they knew of no problems using it on a UPS.

Several weeks later while looking for other information, I found under the Battery section on page 5 the comment that it should never be used with a power converter. As a UPS is a type of power converter, so it is a known problem.

When I pointed that out their support people they said "yes we recommend against using extenders".
Then I pointed out that I had never heard a UPS being called an "extender" they said they knew of no problems using it with a UPS.

Their manual clearly says not to use it on a UPS (power converter)! I guess they don't read their own manual!

Note: page 5 also states use on a power converter voids the warranty!
Last edited by RTC on August 25th, 2018, 6:01 pm, edited 1 time in total.
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Re: Roomba should not be used on a UPS.

Postby RTC » August 25th, 2018, 5:57 pm

After telling them to ask their Engineers, they admitted there were known problems using the Roomba on a UPS and that they would pass on the information as needed and have the manual updated.

Note: the fact that it should not be operated on power converters also prohibits the use of a Roomba in solar powered homes, RVs, and all other similar situations where the electricity is provided by converting a DC source to AC! Their support people still may not be aware of those.
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Re: Roomba should not be used on a UPS.

Postby mfortuna » August 26th, 2018, 10:36 am

There are two kinds of UPS. Off-line provides AC power to the output until a power failure, it then switches to an internally sourced AC waveform which usually is not as good as the source. An on-line UPS always supplies an internally generated waveform so there is no need to switch from the input AC to the internally generated AC. That helps prevent a glitch that can occur when an off-line UPS switches to backup.

Most consumer UPS are off-line so unless there is a power failure I don't understand why you are having trouble with the homebase. It should be receiving the same AC waveform that the UPS is plugged into.
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Re: Roomba should not be used on a UPS.

Postby RTC » August 26th, 2018, 7:40 pm

mfortuna wrote:There are two kinds of UPS. Off-line provides AC power to the output until a power failure, it then switches to an internally sourced AC waveform which usually is not as good as the source. An on-line UPS always supplies an internally generated waveform so there is no need to switch from the input AC to the internally generated AC. That helps prevent a glitch that can occur when an off-line UPS switches to backup.

Most consumer UPS are off-line so unless there is a power failure I don't understand why you are having trouble with the homebase. It should be receiving the same AC waveform that the UPS is plugged into.


Either way, if the UPS is generating the AC from its internal battery power it is a "power converter" and can damage or cause improper behavior on the Roomba at those times. Don't plug the Home Base into a UPS of any type. They finally admitted it when I told them to ask their engineers.

P.S. My apartment has very "dirty" power with frequent short power dropouts that cause the lights to flicker. This was why I put all my computers, the cable box, etc. on UPSs. So regardless of the kind of UPS I have it will be generating the AC from its internal battery much of the time, even if only for short periods. I only accidentally plugged the Home Base into the UPS when I was relocating into a different room after running it for well over a year on a wall outlet where I had initially set it up.

P.P.S. There are also a third kind of UPS called a True Sinewave UPS but these are much more expensive than standard UPSs. I believe the Roomba would run fine on one of these as their output is identical to that provided on the mains.
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Re: Roomba should not be used on a UPS.

Postby mfortuna » August 28th, 2018, 9:26 pm

I work for a Data Center networking company and we discovered issues with off-line UPS. The glitch caused the Ethernet Switch to sometimes detect a power fail but usually would run off of the crappy UPS output. We had no issues with an on-line UPS which produced a perfect AC sinewave output at all times. Note that when either UPS switches to backup they float ground which would not be an issue since the homebase supply uses only hot and neutral (two prong plug).

If you have issues with an off-line UPS detecting a power fail and switching from the AC input to the battery generated output it should still work if the Roomba supply was correctly designed. Which in the case of Irobot may not be.

I have waveforms which may not be shareable (proprietary) that show a off-line UPS produces a 20ms glitch but then provides a decent sign wave to the output after fail-over. Your mileage probably varies.
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Re: Roomba should not be used on a UPS.

Postby RTC » August 28th, 2018, 11:00 pm

mfortuna wrote:If you have issues with an off-line UPS detecting a power fail and switching from the AC input to the battery generated output it should still work if the Roomba supply was correctly designed. Which in the case of Irobot may not be.


As the manual on page 5 clearly states that the Roomba should never be plugged into a "power converter" (and a UPS is a type of power converter), clearly the Roomba supply was not correctly designed (iRobot admits it, although their support people don't seem to have been informed). The manual tells you that so that you are aware of the problem (if you are technically knowledgeable enough to know what they are saying and you read the only place in the manual where they say it). Unfortunately page 5 is in the Battery section (you don't plug the battery into an outlet), not the Home Base section (you do plug the Home Base into an outlet), making it easy to completely overlook (which I did when I relocated the Home Base into another room) this warning.

The warning on page 5 also states that just plugging into a power converter voids the warranty. It does not matter if the power converter is off-line or on-line (or chopper output or sine wave output), the warranty is void.
Although it is not clear in the manual if it voids just the Battery Warranty or the full Roomba Warranty. Being that page 5 (where the warning is) is in the Battery section it might only be the Battery Warranty that is voided by plugging into a power converter (e.g. UPS, DC to AC inverter).
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Re: Roomba should not be used on a UPS.

Postby gregj » September 18th, 2018, 9:40 am

next thing they will tell us is that we can't charge roomba of solar..
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Re: Roomba should not be used on a UPS.

Postby RTC » September 19th, 2018, 10:53 pm

gregj wrote:next thing they will tell us is that we can't charge roomba of solar..


Well, as a solar powered house must use a power converter (e.g. inverter) to convert the DC provided by the solar cells to the AC needed by the Roomba's Home Base, they already told us that! And they also told us doing so voids the warranty.

It is in the text of the Battery section of the manual. I asked them to clarify things by also adding the notice to the Home Base section.
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