Roomba 780 vs others: power consumption vs. cleaning ability

[piokrza]

Just found some reviews of robotic vacs (french gadget reviewer: http://www.lesnumeriques.com) and want to compare them together.

Cleaning ability spec:
(rice spilled on hard floor/carpet in 12 sqm/129 sqft room)

*Roomba 780:
93%/40%/21min
66/68dB on carpet/hard floor (declared: 70dB)

*Samsung Navibot "Silencio" SR8895:
96%/42%/7min
58/65dB (declared: 62dB)

*LG RoboKing VR5902KL:
nd/40%/nd (cocoa powder!; faster than Samsung Navibot SR8855);
48/55dB (declared: 50dB; most quiet bagged vacuum = 63dB, Dyson DC29 Allergy bag-less canister = 80dB)

*Philips Hom-Run:
95%/17%/22min
70dB
(two times slower than Samsung "Navibot" SR8895)


Power-consumption comparative spec:

*Roomba 780:
27W /4W (charging/stand-by)
€6/year more expensive in use than Dyson DC29 canister (regular use - twice a week)

*Samsung Navibot "Silencio" SR8895:
12W/1.7W
€2.6/year (consumes twice as much power as Electrolux Ergorapido* hand vacuum, or half of the Dyson DC29** canister vacuum consuption; comparable to the annual use - twice a week - of 1800W canister vac)

*LG RoboKing VR5902KL:
<6W/<3W
€2.5/year
26kWh/year (comparable to the annual use - twice a week - of 700W canister vac)

*Philips Hom-Run:
40W/<1W
€3.5/year (less than regular canister - more than regular upright or other robotic vac)


__
* - Electrolux Ergorapido; 3.5W/1W (charging/stand-by; 6 times less than conventional vacuum cleaner, but when used less regularly); operation cost is less than €1/year; 75dB (less in "silent" mode)
** - Dyson DC29 Allergy Canister; power: 1360W (declared: 1400W; efficiency comparable to regular 2000Watt vac) €5/year (when used twice a week for 20 minutes; other >2000W vacs - €6.5/year), 80 (tested)/82dB (declared)

[Gordon]

Just found some reviews of robotic vacs (french gadget reviewer: http://www.lesnumeriques.com) and want to compare them together. ...
Power-consumption comparative spec:

*Roomba 780:
27W /4W (charging/stand-by)
€6/year more expensive in use than Dyson DC29 canister (regular use - twice a week) ...
__
...
** - Dyson DC29 Allergy Canister; power: 1360W (declared: 1400W; efficiency comparable to regular 2000Watt vac) €5/year (when used twice a week for 20 minutes; other >2000W vacs - €6.5/year), 80 (tested)/82dB (declared)

Peter, I must tell you that I have very little confidence in what that '"french gadget reviewer" has to say about power consumption. I did some quick calculations showing the "27W" value is too low, and the "4W" value is too high. I also think that 40-mins per week of 1400W canister cleaning can't compare (on a floor area coverage basis) to 2 * 2h = 4 hours per week of Roomba floor sweeping. Based on these simple errors I tend to disregard their entire report.

FYI, I estimate the canister, at the designated use-rate, consumes 488 Wh {WRONG, it should have been: 48.8kWh} per year, and the 780's consumption would be about 11kWh per year for high-rate charging plus maintenance charging {at a 10mA rate}. "stand-by" is not defined in the article, but I can't see it as being maintenance (trickle) charging.

Question: In your area, at the present time, how many kilowatt-hours will one euro buy?

[piokrza]

Gordon, thank you for correction

You're right. When I wrote about "stand-by" I had in mind this "tricle charging" stage

Answer to your question is: 1kWh cost €0.1329, so for €1 i get 7.52kWh.

[gangel]

Ok well im in australia and currently running tests on my 780 bought from USA (then power modded to AUS 240v)

-I'll post the rest of the details in a few hours after my first run, but im getting:
1.1W for when roomba is doing his run
4.1-6W when he is on trickle charge

... when he finishes his run i can tell you what hes charging at.

I bought a little machine that tells me all the values, so ill write them in. Hoping somone can interpret if the power mod was ok or if it was botched

My post on this subject is here:
viewtopic.php?f=1&t=15444

[Gordon]

... but im getting:
1.1W for when roomba is doing his run
4.1-6W when he is on trickle charge

gangel, when you say words like "roomba is doing his run" it makes me think you are measuring operating power of the robot while it is on a cleaning mission. Is that what you mean? If so, then your "1.1W" power value is not a valid number of watts; it would be more in the range of 20 to 30 watts.

Next, I have a couple questions about measurement of the 4.1-6W range. 1) Were those data acquired with a Home Base between Roomba and its PSU. 2) How were you assured the Roomba was doing trickle charging?

... when he finishes his run i can tell you what hes charging at.

It would be good of you to make two sets of measurements, one with the Home Base in use, and one while charging via Roomba's side jack.

I bought a little machine that tells me all the values, so ill write them in. Hoping somone can interpret if the power mod was ok or if it was botched

My current thinking on that matter is: If the PSU can still charge Roomba's battery there will be no indication of excess power being used to operate the PSU. Power input should be on the order of 33 watts during the high-rate charging period. And, if the PSU's conversion work failed to also upgrade or remove the original MOV, it probably removed itself (by exploding). You would have to look inside the PSU's case to learn whether that happened.

[gangel]

Hey gordon:
"doing his run" is measuring home base power use whilst roomba isnt on it (getting 1.1W)
whilst he is charging after a run i get 31-32W for about... an hour and a half charge
Whilst he is sitting on base overnight etc he gets ~4-6W

I havent worked it via the jack yet, ill do that if you think i need to

[piokrza]

Hey gordon:
"doing his run" is measuring home base power use whilst roomba isnt on it (getting 1.1W)
whilst he is charging after a run i get 31-32W for about... an hour and a half charge
Whilst he is sitting on base overnight etc he gets ~4-6W

I havent worked it via the jack yet, ill do that if you think i need to

In this situation these data taken from lesnumeriques would be true...

[Gordon]

Hey gordon:
"doing his run" is measuring home base power use whilst roomba isnt on it (getting 1.1W)
whilst he is charging after a run i get 31-32W for about... an hour and a half charge
Whilst he is sitting on base overnight etc he gets ~4-6W

I havent worked it via the jack yet, ill do that if you think i need to

In this situation these data taken from lesnumeriques would be true...

Peter, to claim that "...data taken from lesnumeriques would be true" is simply too all encompassing. One must select single elements which to apply true or false claims. As an example I will review your quoted gangel data:

1) "measuring home base power use whilst roomba isnt on it (getting 1.1W)". W/o have made such a measurement myself, I see no reason to question the 1.1W value for the sum of the powers of PSU operation powering an unloaded Home Base. However, there is the possibility that the HB shuts off power to its three IR emitters once Roomba docks, hence, the power to operate an HB while charging the Roomba battery might be reduced. IOW, "1.1W" could be greater than true value experienced throughout a charging event.
2) "whilst he is charging after a run i get 31-32W for about... an hour and a half charge". I view this as correct. The data are in agreement with iRobot's PSU label, and I have made matching charging power measurements on earlier Roomba models. (So you see, lesnumeriques is wrong about this input power.)
3) "Whilst he is sitting on base overnight etc he gets ~4-6W". It is this one that I can not reconcile. I think it must be too high by about factor 3X. It is this trickle charger period, occupying most of the time when Roomba is in charging mode, that it is important to know the power being used to operate the Home Base, if in use.

Regarding element (3), let us assume the 780's trickle current is 50mA, i.e., same as for the 5XX series (value seen in its service manual). One may work back to the PSU's input power by comparing ratios of input power vs output current for cases of high-rate charging and trickle charging, in this manner: (33W / 1.25A) = (P_trick / 0.05A); now solve for "P_trick", as: P_trick = 0.05A * (33W / 1.25A) = 1.32W estimated PSU power input for trickle charging Roomba at its side charging jack. I think that value is a little inaccurate due to a shift in PSU efficiency from high load to very low load. I'm guessing, but I think the PSU becomes more efficient, which if true would reduce the 1.32 number. The point is: Trickle charging w/o use of an Home Base consumes on the order of only one watt.

If one then deducts that 1W from element (3)'s "4-6W" we have 3-5W, and further deducting the ~1W from element (1), to account for the HB being in the charging path, we are left with 2-4W of excess power. Who can explain what is causing that power dissipation? Its a mystery to me!

[Gordon]

In my previous post I wrote about being mystified by the 780's trickle-charging (a.k.a., maintenance-charging) power consumption measurement being in what I thought to be a high range of "4W-6W", so I set about making power measurements (actually E & I data were acquired, then converted to watts) on the iRobot hardware on hand. I have no Roomba 780 to play with, thus I was limited to using old 4XXX Discovery series (R2), and 5XX series (R3) PSUs and Home Bases. Their robots, containing batteries and charging controllers, were not involved at all in the measurement process.

Indeed, I learned that the older iRobot equipment hovered around the 4W level while doing simulated trickle charging, with R2 being above 4W, and R3 being between 3W & 4W. Therefore, its not beyond reason to imagine the 780 charging system behaving the same way in the trickle charge region. I can also imagine that iRobot has little concern about how much it costs it customers to power Roomba's charging apparatus annually, hence, the 780 may not have been designed to give any cost relief.

FWIW, here is a summary of estimated electric power consumptions of the R2 & R3 items (PSU, the HB+PSU, and the HB) singly and in combination:

{Measurement details may be found in the attached text document.}

While taking data I learned that Home Bases switch off their IR emitters (RED & GRN buoys + force-field) as the HB recognizes it has the equivalent of a docked robot across its charging contacts. The R2-HB operating power halved (approx.) under its docked state, while the R3-HB seemed to not benefit at all.

For the first time I was able to see for myself that the R3-HB switches its RED & GRN buoys (probably the force-field IRED too, but that action was difficult to see under my room lighting) IREDs ON/OFF at approx. 1s ON, 1s OFF. This action (~50% duty cycle) may be largely responsible for the reduced power consumption of an R3 HB.

[Gordon]

Just found some reviews of robotic vacs (french gadget reviewer: http://www.lesnumeriques.com) and want to compare them together. ...
Power-consumption comparative spec:

*Roomba 780:
27W /4W (charging/stand-by)
€6/year more expensive in use than Dyson DC29 canister (regular use - twice a week) ...
__
...
** - Dyson DC29 Allergy Canister; power: 1360W (declared: 1400W; efficiency comparable to regular 2000Watt vac) €5/year (when used twice a week for 20 minutes; other >2000W vacs - €6.5/year), 80 (tested)/82dB (declared)

Peter, I wish to numerically challenge three errors that I see in the Roomba / Dyson data that was published by lesnumeriques. While I must now postpone any further comments about Roomba's "4W" trickle charging power, I would like to attempt correction of these errors that lesnumeriques is propagating. They are:

A) "27W" as the input power to a 780 Roomba (or any other Roomba that uses a 22.0V/22.5V, 1.25A PSU) during the high-rate portion of battery charging.

B) "€6/year more expensive in use than Dyson DC29 canister (regular use - twice a week)" is backwards. The Dyson DC29 will cost about the same to operate as a 780 Roomba while Roomba spends 6X more time working. IOW, lesnumeriques' claim that a 780 will cost €(5 + 6)/year = €11/year, can't be true.

C) "€5/year (when used twice a week for 20 minutes...)" as the cost of operating the Dyson DC29 canister is less than what Peter would pay for the energy total that I compute. Either lesnumeriques' energy estimate is less than mine, or energy rates are not universal across Europe. If all computations have been correctly done, the fault here is lack of universal expression of energy consumption. A better tactic for expressing the differences is by ratios of energy consumptions, and omission of currency.

I will discuss the above list elements in the same order:
======================================================================
========= "A) '27W' as the input power to a 780 Roomba during .......========
========= the high-rate portion of battery charging."...................========
======================================================================

"27W", as lesnumeriques indicates is wrong because it does not match the input power listed by iRobot on the PSU's label. Also, 27W is roughly equivalent to the PSU's output power, viz., P = E,(V) * I,(A) = 22.5V * 1.25A = 28 watts; and, we know the PSU's input power must be greater than its output power because the conversion from input to output is not lossless.

=====================================================================
========= "B) '€6/year more expensive in use than Dyson ..........==========
========= DC29 canister(regular use - twice a week)' " .............==========
=====================================================================

Discussion of this statement is muddied by the "(regular use - twice a week)" wording. Are we to assume twice a week, 20-mins Dyson cleaning and twice a week 780 cleaning until battery depletes; or, is it 20-mins twice a week for each machine?

I will proceed without an answer to that question, and simply presume Roomba operates for 2-hours each session, or 4h per week. To estimate the energy cost of operating the 780 for each cleaning event, I will draw on a post that was prepared for gangel, in which two tables organized time periods that various power consumptions occurred to prepare Roomba for a cleaning mission. See the "Appendix", ending this post, to review allocated time periods and reasonable power dissipations (factors which have been adjusted for use in this post).

From the calculations in the appendix the energy expense of operating a 780 Roomba for 52 weeks is: 43 kWh.

From element (C), below, the energy cost of operating the DC29 canister twice each week over 52 weeks is: 47+ kWh.

Roomba spends 6X more time working, but uses less energy than the prescribed Dyson operation!

===========================================================================
======= "C) '€5/year (when used twice a week for 20 minutes...)' " .........========
===========================================================================

Relative to the DC29 Canister, I don't know what "declared: 1400W" means, so I will use the Dyson stated power consumption of "1360W" in the annual energy usage calculation for 52 * 2 * 20-minute sessions each year. This results in a total energy accumulation of: e,(Wh) = (52instances/year) * (2/3)hour/instance * 1360 watts = 47147 watt•hours/year, or 47+ kWh/y.

If Peter were to pay for this energy, his annual bill would be:
(€0.1329/Wh) * 47.147Wh/y = €6.27
to operate the DC29 in the manner described. Note that my calculated expense is €1.27 larger than the lesnumeriques' value (of "€5"); and, that could be due to differences in district (Peter's vs. lesnumeriques') rates, or due to miscalculation of the required energy by lesnumeriques (it does not display any calculations, only results), or a combination of both.

================================ IN SUMMARY =============================

List element (A) has been shown untrue.
List element (B) has been shown untrue.
List element (C) has been shown to be questionable.

I again suggest that nothing reported by lesnumeriques is worth spending
time reading.

=========================================================================
================================= APPENDIX ==============================
=========================================================================

=========================================================================

[lucabtg]

I have a Roomba 780 from about one month - dispite to the fact I'm satisfied from the robot itself I was a little surprised about the fact that it never turns off when it's docked.

I checked it with a power comsumption meter and the result is that our little friend consumes 11.8W in standby status - even if it's fully charged it uses almost 12watt!!
This means 103kW every year. In my country the electric power is quite expensive and the  bill for this is ~40 usd.

After this check I was thinking to use a 24hrs timer to disconnect the Roomba power supply during the night. I could power it off for 8 or 12 hours during the night ...

Is there anyone doing something similar?
may the battery be affected?

Thanks,
Luca

[vic7767]

Just remember that there are active circuits that are always on inside the Roomba (remote control IR sensor) System Clock, various battery status registers, etc. To stop battery discharge will require that the battery be removed from the robot when not running a cleaning session or charging.