Roomba 880 melting charging contacts

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Re: Roomba 880 melting charging contacts

Postby TechGuy » January 8th, 2016, 12:54 pm

robocleaner wrote:...
Trust me... the problem lies with a bad electrical positive contact between the robot contact and the charger contact. I'll put good money on that bet!


I agree with the bad contact between the home base and 880 charging contact. Bad contact = high resistance = heat.

I am wondering that those 880 with melting contacts are those used on hard surface floor.
Those 880 used on carpet may not have the same problem as the carpet is acting as self-leveling mechanism to let 880 with good home base contact. I may be wrong. Please post your finding.
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Re: Roomba 880 melting charging contacts

Postby GermanRoombaUser » January 8th, 2016, 1:09 pm

TechGuy wrote:I am wondering that those 880 with melting contacts are those used on hard surface floor.
Those 880 used on carpet may not have the same problem as the carpet is acting as self-leveling mechanism to let 880 with good home base contact. I may be wrong. Please post your finding.

No. My home base is on (ok, quite thin) carpet. But level is not a problem in my opinion, Roomba also docks on hard wood floor. Some shaggy carpets can maybe help to self clean the contacts. But could also be wrong if you think of electrostatics.
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Re: Roomba 880 melting charging contacts

Postby vic7767 » January 8th, 2016, 1:33 pm

The 880 used here in the shop environment uses a home base located on berber style low pile carpet. There is no sign of discoloration or other damage to the charger contacts on the Roomba or home base.
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Re: Roomba 880 melting charging contacts

Postby TechGuy » January 8th, 2016, 1:45 pm

GermanRoombaUser wrote:
TechGuy wrote:I am wondering that those 880 with melting contacts are those used on hard surface floor.
Those 880 used on carpet may not have the same problem as the carpet is acting as self-leveling mechanism to let 880 with good home base contact. I may be wrong. Please post your finding.

No. My home base is on (ok, quite thin) carpet. But level is not a problem in my opinion, Roomba also docks on hard wood floor. Some shaggy carpets can maybe help to self clean the contacts. But could also be wrong if you think of electrostatics.

I used "self-leveling" for lack of better words. The carpet may act as "spring" to push the home base up against the 880 to get better contact.
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Re: Roomba 880 melting charging contacts

Postby robocleaner » January 9th, 2016, 6:27 am

Dargo's post gives the best clue yet...

Note the profile of the plastic around the positive dock contact in Picture 1 (reproduced below).

charger contact.jpg
charger contact.jpg (46.58 KiB) Viewed 7203 times


Now note the deformed plastic on the mating contact of the robot on Picture 2 here:

robot contact.jpg
robot contact.jpg (36.84 KiB) Viewed 7203 times


Ideally when charging, the charger contact would mate at the centre of the robot charging contact making good electrical contact.

However, the profile of the charger plastic being embedded into the underside plastic of the robot suggests this robot is travelling TOO FAR onto the dock plate (or at a slight angle) sufficient that the charger contact is being held AWAY from the robot contact, causing current to jump and heat the metals.

Make sense?

Someone with this robot maybe needs to visually check the contact positions when the robot is docked, and maybe experiment using a packing piece at the head of the dock to prevent the robot riding up too far onto the dock when charging?
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Re: Roomba 880 melting charging contacts

Postby aarolar » January 9th, 2016, 11:33 am

Ok I'm now very interested in this discussion I have a new 880 that is still within its 30 day trial and I'm very happy with its performance but the wife mentioned to me today that she thought it was clicking while on the charging base. Ironically I had just read this thread front to back so now I'm wondering if I should be concerned, I'm ocd about keeping it clean as I'm always messing with something and it gets serviced two or three times a week so I know the contacts are clean yet I still see arcing on the base contact. So what course of action should I take maybe call Irobot and confront them about it and see what they say or wait it out and see what happens?
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Re: Roomba 880 melting charging contacts

Postby vic7767 » January 9th, 2016, 11:41 am

aarola Can you describe your home base location and what surface it is located on. There seems to be a trend that if the base is located on carpet, it is less likely to cause issues due to better electrical contact between the base and the battery plates on the underside of the 880.
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Re: Roomba 880 melting charging contacts

Postby aarolar » January 9th, 2016, 12:05 pm

On hardwood in my hallway I have no carpet in my house at all besides area rugs. The base is secured using carpet tape because it slid all around when it tried to dock.

ETA the arcing was very light in fact I was able to polish it off with only my thumb.

uploadfromtaptalk1452355455257.jpg
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Re: Roomba 880 melting charging contacts

Postby vic7767 » January 9th, 2016, 12:55 pm

Is there still an audible clicking sound? As a possible test, consider using a very low pile carpet sample similar to outdoor carpet to place the home base on and then test for audible clicking during a charging session.
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Re: Roomba 880 melting charging contacts

Postby aarolar » January 9th, 2016, 4:19 pm

vic7767 wrote:Is there still an audible clicking sound? As a possible test, consider using a very low pile carpet sample similar to outdoor carpet to place the home base on and then test for audible clicking during a charging session.


I'm going to keep my eye on it and see and listen out not really planning to go out and buy some carpet to test it with.
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Re: Roomba 880 melting charging contacts

Postby GermanRoombaUser » January 9th, 2016, 6:58 pm

vic7767 wrote:There seems to be a trend that if the base is located on carpet, it is less likely to cause issues
Trend based on what kind of data? As I mentioned, my damaged Roomba was home based on carpet.
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Re: Roomba 880 melting charging contacts

Postby GermanRoombaUser » January 9th, 2016, 7:03 pm

robocleaner wrote:However, the profile of the charger plastic being embedded into the underside plastic of the robot suggests this robot is travelling TOO FAR onto the dock plate (or at a slight angle)
You cannot know if this is cause or effect. Maybe this only happened because of another event happened before.
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Re: Roomba 880 melting charging contacts

Postby robocleaner » January 9th, 2016, 7:36 pm

GermanRoombaUser wrote:
robocleaner wrote:However, the profile of the charger plastic being embedded into the underside plastic of the robot suggests this robot is travelling TOO FAR onto the dock plate (or at a slight angle)
You cannot know if this is cause or effect. Maybe this only happened because of another event happened before.

No, I do not know... that's why I used the word "suggest". But as a qualified electrician who has seen enough wiring running hot through bad contacts and over-current over the last 40 years, and to see the impression of that wiring being left on adjacent mouldings, the transfer of that arched impression is a very strong indicator that the charger contact is sufficiently offset from the robot contact plate to cause arcing (the cause) and the melting/pitting/blackening/smell of melting plastic (the effect).

All I am suggesting is that someone who owns this 800 series model visually checks to see if that offset position suggested by this transfer of shape would in fact be possible (probably through simple misalignment when docking)... to either add weight or eliminate such a theory.

EDITED to add additional pic to help explain reasoning/theory:

Signs of arcing and heat from poor contact.jpg
Signs of arcing and heat from poor contact.jpg (56.32 KiB) Viewed 6958 times
Last edited by robocleaner on January 10th, 2016, 8:45 am, edited 1 time in total.
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Re: Roomba 880 melting charging contacts

Postby vic7767 » January 9th, 2016, 7:45 pm

GermanRoombaUser wrote:Trend based on what kind of data? As I mentioned, my damaged Roomba was home based on carpet.
The data I based that statement on is from personal experience with several 800 models that I operate as well as several comments sent to me via my web sites.
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Re: Roomba 880 melting charging contacts

Postby mroogi777 » January 26th, 2016, 10:06 pm

Have the same melted dock/charging plate issues with our 880 (only a year and a half old). Upon reading through the many posts, I noticed someone said the short may be caused by an uneven surface. We have our charging dock on the edge of the CARPET in the living room BUT the roomba rests on the LINO in the dining room !!! thus, there is an uneven pairing of robot and docking station which MAY explain the shorting contacts. Any ideas where a person can order replacement parts for the dock ... I've managed to "fix" the contacts on the machine itself. Any help would be greatly appreciated.
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Re: Roomba 880 melting charging contacts

Postby TechGuy » January 26th, 2016, 10:30 pm

mroogi777 wrote:Have the same melted dock/charging plate issues with our 880 (only a year and a half old). Upon reading through the many posts, I noticed someone said the short may be caused by an uneven surface. We have our charging dock on the edge of the CARPET in the living room BUT the roomba rests on the LINO in the dining room !!! thus, there is an uneven pairing of robot and docking station which MAY explain the shorting contacts. Any ideas where a person can order replacement parts for the dock ... I've managed to "fix" the contacts on the machine itself. Any help would be greatly appreciated.

Call iRobot for free replacement. iRobot knows about the problem. Some people called and got a replacement even their 880 are over 1 year old.
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Re: Roomba 880 melting charging contacts

Postby realworld2k » February 12th, 2016, 8:23 pm

I just replaced the chassis on my Roomba 880, because one of the charging contacts was sunk in because the area around it melted. Thank goodness the chassis only cost me about $40 BECAUSE TWO DAYS LATER IT HAPPENED AGAIN. I nearly took a hammer to it. The area around the contact on the charging station looks a little melted too, but it still functions. Is anyone having a similar problem or have a cure for this other than replacing the entire Roomba?
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Re: Roomba 880 melting charging contacts

Postby pa4wdh » April 2nd, 2016, 7:26 am

I also have the same issue with my 880, it got bad enough for the robot to drag the homebase with it when it started it's mission. Although it's nearly two years old I got a replacement 880 (service robot, without battery) and homebase under warranty.

Now what's interesting is that I have both robots and can compare them to see what's different. probably getting a clue on what was wrong in the first place. On the homebase the contacts have changed, the three "blobs" on both of them are gone so it's a smooth surface now, probably ensuring better contact. On the robot side I don't see any difference on the contacts but the springs on the battery seem to be a bit more firm now, it took a bit more effort to close the battery lid. Of course this could also be just be the difference between a 2 years old device and a new one.
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Re: Roomba 880 melting charging contacts

Postby a1robotrepair » April 2nd, 2016, 9:41 am

Great pics robocleaner. It appears the contact nubs of the dock were not a good idea, the robot sees contact with the dock when only a very small point of contact is made causing excesive heat at that point. As someone wrote, " driving on farther than it should have", the area of the bottom cover is raised, lower to floor, as compared to the charging plates, pushing the dock plates lower causing poor contact. The integration of the charger and dock doesn't appear to be a problem. A new 650 I just received has flat, no nub contacts, on the dock. I double face tape my dock to the tile floor.
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Re: Roomba 880 melting charging contacts

Postby Nunya » June 19th, 2016, 12:48 pm

Roomba 880 charging contacts melting defect confirmed.
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