Jun 28, 2025

Robot mops for large rooms, gyms or similar

For our sports club we tried to get robot mop to support our cleaning staff. So we tried a

  1. Dreame X40
  2. Roborock S8 MaxV Ultra
  3. Eufy S1 Pro

All of them a little bit different. A vibrating mop, rotating mops and a rolling mop...

But that kind of things do not matter - the challenge is:

Does the robot navigate in a empty room with next wall about +5m away. 

If you read all the advertisements about LIDAR, you think that this is no problem at all, but this is really problem.

One remark: None of these vendors promise anything for such conditions. All robots are for typical households. 

Dreame 

So let's start with the Dreame:

Mapping went well, but the robot stopped in the middle of the gym with "Laser distance sensor error". 

So even the robot had a complete map - no chance to do the cleaning. It just stopped and was not even able to return to the station. 

Roborock 

What about Roborock? Even worse. During the mapping phase, the robot was only able to drive on the area, which was already detected. And detection is only possible if the LIDAR is reflected. Workaround: Walk around, because he can recognize humans and the area between the robot and you is tagged as detected:

You can still recognize the black area which was not detected - which means the robot will not clean there. And the proportions do not fit. Means the robot lost orientation so the gym is some meters to short...

And: LIDAR error when 5m away from the walls... no return to base station possible. 

Eufy

Mapping did not work. Funny thing: the app was showing the path of the robot with a white dotted line. The map is not drawn in the correct way - it is point mirrored. But this does not matter. The real problem is, that the wall on the left of the picture is there twice and it does not match. So the robot lost some meters on one side of the gym: 

The robot itself got so confused with that double wall, that it hits the wall several times and then it was not able to finish the mapping. I forced the robot to return to the base station and it bravely tried to cross the gym - stopped in the middle with:

"Lidar scanning abnormal" - that means nothing to detect :( 

Summary

May be i start with a word to the developers, which are responsible for such algorithms: If there is nothing to detect, than of couse the LIDAR might be blocked. But consider an empty gym: Then you can send this error, but if the users confirms, that LIDAR is not blocked - ever considered just to keep speed and direction until a wall is detected?

If anybody has comments please let me know! Ideas are welcome! 

Jun 27, 2025

Small Solar Plant with Growatt Nexa 2000

Requirements 

There are many drivers for using solar power at home. Key requirements for me were

  • Storage with off grid functionality
  • Deliver max. 800W on grid (due to german regulation) 
  • Solar input up to 2000W
  • Battery with >1kWh

Decision 

My decision was to buy a Growatt Nexa 2000


Installation (non IT parts) 

Physical installation (wiring, etc.) was easy. Just connect :) 

Installation (IT part) 

Connecting the device to the network was very well explained in the manual and the app confirmed the connection. But:

  • Device is shown as offline in the app
  • In you Wifi you can not find anything like "Nexa" or "Growatt"

What can you do? I tried to delete the device in the app and repeated to onboarding. Best thing you can do is:

WAIT 

Because the device was shown in my network with its serial number 0XXXXXXXXXXXX072 and an IP used (and i could ping it).

After 30 minutes the app started to show the device as "online". But changing the configuration did not work. 

After another wait (may be another 10 minutes) adjusting the operation mode could be change (load first <-> battery first).

Now (after >2h) i was able to start the firmware update (the app signaled from the beginning, that an update has to be installed).

But that stalled by 83% - device went offline (i did a ping all the time). Came back, went offline again, came back, .... Then: close the app, enter app again and firmware version is from 9.05.05.04 to 10.09.07.07 and ping is working faster than before. With stalling at 83% i thought, i lost the device completely but it went well and works better than before...
 

I am not sure, if i just hit an maintenance on Growatts side or the device onbaordings are queued and until you can fully operate, some time has to pass.

Integration

The app is quite nice, but for all other things i have my grafana dashboard. So next is to see, how to extract data from the Nexa.  

I will tell about my attempts in the next weeks :)