Robot Reviews

Troubleshooting the Roombas

• Which Model do I have?
• Roomba 5xx Troubleshooting
• Roomba 4xx Troubleshooting
  • How do you know that your battery is at the end of its useful life or your Roomba charging circuit is not working?

Symptom:

After charging the battery overnight, the power light turns solid green.  Press clean button.  Roomba power light turns red and do nothing.

Reset the Roomba and charge the battery 16 or 72 hours without interruption.  Results are the same.  Red power light and Roomba does not moved.

How do you know that your battery is at the end of its life or your Roomba charging circuit is not working.  Do the following tests before opening your wallet for a new battery.

Tests:

There are quite a few methods which can be used to check the battery.  Some methods require a multimeter to measure the battery voltage or an automotive tail light bulb for battery load test.  My test method only requires 2 pieces of wires.  I called it “Charge Battery Directly Without Roomba” method.

You can charge the battery directly using Roomba charger without Roomba.

• Connect the charger positive terminal to the battery positive terminal (RED wire)
• Connect the charger negative terminal to the battery negative  terminal (Black wire)
• Charging too long may damage the battery without the overheat shutoff protection. Please do not leave the charger and battery unattended during the 15 minutes.
• If your battery runs your Roomba longer than a few minutes after 15 minutes charge, your battery is good. The U2 and U4 MOSFETs on your 400 series Roomba may have failed.
• Make sure you get the polarity correct. Reversing it will damage either the battery,charger or both also doing this could also cause fire. Another thing to check is that bare wire is not touching as this will cause a short and cause the same affects as mentioned. If you are not confident that you can do this safely, don't do it
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• Roomba 4xxx Troubleshooting
• Roomba Original Troubleshooting
• Troubleshooting with Roomba SCI Cable
  • How to use Roomba SCI cable to diagnose the Roomba charging circuit failure?

Lot of Roomba or Scooba information can be obtained by connecting Roomba SCI cable to the Roomba or Scooba SCI port.

• Use a terminal program such as Windows Hyperterminal or realterm to read data from the Roomba SCI port.  For 400 Series Roomba set the PC serial port to 57600 baud, 8 data bits, no parity, 1 stop bit and RTS/CTS handshake.  For the 500 Series Roomba, use 115200 baud.
• Connect the charger directly to the Roomba without the homebase.
• Roomba will send out charging messages to the terminal.
• The following output message indicated that the battery voltage was around 16.2V and the charging current was around 1.3A.  The charging circuit in this Roomba was working.  The Roomba was putting power into the battery.
• bat:   min 2  sec 24  mV 16198  mA 1335  deg-C 10  
  bat:   min 2  sec 25  mV 16198  mA 1348  deg-C 10  
  bat:   min 2  sec 26  mV 16198  mA 1328  deg-C 10  
  bat:   min 2  sec 27  mV 16198  mA 1354  deg-C 10  
  bat:   min 2  sec 28  mV 16198  mA 1328  deg-C 10  
• The following output messages indicated that the battery voltage was around 13.97V and the charging current was around -50mA.  The charging circuit in this Roomba was NOT working because the current was flowing in the wrong direction. i.e. power was drawn from the battery to power the Roomba.  The Roomba charging circuit was not putting any power into the battery.
• bat:   min 22  sec 0  mV 13971  mA -39  deg-C 27  
  bat:   min 22  sec 1  mV 13971  mA -59  deg-C 27  
  bat:   min 22  sec 2  mV 13971  mA -46  deg-C 27  
  bat:   min 22  sec 3  mV 13971  mA -59  deg-C 27  
  bat:   min 22  sec 4  mV 13971  mA -46 deg-C 27