Roomba Power Supply - iRobot Roomba 570 Service Manual

Roomba Power Supply

Roomba's are charged by either a Universal (100-240V) or Domestic (120V) Power Supply. The
Power Supply steps the voltage down to 22.5VDC and 1.25A. A solid green LED light on the Power
Supply is an indication that it is plugged in and operating properly.
Roomba 500 Series Charging Algorithm Overview
High level sequence
1. Check charging FETs – If FETS fail then charging is aborted
2. Pre-charge cooling { 0mA } - Runs until battery temperature is less than 50°C, or an end
of charge condition is true. Sets the charging state to NORMAL or RECOVERY based on
the battery voltage.
3. Charging - Runs until an end of charge condition is true, in one of the following modes:
a. Normal { 1250mA } – for initial battery voltage greater than 10.8V .
b. Recovery { 300mA } - for initial battery voltage less than 10.8V .
4. Post-charge cooling { 0mA }- Runs until battery temperature is less than 35°C, or 2hrs
passes. Sets charging state to WAITING/TRICKLE.
5. Trickle { 50mA }- Runs indefinitely. If the temperature goes above 42°C, trickle turns off
until the temperature drops below 40°C, then re-enables.
End of charge conditions
Charging is terminated as soon as one of these conditions is true. These conditions are tested in
variable times during charging.
o Voltage Dip : Voltage dips more than a 30 mV from the maximum voltage.
o Temperature Slope : Temperature increases by more than 0.5°C per minute.
o Coulombs Max : If battery level is more than 2 times the nominal capacity.
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