linyakov wrote:Hi Gordon re:batteries my one surviving battery is yellow and doesn't have any numbers.
They never did. To learn their capacity, we had to tear them open and read numbers on the cell sleeves. Yellow battery casings signified "APS" battery
(Advanced Power System), and, had NiMH capacities of 3000mAh or 3300mAh.
The two deceased are black and are 2200. I don't know if I mentioned that I have another one on the way! (another black one)
Yes, but w/o stating that you knew its color. iRobot
seems to be shifting to NiCd, totally.
... the company is asking me to send back the power supply the homebase and the robot. I am going to call them this AM and see if they will go along with idea of just returning the power suppy. However if they insist do you think from your experience that they would know the difference if I returned my first robot (which was truly a problem) and held onto the 2nd and good one?
Any "experience" that I possess in this arena is due to reading what others have done!
If I were to guess, I would say it depends on whether both of your 5XXs have the same model number, coupled with how precisely you have identified the offending robot.
Rather than returning the whole kit, I would be more inclined to keep everything, but buy a new PSU, to try. They are not too expensive, and a 2nd PSU on hand can be a good troubleshooting aid.
... Am I correct that when the power starts blinking and in the past I left my robot plugged in for extended periods in this state that it will start to drain the battery and kill the battery?
Providing a full answer to this question can require many words. You may not need or want them all. Mike's post might have come close to giving you the answers, but I can see it might require a little elaboration, so I will play off of his inputs in an attempt to be brief.
mfortuna wrote:If your battery is in the roomba and is not being charged (due to an unplugged or defective charger) it will drain to a point that is bad for both the roomba and battery.
First, I would replace the "or defective charger" phrase with "or inactive charging system
" to encompass both the PSU and robot's charging controller elex. Then, to expand on Mike's first sentence: An inactive charging system may be due to:
a) No AC power being supplied to the PSU.
b) the PSU has an internal fault (flashes its pilot LED ON/OFF), and can't deliver 22.5Vdc to the robot, or
c) the robot has an internal short-circuit which prevents a working PSU from increasing its output current to the normal 1.25A level (an action that causes the PSU to pulse its LED as it endlessly cycles between high power then low power, as a self-preservation tactic).
Any of (a) through (c) will prevent the robot from the normal switchover to "charging mode" (when IN charging mode, the system is powered by the PSU, and the battery-voltage is isolated (by bucking via a diode) by the higher level charging voltage') and the MCU senses this state, causing it to invokes its battery-charging routine). Hence, if the battery is not isolated (due to an inactive charging system) from powering the system, it must continue to power the MCU, as well as power what we call the "phantom load" which monitors Roomba's external space for a remote-control signal.
If no electrical fault exists in the battery section of the "system", it is the slow drain (only 0.006A, in a 4XXX Roomba) that will drain charge from the battery when an owner leaves the "...robot plugged in for extended periods in this state ...".
It is that tiny drain current, plus the battery's own self-discharge rate that can pull battery voltage down into dangerous (for the cells) territory below 12-volts (no load) in two to three weeks.
The 4XXX Roombas sometimes suffered failures of protective devices called "transient voltage suppressor" (TVS). TVS were connected across the battery-voltage terminals, across the battery-thermistor's terminals, and across the two PSU input ports. Some of the TVS failed by shorting themselves, while in the service of their robot. If that shorted condition happened to the TVS across the battery-voltage, you might guess that the time to drain the battery's charge would be very short! (A case like that would require a "resistive short", i.e., not zero ohms, else the charging controller -- if working right -- would sense too much charging current being required, then quit, and issue an error).
mfortuna wrote:Since you have a 500 series there may be less of a chance with a deeply discharged battery damaging the roomba's internal charging circuit.
This statement is partly explained by the preceding parenthetical info, IOW, a 5XX charging control circuit & firmware ought to be able to avoid starting a re-charge of a dangerously low-voltage battery (a condition that has high initial charging current); but, if battery voltage is at an intermediate low-level, say 9 to 12 volts, the controller may decide to start the re-charge but invoke a routine that has been designed to handle that case.
I wonder how long this might have been if I had not been "brief"(?)!
...Many thanks for your help in my growth! Linda
You are quite welcome!