Hi kathy-momx8,
Welcome to the RobotShop forum.
We received and answered your ticket that was sent through the support center yesterday with this same question; we will repost the answer here:
"iRobot has been recently updating some of their models. The 531 is the newer robot as far as production date goes. The main differences are:
The red CHM is the older style, and will pack up with hair inside it’s brush gears faster than the green one. As well, the newer brushes will pick up debris better overall.
The virtual walls have changed as well, they now have gone to compact, or auto-virtual walls on the 531; it depends on which model you have.
The brush cleaning tools also change according to the type of brush that comes with the robot.
As far as intelligence of the robot, we don’t have access to the manufacturer’s programming, but we know of no software change so far.
If you really prefer the voice demo, keep the 530 (though it’s not really necessary to use the robot or to learn what all the different features on the robot are). But considering the differences between the brush decks, we’d recommend the 531 because of it’s green brush deck, it will last you longer.
One thing to note: The 531 usually comes with auto-virtual walls, and they are only compatible with certain models of Roomba. As well, the difference between the ‘0’ and ‘1’ models of certain Roombas changes as you move from model to model. So far, the 530 and 531 don’t have too many differences, but other models have larger gaps in what the old ones would do versus the newer models."
A few other things we can point out to you:
The 530 and 531 may have different batteries. You may want to remove the bottom plate of the robot (you have to remove the side ‘corner’ brush first) to see what kind of battery you have in the robot. The 530, since it was manufactured in 2007, may have an APS battery in it (they’re yellow). These are the best batteries available for the Roomba. The 531 likely has a standard black or blue NiCD battery that should run fine, but will not run as long nor last as long as the APS yellow battery. That being said, the 530 is from 2007, and if it was sitting on the shelf at a distributors for a long time, it may be the battery has aged somewhat on the shelf. You would need to test the robots with their respective batteries to see which one lasts longest, or if either battery is running for shorter than normal.
The side brushes are different too. The older 530 has the six-arm version, which would break easier. iRobot upgraded the brush to the newer 3-arm design with harder rubber/plastic, so the brushes would last longer.
So there you have it. Some minor differences are the virtual walls, side brush, and the voice demo, while major differences would be the battery and brush deck. From the info we have now, we’d lean towards the 531 due to the green brush casing, but you must also take a look at the batteries and their performance, and once you have as much information as possible, make your decision from there.
We hope this all made sense; if you have any questions, do not hesitate to ask.
Thanks,
