Do you own an iRobot Roomba? Is your battery lasting about a year and then stops holding a charge?
Well you may rest assured you are not alone. The batteries used on these devices are not designed to last very long, or to run very many charge cycles, contrary to what the package and marketing material may say, you should plan to replace the batteries about every year or two, if you get two years out of it, consider yourself fortunate.
The batteries run around $40.

iRobot
Roomba Advanced Power System (APS) Battery # 4905

Features: High capacity battery compatible with Roomba 500 and 600 series robot vacuums Charges in 3 hours with APS charger Provides up to 100 minutes of run time 50 percent greater useful life than original Roomba batteries Not the original OEM battery from iRobot. Metapo is not affilated with iRobot Corporation. iRobot, Roomba and Scooba Battery: Battery: Voltage: 14.4V. 12 pcs high quality NiMH sub C cells in 2×6 configurations Capacity: 3300mAh Compatible with following Roomba models: * iRobot Roomba 510 * iRobot Roomba 530 * iRobot Roomba 532 * iRobot Roomba 535 * iRobot Roomba 540 * iRobot Roomba 550 * iRobot Roomba 560 * iRobot Roomba 562 * iRobot Roomba 565 * iRobot Roomba 570 * iRobot Dimensions: 5.7″ x 2.2″ x 2.5″ Labor: 180 days limited Parts: 180 days limited

Here’s one review:
Ordered this battery for my Roomba Discovery. Charged it up according to the manufacturer’s instructions. It worked great the few times that I used it and then stopped charging/working altogether. 🙁 Would not recommend this product if you want something that lasts more than a few months.