Review on Tenergy 14.4V 3850mAh NiMH Battery for iRobot Roomba 900/800/700/600/500 Series - Extended Life 🔋 1000 Cycles, Vacuum Replacement Batteries with Bonus: 4 Side Brushes & 1 Brush Cleaning Tool by Yousef Dudley

First I ordered two different batteries which said they were 4500mah and got a lot of good reviews but the run time on both was no better than the first. a well used 6 year old battery which I replaced. I have a charger that can measure actual battery capacity and the ones tested are only around 2000mAh which is less than half of the advertised capacity. I should have known given the low price, but I was fooled by the positive reviews. Then I decided to try this Tenergy pack and ordered a pair for my robot vacuums. They cost about 50% more than previous batteries I've tried, but they're still significantly cheaper than the OEM packs that iRobot sells. What a difference it makes, after charging it overnight I ran a cycle to clean everything on top and when Roomba returned to the dock over 90 minutes later the light was still green, great! I installed another one below in my Roomba and it works the same. I measured the capacity and when discharging to 10.5V at a discharge rate of 1.5A I got 3350mAh which is a little under the advertised capacity but pretty close and the actual performance of my Roombas is much better. Now the life cycle remains to be seen, they claim to have a longer lifespan but only time will tell if they live up to it. I have a couple of cats and I quite actively tuck my Roomba into the quilt to keep up with the fur and the trash they throw around, usually 5-6 times a week and I have quite a thick carpet in my bedroom, which gives them a good workout. Getting a few years out of the battery before it noticeably degrades makes me feel like I got my money's worth. I will update this review when I have something new to report.