I have a Roomba (600 series) that has served us great in the last 4.5 years. Probably the best value for money purchase ever.
In the last year or so it hasn't run very long after each recharge. I bought a third-party battery pack, which helped at first but after about 6 months it also quickly runs out of charge (running time is now less than half an hour).
I'm thinking of buying a new OEM battery pack but it's quite pricey ($169). Do you think it will help, or is there any problem which I should be aware of for a Roomba at this age? Thanks.
I haven't heard of a device drawing more power as it ages, normally it's just the battery that wears down and needs replacing. I too bought a third party battery for one of the Xiaomi Roborocks I have and it crapped out in less than a year. I then bought an OEM one from the Xiaomi store in Sylvia Park and it's still going strong two years later.
Given this I assume you may have the same result so all you probably need is an OEM battery.
Edit: In saying that, 4.5 years for a robot vacuum means it will be showing it's age and it's likely you may encounter another hardware issue with it soon. Instead of getting a new battery, it might be time to sell it off and get a new one. Or if you don't think you will get much back for it and you have a small area in your house you want to automatically clean separately e.g a garage, you may want to relegate it to there as it won't matter if it only has a short run time.