I can't speak to the gel batteries, but like Danny, my own Powersonic PS-121000U also lasted 8 years - Jan/2014 to Jan/2022. (I have 5 devices on it, split between 5V, 7.5V, 9V, and 12V, but I suspect the total current draw is pretty low.) I wonder if it might have gone longer if I'd been better about running the reconditioning cycle on the CTEK 7002 charger occasionally. I replaced that battery with the exact same model and now have a reminder on my phone to run the recondition cycle every 6 months.