My batteries are over 5 years old running two/three pumps 9 kw boiler and charged every night and they are still like new , these cheap and nasty ordinary batteries are not suitable for our type of use get a couple of gell 180 amp haze batteries they are brilliant. Your charger might need adjusting though , also some cheap chargers cook the batteries when charging , again a quality charger will charge at a slower rate , that won’t damage the battery , when I was cold I had the batteries you have got and found they lasted about 3-4 years