Lead acid batteries

All the batterys we use on emergency equipment would last 4 years now they only last1 1/2 to 2 years with a charger on them to prevent heavy drainage. may be its the recycled lead ,you cant get fresh lead anymore? but the electrical loads have gone down with led lighting and the alt. puts out 300amps about a 33% higher then needed. to keep up 4 group 31 batterys at 4800 amp hours.