BATTERY CHARGING TECHNIQUES Sealed lead acid batteries may be charged by using any of the following charging techniques: Constant Voltage Constant Current Taper Current Two Step Constant Voltage To obtain maximum battery service life and capacity, along with acceptable recharge time and economy, constant...
I can't say that pulse chargers (or desulfators) work but in my experience they did help with two battery while i had no luck with third one. I also tried simple 12V transformer and bridge rectifier and i had no luck bringing that first battery to life, it simply got hot and voltage...