Alrighty, now that I installed two 6v batteries in series, I need to keep them fully charged. I was informed the proper way is to use a 3 stage charger. Now, here it comes.... since the batteries are producing 12v (2 6v) do I use a 12v charger or do I use 2 6v chargers or can I use one 6v and will it charge both equally? I know some of you guys are electronics wizzkids (not like our teenager type though)...thanks...Paul