in my case i have some 4v lead acid battery laying around…. and i have not used for a while so obviously they are dead or dried out…. i tried to search some way or result on how to refill it… but i got up with two answers…. which is really confusing…. also many videos states that they are using distil water to refill the battery and others are just using the liquid/acid of a new bought battery to refill the 4v battery……… so basically i couldn't understood what should i use to refill my battery, distil water or the liquid/acid of the new battery…./??