Lead-acid batteries, add water, drop in capacity

My electric vehicle batteries have spent a year and a half, the capacity of the original 60 percent, in a few days ago to repair a battery increases, the weak acid water, but the battery very strange feeling over the past few days, I generally ride , To speed the time can be, back when some of the slow pace of home would be delayed (and downhill).And come back the way power is no strong feeling that this is the problem of water it and how to remedy? First Thank you, the

replacement battery is the most economical worry