OTC 4619
http://www.amazon.com/OTC-4619-Professional-Battery-Hydrometer/dp/B0050SFVHOLeave charger on until all cells are 1.275 or higher.
If the wall wart/charger cannot get the cells to 1.275, you need a bigger charger.
After the cells are 1.275, then the maintenance charger should be able to hold them there.
Obsessing over voltage is common but unhealthy. Battery voltage when charging or discharging is like throwing a rock at a rubber band and trying to guess the weight of the rock by how far the rubber band stretched.
Most people cannot even hit the rubber band, much less see how far it stretched, but call their method gospel anyway.
