These are symptoms that batteries need replacement.
1) If the voltage rises rapidly when charging (you'll see this when the charger shuts down early), or drops rapidly under the load, this is a sign of battery wear.
2) Cell to cell voltage variations of 0.05V to 0.1 volts.
3) Increased water consumption.
4) Drops in overall specific gravity in the battery; this usually means that the solute has run out.
When you replace batteries, replace entire battery banks, rather than individual cells; putting a fresh sell in series or in parallel with one that's older will cause the newer battery to degrade down to the performance of the older one, rather than boost the older one up to new.