What sulfation is
Battery University BU-802 describes capacity loss when lead-acid sits at a low state of charge: sulfate crystals harden on the plates and the pack will not take a full charge again. A bass boat that sat in a Polk County driveway for three weeks with the switch on, or a pontoon whose charger lost power, is that condition. It is chemistry plus time, not a mysterious Florida curse.
Resting voltage is a table, not a slogan
BU-903 publishes BCI open-circuit voltages for a rested starter battery after about 24 hours: about 12.65 volts at 100 percent, 12.45 at 75, 12.24 at 50, 12.06 at 25, and 11.89 at empty. We use that table as a clue after a real rest, surface charge removed. 12.06 volts on that chart is near 25 percent. Load testing and age still decide replacement.
A charger that never finished is the same story
Sulfate from storage and sulfate from a charger that sits in float too low look similar on the water: the engine cranks slow, the trolling motor dies at noon. We inspect the charger program before we condemn three group 31s. Sometimes the batteries are done. Sometimes they were never refilled.
Can sulfation be reversed?
Some packs recover with a correct charge if the sit was short. Hard crystals from a season empty usually do not. We will not sell a pulse gadget as a cure. We will try a proper charge and a test when the case history says the pack was healthy last month.
Lake-country pattern
Leesburg and Orlando trailer boats that sit between weekends need a maintainer or a disconnect. We come to the driveway. The quote is honest about whether the string is one tired battery or three.
Trailer weeks versus a dead cell
A battery that sat three weeks and still takes a long, correct charge may come back. A battery that sat all summer, or a cell that is shorted, will not. We use the rest table and a load, then we say charge-and-retest or replace. Central Florida trailers in Polk and Osceola are the weekly version of this. A tender that actually finishes is cheaper than a new string every spring.
Sources
- Battery University BU-802 — What Causes Capacity Loss
- Battery University BU-903 — How to Measure State of Charge
If this is the job on your boat, see how we replace batteries at the boat. We come to you — Florida towns and counties.