Florida heat shortens battery life on its own — a Group 31 AGM that lasts 5 years in Maine lasts 2-3 years here. If yours is dying faster than that, something else is wrong.
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Most common causes
- Stereo or bilge pump drawing with no main switch (parasitic drain)
- Bad ground from battery to engine block (high resistance, won't charge)
- Failing alternator/stator on the outboard
- Dirty or corroded battery terminals (looks fine, isn't)
- Battery is older than 3 Florida summers and just done
How to diagnose at home
- Disconnect the negative cable overnight. If it holds charge, you have parasitic drain.
- Multimeter on terminals with key off: should read ~12.6V. Below 12.0V means it's discharged or sulfated.
- Voltage at engine RPM should be 13.8-14.4V. Lower means the stator/regulator is failing.
FAQs
Should I switch to lithium?
If you can budget for it, yes. LiFePO4 batteries handle Florida heat better, last 8-10 years, and weigh half as much. Make sure your charger is lithium-compatible first.
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