What is usually happening
- Solar shortfall exposes hidden inefficiencies fast.
- One weak string or one bad connection can pull the whole bank down.
- Battery monitors often look confident even when the real state of charge is slipping.
First checks to run
- Check resting voltage after loads have been quiet long enough to matter.
- Compare charger contribution from solar, alternator, shore charger, and any DC-to-DC path.
- Feel and inspect the main terminations for heat, looseness, or corrosion.
Battery chemistry matters
- Flooded batteries benefit from specific gravity readings.
- AGM banks need good rest data and a trustworthy shunt.
- Lithium banks need battery management system data plus correct cable symmetry.
When it is urgent
- Bank voltage collapses abnormally under modest load.
- Critical electronics are losing power overnight.
- Cables, fuses, or terminals are heating under normal charging.
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