Off-grid, RV & cabin
Enter your battery chemistry, starting charge, and storage months. See your battery's charge level when you return, and whether a mid-winter check is worth it.
How it works Your panels can only charge what your battery can hold. The backup runtime estimator in our Battery & Storage section can help you size the bank for your actual daily load.
Step 1
Different chemistries lose charge at very different rates while sitting unused.
Step 2
50% is the standard recommendation for lithium batteries, avoiding the stress of full-charge storage.
Step 3
Know whether your battery will be ready to go, or whether a mid-winter check is worth planning.
An LFP battery stored at 50% state of charge typically drops to around 45% after 5 months of self-discharge, a lead-acid AGM battery drops to about 42%, and a flooded lead-acid battery drops further to around 38%, reflecting each chemistry's different self-discharge rate. All three remain in a safe range for a typical seasonal cabin closure without needing a mid-winter visit. Pair this with the battery lifespan estimator to see the full picture before you commit.
Storing a lithium battery at full charge for extended periods accelerates capacity degradation compared to storing at a partial charge like 50%, since the battery cells experience more stress sitting fully charged for months without use. At the same time, storing too low risks the battery drifting into a damagingly deep discharge state if self-discharge continues unchecked for an extended period, so 50% strikes a practical balance between these two risks. Current figures live on the DOE's overview of battery and energy storage technology, which updates them when the program changes.
Lead-acid batteries, especially flooded types, self-discharge notably faster than lithium chemistries and are also more sensitive to sitting at a low state of charge for extended periods, which can cause permanent capacity loss through sulfation. A cabin with a lead-acid battery bank closing for a long season benefits more from a mid-winter check-in than one with a modern LFP bank, given the faster charge loss and greater sensitivity to deep discharge.
For most seasonal closures of 5 months or less, a well-chosen storage charge level means no mid-winter check is strictly necessary for a healthy lithium battery bank, though a single visit partway through to verify charge level and top up if needed adds a useful safety margin. This is especially worth planning for longer closures, colder-than-expected winters, or any lead-acid battery chemistry with a faster self-discharge rate. Residential battery storage cost and performance data from the National Laboratory of the Rockies Annual Technology Baseline is a useful background read on how calendar aging like this compounds over multiple seasons.
Disconnect any parasitic loads that might drain the battery beyond normal self-discharge, and confirm your charge controller isn't set to a mode that would attempt charging with no one present to monitor it. Check the cabin seasonal use sizing tool if you're also reconsidering your system size for next season's use pattern. The battery calendar aging calculator in our battery chemistry storage tools projects this same self-discharge effect out across multiple seasons rather than just one winter, and the battery lifespan estimator in our maintenance and lifespan tools folds seasonal storage patterns into a longer-range projection. DOE's overview of battery and energy storage technology covers the fundamentals if any of this terminology is new.
Questions
50% state of charge is the standard recommendation for long-term storage of lithium batteries, since it avoids the stress of storing at full charge while leaving enough margin that self-discharge over several months won't bring the battery dangerously low.
An LFP battery stored at 50% state of charge typically drops to around 45% after 5 months of self-discharge, a lead-acid AGM battery drops to about 42%, and a flooded lead-acid battery drops further to around 38%, reflecting each chemistry's different self-discharge rate.
Storing a lithium battery at full charge for extended periods accelerates capacity degradation compared to storing at a partial charge like 50%, since the battery cells experience more stress sitting fully charged for months at a time without use.
For most seasonal closures of 5 months or less, a well-chosen storage charge level means no mid-winter check is strictly necessary, though a single visit partway through to verify charge level and top up if needed adds a useful safety margin, especially for lead-acid chemistries with faster self-discharge.
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