Batteries are an essential component of any off-grid or hybrid solar system. Besides energy storage, they provide the extra surge power to start up large appliances, well pumps, power tools, etc.

Whether you’re storing energy in traditional lead-acid batteries or newer lithium chemistries, taking care of them properly can add years to their useful life, saving you from costly replacements. While all solar batteries degrade over time, small tweaks in how you use, charge, and maintain them can make a big difference.

How to extend the lifespan of your lead-acid solar batteries

Although we advocate upgrading to lithium batteries whenever the opportunity arises, you don’t have to discard perfectly functioning lead-acid ones. Here’s how to make them go further:

1. Don’t go below 50% depth of discharge (DoD)

The science: Lead-acid batteries undergo chemical reactions between lead plates and sulfuric acid. Deep discharges cause lead sulfate crystals to form and harden through sulfation, which reduces active material and permanently lowers capacity.

The how: Use an inverter with programmable DoD limits. Set alarms or auto-cutoffs to prevent the battery bank from dropping below 50%. Your battery bank should be dimensioned to only rarely dip to 50% DoD. (See #5 if it’s not dimensioned to do so.)

2. Top off your solar batteries regularly

The science: If lead-acid batteries sit partially charged (even at or below 90%) for prolonged periods, sulfation accelerates, shortening their lifespan. A full recharge dissolves soft sulfate crystals back into the electrolyte. If you let the sulfate sit for more than a week, it’ll ruin the battery.

The how: Schedule weekly full absorption charges. Use SCCs with multi-stage charging (bulk, absorption, float). If your system isn’t producing enough solar, you may add panels to boost production capacity or occasionally top up the batteries with a generator.

3. Equalize flooded batteries periodically

The science: Over time, electrolyte stratification occurs, where the heavier acid sinks to the bottom and lighter water stays on top. Equalization (a controlled overcharge) agitates the electrolyte, balances cell voltages, and prevents capacity loss.

The how: Follow your battery manufacturer’s recommendations and flood the batteries once every 1 to 3 months. Use an SCC with equalization mode, and check electrolyte levels before and after the procedure. (Don’t perform this process on AGM or gel batteries, and definitely NOT with lithium ones!)

4. Maintain proper operating environment

The science: High heat accelerates chemical reactions that corrode plates and boil off water in lead-acid batteries. Meanwhile, low temperatures reduce available capacity. The optimal operating range for lead-acid batteries is typically 20 to 25°C (68 to 77°F).

The how: For the Caliente area, where heat and radiation are more of a concern than cold temperatures, install batteries in a shaded, insulated, well-ventilated enclosure. Insulate with radiant barriers if possible, and don’t place batteries in direct sunlight or unventilated sheds.

5. Boost capacity with lithium batteries

The science: If your lead-acid batteries have declined in storage capacity, resulting in them discharging below 50% DoD often, you can supplement your battery bank with new lithium batteries. We program lithium batteries to discharge before the lead-acid ones do, thus “protecting” them from frequent deep discharge if dimensioned correctly.

The how: Our proprietary battery technology enables the mixing of battery chemistries, so you don’t have to throw out your existing lead-acid batteries for a costly overhaul. See how we can help you orchestrate a phased approach to maximize your investment without compromising your lifestyle.

*Custom-building an LFP battery pack in our workshop.*

How to extend the lifespan of your lithium solar batteries

Lithium chemistries (lithium cobalt and lithium iron phosphate) have a longer lifespan and require less maintenance than lead-acid batteries. However, not all battery packs are equal. If you order some “good deals” from Amazon, chances are they aren’t configured to optimize longevity. Here’s what you need to know:

1. Avoid regularly draining batteries to 0%

The science: Lithium batteries degrade faster with full discharges. At very low states of charge (SoCs), side reactions increase internal resistance and reduce cycle life. Lithium iron phosphate (LFP) is more tolerant, but still benefits from avoiding deep discharges.

The how: Program your inverter or battery management system (BMS) to set daily cycling between 10 and 80% SoC. For all our solutions, we configure the BMSs so that the battery will have something left in the tank even if a client uses up all available capacity. We can even program a more conservative DoD if the client wants to prioritize battery longevity.

2. Don’t keep batteries charged at 100% for long periods

The science: At high SoC, lithium cobalt chemistries (NMC, NCA) experience more stress because high voltage accelerates electrolyte oxidation. LFP is more stable, but prolonged high charge still slightly reduces lifespan. (Sidebar: If you keep your smartphone plugged in all the time, the battery will die much faster!)

The how: If you don’t need full capacity daily, set your charging limits to 80 to 90%. You can also customize the maximum charge voltage via your BMS. If you need to charge your batteries to the brim and then discharge them deeply on most days, consider adding storage capacity to increase the battery pack’s longevity.

3. Control battery temperature

The science: Lithium batteries degrade quickly under extreme heat (>40°C/104°F). Heat accelerates electrode breakdown and electrolyte decomposition. Cold temperatures (<0°C/32°F) can cause lithium plating during charging in LFP cells, permanently damaging them if your batteries don’t have protective circuitry.

The how: Install batteries in a climate-controlled space or insulated cabinet. Double-check that your LFP batteries have a protective circuitry to cut off charging when the temperature drops below freezing. You may also implement our cold-temperature-tolerant battery pack if you house your batteries in an environment susceptible to freezing temperatures.

4. Ensure correct BMS settings

The science: High-quality BMSs balance cells, prevent overcharging/discharging, and monitor temperature at multiple spots. Without balancing, individual cells can drift apart in voltage, stressing the weakest ones and impacting the pack’s longevity.

The how: We custom-configure BMSs for all our solutions based on each client’s requirements and environment for optimal performance. If your battery pack comes with a preset BMS, don’t bypass or disable it. Also, ensure your inverter and SCCs are compatible with your battery’s BMS protocols.

5. Apply proper pressure to cells

The science: Chemical reactions and thermal cycles cause LFP cells to expand over time, reducing the contact area between the electrodes and active materials. Applying the right pressure can add several years of high performance to a battery pack.

The how: There isn’t much you can do about this if you buy off-the-shelf battery packs. However, we custom-build all our LFP packs using high-quality cells. Then, we 3D print braces to hold the cells in place with high-tension straps and put non-compressible isolating material between them.

Extend battery lifespan and maximize your solar investment

Whether you’re running lead-acid or lithium solar batteries, the key to longevity is minimizing stress: avoid deep discharges, keep temperatures moderate, and follow proper charging practices. Additionally, proper dimensioning of your system (e.g., generous production and storage capacity) and correct configurations of each component will make everything go further.

Ready to improve your existing off-grid solar setup? Learn more and get in touch.

How to Extend the Lifespan of Your Solar Batteries