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| srna wall-mounted inverter |
Installing a home inverter system provides an efficient way to utilize renewable energy sources and reduce reliance on the main power grid. A key component of any home inverter setup is the battery bank that stores power and delivers it on demand. With many battery options available, it's important to select the right type to get the best performance and longevity out of your system. In this comprehensive guide, we'll explore the pros, cons, and ideal uses of the most common battery types utilized in home inverter systems.
Lead-Acid Batteries
The workhorse of off-grid energy storage, lead-acid batteries have been used for decades thanks to their mature technology, low cost, and availability. Within lead-acid batteries, there are three main types:
Flooded Lead-Acid Batteries
Flooded lead-acid batteries are the most affordable option. They consist of lead plates immersed in a liquid electrolyte. The "flooded" designation comes from the fact that water is lost during charging and needs to be replenished or "flooded" periodically. While inexpensive, they require maintenance, give off harmful fumes, and are at risk of leaking or spillage.
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| srna Lithium-ion battery |
Sealed Lead-Acid Batteries
Sealed lead-acid batteries enclose the electrolyte so no maintenance or checking of fluid levels is required. The two types of sealed lead-acid batteries include:
- Gel Batteries: The electrolyte is suspended in a gel. No leakage or spillage issues.
- Absorbed Glass Mat (AGM) Batteries: The electrolyte is absorbed in a fiberglass mat. More resistant to damage from vibration or shocks.
Both sealed versions provide benefits over flooded types for inverter use, especially in RV and marine applications. However, all lead-acid options are heavy, have a shorter cycle life, and degrade faster than lithium-ion.
Lithium-ion Batteries
Lithium-ion batteries have become a popular choice for home energy storage thanks to advantages in weight, lifespan, efficiency, and rapid recharging. The high energy density of lithium-ion means smaller, lighter batteries can store as much or more energy than larger lead-acid ones.
There are several types of lithium-ion batteries:
Lithium Cobalt Oxide: One of the most common types, with high energy density but stability issues at high voltages.
Lithium Manganese Oxide: A safer alternative to cobalt oxide, but lower energy density.
Lithium Nickel Manganese Cobalt Oxide: Contains less cobalt providing safety and performance advantages.
Lithium Iron Phosphate: The most stable type, with a lower risk of overheating and no thermal runaway.
Lithium-ion lifespan is two to three times longer with over 2000 cycles versus 500-800 cycles for lead-acid. Cold temperature operation is better as well. On the downside, lithium-ion batteries have a high upfront cost. Prices are dropping over time though as production volumes increase.
Also read: How To Diagnose Faulty Inverter Battery
Deep Cycle Lead-Acid Batteries
When it comes to lead-acid batteries for inverter systems, deep-cycle versions are superior to starting batteries used in vehicles. Deep cycle batteries utilize thicker lead plates that better withstand repeated discharges of up to 80% capacity. Deep cycle batteries include:
Trolling Motor Batteries: Intense discharge tolerant with steady power delivery.
Golf Cart Batteries: Durable construction and deep cycling ability. 6 or 8-volt versions can be combined.
Forklift Batteries: Rugged and high capacity for serious battery banks. Requires maintenance though.
Marine Batteries: Withstand vibration and shock in boat installations. 20+ year lifespans.
AGM and gel cell technology are recommended for deep-cycle lead-acid batteries because the electrode materials are less prone to degradation from partial state-of-charge cycling.
Lifepo4 Lithium Iron Phosphate Batteries
One lithium-ion variant better suited to home energy storage is the lithium iron phosphate battery (LiFePO4 or LFP). LiFePO4 batteries provide:
Excellent stability and safety. No risk of thermal runaway or fire.
Long 3000-5000 cycle lifespan. Up to 10 times longer than lead-acid.
High current rating for efficient power delivery and recharging.
Low internal resistance enables high discharge currents.
Wide operating temperatures from -4°F to 140°F/-20°C to 60°C.
LiFePO4 is more stable during short circuits and has lower self-discharge than other lithium-ion types. The tradeoff is marginally lower energy density. LiFePO4 batteries are a top choice for offenders, RVs, cabins, and remote homes running essential loads.
Key Selection Criteria for Inverter Batteries
When selecting a battery type and models for your home inverter system, keep these key criteria in mind:
Depth of Discharge Tolerance
A battery's depth of discharge rating indicates how much it can be depleted during a cycle before damage occurs. Lead-acid batteries should not be discharged over 50-80% routinely or lifespan will suffer. Deep cycle and lithium-ion batteries can tolerate deeper discharges up to 80-90% repeatedly.
Cycle Life Ratings
Cycle life indicates the number of discharge/charge cycles a battery can deliver before capacity drops below 80% of the original. Lifespans of 500 cycles for lead-acid pales in comparison to 2000+ cycles for LiFePO4. Higher cycle life means longer usable battery life.
Capacity and Runtime
Batteries with larger amp-hour (Ah) ratings and watt-hour (Wh) capacity provide longer runtimes. Choose batteries that can provide backup power for essential loads for the timeframe you need. Factor in usable capacity after depth of discharge limit.
Voltage
Most inverter systems run on 12V, 24V, or 48V DC power. Select batteries that align with your system voltage - either single cells or multi-cell packs configured correctly. Lithium cells are 3.2V (nominal) per cell versus 2V for lead-acid.
Physical Size and Weight
Lithium-ion batteries provide far more capacity in a smaller, lighter package. A 250Ah lithium battery can weigh under 25 pounds, compared to over 100 pounds for an equivalent lead-acid option.
Operating Temperature Range
Batteries perform best at moderate temperatures. Lead-acid batteries are hindered below 50°F/10°C. Lithium-ion can operate down to -4°F/-20°C or below. Understand battery limitations for your climate.
Cost and Budget
Lithium-ion batteries are still 2-3X more expensive upfront than comparable lead-acid batteries. However, the long lifespan, efficiency, and space savings of lithium-ion can provide long-term value. Weigh upfront costs versus longer-term benefits.
Management System Compatibility
Lithium-ion batteries require sophisticated battery management systems for safe operation. Make sure they are compatible with your particular lithium battery chemistry and inverter system. Lead-acid batteries are simpler to integrate and manage.
Certified Standards Compliance
Reputable lithium battery brands adhere to UN 38.3 standards for safety during transportation as well as UL listing standards for the US and IEC standards in Europe. Look for legit marks and lab certifications.
Configuring Your Battery Bank
To obtain your desired voltage and capacity for home energy storage, batteries can be combined into "banks":
Series Wiring
Batteries wired in series combine their voltages - for example, two 12V batteries connected in series produce 24V. This allows smaller batteries to be combined to match inverter voltage requirements.
Parallel Wiring
Wired in parallel, batteries combine their amp-hour capacity while maintaining consistent voltage. Take two 100Ah 12V batteries - in parallel they form a 12V bank with 200Ah capacity.
Series-Parallel Combinations
With series and parallel wiring, large battery banks can be created for high-capacity home energy storage and backup. For example, four 12V 200Ah batteries can be configured as a 24V 400Ah bank.
Installation and Maintenance
Proper installation and maintenance ensures your batteries provide maximum performance and lifespan:
Install batteries as close as possible to inverters to reduce cable losses.
Securely mount batteries on non-conductive surfaces to avoid ground faults.
Allow adequate room for ventilation and cooling airflow around batteries.
Follow manufacturer guidelines regarding space between batteries.
Regularly inspect for corrosion and loose connections.
Check water levels and follow maintenance procedures for flooded lead-acid batteries.
Prevent over-charging and under-charging within recommended voltage limits.
Store lead-acid batteries fully charged; lithium-ion is around 50% charge.
Safety Considerations
Any industrial battery system requires strict safety practices:
Wear eye and skin protection when servicing batteries.
Have vinegar or baking soda solution on hand to neutralize spilled electrolyte.
Follow protocols for safe handling and disposal of batteries.
Only use compatible chargers approved for the battery type to avoid fire risks.
Ensure proper ventilation for outgassing during charging.
Disconnect batteries before service and use insulated tools.
Check for certification marks indicating tests to safety handling standards.
With proper selection, configuration, and maintenance, you can assemble a battery bank that delivers the runtime, power, and performance.