Blog Post

Replacing and Upgrading Lead Acid Batteries with Lithium Ion

Despite being the energy storage solution of choice for over 150 years, industries and consumers alike are migrating from Lead Acid Batteries (LABs) to superior solutions like Lithium Ferrous Phosphate (LFP) batteries. If a homeowner or business currently has lead acid batteries installed for backup power without solar, grid-tied or off-grid systems with solar, or mobile applications like RV and food trucks, there are many benefits to replacing LABs with high performance lithium-ion batteries.

Lead Acid Lithium Ferrous Phosphate
Heavy Lightweight
Toxic, dangerous acids that can leak Safe and Non-Toxic
Require On-Going Maintenance Maintenance Free
Limited Performance 2x Energy Density, Up to 4x Usable Capacity
Inefficient Highly Efficient (7.5x more efficient)

While lead acid batteries are well understood workhorses, lithium-ion batteries are high-performance energy storage solutions that can be easily substituted without all the downsides – making them an ideal choice for replacing and upgrading worn out lead acid batteries. And with costs rapidly declining over the past decade, LFP batteries are a cost-effective solution.

Total Cost of Ownership

When comparing different batteries, an important metric to understand is the Levelized Cost of Energy Storage (LCOES), which reflects the total cost of ownership over the life of the battery. LCOES factors in upfront cost, battery performance, and longevity of the system so that installers and customers alike can understand the overall value of a product over its lifetime.

LABs certainly look inexpensive up front, but ongoing maintenance costs and watering, reduced performance, and shorter lifespan severely limit their value. For example, where a LAB may only last 3-5 years before needing to be replaced, a SimpliPhi LFP battery will last 10 years or more and provide 20 times as many charge/discharge cycles under warranty – making them a much better investment.

The Many Benefits of Replacing Lead Acid Batteries with Lithium Ion

On top of significant cost savings over their lifetime, SimpliPhi’s advanced LFP batteries outperform lead acid batteries in numerous ways.

Safety: Many types of LABs require enclosures and active ventilation to prevent the caustic acid and gasses from building up, as well as controlled operating limits. SimpliPhi LFP batteries are safer, non-toxic, and don’t build up explosive hydrogen gas or leak sulfuric acid.

Ease of Installation: SimpliPhi LFP batteries are much lighter weight and take up 1/3 the space of LABs– making installation much simpler and frees up valuable space.

Shelf Life: When not in use, LABs ‘self-discharge’ – meaning they leak energy – and require routine maintenance and trickle charging when not in use. SimpliPhi LFPs lose less than <1% per month when stored and won’t degrade or require maintenance, giving you confidence that they will be ready when you need them. 

Maintenance: FLA batteries require constant maintenance and watering, cleaning of battery terminals, ventilation, and monitoring, and while VRLA require less maintenance, they have much shallower DoD limitations. SimpliPhi LFP batteries require no maintenance after installation.

Warranty & Lifetime: Lead acid batteries reach their end of life after 2-7 years and on average last about 500 – 1600 cycles. SimpliPhi LFPs come with a 10-year warranty and will perform well for more than 10,000 cycles. This minimizes replacement costs and provides lasting performance and confidence for customers.

System Performance, Sizing and Efficiency

LFP batteries have many performance advantages compared to lead acid batteries.

Energy Density: SimpliPhi LFP batteries are more energy dense than LABs and can store up to 6 times more energy in the same space meaning it takes fewer batteries to get the same amount of usable stored energy.

Efficiency: For each kilowatt of energy you store in a LAB, you can only get 80% or less of it back due to round trip efficiency losses. SimpliPhi LFPs are 98% efficient, which means 7.5x more energy and less money wasted – equaling thousands of kilowatt hours of electricity over the lifetime of your system.

More Usable Capacity: LABs can only be discharged 20-50% of their total capacity (depending on type) even before performance degrades, further decreasing their usable capacity. Discharging at a deeper depth of discharge can potentially damage the batteries. This means a 10kWh install can only use 2-5kWh of total capacity. SimpliPhi LFP can be discharged 80-100% with no adverse effects on the battery.

Drop-In Lead Acid Replacement with SimpliPhi LFP

SimpliPhi LFP batteries are an effective and efficient replacement for lead acid batteries for homes and businesses, RV’s and boats, or anywhere else you may have lead acid batteries installed, with minimal downtime and increased benefits for system performance that saves time and money.

To help installers and customers alike to determine how many PHI batteries are needed to replace a LAB system, SimpliPhi has created a handy calculator that you can access here:

Replacement Example: A homeowner currently has eight (8) 48V lead acid batteries installed as backup power with a set of solar panels at their house and would like to replace them with high-performance LFP.

  • 8, 6V 428Ah LABs = 428Ah of storage
  • 428Ah x 48V = 20,544Wh
  • 50% depth of discharge limit = 10,272Wh of capacity
  • 85% round trip efficiency = 8,731Wh of usable storage in 8 LABs

SimpliPhi’s most popular LFP battery is 3.8kWh, and the same calculations would be:

  • 3 x 3.87kWh = 11,610Wh
  • 80% depth of discharge = 9,288Wh
  • 98% round trip efficiency = 9,102.24Wh usable storage

You only need 3 batteries, at roughly the same usable storage, taking up significantly less space. And the LFP system will last more than twice as long as a lead acid system.


SimpliPhi Power’s industry leading LFP batteries have a number of advantages compared to lead acid batteries and are a cost-effective and long-lasting replacement option. SimpliPhi batteries are compatible with most inverters and charge controllers, making for an easy drop-in replacement when LABs wear out or fail.

Learn more about lead acid replacement by visiting our Product Documentation page. There you will find our integration guides for more technical information. Or, if you prefer, don’t hesitate to contact us directly: