Why You Should Upgrade Your Existing Solar Batteries to Lithium

Why You Should Upgrade Your Existing Solar Batteries to Lithium

Do you have an older grid hybrid or off grid solar system with batteries? If so, chances are your deep cycle solar batteries are either Flooded Lead Acid (FLA) or Absorbed Glass Mat (AGM) batteries. That’s because these battery chemistries have been the leading energy storage solution for renewable and emergency backup power systems for decades. 

Today, however, lithium battery chemistries are revolutionizing how energy is stored for those living off the grid or needing emergency power during a utility outage. And for good reason. Read on to learn about the benefits of lithium solar batteries over AGM and FLA solar batteries. For the purposes of this article, we specifically reference the safest and our recommended lithium battery chemistry, Lithium Iron Phosphate, (also known as lithium ferro phosphate, LFP or LiFePO4).

If you have an AGM battery bank, here are the benefits from upgrading to LiFePO4:

  1. More Power. Lithium batteries are 98-99% efficient, which means you get the most energy possible from your battery bank. On the other hand,a brand-new AGM battery is at best around 85% efficient. AGM batteries lose 15% of their power while charging and another 15% while discharging, totaling up to 30% of power loss during a cycle. That’s a lot of lost power. Another difference between AGM and LiFePO4 batteries is that AGM batteries lose efficiency over time while LiFePO5 batteries do not. Lithium batteries keep the same efficiency over the life of the battery.
  2. More Usable Power. The industry standard for AGM batteries is a 50% depth of discharge (DoD) rate. Practically speaking, this means you can only use half of the battery’s storage capacity. This is because AGM (and FLA) batteries can be ruined if you frequently discharge them more than 50%. On the other hand, lithium batteries technically can be discharged 100% without damage. (However, we recommend you only discharge to 80% (90% max) of capacity to avoid a potentially complicated revival process necessary to restart the internal battery management system after full discharge.)
  3. Longer Life. Battery life expectancy is not measured in an amount of time, but rather by the number of cycles and depth of discharge. One battery cycle is when you discharge a battery then charge it again.  If cycled every day at 50% DoD and taken care of properly, a realistic cycle count for AGM batteries is approximately 1,500, or about 4-5 years of usable life if cycled once a day. For flooded lead acid batteries (FLA), a popular manufacturer of solar batteries quotes 2,000 cycles at 50% depth of discharge, or about 5.5 years if cycled every day.  The cycle life of LiFPO4 batteries varies by manufacturer, but many provide 7,000 cycles in their lifetime at a 70% discharge rate, providing up to over 19 years of power if cycled every day.
  4. Safer. Lithium batteries, such as RELiON or SimpliPhi LiFePO4 batteries, have an internal battery management system (BMS). The BMS monitors various aspects of the system and will shut the battery off to protect itself and your system in the event of unsafe operating conditions such as over or under-voltage, over current, high temperature or external short-circuiting. Additionally, unlike lithium-ion chemistry (LiON), LiFePO4 chemistry operates cool, almost completely eliminating the possibility of thermal runaway (overheating). That means there is little to no risk of explosion in the event of a structure fire or if the battery casing is punctured.
  5. Lightweight and Smaller Size. Lithium batteries are a fraction of the dimensions and weight compared to AGM batteries for the same capacity rating. You can save in overall space by getting one LiFePO4 battery rather than 8-16 AGM batteries.
  6. Faster Charging. LiFePO4 batteries can accept a high amount of current which reduces your charging time. For off grid clients using a generator this can result in significant fuel savings. It also means that you need fewer hours of sunlight to recharge lithium batteries from solar.

If you currently have a FLA (Flooded Lead Acid) battery bank, you will get all of the same benefits listed above when you upgrade to LiFePO4, plus:

  • Maintenance Free. You do not need to equalize or add water to LiFePO4 batteries like you do for lead acid batteries. All lithium batteries are maintenance free, making them a great choice for seasonal off grid or battery backup properties, and to reduce the time you spend maintaining your off-grid power system at a full-time residence.
  • No Off Gassing. No need to vent hydrogen build up because lithium batteries do not produce any gas.
  • Less sensitive to high and low ambient temperatures. FLA batteries usually have a fairly narrow temperature range for operation and charging to maintain efficiency and life expectancy. LiFePO4 batteries are less sensitive to changes in ambient temperatures with a wider operating and charging range. Always refer to the manufacturer’s instructions for your brand of batteries for exact temperature range information.

Want to know more about lithium solar batteries? 

Browse Lithium Solar Batteries

Read our article Solar Battery FAQ’s – Lithium Iron Phosphate LiFePO4 to get answers to commonly asked questions about these solar batteries.

At Fire Mountain Solar, we strive to serve our community through providing the best power solutions for our clients. If you are interested in learning more about the benefits of upgrading your battery bank, contact us today for a free consultation.