Apart from a greater immediate efficiency, there are factors that make Lithium-Ion superior. Firstly, to understand batteries better, a battery is usually measured in Amp Hours or Kilowatt Hours. A kilowatt hour is one unit of power.
To calculate power on a battery is as follows: A 100-amp hour battery at 12 volt is equal to 1.2 kilowatt hours (or 1.2 units of power).
Watts = Amps x volts.
Lithium-Ion batteries allow you to discharge (use) between 80 – 100% or the battery whereas Lead Acid only allow you to discharge 30 to 50% of the power. In addition, the Lithium batteries allow you to rapid charge. From completely depleted, you can charge to full a time of 1 to 2 hours. By comparative, a lead acid would like to be charged up in an 8-10- hour period. With charging Lead Acid, you can lose approx. 15- 30% of the energy due to heat loss, but with Lithium Ion is approx., 92-98% efficient in comparison.
Lithium batteries are guaranteed for more cycles (4000 +), when compared with 200-500 cycles on Lead Acid. Another significant advantage is that you can add batteries to a lithium battery bank (expandable), but the lead acids, The lithium batteries are also able to withstand a partial charge for longer, whereas lead acid constantly needs to receive a trickle charge, to avoid degradation.
Lithium batteries are far more compact and weight less, thus making it a far more energy dense. Lithium takes up to approx. 25% of the space of a lead acid installation. Most lithium-ion batteries today also provide you with a 10-year warranty compared with approx. limited warranties of 12/24 months on Lead Acid.
What does this all mean?
Cost of ownership is just far more attractive on Lithium Ion, even although the upfront cost is more. There is less replacement, relatively little to no maintenance and complete monitoring on Lithium Systems.