Round-trip Efficiency of Lithium Ion Battery

Another common term with batteries is round-trip efficiency. When you put energy into a battery and then take it out again, the battery system consumes some of that energy during the process. In a nutshell, round-trip efficiency refers to how much energy you can draw from the battery, compared to how much you put in.

As a quick example, if you put 5 kWh of energy into your battery, and can only draw out 4 kWh of usable energy, your battery has a round-trip efficiency of 80%.

As you may gather, the higher the percentage, the more efficient your system is – and the more usable energy you can access.

Lead acid batteries generally have a round-trip efficiency somewhere in the ballpark of 80%. This means that for every 10 kWh of energy you put into your battery, you can draw 8kWh back out.

Lithium batteries offer an even higher round-trip efficiency, generally around 90% (such as the Tesla Powerwall 2). Lithium batteries are very efficient at storing and discharging energy, consuming very little in the process.

In summary, both battery types are efficient, but lithium has the edge in terms of how much stored energy is returned as usable energy. It’s a significant factor to consider, as even a 5% difference can equal thousands of kilowatt-hours of electricity over the lifetime of your system.

Click below to Read our other article /blog related to Lithium Ion Battery

https://blog.emerich.in/2020/08/li-ion-vs-lead-acid-forklift-batteries.html

https://blog.emerich.in/2020/08/depth-of-discharge-dod-and-usable.html

Depth of Discharge (DOD) and Usable Energy in Lithium Ion Battery

The term depth of discharge (DOD), and this refers to how much of the total capacity can be used before the battery needs to be recharged again.

To help explain this one, it’s time for a quick exercise:

Suppose you have a 10-litre bucket, and you fill the bucket with water. Now, how much water can you take out of the bucket?

10 litres, right? Of course, you are correct.

Now, suppose you have a 10 kWh (kilowatt-hour) battery, and you fill the battery with electricity. How much electricity can you take out of the battery?

10kWh, right? Well, in this case, not quite.

Batteries don’t work in quite the same way buckets do. It’s important to understand that the capacity of a battery is not the same amount of energy you can draw from it. You’ll often hear the term depth of discharge (DOD), and this refers to how much of the total capacity can be used before the battery needs to be recharged again.

Lead acid batteries have a somewhat shallow DOD, which is generally recommended around 20-30%. This means if your battery bank can hold 10 kWh of energy, you can only access 2-3 kWh of usable energy. You can draw more than this, but you risk damaging the batteries and shortening their lifespan. To this end, most systems have control systems to prevent this from happening.

Lithium batteries can be discharged much further – as much as 80% or in some cases even 100%. This means that with a 10 kWh battery, you’ll get at least 8 kWh of usable energy – or maybe even the full 10 kWh. The Tesla Powerwall 2, for example, permits a 100% DOD without any adverse effects on the battery lifespan or warranty. At Off Grid Energy, we recommend around an 80% DOD to extend the battery lifespan as long as possible.

In summary, lithium batteries easily have the advantage when it comes to how much electricity you can draw from them. With some batteries able to discharge all the way down to 0% capacity and recharge back up to 100%, they give you access to more usable energy, more often.

See the below article for the difference between Lithium & Lead Acid Batteries

https://blog.emerich.in/2020/08/li-ion-vs-lead-acid-forklift-batteries.html

Li-ION vs. lead-acid batteries - which is best for your operation?

One of the most important components of an electric kart is the battery. So, we will help you compare the most common solutions:  lead acid or lithium.

Most of the electric karts on the market equip lead acid batteries. However, even though more than 90% of the sector is concentrated on this type of batteries as they are more economical, acquiring lithium batteries will make the investment much more profitable because of its multiple advantages.

Differences between lithium and lead acid batteries

The main differences wherein lithium batteries stand out more than traditional lead acid batteries are as follows:

They provide higher energy density: Lithium ion is a more cutting-edge type of battery, unlike traditional lead acid battery, has a much higher energy density and therefore can store energy while taking up less space with a lower weight. In addition, they are differentiated by their energy efficiency and higher performance, since they are 30% more energy efficient than a tradition battery of lead acid, that is, they represent a lower energy consumption, achieving even better results than those that would be achieved with lead acid batteries.