When you’re choosing the right battery for your application, you need to run through a list of criteria and conditions that need to be met. After all, there are lots of different batteries, so you need to think about the voltage, capacity, and composition of the cells that you plan to use. Two of the most common types of batteries are lithium iron phosphate and lead acid batteries. To help you decide which you need for your application, we introduce them both in this article and explain the differences between the two.
Cyclic performance
One key distinction of Lithium Iron Phosphate (lithium for the rest of this article) batteries is that their capacity is independent of the discharge rate. Therefore, in cyclic applications when the discharge rate is more than 0.1C, a lower grade lithium battery will outperform a comparable lead acid battery, which is one of the most advantageous aspects about lithium technology. However, the lithium battery will cost more, but because you can use it at a lower capacity, you can typically run your appliance for a lower price when you choose lithium.
This further increases the appeal of lithium batteries compared to lead acid cells, as the cost of ownership is typically lower. What’s more, lithium has approximately ten times the life cycle of lead acid batteries in most circumstances. Again, this means that the cost of lithium is significantly lower than lead acid and the need to replace the batteries is less pronounced.
Constant power delivery
Over the course of a discharge cycle, lithium delivers the same amount of power. In comparison, a lead acid battery starts strong but will drop off and dissipate over time. This means that lithium batteries have constant voltage throughout the entire discharge. For example, if you switch on a torch and notice that the light is dimmer than usual, it means that the battery is dying. It’s producing enough energy to power the bulb, but not enough to power the device completely.
This scenario wouldn’t happen with a lithium battery. Instead of dimming and dying out slowly, a lithium battery would power the torch at full brightness until it had no more charge and it would simply shut off when it has no more power. This is another key difference between lithium batteries and lead acid cells that is important to consider before choosing the right battery product.
Charging time
If you’ve ever charged a lead acid battery, you will be aware that it’s a notoriously slow process. This means that if you have a big application that is powered by lead acid batteries, you usually need to have spare batteries on stand-by while you charge the current crop. When stored in a standby application, you must keep a float charge for the lead acid battery, which is a hassle and can become expensive.
In contrast, lithium batteries charge up to four times faster than lead acids. This means there is more time for the battery to be in use, meaning you don’t need anywhere near as many batteries to power your application. Lithium batteries also have a quicker recovery time, and you don’t need to keep spare lithium batteries on a float charge for storage.
Temperature performance
When it comes to high temperature applications, lithium outperforms lead acid batteries. For instance, at 55C, lithium still has double the life cycle that lead acid does at room temperature. Ultimately, lithium will outperform lead acid at most temperatures, but it is particularly strong in the heat.
As for cold temperatures, it’s common knowledge that the cold can negatively impact battery chemistries in several ways. Lithium cannot be charged at temperatures below 32F, while a lead acid battery can be charged in cold temperatures.
Battery weight and storage
Lithium batteries are approximately 55% lighter than lead acid batteries on average. Therefore, if you’re hoping to use a battery in a mobile application, it’s much better to turn to lithium over lead acid. Weight is also an important consideration in remote applications like solar fields, where installation is particularly challenging.
As for storage, lithium batteries should not be stored at a 100% state of charge, while lead acid batteries do need to be stored at 100%. The reason for this is that the self-discharge rate of an lead acid battery is five times or more of that than a lithium battery. Many customers actually keep lead acid batteries in storage with a trickle charge so that the battery life doesn’t decrease when it’s kept in storage.
The verdict
As you can see, there are lots of differences between lithium and lead acid batteries that you need to consider before investing in the right product. Overall, lithium batteries are widely regarded as the stronger of the two, but there are instances when a lead acid battery will serve you well.
If you have any questions about which battery you need for your appliance, feel free to get in touch with our team and we would be delighted to assist. You can call us on 01952 293 388 and one of our experts will be ready to assist you.
