A reliable power source is crucial for efficiently operating a fleet of mobile medical carts. But with so many types of batteries available, choosing the best power source for your medical facility can be difficult. Two of the most common battery types – lithium iron phosphate (LiFeP04) and sealed lead acid batteries – can be used for medical equipment, such as mobile computer workstations.
Both lead acid and lithium-ion batteries offer advantages and disadvantages; however, as a healthcare provider, it is essential to fully understand both battery types and how they work. Choosing the best type of battery for your operation can improve productivity and increase the level of care at your facility.
How Do Lead Acid Batteries Work?
A lead acid battery is a rechargeable power source that uses lead and sulfuric acid. The lead is submerged in sulfuric acid, causing a chemical reaction to occur. This chemical reaction is how lead acid batteries create electricity.
The electric charge is created when the sulfate, a component of the sulfuric acid, bonds to the lead. When charging the battery, the process is reversed, meaning the sulfate returns to the sulfuric acid.
However, since there is a limited number of sulfate ions in the sulphuric acid, the charge weakens as the sulfate is depleted. As a result, lead acid batteries are ideal for settings that require quick bursts of powerful energy as opposed to a sustained level of power production.
How Do Lithium Batteries Work?
Compared to a lead acid battery, a lithium-ion battery uses a more complex chemical reaction to produce energy. There are six primary components in a lithium-ion phosphate battery: the anode, the cathode, the separator, the electrolyte, and one negative and positive current collector each.
The lithium is stored in the anode and cathode. The electrolyte transports positively charged lithium ions from the anode to the cathode (and reverse) via the separator.
As these ions move through the battery, free electrons are created in the anode, creating a charge at the positive current collector. The electric current then flows from the collector to the device being powered before returning for collection at the negative current collector.
When a lithium-ion phosphate battery pack is used, the lithium-ions pass from the anode to the cathode, generating a flow of electrons. The reverse occurs when the battery is being charged, and lithium ions flow from the cathode to the anode.
Comparing and Contrasting Lead Acid and Lithium Batteries
Since the two battery types have varying operations, they are best suited for different applications. Here are some factors to consider when determining which type of battery is best for your facility:
When comparing lithium-ion and lead acid batteries, one of the main differences is in the length of each battery’s cycle life. Of the two types, lithium-ion batteries have a significantly longer life cycle.
With typical use and proper maintenance, a lithium-ion battery can last over 1,000 charging cycles. This is a considerably longer lifespan than lead acid batteries, especially when you consider lithium batteries’ improved energy density.
Another major difference between the two battery types is their energy density. Energy density is a measurement of how much energy can be stored in a given space. Lithium-ion batteries offer around 450 watt-hours per liter (Wh/L), while lead acid batteries typically offer between 80-90 Wh/L.
Battery Storage Capacity and Charge Time
Between the two battery systems, lithium-ion batteries are capable of holding significantly more energy than lead acid batteries. When fully charged, lithium-ion batteries provide between three and ten times more usable energy capacity than comparable lead acid batteries. This significantly improves the device’s operational time, particularly in medical settings.
Lead acid batteries are charged using a variable current algorithm to ensure proper charge and to maximize cycle life and performance; however, this process takes time. At lower voltage levels, lead acid batteries are designed to charge slower.
Lithium-ion phosphate batteries use a constant current algorithm, meaning they are charged at the same speed regardless of voltage, allowing the battery to be charged much quicker.
There is a significant difference in efficiency between lithium-ion phosphate and lead acid batteries. Lithium-ion phosphate batteries are approximately 95% efficient, offering a significantly improved usable capacity compared to lead acid batteries. Lead acid batteries are only about 50% efficient.
Lithium-ion phosphate batteries are considerably more efficient, so a smaller battery can be used to achieve similar results as a larger lead acid battery.
Because a smaller lithium-ion phosphate battery can be used to deliver the same amount of energy as a larger lead acid battery, there is a large difference in weight between the two batteries of comparable strength. This makes lithium-ion phosphate batteries an excellent choice for portable devices, like medical computer carts.
Discharge Rate and Depth
A battery’s depth of discharge measures the proportion of the battery that can be drained without damaging the battery’s cells. During the typical use of a lithium-ion phosphate battery, more than 85% of the battery’s total capacity is often used.
Lead acid batteries should not discharge more than 50% of their total capacity. If a lead acid battery is discharged more than 50%, it will likely shorten its lifespan due to the battery’s chemistry. This disparity contributes to the significantly higher usable capacity of a lithium-ion battery.
Lithium-ion batteries are more complex and contain more parts than lead acid batteries. This means lead acid batteries are easier and more affordable to produce than their lithium-ion counterparts.
While lead acid batteries are often much less expensive to purchase initially, the longer lifespan of lithium-ion batteries often means a lower cost of ownership and operation long term.
For lithium-ion phosphate batteries, there is a possibility of explosion due to their immense energy storage capacity. Lithium-ion batteries store considerably more energy; however, this means the battery can explode if all the energy is released at once. While this is rare, it still happens.
Typically, explosions are caused by poor design or quality control leading to a short circuit, though they can also spontaneously combust due to exposure to excess heat. Other events can lead to combustion as well. A process called thermal runaway may occur, where one lithium cell fails and causes the rest to fail.
Lead acid batteries also pose their own risks. The highly-corrosive acidic electrolyte used in the battery can melt surfaces and cause injury to individuals that are exposed to it. Similarly, lead acid batteries can release highly-toxic hydrogen sulfate gas, which smells like rotten eggs and is highly corrosive, flammable, and poisonous.
Despite the risks associated with each type of battery, incidents occur rarely and are typically due to battery abuse or poor storage or manufacturing processes. Both types of batteries are considered safe and are widely used.
Lithium-ion technology is used in almost every personal electronic device on the market, and there are very few incidences of explosions; these combustions typically occur with larger lithium-ion batteries that are still being developed, such as those used in electric-only vehicles. Lead acid batteries have been used safely for decades and typically include safety features like safety valves to prevent the release of hydrogen sulfate.
Shop for Power Supplies at Scott-Clark Medical
When it comes to powering medical devices, lithium-ion phosphate batteries are the best choice for your facility. Compared with lead acid batteries, they have a higher energy density, longer life cycle, improved capacity, and increased efficiency.
If you’re shopping for medical carts and need to find the ideal power source, lithium-ion batteries can help you optimize your practice’s productivity and bring your technology up-to-date.
Scott-Clark Medical is a leading provider of lithium-ion batteries for medical devices, and our team can help you select the perfect battery for your application. Call Scott-Clark Medical today at (512) 756-7300 to discover how we can help power your practice.