Superior Technology Integration Knowledge
Batteries are available in many shapes and sizes, from the tiny silver disc powering a wristwatch to the battery used to start a semitrailer. Beyond size and shape, there are dozens of battery chemistries to choose from.
Batteries are not a one-size-fits-all solution. Selecting the best battery for an application requires knowing the load requirements and operating conditions.
Lithium batteries provide power at almost full capacity regardless of the discharge rate. When they are discharged at a high rate, no change in power output is seen until the last 10 or 20%. At this point power is still available, but at reduced voltage and rate.
Overall capacity (in amp hours) can be deceptive because a lithium battery can be deeply discharged, effectively using nearly all of the rated capacity. By contrast, lead-acid batteries are held to 50 to 70% of the capacity during discharge in order to extend battery life. For this reason, many people consider a lithium battery of the same capacity to actually have roughly twice the usable capacity of a lead-acid battery.
Best Uses of Different Battery Types
Lead-acid Best Uses
Deep-cycle Batteries: A deep-cycle battery is designed for maximum energy storage capacity and high cycle count, or long life, and is rated in amp hours (Ah). These attributes are achieved by installing fewer and thicker lead plates with limited surface area. Typical applications for deep-cycle batteries are boats, golf carts, wheelchairs, solar applications, RVs, and uninterruptible power supply (UPS) systems.
Engine-starting Batteries: Starter batteries are made for maximum power output and are usually rated in cold-cranking amps (CCA). The battery manufacturer achieves this maximum, short-burst output by combining many thinner lead plates to obtain larger surface area for maximum conductivity. Typical applications for engine-starting batteries are cars and motorcycles.
Battery storage capacity and deep cycling are less important in automotive applications because the battery is being recharged while driving. If continuously cycled, the comparatively thin lead plates of a starter-type battery would wear down rather quickly.
LiFePO4 Best Uses
The energy density of a lithium battery is significantly higher than other battery chemistries. For example, a lithium battery that weighs 35 kg will provide the same amount of energy as a lead-acid battery that weighs 70 kg. This is a highly desirable feature when considering the portable power market. Additionally, lithium batteries can endure more charge/discharge cycles than other chemistries.
Early cell phones required large bulky batteries to operate. If you are old enough to remember the 1970s, then you may remember that a portable communications radio often required a battery that weighed more than the radio itself. With lithium batteries, cell phones and radios today are much lighter in weight with much more power.
The conversion efficiency of a battery denotes how efficiently it converts an electrical charge into chemical energy and then back again. A higher efficiency (expressed as a percentage) means that less energy is converted into heat (heat is lost energy) and that the battery can be discharged faster without overheating—assuming all other factors are equal.
Efficiency of Different Battery Types
Lead-acid batteries are not 100% efficient at converting charging amp hours back into stored amp hours. One of the main reasons why lead-acid batteries dominate the energy storage market is that the conversion efficiency of lead-acid cells is 85 to 95%. Generally speaking, this is often much higher than other types of rechargeable battery technologies. However, even at 90% efficiency, it will take approximately 110 Ah of charge to replace 100 Ah of consumed capacity from a lead-acid battery.
The lower the internal resistance of a battery, the better its conversion efficiency will be. This is another reason to avoid the buildup of “rock content”, which increases the resistance of the battery similar to the way a buildup of solutes within a pipe decreases the flow rate of water through the plumbing.
The conversion efficiency of lithium batteries is virtually 100%. Lithium batteries have a very low internal resistance, and that is one reason they are both more efficient and more powerful than other batteries, pound for pound.
No other batteries are as close to 100% efficient at converting charging amp hours back into stored amp hours. The efficiency of lithium batteries and their low internal resistance are some of the reasons why they may recharge three to four times more quickly than lead-acid batteries. However, this also means they put a higher demand on conventional alternator or generator charging systems, so the entire system should be engineered with these differences in mind.
The voltage of a battery is the amount of electromotive force (or the amount of push) that moves electrons from negative to positive fields.
Voltage of Different Battery Types
The voltage of a lead-acid battery is a direct indication of its state of charge (SOC). Voltage is a function of the specific gravity of the electrolyte at the place in the battery where the chemical reaction occurs. Specific gravity is a measure of the health of the electrolyte in a lead-acid battery.
A battery management system (BMS) ensures that individual battery cells are charged and maintained optimally. In a working configuration, lithium batteries usually require unique charging times, voltages, and amperages, and they can be easily and permanently damaged if they are not used with a proper BMS .
Cell damage can range from significantly shortened life to general poor performance, and in extreme cases a damaged cell can overheat, causing an explosion or fire. While it will not spew caustic electrolyte like a lead-acid battery, it will likely be a memorable event.