If you're considering making the switch from lead-acid to lithium-ion batteries, there are a few technical and practical tips you should be aware of to ensure a successful transition. Here are some essential tips to keep in mind
Lithium-ion Battery Types
The two main types of lithium-ion batteries are lithium iron phosphate (LiFePO4 or LFP) and lithium-ion. LFP have a nominal voltage of 3.2 volts per cell, meaning four cells in series (a 4S battery) is 12.8 volts, perfect as a 12v lead-acid replacement.
Lithium-ion refers to a few different chemistries that include cobalt. These include lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel manganese oxide (NMC), lithium nickel cobalt aluminum (NCA), as well as mixtures between them. These chemistries generally have 3.6 to 3.7 volts per cell. NMC has become synonymous with cobalt-based batteries simply because it is the most popular chemistry for electric vehicles (EVs). We even typically use NMC as a catch-all for all cobalt batteries, even though many 18650 cells - those labeled ICR18650 - are LCO.
Battery Voltage and Capacity
Lithium-ion batteries have a different voltage and capacity rating than lead-acid batteries. For 12 volt applications, we recommend lithium iron phosphate (LiFePO4 or LFP), which will have four cells in series (at 3.2v each) to make 12.8 volts nominal. 24, 26 and 48 volt applications match up well with either LFP or cobalt-based chemistries. One big advantage to lithium-ion batteries is the flat voltage curve. While lead-acid lose voltage in a linear fashion, lithium-ion batteries spend the majority of their capacity near their nominal voltage. Make sure to choose a lithium-ion battery that matches the voltage and capacity requirements of your device or equipment.
Lithium-ion batteries require a different charging method than lead-acid batteries. The most immediate difference is that lithium-ion don't need multiple charging stages. Both lithium-ion and lead-acid go through a bulk charge to about 80% followed by an absorb charge to 100% (though we recommend 90% max for cycle life). However, lead acid also require float and potentially equalize charges. Float is essentially a trickle charge, while equalize is required every once in a while on some lead-acid chemistries to maintain consistency between cells. Even though our 12-volt LFP drop-in batteries can be used with a lead-acid charger, it is best to use a lithium-specific charger. If you have a charger that allows you to change the charge voltage, we recommend the settings below. For other lithium-ion batteries, make sure to use a charger that is specifically designed for your batteries and follow the manufacturer's instructions for charging.
|12 Volt Lithium Iron Phosphate Voltage Setting
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Lithium-ion batteries have a more limited temperature range than lead-acid batteries. We don't recommend charging below freezing (32°F or 0°C) or above 50°C (122°F). Because discharge naturally creates heat, lithium-ion can typically be discharged as low as -10°C (14°F). However, performance is limited by a significant rise in internal resistance at lower temperatures, and charging can cause irreversible damage that reduces capacity. Some batteries include a heater for low-temperature operation. Use those or an external battery heater if you plan to operate your batteries in cold climates. Lead acid is more tolerant of lower temperatures, but charge and discharge will be severely limited until they warm up. Make sure to store and use your lithium-ion battery within the specified temperature range to prevent damage or performance issues.
Charge and Discharge Rate
Lithium-ion batteries are far more efficient and have a higher discharge and especially charge rate than lead-acid batteries. Make sure that the device or equipment you're using the lithium-ion battery in can handle the higher discharge rate without causing damage.
Unlike lead-acid batteries, lithium-ion batteries require little to no maintenance. Flooded lead-acid batteries contain water and sulfuric acid solution called electrolyte, which requires regular maintenance to ensure the lead plates are completely submerged. Lithium-ion, on the other hand, don't require regular maintenance, and usually include a battery management system (BMS) that ensures cells are balanced. However, it's still essential to follow the manufacturer's recommendations for care and maintenance to ensure optimal performance and lifespan.
A typical BMS found inside a lithium-ion battery. This one is manufactured by Daly.
Lithium-ion batteries are generally safe when used correctly, but they can be dangerous if mishandled or abused. Nearly all lithium-ion batteries have a BMS that protects from over- and under-voltage, over-amperage, temperatures and even balance cells. While lithium-ion batteries get a bad rap from coverage Despite this, it is essential to follow safety precautions when handling and using lithium-ion batteries, such as avoiding overcharging or overheating, and never puncturing or damaging the battery.
In summary, we've made switching from lead-acid batteries to lithium-ion batteries a breeze by designing and manufacturing drop-in replacements. That said, the switch to lithium-ion requires a bit of technical knowledge and care. By choosing the right battery voltage and capacity, using the proper charging method, keeping within the temperature range, checking discharge rate compatibility, following maintenance recommendations, and observing safety precautions, you can ensure a successful and smooth transition to lithium-ion batteries.