Lithium Iron Phosphate (LiFePO4) is the chemical component of Keheng’s lithium power batteries and has been in the spotlight since its introduction in 1996. Even though LiFePO4 is a relatively new lithium chemistry, it has become a popular choice for lithium starter batteries.
When choosing a lithium starter battery, you may notice that unlike SLA batteries, lithium starter batteries typically do not have a cold cranking current (CCA) rating. Our blog series “What’s CCA for Motorcycle Batteries” explores why CCA is not typically applicable to Powersports applications. In addition, automotive CCA test standards do not apply to lithium batteries.
You may wonder, “Will my lithium batteries work in cold weather?” The straightforward answer is “Yes.” A more detailed explanation is that automotive CCA testing does not apply to lithium batteries, and there is currently no standardized test for this chemical.
The Continuing Power of Lithium
Without worrying about the lack of standards for lithium batteries, there are other factors to consider when comparing them to other chemicals. For example, lithium batteries maintain a constant voltage throughout the cycle, whereas the voltage of SLA batteries fluctuates with the state of charge (SOC). This means that Li-ion batteries are able to provide the same output power at 15% discharge as at 85% discharge, so voltage testing is not as meaningful for Li-ion batteries. For more information on the constant power benefits of lithium batteries, check out our blog The Complete Guide to Lithium vs Lead Acid Batteries.
Continuous Starting Current
A frequent test in LiPo batteries is continuous starting current. In our Hyper Sport Pro range, the test is carried out after the battery has been left at -20°C for 20 hours, followed by a 15 second continuous current test. Unlike the JIS standard, which checks the voltage after 5 seconds and is specific to SLA batteries at -10°C, this method is more suitable for lithium batteries.
Therefore, a continuous starting current (especially when tested at low temperatures) is a reliable indicator of a battery’s ability to start at low temperatures. It is necessary to clarify whether the “CCA” rating refers to “Continuous Starting Current” or “Cold Starting Current” and to understand the test method used. As mentioned earlier, there is no official standard for CCA or continuous starting current testing of lithium batteries, so it is up to the manufacturer to define their test program.
Lithium batteries in cold weather
One limitation of lithium batteries is their performance in cold weather. Similar to SLA batteries, the capacity and life of lithium decreases with temperature; the lower the temperature, the lower the capacity and the longer the cycle life. While lithium batteries can be discharged in cold conditions (down to -20°C or -4°F), the charging temperature should not fall below freezing (0°C or 32°F). However, it is unlikely that you will need to charge your lithium battery starter outdoors during the winter months; you may be able to charge it in your garage, where temperatures are above freezing.
Lithium-Ion Battery Starter
In our CCA blog series, we discussed the concept of continuous current in SLA starter batteries.The 5-second continuous current test is designed to provide enough power to start a motorcycle engine. Looking at the performance graphs below, you can see that Li-Ion batteries provide constant power compared to SLA batteries and show how much cranking each battery type can provide before recharging.
A few amps. The power equation is P = V * I, where P represents power in watts, V represents voltage, and I represents current in amps. A cranking cycle consists of 5 seconds of power for engine startup.
In the chart below, the test consists of 5 seconds of cranking at 400 amps, followed by a short pause and another cranking cycle, and so on. The test was conducted at an ambient temperature of approximately 70 degrees Fahrenheit.
The lead-acid battery (shown by the dotted line) drains battery energy with each rotation, resulting in a voltage drop. This leads to a reduced supply of energy for subsequent rotations and ultimately prevents the lead-acid battery from continuing to rotate. In contrast, the lithium battery (shown by the solid line) also drains energy, but the voltage remains stable. As a result, each crank rotation produces roughly the same amount of power. During the initial cranking rotation, the Li-ion battery heats itself up, which is very beneficial in cold conditions as the heat increases the capacity and performance of the battery. Notably, SLA batteries do not exhibit this behavior. Typically, in cold weather, it is recommended that the bike’s headlight be turned on prior to cranking to help heat the battery, i.e. the cranking heating effect.
BCI Group 30 Motorcycle Powersports Battery Output Power: SLA batteries drop in voltage during discharge, with a subsequent reduction in power. From one cranking rotation to the next, the SLA battery’s output power decreases, up to a 25% loss of power, and the engine may not start after 12 cranking rotations. In contrast, Li-Ion batteries maintain a constant voltage throughout the discharge process, delivering steady power from the first crank rotation to the last until they need to be recharged.
Charging and Self-Discharge: In addition to providing constant power, Li-Ion batteries support more starting cycles between charges than SLA batteries. Referring to the previous chart, SLA batteries complete fewer starting cycles than Li-ion batteries and lose power. This means that lithium batteries require less frequent charging than SLA batteries.
SLA batteries self-discharge at ten times the monthly rate of equivalent lithium batteries. So if you ride your motocross bike a few times in April and then don’t ride it again until mid-July, the SLA battery will further discharge from inactivity and self-discharge. On the other hand, Li-Ion batteries do not experience this problem and can maintain a high state of charge (SOC) without trickle or float charging during long-term storage. Since there is currently no cold-start current test standard for Li-ion batteries, comparing the performance of SLA and Li-ion batteries provides a practical, real-world test to determine which battery performs better.