Before answer this question, you need to know several types of lithium-ion batteries, the classification mainly depends on the composition of the different materials used for their cathode materials. These different compounds can provide extra power per kilogram of battery weight (2.2 Lbs). This extra power increases the risk of thermal events. To ensure that lithium-ion batteries are safe and that thermal-related failures are rare, battery manufacturers do below protection method.
Limit the amount of active substance in the lithium battery.
Added protection circuitry to the battery pack, including battery management system (BMS). The following table compares the power per kilogram (Wh) that these various battery types can store. Please note that standard lead / acid batteries can only store 40 watt-hours, while the most efficient lithium battery NCA (nickel, cobalt and aluminium) batteries can produce 250 watt-hours or six times more than current RV batteries. If not for cost and potential hazard considerations, NCA will be an excellent RV battery. For safety and cost considerations, LFP (lithium iron phosphate) batteries are more widely used in RVs. A lithium iron phosphate (LFP) battery has approximately three times the energy of lead / acid and weighs about half that.
2. BMS security features
Each of four (3.2 volts) lithium batteries in series were continuously monitored to produce a 12.8-volt lithium battery. This monitoring includes the voltage of each battery under high or low voltage limits and disconnects the battery from the load or charger to prevent damage. Monitor the temperature and excess current of each battery, and if these limits are exceeded, disconnect the battery from the load again. BMS also monitors the charge status of each of the four batteries and automatically balances its voltage during the charge cycle to charge all batteries simultaneously. This balance ensures a safe full charge and extends battery life. Based on these features, lithium iron phosphate batteries (LFP) are very safe and reliable.
We usually use the number of cycles to explain the life of the lithium battery, fully charged 100% SOC, and then discharged to 0% SOC, this is called one cycle. The rated life of a lithium battery is usually around 2000-3000 times. This is a theoretical value, and many factors can increase or decrease battery life, including discharge depth, operating temperature, and material ageing. Lead-acid batteries typically only use 300-400 cycles. If based one cycle per day, that means your RV battery can use about 5-10year. Lead-acid batteries cannot be stored for a long time, while lithium batteries can be stored for one year or more, and the power can be maintained above 90%. To extend the life of the lithium battery, the lithium battery should not be stored fully charged. It is recommended to charge about 50% to 60%.
4. (LFP) What are the maximum and minimum operating temperature limits for lithium batteries?
Lithium batteries have a wide operating temperature range (-4℉ to +160 ℉ / -20℃ to +70 ℃). Lithium batteries can be stored and discharged at the upper and lower temperature limits, but lithium iron phosphate batteries cannot be charged at temperatures below 0 ℃. For temperature limit specifications, kindly refer to the manufacturer’s detailed specifications.
5. What are the other advantages of lithium battery systems?
Lithium batteries have a longer service life than lead / acid batteries and require minimal maintenance. They can be stored for a long time (rechargeable once every 6 months or 1 year). Their weight is about AH rating of lead / acid batteries ½ or less of the value. They also provide 3 times the power of lead-acid batteries and can charge up to 6 times faster with the same size charger. This can reduce the working time of the generator and speed up the charging speed. The reason for the faster-charging speed is the unique chemistry of lithium batteries, which enables them to accept the charger’s full charge rating until it is almost full. The chemicals in lead / acid batteries can only be fully charged in the absorption phase, and then the charging current drops rapidly, making it take longer to fully charge.
6. Can I use my solar charging system for my lithium battery charger?
Yes, both systems can run simultaneously. Your solar system should have a solar controller that can be set to limit the maximum charging voltage of the solar panel. The maximum voltage of the lithium iron phosphate battery should be set to 14.6 volts. Can I charge the lithium battery from the vehicle alternator? – Yes, but not necessarily fully charged, as most alternators have been adjusted for the lower voltage requirements of automotive lead-acid batteries (approximately 13.9 volts). Lithium batteries require 14.4 to 14.6 volts to be fully charged. Of course, you can also get 70% of the power, depending on the depth of discharge and the distance travelled when recharging from the vehicle alternator.
7. My current RV has a 45 amp converter/charger. Can I install a larger 60A or 80A device to further reduce charging time?
No, your RV wiring system is designed to safely handle 45 amps of current, increasing it to a 60 amp or 80 amp charger could cause a thermal event! When updating to a lithium battery system, use a converter/charger of the same size as the one currently installed in the RV! Similarly, lithium batteries can even accept faster charging rates. Even a 45 amp lithium battery charger can charge a 100 amp battery (100 amps divided by a 45 amp charge rate), which is equivalent to about 2.2 hours plus the extra time required is due to the lower charging rate. At the end of the charge, the estimated charging time is about 3 hours.