If you are an RV enthusiast or plan to become one, then you are likely aware of the various sizes and options available in today’s RV market. However, you may be less aware of the power of each RV size and the importance of the battery charging system.
Below is a chart detailing the different RV classes, their typical power systems, and the Cohen lithium batteries we recommend for each class. Please note that these batteries are suitable for home powering and not for starting applications (e.g., starting a Class A, B, or C motorhome).
Why lithium batteries for RVs?
The LiFePO4 Lithium Iron Phosphate (LiFePO4) battery from Tech Heng is capable of meeting a wide range of needs on the road. Designed for harsh environments, this battery ensures that the vehicle can travel farther and more efficiently without compromising reliability and performance.
More power available
Lithium-ion batteries allow you to utilize 100% of their capacity, regardless of discharge rate. Lead-acid batteries have a high discharge rate, for example, 0.8C, but can only deliver 60% of their rated capacity. This ensures that lithium batteries still have plenty of spare capacity when you run all your electronic devices.
Ultra Safe Chemistry
TechHelix lithium batteries utilize lithium iron phosphate (LiFePO4) chemistry, which is the safest lithium chemistry available. For added safety, our lithium RV batteries are equipped with an advanced Protection Circuit Module (PCM) that protects against overcharging, over-discharging, overheating, and short-circuit conditions.
Longer lithium battery life
The cycle life of Tech Heng RV lithium deep cycle batteries is 10 times longer than that of lead-acid batteries. This reduces the cost per cycle of lithium batteries, which means you’ll have to replace lithium batteries less often than you’ll have to replace lead-acid batteries in your recreational vehicle.
Lithium charges faster
Lithium batteries charge up to 4 times faster than lead acid batteries. Faster charging means batteries last longer. In addition, solar panels’ fast and efficient energy storage can be seamlessly integrated into your leisure vehicle. For more information on effectively charging batteries, see our full guide on charging lead acid batteries.
Lithium batteries are lighter in weight
Lithium batteries are 50 to 70% lighter than lead-acid batteries of the same capacity. Weight savings of 100 to 200 pounds can be achieved for larger RVs.
Flexible installation
Cohen lithium batteries can be mounted upright or sideways, making them flexible to install and easy to configure.
Alternative to lead-acid batteries
Cohen lithium batteries are available in various BCI standard specifications and can be used as a replacement or upgrade for lead-acid batteries.
Low self-discharge
Lithium batteries have a low self-discharge rate, so there is no need to worry about storage, and even seasonal use will not affect battery performance. We recommend an OCV check on all lithium batteries every 6 months.
Maintenance free
With a plug-and-play design, simply connect the battery and go! No need to add water, completely maintenance free.
Charging Lithium Caravan Batteries
Along with many types of recreational vehicles, there are various power sources and methods of charging caravan batteries. A charging power source is the way in which electricity is generated and includes:
- Shore power – where the caravan is connected to an AC outlet
- Generator – equipped with a generator for generating and charging electricity Solar – the caravan is equipped with solar panels for generating and charging electricity
- Alternator – drives the engine to charge the batteries while the RV is traveling
Methods are how the voltage and current are controlled when charging the batteries. Methods include:
- Trickle charging – slow and steady charging to keep the battery healthy
Charging Methods for RV Batteries
There are a few main methods to consider when it comes to charging RV batteries:
- Low constant current charging: this method charges the battery at a constant low current.
- Float charging utilizes current limitation and constant voltage to maintain battery power.
- Multi-stage charging: this method includes constant current charging, voltage absorption charging, and float charging to maintain the battery at 100% charge (SoC).
RVs may have multiple battery charging sources, but only one charging method is usually used. The main difference between these methods is the charging speed; multi-stage charging systems are designed for fast battery charging.
Charging specifications for different battery types
Sealed lead acid (SLA) and lithium batteries have slightly different charging current and voltage parameters. Sealed lead-acid (SLA) batteries are typically charged at 1/10 to 1/3 of their rated capacity. in contrast, lithium batteries are charged at 1/5 to 100% of their rated capacity, and the charging time is significantly shorter. The voltage settings for absorption charging and float charging are so close that they are usually negligible when switching from SLA to Li-ion batteries.
Charger types and recommendations
There is a lot of conflicting information on the web about charging configurations for SLA and lithium iron phosphate (LiFePO4) batteries. While RV charging systems may differ, this overview is intended to provide general insight. One of the reasons that Techhem chose LiFePO4 over other Li-ion batteries is that LiFePO4 batteries are similar in voltage to lead acid batteries – LiFePO4 batteries typically operate at 12.8V, while lead acid batteries operate at 12V. This voltage similarity makes the charging characteristics comparable.
As shown below, the charging curves of lead-acid and lithium batteries are similar, and the operating voltage ranges are approximately the same. Therefore, SLA chargers can effectively charge Li-ion batteries but cannot utilize the fast charging capabilities of a dedicated Li-ion battery charger.
To take full advantage of lithium technology, upgrading to a dedicated lithium battery charger is recommended. However, using SLA chargers will not cause serious damage to LiFePO4 batteries because the charging voltages are relatively close.
It is important to note that LiPo batteries do not require float charging like SLA batteries. In fact, it is better not to keep the lithium battery at 100% state of charge. If the LiPo battery is equipped with a protection circuit, such as Tech Heng’s PSL-SC and PSL-BT models, it will stop charging when it reaches 100%. Therefore, float charging with an SLA charger is unnecessary and will not damage the battery. In addition, chargers with sulfur removal modes should be avoided as they may damage the lithium battery.
Charging Lithium Ion RV Batteries in Series or Parallel
After upgrading your RV to lithium batteries, you may wonder how to charge them efficiently. While the SLA charging system is acceptable, there are some considerations for series or parallel charging.
You can charge RV lithium batteries in series and parallel like any other battery configuration. The RV’s existing charging system is usually sufficient, but lithium chargers and inverters can be added to improve charging efficiency.
For batteries connected in series, ensuring that all batteries have the same State of Charge (SoC) during installation is critical. This means that all batteries must be at 100% state of charge. Keep in mind that the voltage of a series-connected battery pack can vary. Any cell exceeding the protection limits set by its Battery Management System (BMS) or Protection Circuit Module (PCM) could cause problems.
When charging a battery pack, it is critical to use a charger that matches the total voltage of the series. The recommended charging voltage for lithium iron phosphate batteries is 3.65V per cell, which translates to 14.6V for a 12.8V battery. To determine the total charging voltage, multiply the charging voltage by the number of cells in the string. For example, if the total voltage of your string is 51.2V, set the charge voltage to 58.4V.
If you are connecting in parallel, you can charge the batteries at a rate of 1/3 C of the total rated capacity. For example, if four 10 amp-hour (AH) batteries are connected in parallel, you can charge them at 14 amps (A) because 1/3 of 40 is 14. Suppose the charging system exceeds the protection limits for an individual battery. In that case, the battery management system (BMS) or protection circuit module (PCM) will disconnect that battery from the charging circuit and allow the remaining batteries to continue charging.
To prolong the life of your battery pack, it is recommended that you periodically disconnect your batteries and charge them individually.
Overall, the Power-Sonic PSL-SC and PSL-BTP batteries are an excellent alternative to the standard SLA batteries in RVs. There are many benefits to switching to lithium batteries and the convenience of plug-and-play without replacing the charging system. For further information on the advantages of lithium batteries over SLA batteries, check out our blog.