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CHOOSE THE BEST BATTERIES FOR YOUR RV
With lithium batteries becoming a more common option in RV solar, it can cause confusion for RVers. Do they go with the traditional absorbed glass mat(AGM) or move to lithium? Here are a few tips to weigh the benefits of each battery tupe and help you make a more informed decision.
- Budgets play a huge role in deciding which battery to get. Lithium batteries use more expensive materials with some being harder to come by. AGM batteries are sensitive to depth of discharge. This means the deeper the battery is discharged, the fewer cycles it has. AGM batteries are generally recommended to only be discharged to 50% of their capacity to maximize their cycle life. This limited depth of discharge (DOD) of 50% means that more batteries are required to achieve the desired capacity. This means more upfront costs, and more space needed to store them.
- A lithium (LiFePO4) battery, on the other hand, is not affected much by depth of discharge so it boasts a much longer cycle life. Its DOD of 80-90% means fewer batteries are required to achieve the desired capacity. Fewer batteries mean less space needed to store them. More on discharge depths later.
INITIAL COST PER CAPACITY ($/KWH)
AGM – 221; Lithium – 530
Initial Cost Per Life Cycle ($/kWh):
AGM – 0.71; Lithium – 0.19
Size and Weight
Lithium batteries have the added bonus of not containing the heavier lead-acid found in AGM’s, therefore, are much lighter. Since their DOD is 80-90%, lithium a battery bank generally occupies less space. (Less batteries are required for a desired capacity.) Because of this, lithium batteries can save quite a bit of volume and weight in comparison to the traditional AGM’s.
DISCHARGE
The depth of discharge of a battery refers to the percentage of the battery that has been discharged (used) relative to its overall capacity within a charge cycle. A lithium battery with an overall capacity of 100Ah will discharge to 80%-90%, while AGM’s offer 50Ah before needing to recharge. Based on these numbers, AGM’s are the better option for those who use their RV only a few months at a time, and lithium batteries are preferable for those who are off-grid all the time.
Summary
Lithium – A fairly new entrance into the RV battery market compared to the AGM, the lithium battery is an efficient powerhouse. Its benefits are as follows:
- Up to 15% higher charging efficiency
- Up to 50% lighter than AGM
- Longer lifespan
- Deeper depth of discharge
- While more expensive up front, they make up for the difference over time
