Airstream uses two different power converters across the travel trailer lineup.
- WFCO WF-9855-LiS (integrated and deck mounted)
- Progressive Dynamics PD4045LCSV (integrated only).
At the most basic level, a power converter takes 120 volt AC (alternating current) shore power and converts it to 12 volt DC (direct current) for battery charging and powering the 12 volt DC system in the travel trailer.
WFCO WF-9855-LiS converter integrated in a 30-amp power center, circled in red.
Deck-mounted WFCO WF-9855-LiS converter for a 50-amp power center.
Progressive Dynamics PD4045CSV integrated in a 30-amp power center, circled in red.
A Deeper Dive
The power converters used by Airstream utilize a 3-stage charging system when the Lead Acid charge profile is selected. The three stages of the charging system within the converter are Quick Charge/Bulk, Nominal Charge/Absorption, and Trickle Charge/Float modes.
When a battery is at a low state of charge, the converter will enter Quick Charge or Bulk mode. The voltage applied to the battery(ies) increases to 14.4VDC for up to four (4) hours while still providing 12VDC power to appliances in the trailer. As the voltage of the battery(ies) increases, the current draw will decrease until a preset voltage-to-current-draw limit is reached, and the converter will enter Nominal Charge/Absorption mode.
This is the default operation of the converter, providing 13.6VDC for battery charging and running 12VDC components in the trailer. If the converter has timed out of Quick Charge/Bulk mode or detected a significant change in current draw, it will enter Nominal Charge/Absorption mode and continue charging the battery(ies) to full. Depending on the charge level of the battery(ies), the current draw from the converter to the battery will vary from high to low.
After monitoring the battery(ies) for 44 hours with no significant change in current draw, the converter will drop to a 13.2VDC output to keep the battery(ies) charged when no 12VDC components are in use. Any change in the current draw will cause the converter to leave Trickle Charge/Float mode and enter Nominal Charge/Absorption mode. Trickle Charge/Float mode is a protective state to keep the battery(ies) full without damaging them or connected components.
A power converter can’t tell the difference between the 12VDC systems in Airstream travel trailers—from Basecamp to Classic and every line in between. The difference between units lies in the type of battery used and how the power converter interacts with each.
Lead acid deep-cycle, AGM, and Lithium (LiFePO4) batteries are used.
Alternate charge profile
Both the WFCO and Progressive Dynamics converters are equipped with an alternate charge profile for Lithium batteries ONLY. When connected to a WFCO or Progressive Dynamics converter, a 2-stage charging system is utilized. This is very similar to the 3-stage charging system except there is no Trickle Charge/Float mode.
LiFePO4 batteries are different than other batteries, therefore the Quick Charge/Bulk mode accomplishes two tasks when in this mode; the first is to quickly charge the battery(ies) while supplying 12VDC power to components of the trailer and active balancing of the lithium cells within the battery(ies). The output voltage is raised to 14.6VDC for a minimum of one (1) hour to a maximum of four (4) hours.
The default operation of the converter, providing 13.6VDC to the 12VDC system of the trailer. The converter will stay in Nominal Charge/Absorption mode until a higher charging voltage is needed.
Trailers can be upgraded to Lithium (LiFePO4) batteries. Lithium batteries have several advantages over Lead Acid or AGM batteries; they have a longer lifespan, faster charging rate, deep discharge without damage, and are lighter in weight.
For the WFCO WF-9855-LiS integrated converter in the 30-amp power center, a slider switch covered by the faceplate will change the charging profiles of the power converter.
For the Progressive Dynamics PD4045LCSV integrated converter in the 30-amp power center, a slider switch covered by the faceplate will change the charging profiles of the power converter.
LA (‘1’ on the slider switch) is for Lead Acid-type batteries. For this charging profile, normal deep-cycle and AGM batteries are considered Lead Acid.
LI (‘ON’ on the slider switch) is for Lithium ONLY. The Lithium charge profile is slightly higher and has NO float mode.
For the deck-mounted WFCO WF-9855-LiS power converter, a jumper wire (14AWG) is needed to complete the circuit of the “Lithium switch” and change the charging profile from Lead Acid to Lithium.