Rick March, General Manager
Customer Relations Group

Greetings! I hope you enjoyed the Holiday season as much as I have. The only thing that could have made the
week better was some warmer weather. It is bitter cold as I write this article in January in Ohio!!
I have had a question or two lately concerning power converters that we install in the trailers. In our 2018 model
year line up we replaced the single stage converter we have used for many years and started installing a three
stage converter in all models. I will explain the three stages of charging. I will also explain the battery
disconnect switch and the change that we made to this as well.
I appreciate all the feedback I have received. Keep it coming for future articles!!

Single stage converter vs three stage converter.
There has been a lot of discussion over the last few years about why Airstream uses a single stage converter
system in its products. With all the newer technology available today why have we not switched to something
better? This was always a tough question to answer. Some of our owners who have owned their Airstream for
many years have enjoyed the reliability of the single stage converter and had not really experienced any issues.
Why change? Most of this feedback from you, our owners, has come from mens and womens feedback sessions
during Alumapalooza or the International Rally. Many of you have taken part in these sessions and hope you
will continue. Great feedback!! So the change was made. Here are the differences.

The Parallax 7300 series power center
model 7355A had a single stage convertor
with an output of 55 amps. The battery
charging portion will charge the batteries
at 13.6 to 13.8 volts.

Single Stage Converter

The WFCO WF-8900 series power center
has a three stage converter with an output
of 55 amps. The three stages are listed
below.

Three Stage Converter

Absorption Mode: This mode is the normal operation mode, this supplies 13.6 volts to the 12 volt appliances
as well as a slow charge to the batteries.
Bulk Mode: In this mode if the batteries are low the charger will switch to 14.4 Volts for a maximum of four
hours and then return to Absorption mode.
Float Mode: In this mode the converter will trickle charge the batteries at 13.2 volts. When the converter senses
a demand (by turning on lights) the converter will automatically return to Absorption Mode.

Note: I know the first question I am going to be asked. Can I replace my existing single stage converter with the
three stage model? First, the three stage converter is 9 inches deep versus the single stage converter only being 7
inches deep. In many installations there is not an extra 2 inches of space available for the change-out. You may
be up against a wheel well, wall, or some other obstruction. Second, the new three stage converter that we
purchase comes modified to have the battery disconnect solenoid installed in it. All single stage applications
will have the battery disconnect solenoid installed in the front end of the trailer separate from the converter.
You could order the WFCO three stage converter without the disconnect solenoid modification and then you
could replace it.

Battery Disconnect Switch

In 2018 models Airstream changed the wiring from the disconnect switch above to be able to charge the
batteries from either the use or the store position. This was a big change as all previous years the disconnect
panel had to be in the use position to be able to have the converter charge the batteries. The store position
completely disconnected the converter from the batteries. By using the new three stage converter with the built
in solenoid it provides better control of battery charging by engaging as soon as the shore power connection is
hooked up.

I would love to hear from you and if you have a suggestion or topic you would like to see covered in a future article, or
have a question just drop me a line at rmarch@airstream.com .

Have a great month!

Rick March