This service attempts to eliminate the parasitic current draw by the Magnum Inverter/Charger when the Interstate is being stored. See this earlier thread
for more info.
DO I NEED THIS?
This repair turns off the Magnum Inverter/Charger when the battery disconnect switch is used to turn off the van’s electrical systems. The repair applies to Interstates for entire 2014 and 2015 model years, and part of the 2016 year (vehicles in the VIN range of 302701 through 304627).
If you park the van unconnected to 110V power, yeah, you probably want the repair.
WHAT IS THE REPAIR?
The repair takes about 45 minutes.
1. Disconnect 12V
2. Mount the solenoid on the roadside panel of the electrical compartment
3. Disconnect red 12V
00 power cable to the Magnum Inverter
4. Attach that power cable to the solenoid large terminal
5. Attach a new length of 00 red between the other solenoid large terminal and the Inverter
6. Attach 2 blue and white 12ga. wires to the solenoid small terminals
7. Connect blue to an open spot on the fuse panel. Connect white to ground. Insert 5A fuse
Solenoid is SAS 4202, specification 200A continuous, SPST-NO. Solenoid is normally open, and closes when the coil is energized. If I’ve looked up the right part, coil is 14.5 ohm, so it draws 850 mA when closed.
WHAT DOES IT DO?
For affected vans, the Magnum was left energized even when the van was parked (batteries disconnected using the battery disconnect switch). The Magnum uses hella power when it is sitting energized unused. You don’t need it to be energized when the van is parked, obviously. So how much power does it suck up? If your van is parked without 110V power, the Magnum will drain away about half your batteries’ capacity in 10 days, 8 Ah each day, or about 5% each day.
Your solar panels might be able to undo the drain of the Magnum. Depending on how sunny it is, your solar panels might contribute 8 Ah of energy to your batteries, preventing any drain from the Magnum. Keep in mind, however, that solar only contributes during the day, so even if your solar keeps your batteries fresh, the batteries are being drained of 4 Ah at night and refilled when the sun is up. That constant cycle of night-time drain and daytime refill, every day and night, is not good for the batteries.
WHAT IF I DON’T HAVE IT DONE?
Keep your van plugged in. Keep in mind that if you cannot plug your van in for a period, you might have to refresh the batteries every week or so to prevent damaging them. Without the repair, the Magnum may drain the battery bank below 50% in about 10 days.
IS THERE ANY DOWNSIDE TO THE REPAIR?
I’m glad you asked. Airstream, in all its wisdom, chose a cheap relay to turn off the Magnum. When using the van, the Magnum will be energized and the relay will draw about 850 Ma. That’s no problem if you are connected to 110V power, but may be a problem boondocking.
Before the repair, the Magnum would use 300 to 400 mA by itself. After the repair, the Magnum and the relay together use more than 1.2 A, three or four times the draw of the Magnum alone. Boondocking, you’ll get a lot less time from your batteries. The Magnum and relay together will use about a fifth of your total battery capacity per day.
CAN I FIX IT SO I CAN STILL BOONDOCK?
There are a couple of things you can do:
1) When you are off 110V power, using the van, but are not using the Inverter, pull its fuse. You don’t want to do that too much, however, because eventually the fuse holder will wear out.
2) Install a switch so that the relay and Magnum can turned on and off manually.
3) Replace the crappy SAS-4202 with a latching or low-power relay. There is at least one low-power, solid state relay that is a direct drop-in replacement for the SAS-4202. If you go with a more common Intellitec latching relay, you may still have to add a switch to turn the relay on and off manually.