Eric,
Carl is right in that the Echo Charger even though SMC made it standard equipment on the Marquis, for many Patriot models it was an option. However, it was a very badly needed option that should have been standard equipment.
If you are going to add an Echo Charger or the Magnum equivalent, there is another option that you might consider that gives you much more amperage capacity and operator control. When I purchased my current coach, the Echo Charger had apparently failed an it had been replaced with the Magnum unit that had also failed by the time I purchased the coach. So I chose to replace it with a Blue Sea unit, (
https://www.amazon.com/Blue-Sea-Automatic-Charging-Equipment/dp/B01HJTFDKG/ref=sr_1_10?keywords=blue+sea+battery+isolator&qid=1584234837&s=amazon-devices&sr=8-10).
To get full benefit from the Blue Sea unit, you need to make a change in the engine alternator charging circuit to basically replace the battery isolator with the Blue Sea unit, and it becomes a fully automatic battery isolator/combiner with complete driver override control when needed, and with its 500 amp capacity, it can also be used as a boost switch. The Blue Sea unit functions like the Intellitec Big Boy isolator/combiner, but it gives you driver control as well as being automatic so that if you do not want to combine your batteries for charging like when you have been dry camping for the night, and you want to start driving the next morning without running the generator, your engine alternator will not have to recharge the house bank if you flip a switch at the driver's seat. Likewise, if your engine alternator fails, you can flip a switch to run with both battery banks combined unit you need to start the generator to recharge them. The Blue Sea unit also gives you the ability to replace your engine alternator with the standard less expensive alternator used on trucks instead of the Duvac alternator that SMC used.
If someone wants to know how to wire the Blue Sea unit into their coach, just call me. 713-254-4156
Gerald
