Connecting Battery Isolater (7622) To D+ (Alternator) Terminal under seat?

[van.on.the.run]

I have a 2015 MB Sprinter. There are three studs under the drivers seat. One is always hot, the second is hot when the key is in position 2, and the third is only Hot when the engine is running and the alternator is providing power.

I have a Blue Sea 7622 and I am wondering if there are any practical differences between which of the three lugs I tie my charging relay to. My main goal is to have house loads powered by alternator while I'm driving. Also, I've understood that the D+ terminal is "cold" while the engine is cranking, so I wouldn't have to worry about any electrical issues with my house loads during cranking/start-up.

Thoughts?

Thanks in advance!

Also, if anybody has any idea advice on where to hook up the brown wire to in the diagram (http://assets.bluesea.com/files/reso.../990180180.pdf) on left hand side of page 3 of 4. I'm stumped. I've heard that it's not actually necessary, but I don't understand why it wouldn't be necessary if it was designed into the product.

Thanks again!

[Scalf77]

I don't have a Sprinter, so I may not be the best to answer. You need to be a little clearer on what you mean by tying the 7622 to these terminals. Are you talking about (Terminal B of the Blue Sea 7622)? This would normally connected to the starting battery.

On the Sprinter I believe:

Terminal 1 (D+) is hot while running, but is only a 10 Amp circuit.

Terminal 2 is direct battery power, 25 amp circuit

Terminal 3 is ignition powered and a 15 amp circuit


While terminal 2 is direct battery power, the 25 amp limitation, makes it a poor choice for a bluesea 7622 terminal B connection. It would be better to go directly to the battery.


The brown wire is the start isolate input, it should be connected to a source that is hot why the key is in the start position , i suspect that terminal three would work for that.

hope this helps

-greg

[van.on.the.run]

Thank you for reminding me that those three under seat terminals had amperage limits. I had forgotten that they were fused.

The way I've understood the intended location of the brown wire, is that it should be tied to something that is ONLY hot while the key is in the start position. Terminal three is hot when the key is in starting position, but it is also hot while driving, right? Do you think this would affect the functionality of the 7622?

I may just hook it up to my DC power supply and run through a bunch of logic sequences to see how it responds.

Thank you for your note!

-Rob

[Scalf77]

It needs to only be hot during start, not during run. So terminal 3 would not work than. I suspected that ignition meant start only, sorry.

-greg