Dual batteries in e350


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I wonder if the contacts on a maxi fuse are the same as 1/4" solderless crimp terminals. Then we could use a maxi holder and tap an ATO off of it to power the Bosch relay. I haven't been able to find an add-a-fuse tap for maxi. ATO is easy. We need to be careful with this - Our tap connection fails and the van stops. I'd want the Bosch fused, close to the Maxi, so anything wrong with the Isolator circuit wouldn't blow the maxi and disable the van.
Yes, a short and safe distance to an in-line fuse holder for the wire headed to Pin 86 on the Bosch relay would be a good idea. I imagine a 5 or 10 amp fuse would suffice for the small amount of amperage required to energize the Bosch relay coil.
Wow jd, a lot for an old fart like me to absorb all at one time, but I sure do thank you and I will keep re-reading it.
The van is an 2006 e350, 5.4 liter, cargo van
the isolator I plan on using is rated at 80 AMP with a 150 AMP Surge
Mobile Dan is right on the money as to my goals in his last post. I could not have put it into better words
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I noticed that in my owners manual it shows a "15A Back -up lamps, Auxiliary battery relay"

Located in the Passenger compartment fuse panel, position 12

Would this be of any use?

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Is the fuse a "true ignition source"? Do you know the location of the AuxBattRelay? If you find that AuxBattRelay and associated circuits work as needed, you could attach to your isolator solenoid and get your new system to work that-a-way.
The location of the AuxBattRelay is location 20 of the PDBox, PDB fuses 8 and 24.

I already have everything installed, except frame battery is not in the box yet, and I have not hooked up to a "true ignition source"
Question, When hooking up the 10 Amp in-line mini-fuse for the "Bosch Relay" should it be attached to the fused side or the hot side of the 20 Amp Maxi-Fuse for the Fuel Pump when in "true ignition source" mode.
JB Weld Quick Set epoxy over the top of the exposed jumper wire solder connection
If you are doing that for insulation, then I would say NO. I believe JB weld is slightly conductive.

If you are doing it for a better connection then it would be OK, although the solder joint should be fine without it.