Grit Dog - You bet.... I am aware of the problems and fixes. My additional battery install is primarily to support my two way Radios Operations from the stand alone truck as well as adding additional batteries to the OFF-ROAD Trailer setup when camping back off the grid. On my diagram above you can see where I plug a second 2-conductor cable into the truck bed battery bank when in camping mode with the off-road trailer. An additional feature is going to SI-ACR manual mode I can switch in the truck bed batteries to help start my truck if the truck start battery has discharged some...
I love PLAN Bs...
My 2010 F150 truck has all kinds of system items running when I turn the key off... Once the truck start battery gets down abit it goes pretty fast just sitting in the driveway for a couple of weeks not being used... My older 2004 F150 wasn't quite as bad doing this compared to the newer F150... If I drive my truck alot I don't have this problem so this is telling me I am not getting a fully charged truck start with my short runs every three or four days. The problem of being retired haha...
I used to solve the problem with a small solar panel sitting on the dash... Probably should dig that out again and use it more...
I won't be disconnecting the truck start battery to keep it from discharging. That will cost you $90 at the Ford place for 5 minutes work effort to reset all of the computer settings that the books says will re-learn when the truck start battery has been disconnected. Been there done that already...
Another golden rule I have is to never mess with the truck start system when camping off the power grid. This is you only way to get back home haha...
Thanks for the reality checks...
Roy Ken