Ahhh. That's the good stuff! Thank you for explaining a more applicable DC-DC scenario. That makes sense. For what it's worth that Victron I linked can limit its current draw. Now I know why that would be useful.
I have gone back over your exchange with
@lazergeek regarding the relay setup, and I'm really digging that that approach. I have not fished wires through the boat and was looking for an alternative to having that experience, BUT I see the merits of doing it that over what I was cooking up. I'm going to take your idea and put in the shunt to monitor and see what I learn about consumption vs. current capacity before changing anything. Part of this stems from enthusiasm to play with the new boat while she hibernates for the winter, so forgive my inclination to overcomplicate.
Love what you're thinking about charging going down the road. The ability to essentially take shore power with you down the road using the same path and equipment as if in a slip/barn sounds awesome, and a good choice over adding a separate DC-DC setup. I'd like to pass someone on the Interstate with an extension cord jacked into the side of their boat!
Love the enthusiasm to make your awesome boat even more awesome.. the LFP batteries are pretty remarkable in their ability to store a lot of energy, maintain their voltage, and charge 5 times as fast as a FLA battery. FLA batteries are tough though, you can beat them up pretty good and as long as you don’t let them sit at some level of discharge, don’t discharge them beyond 50%, and once a month during heavy usage you check them with a hydrometer and run a monthly equalization charge they perform decently.
With the way
@lazergeek did his DVSR thing, you just have to be sure not to leave the key on, which come to think of it may not be an option for you, don’t you have to leave the key(s) on to keep the connext screen powered up so you can control lighting, tunes, etc? For us 210 FSH owners, there is very limited control function from the connext screen, the only thing I can think of is setting the basic functions like clock, language etc, and the on / off times for the aerator for the live well when it is in auto, everything is done by rocker switches, except the stereo it is done from the control head. If that is true then you will just have to wire in a rocker switch.. easy peasey.. not sure what plans you have for other things on your boat, what about an auxiliary 12V buss behind the helm for future add ons?? I installed an aux buss to feed my second bilge pump, electric raw water wash down, thats something you may want on your boat, they are very handy for cleaning up the boat while on the water, perhaps some kind of spreader lights or extra mood lighting on the boat?
Suggestion; when you pull in wires run at least two extra spare sets of wires for future. If you don’t use them no big deal, but if you want to wire in, I dunno, perhaps an air pump for SUP’s and towables? I know I want to wire in at least two more 12V power ports, and a few usb charger ports. Here’s a link to the 12 V buss that I put in.
https://jetboaters.net/threads/12-volt-accessory-buss-additional-switches.37156/#post-604853 I can run all kinds of stuff off of that buss, just use in line fuses for ckt protection. Man this is reminding me of all the stuff I want to do!
The nice thing about that shunt is there is another voltage port for the start battery, and you can see how many amps are going into the house battery while you are running, that is really handy on the LFP’s as you can see when they are getting pretty well charged as the amps start dropping off. The most I’ve seen on my boat is 26A with both engines going.
The updated Victron Battery chargers have a plethora of settings in them. This is pretty useful if I was at a camp ground or whatever and the outlet would not support the 25A per battery charging of my three trolling motor batteries, I can just go in via the app and turn them down to 10A. Here’s another thing about LFP charging, a Li charging profile has a very short absorption cycle because Li batteries do not need that like a lead acid battery battery does, both agm and fla.
As far as extension cord while driving, its not that far out of the norm really, there is a cord connecting your boat trailer to the truck. You just have to be smart about how you run it. By 120 volt port is on the side of the helm in my boat, so it would just go from the bed of the truck up over the bow and down inside… I put an anchor roller on so that would be a very convenient place to run it.
