I think the bigger problem with Diode isolators is that they drop the voltage, which may not allow a proper charge. FETs and relays allow bi-directional current flow which may cause problems.

 

I've read that but it looks like I can avoid the isolator completely at this point.
I can just run direct from the battery to a bus where I can install the DC/DC charger.

This is all for while underway and only as a backup in the unlikely event I have too many successive cloudy days to power my system.

I appreciate all the dialog here.... this stuff is very cool to me and how I learned to install the very first off-grid solar array at our old place in Bahia de Los Ángeles, Baja California.... many, many years ago!

 

Cool, Sol.


I think you'd be better off doing what you planned earlier: running a completely isolated battery, and charging that one via solar.

I built a system two years ago for a small camp trailer, centered around a 100-amp-hour Odyssey AGM battery (Group 31). The Odyssey requires an adjustable charge controller because the battery needs to see 14.7 V for a 4 to 6-hour absorption phase (roughly 80 SoC to 100%). I use two 100-watt panels (36 cell monocrystalline, I believe) on 10 ga extensions (20'), 12V trolling motor plugs as bulkhead fittings, then 8 ga stranded marine cable to the charge controller which is mounted within 2' of the battery, also using 8 AWG.


This system requires only one 100W panel to run well in full sun, but the second 100W panel was to be added for cloud cover. I just run both all the time now and in series, for a nominal 24V input which nets another amp! at the battery thanks to the Morningstar MPPT controller...

The whole thing powers an Engel MT-45 and a small inverter used for charging a laptop, cellphone, etc... anything requiring less than 100 watts @ 110V.

I don't like the idea of tapping into my vehicle's factory battery and charging system... I'd like to leave well enough alone, there, for the sake of transportation reliability.

 

Thanks Apples,

I appreciate that.

I like your suggestion and that is where I will start with it.
It is certainly is the easiest route and one I am very comfortable with.

Plus, I like the economy of it all.

At some point I may add the backup component of using the truck as last stop charger if I have to.
Worst case scenario I throw a couple jumper cables into the mix and work it all out.

Right now it is a matter of time and running out of it before we head out on our great Western States, USA camping trip for the entire summer.

I am heading to San Diego the last week of this month to install my Icon Stage 5 suspension, Icon wheels, BFG KO2's, ARE HD CX shell with side opening windows and roof racking..... pick up my camping fridges, tent, stove, sleeping pads.... all while remembering I am a husband and father to 12 year old twins.
Gotta finish a 5.2kW solar array this week, too!

For the life of me I can't figure out why I don't have more spare time

I know I have been all over the place with this thread but I am a kind of "think out loud" guy and it is part of my process and I want to thank all the positive feedback I have been gifted.