Shunt Battery Life W/Dual Battery Red Arc

Hey guys,

I've been running a dual battery system with the Redarc bcdc25 and a 100W solar panel with no issues. My aux is in the bed of the truck. I'm cleaning up the rear wiring which means adding a fuse box and a shunt to read battery life, charge in and charge out etc.

The wiring diagrams are dumbed down just to show the routing. No fuses and no loads shown such as lights, fridge etc.
The first diagram is what I have been running with no issues.

The second diagram is what I'm currently wiring. I understand the principal of a shunt. The "load grounds" and battery ground are between a "resistor" and we get current from the dV across the resistor. I=V/R, simple. It was mentioned in a van life that the Aux shouldn't be grounded to frame or the redarc would cause the shunt to read a negative amperage since it's already grounded through the starter battery. Not sure I understand this. It seems weird to "float" the aux battery.

 

Crickets in here...

A more circuit savvy friend of mine explained option 3 to me and it makes sense now. I will finish wiring it up and report back.

Blue line is the full red-arc circuit
Magenta line is the full aux battery charging circuit

As for me mentally not accepting that the aux battery doesn't have a physical ground cable from negative post to frame, that is resolved.
The battery is still grounded to frame, but through the shunt. It doesn't make sense to connect aux negative post to frame, when you connect aux negative post to shunt. That would throw off the reading.

 

Checking back in.
Looks like battery was full and floating upon first startup. No light for solar either so I was getting no charge.
Attached some loads (fridge,shell lights ) and was getting perfect numbers so I’m pretty sure it’s all good. Will report back if any issues.

 

The ground connection through the shunt is what allows you to measure the battery. If you were to bypass the shunt with another ground from the battery to the frame or wherever you won't get accurate readings.

 

Good way to put it.
It's choochiinnnnn. Today had my solar panel and fridge showing good numbers. Super happy with the set up.

 

Isn't it nice! I've got a 315w LG panel on top of my tent that makes more power than I can use and tops the battery up with 2-3 hours of sun. Not being tied to ice allows you a lot of flexibility in where you go.

 

Yeah I got 1 100W Renogy and looking at the numbers off and on today, it's pretty much just keeping up with the Fridge as my truck sits in the sun.
My fridge compartment 20F/30F. Maybe I'll get a second panel someday but this is fine considering I usually drive the truck a little on trips.

 

Just looked at your profile pic...is that up at Usal Creek?

Lost Coast is about all I miss from CA.

 

Also, there is a place on Dell in Campbell where I used to buy all of my panels. Great prices and they have everything in stock.

ML Solar
1190 Dell Ave, Unit O, Campbell, CA 95008, United States
+1 408 425 2079

 

Agua Verde Baja California!

Haha, I love CA, politics aside. Moving down to the OC and a little sad.

 

That LG Panel you have is massive, but nice providing 300 watts.
I know exactly where that is. Thanks

 

The politics is what pushed me over the edge. I was dating a girl with the worst case of TDS I had ever seen and I had to dump her. Living in Boise is like living in America again. I'm in good company here, minding my P's & Q's and assimilating into Idaho culture. It's heaven here.

 

I started with a single 100w panel, then added a second. When I got my new tent I mounted the 300w on the load bars and never looked back. A buddy of mine has a sprinter with three 300w panels on it and he can run his AC while parked and still have enough power to run the fridge, freezer and stereo.

 

I might consider the move up there. I need to get 4 years done in socal and reassess.

 

If you like crime, homeless pissing and shitting all over, parks full of junkies and being around people with no common sense, you would hate it here. I grew up in CA and it kills me to see what it is turning into. So sad.