12v system thoughts

Joined
Jan 23, 2019
Messages
1,869
Location
USA
Do you know a good route to chassis ground in the PS rear cargo area?

If you go under the vehicle is easiest to spot the "hole" to route wires to the cargo area from the engine bay.
The hole is just behind the 2nd row seating about 10" and about 12" in from the outside edge of the body. You can spot the grommet from under the vehicle easy.
If you have Cargo boxes it will come in about 2" under the cargo box edge closest tot he front of the vehicle.
There is also grounding bolt near that hole.

There is a place to ground near the hole, and it's also an easy spot to route power to the back cargo area.
I put a breaker on both ends of that 4 AWG you have running from the Aux battery to the Prion-TR. I used 2 AWG for less loss here.
FYI you can connect that solar MPPT up to the input of the Orion-TR and use that 4 AWG line as the feed back to your Aux Battery instead of running a 10 AWG that whole way. It is a long run to go from the solar MPPT all the way to the aux battery, and then all the way back to the Orion-TR vs just going directly to the Orion-TR.
 

LandLocked93

SILVER Star
Joined
Jun 11, 2018
Messages
1,589
Location
Colorado
Regarding the SBI212D, I figured since it has 200amp rating it would work better in high amp "jumping and winching" situations. I think it only opens at 13.2v+ and closes at 12.7v, so I thought the primary starting battery would be protected from dropping below 12.7v? Also, I thought about running the winch of the 2nd starting battery since the wire cable runs are shorter.
Run the winch cables to each batt - My winch + goes to the aux batt, winch - to the crank batt. You still get access to the headroom provided by two batts, but it alleviates the need for the SBI to support that current flow altogether. Can do the same with jumper cables. All the SBI needs to support is charge equalization between the two front batts, which amounts to maybe 50A at most and usually only for brief periods of time before it starts to ramp down anyway (charge equal). When binding the batts to crank from the aux batt (dead crank batt), you're still less than 75Amps by and large.

With engine off and 18V hitting the aux batt, my concern would be that the 212D may become energized because of its dual-sense nature. (manual switching notwithstanding). The 12D will only energize when the aux batt voltage is lower than the crank batt voltage, and then only with engine running (full isolation otherwise).

Honestly the monitoring stuff is over my head right now. I need to spend some time reading up on it. Same for figuring out switches/displays/LEDs that will fit the dash. Not my cup of tea and where s*** like the Delta shifter console with a bunch of cutouts for switches and displays starts seeming like a good waste of money.
Also dont like the idea of the SBI draining the starting battery! Guess I'll get religious about plugging in the NOCO at home.
Yeah I made an ABS panel the size of the 2-din radio hole and mounted all the monitoring and control switching it in. Too busy listening to the truck during its operation (for audible indications of malfunction) to be bothered with a radio. lol

Updated diagram with some fuses and wire gauges added.
NOW it's looking like a proper s*** show. lol (as diagrams always seem to turn out when I draw them too)

PS- Do you know a good route to chassis ground in the PS rear cargo area? Dont really want to cut a hole if I dont have to.
So here, inside the truck I ran a single 6ga ground to one of the bolt holes for the bar that the middle row seats clamp down on. This will get your ground to the chassis body.
Underneath the truck - somewhere just ahead of the rear axle IIRC - I ran a 12" piece of 2ga (leftover) from the chassis body to the frame/chassis using existing threaded bolt holes. One end went to a brake line mount hole, the other went to an unused threaded bolt hole on the under side of the chassis. body.
Be sure to wire wheel these areas clean, film with dialectric, bolt the wire terminals down, then cover the entire wire-wheeled area and terminal with RTV of your choice for the underside connections to prevent (or slow) corrosion.
No holes needed or created.

edit:clarity
 
Last edited:

bpenn1980

SILVER Star
Joined
Nov 15, 2007
Messages
1,121
Location
Los Angeles
Well, I've gone and got myself confused (or spotted a limitation in my chicken scratch design)

I was thinking of doing as suggested and wiring my solar output to the LFP battery and not using solar to charge either starting battery. Ideally, I'd want solar to run through the DC to DC controller/charger so it manages both alternator/starter input and solar input. Unfortunately the Victron Tr Smart controller doesnt have solar input. The only input is from the starting battery. So....

It looks like I either am forced to: 1) wire it up as drawn (i.e. charge 2nd starting battery from solar) or 2) buy a different DC to DC controller that will take solar input in addition to battery input. Option 3 is to bypass the DC to DC controller and hook the solar output straight to the LFP battery, but I'm worried the LFP will get hit with both solar and alternator voltage during daylight hours. Maybe both Victron controllers will just turn off if the LFP shows high voltage, so a non-issue???

And here I was feeling like I had figured this out...
 
Joined
Jan 23, 2019
Messages
1,869
Location
USA
buy a different DC to DC controller that will take solar input in addition to battery input.

Looks like you are over thinking things.

Once the output from the solar comes out of the MPPT controller it will only charge where it's attached to if that attachment point drops below a given voltage.
If you hook up the output from the MPPT up to the input of the dc 2 dc; and hook the dc 2 dc input up to the aux battery; then solar MPPT will charge that point of the connection when voltage drops.
Voltage will drop there when the dc 2 dc draws power to charge the lithium, or if the aux battery drops voltage.

So you do not need a dc 2 dc that takes in both power and solar, because you already ran the solar through the MPPT.

Hope that makes sense.
 

sdnative

SILVER Star
Joined
Oct 28, 2007
Messages
5,100
Location
San Diego
Looks like you are over thinking things.

Once the output from the solar comes out of the MPPT controller it will only charge where it's attached to if that attachment point drops below a given voltage.
If you hook up the output from the MPPT up to the input of the dc 2 dc; and hook the dc 2 dc input up to the aux battery; then solar MPPT will charge that point of the connection when voltage drops.
Voltage will drop there when the dc 2 dc draws power to charge the lithium, or if the aux battery drops voltage.

So you do not need a dc 2 dc that takes in both power and solar, because you already ran the solar through the MPPT.

Hope that makes sense.

I'm not sure it works like that. I believe the power point tracking needs to measure the battery directly to work optimally or at all. Otherwise just get a PWM controller.

There is nothing wrong with connecting two charge controllers to the same battery. In this case you could connect a Victron Orion DCDC and Victron MPPT directly to the LFP battery (through proper fuses of course)
 

LandLocked93

SILVER Star
Joined
Jun 11, 2018
Messages
1,589
Location
Colorado
In this case you could connect a Victron Orion DCDC and Victron MPPT directly to the LFP battery (through proper fuses of course)
This is correct. Both the Victron and Redarc BCDC go to the batt bank in the rear of my truck.
This ensures the batt bank can be charged through the RedArc when the truck is running.
And the Victron does it's trickle thing when the truck is not running.
When running, and I turn the RedArc on, the Victron shuts off when it sees the voltage from the RedArc, thinking it is the actual batt voltage.
Then when the truck shuts off (so too the RedArc) and the batt voltage stabilizes, if it's still too low the Victron kicks back in.
 

LandLocked93

SILVER Star
Joined
Jun 11, 2018
Messages
1,589
Location
Colorado
Ideally, I'd want solar to run through the DC to DC controller/charger so it manages both alternator/starter input and solar input. Unfortunately the Victron Tr Smart controller doesnt have solar input. The only input is from the starting battery. So....
Ok hang on.
The Orion should be connecting the engine room aux batt to the rear batt. (LFP)
I thought you already had a solar controller? If so, no need another device to manage that charge source. Just run it to the LFP.
Besides, in the interest of redundancy, you don't want a single device handling too many critical chores.
If you haven't picked up an inverter yet, you can get one with a solar controller built in so that if your stand-alone controller craps out at camp, you have a fail-over inside the inverter. Don't forget to leave enough extra solar cable on the run to the LFP in the event you have to move it to the inverter. (a couple feet extra maybe? really depends on the distance between the two)
A RedArc BCDC also has a solar controller built in, tho I think you've already bought that component (Orion). No biggie.
It looks like I either am forced to: 1) wire it up as drawn (i.e. charge 2nd starting battery from solar)
Why? The SBI handles that chore, maintaining charge between the engine room crank and aux batts.

or 2) buy a different DC to DC controller that will take solar input in addition to battery input. Option 3 is to bypass the DC to DC controller and hook the solar output straight to the LFP battery, but I'm worried the LFP will get hit with both solar and alternator voltage during daylight hours. Maybe both Victron controllers will just turn off if the LFP shows high voltage, so a non-issue???
You could get a diff BCDC, but what you have there is fine.
And yes, it will work exactly as you imagine here. The Victron will shut off when it sees the BCDC voltage. See above.
 

bpenn1980

SILVER Star
Joined
Nov 15, 2007
Messages
1,121
Location
Los Angeles
Looks like you are over thinking things.
Indeed!

There is nothing wrong with connecting two charge controllers to the same battery. In this case you could connect a Victron Orion DCDC and Victron MPPT directly to the LFP battery (through proper fuses of course)
Thank you!

I thought you already had a solar controller?
Yep, already have the solar controller. I just had a freak out I missed something obvious
 

e9999

Gotta get outta here...
Moderator
Joined
Sep 20, 2003
Messages
18,356
Location
US
talking about the big picture, maybe worth noting that -if you already have paid for the solar panel and charge controller- electricity form the panel is then free whereas electricity from the alternator you still have to pay for as gas and engine/alternator wear. So seems that the former should be prioritized, although admittedly it may not be a lot of gas $.

Also, I would think that manual switches for control can be quite useful and are cheap compared to fancy automatic electronic switches. I don't mind flipping a couple of switches here and there to redirect juice if I think I may be running out of battery power. Easy enough.

added: come to think of it, when I say switches, more and more nowadays I'm just using Anderson PPs that I just plug and unplug to reroute as needed. Even easier to set up.
 
Last edited:

bpenn1980

SILVER Star
Joined
Nov 15, 2007
Messages
1,121
Location
Los Angeles
Appreciate everyone's help here. Getting close to having this all set up. Did a test run yesterday without solar and it appears to be running perfectly. Will hopefully have it buttoned up by next weekend and will try and post up some pics.
 

bpenn1980

SILVER Star
Joined
Nov 15, 2007
Messages
1,121
Location
Los Angeles
A little overdue, but some follow-up with pictures! I ran this while on a trip a couple weeks ago and didnt seem to be any issues. Will use it again tomorrow on another trip. So far so good.

Engine compartment
FLA batt 1 and 2.jpg


Flooded lead acid starter battery #1
FLA batt 1.jpg


I made a bracket to mount the isolator to and welded it to the battery hold down. I put rubber pad to prevent any wear on the side of the battery. Also used a small piece of rubber to give the output cable a little cushion from the radiator bracket. I havent wired the isolator override switch yet (in case need to jump #1 battery).
FLA batt 1 SBI.jpg



FLA starting battery #2
FLA batt 2.jpg


Cargo area of truck. The LFP battery and controllers etc are under the removable panel on the right side. I've had these very basic homebrew storage boxes in for probably 10 years at this point. The height isnt for everyone, but it has been working for me and worked really well for giving me the space for the batt/controllers you see below.
cargo area.jpg


This is the fridge I mentioned and the cage I made for it. So far so good.
fridge and cage.jpg


LFP batt and monitor, DC and solar controllers, and fuse panel and neg bus for load. The "front" portion of this area is open to the 2nd seat area. This will potentially be useful for airflow because the 30amp DC charger is known to get hot. I have a small 12v fan I will wire up to cool the DC charger heat sink if I end up needing to pump a lot of amps into the LFP batt in the future during recharge after deeper draws. The board that the controllers are mounted to is in turn mounted to the truck via a bolt I bought off McMaster Carr to use the third row attachment/bracket. The board is actually sitting on that metal piece and crushed between it and the bolt with washers. Sorry I dont have a good picture.
rear power setup w labels.jpg


And finally hood mounted solar panel is working out nicely. I think I could keep the fridge alone running permanently here in sunny socal.
hood solar.jpg


The only issue I've been having is that using the NOCO Genius 10 charger at home has been a little odd. It will get the FLA batteries up to 13.8v pretty quickly since batteries are new, but once the DC charger kicks on (at 13.8v) and it pulls 30amps the voltage on the FLA batteries drops quickly (less than 5 seconds) under 13v which turns the DC charger off. It kind of cycles like that slowly getting the LFP batt topped up. I'm surprised that two 165a reserve capacity FLA batteries cant handle a 30a draw for more than a few seconds without dropping a full volt, but I haven't done any math on it. Maybe I just need a higher amp NOCO or lower amp DC charger, but it eventually gets the job done though with the DC charger cycling ON/OFF.

Thanks all for the help getting this done! And special thanks to @Fourrunner for hooking me up with awesome connectors, cables, sheathing, heat shrink, etc.
 

Users who are viewing this thread

Top Bottom