Chinook RV

So, finally decided how I was going to monitor my batteries/charge/consumption, etc.
Purchased this Victron Smart Shunt Opened up my battery bank and found this: So, total novice on this stuff, but for whatever reason I didn't expect to see this - all the cables and various connection points...
Shunt instructions are pretty basic - Attach all the drawing loads to the Negative side of the shunt, run the positive lead to the positive on the battery and done! There's a video on the Victron Site and YouTube, but...
How do I know what's what? I also expected to see a different config of the two batteries cabled in series, but I don't think they are - it seems like they are independent of each other, or at least have the loads split between to two? I have no idea. Which cable is going to the Start Battery, or none? and does that even matter? Should the start battery cable also go through the shunt? So many questions.
Anyway, I'm confused and need a little guidance if there is any to offer here.
I'm assuming before I start disconnecting anything that I need to obviously be off shore power, in "store" mode - anything else need to be shut down/disconnected to preserve my life!
I prefer to figure this out myself (with your help of course) versus seeking help somewhere.
It seems simple enough, just a bit intimidated by it all and need to be confident I have a plan going in - which at this point I do not (have a clue).
Oh, 2003 with a 7.3L Diesel if that matters.

Not sure if this is complete. If anyone else reads this and sees something I've missed, please chime in.

a) Put the coach in Store mode, where the red light is on. This is needed for working on the battery cables, as if it is on and you remove the negative wires (ground), you can burn out your LVD.
b) Engine off, so no charging coming from there.
c) Shore power NOT plugged in, so no charging from there.
d) If you want to be super-safe, you can throw a blanket over the solar panel, so no power charging from it.

e) Take off ALL jewelry from both hands. This INCLUDES wedding band.

This step is important because if you have metal on your hand/fingers and accidently touch a positive cable to it, you can get shocked and burned. It happened to a service tech while I was in a RV repair center once, and he got a nasty burn around his finger because of his wedding band, which he'd forgotten to take off. So long as you have no metal and are not working in wet weather, you should be fine so long as you don't let a wrench or screw driver or something lay across both positive and negative cables at the same time.

f) When removing a lug from its position on the battery, unless I'm moving it to somewhere else right then, I always immediately wrap a little plastic baggy or two around it (I have small ones that are just a few inches square). This way if the cable gets pushed out of the way while I'm working, I don't accidently push it into something like a cable/battery pole of the opposite polarity and cause a short (as in Boom, sparks, bad things!). If you have little rubber caps or something, that'd be even better. Otherwise wrap some electrical tape around the lug. Generally speaking, try to only work with negative or positive cables at any given time.

g) Your batteries are hooked up in parallel. This means they output 12 volts, and the sum of the amps of the two of them. You can tell this because the black cable goes between the negative poles. If they were in series, then one battery's negative would connect to the other battery's positive.

All the negative wires coming in to the top battery are also connected to the bottom battery's negative by the short black cable. Technically that 12" cable means the first battery has slightly less resistance involved in power coming/going, so it will be used slightly more, and wear slightly more/faster than the second battery. If there were enough space, or fewer positive cables, then you'd want all the positive cables going to the second battery, with just a single positive cable between it and the first battery - this way the overall distance travelled from any device/charger would be the same, either 12" longer on the outgoing positive side or 12" longer on the incoming negative side. You can see that someone did try to put all the larger cables on the bottom battery, so its close to perfect positioning.

Now regarding installing your new shunt.

Nice pictures. The shunt has 2 large bolts on top, these are for the negative wires.

1) You need to find a place to mount the shunt. I don't think you want it free standing, just held by the large black cables on each side, as vibrations over time might make things come loose. I mounted mine to the fiberglass wall of the compartment (after figuring out where it fit best with the 3 incoming cables).

2) You move the 3 large black cables coming in to the top battery in the 3rd picture over to the left of the large bolts on the shunt.

3) Then make a new short black cable and attach one end to the free right bolt on the shunt, and the other end to where the 3 incoming cables used to go on the top battery. So you now have the shunt in between the incoming cables and the negative pole of the top battery.

Make the new short cable as large a gauge as the black cable going between the two batteries (or larger). And make sure its lugs are attached tight and correct. If you don't have the tools, you'll need to find someplace to create the short cable for you. Note that if the lugs aren't attached tight and solid, there can be extra resistance and they could heat up when in use, and eventually even melt their insulation.

4) Now you need to connect the included small red power wire going from the Batt+ on the shunt to the red positive pole on either of the batteries. Looks like your positive poles are already very crowded with lugs, so good luck with that

- Note, I have a similar shunt from Victron and the brass hex head screw that came with it was too short when I attached 2 large 4/0 cable lugs (it wouldn't screw in enough to make me think it'd hold them tight over time, with all the bouncing when driving, especially as brass is a soft metal). If this happens to you, then know you can buy the exact same screws at McMaster-CARR. They ship fast and their pricing is reasonable, and shipping is decent, and though they don't calculate it until after your order, I found you can trust them. Brass Hex Head Screw, M10 x 1.5 mm Thread was my size, though double-check your manual. You'll need to decide on the length - I bought a couple each of 20mm, 25mm, and 30mm, and then just tried them with my lugs until I got the perfect length for a tight solid fit.

Maybe we should have a safety related thread on the reference section so people can refer to it whenever they do the work on DC. This way, we don't have to type it every time.

On the metal ring topic, it can glow red when the current is passing thru it and sparks. Basically it cooks your finger at near the base of your palm, and if you try to take it off, it is too hot to the touch, and if you let it stays on, it would continue to BBQ your finger as if you are pointing a blow torch at it. Not fun.

Anyway, I would add that I would disconnect all negative terminals (both coach batteries and the start battery in the front). This way, even if you accidentally drop a wrench or hit the metal frame (which otherwise would be grounded), it will give you a nasty sparks. This way, the only thing that you need to watch out for are the negative terminals of the two coach batteries. Just put plastic caps on them (I save the caps when I brought them new from the store), and it keep my blood pressure reasonable when I work on it.

I think you will need to install the shunt on the positive side of the battery (red wires), but I have not read the manual....

The Victron Smartshunt's installation manual explicitly states to connect it to the negative terminal of the battery. I believe for shunts with a battery monitor, in order to be able to measure voltage as well as current, the shunt is usually required to be on the negative side, though obviously a specific shunt's installation guide will always be the last word.

It might be a good idea to purchase the separate special temperature wire and hook that up for the Smartshunt (get exactly the part number specified in the manual, as Victron has multiple temperature wires for different shunts, and they are different and not compatible, even though some might look identical). When it knows the battery temperature at all times, the monitor can more accurately predict depth of discharge.

Thanks a ton guys!
I think with the provided details I can plan/figure this out with relative confidence.
Would a Auto Parts store have this 12" cable I need to go from Neg to Neg, or do I truly need to build this myself?
Any further input is welcome, so chime in if there's is more to understand or share.
I may post my plan/steps prior to getting after this to validate the understanding, or I may just go for it - soon.
I'm in the PNW, so there might be a break in the rain here in the next 6 days or so...

If the shunt is to be on the negative side, then I would remove all the positive connection on both start and coach batteries first to minimize sparking.

My experience with auto part store's cable is that many of them are mediocre quality (some for jump starting, which you only need maybe once every 5 years), so make sure you get a good one. All the DC will be going thru the cable between the shunt and the battery, so it is important.

I agree, auto-part stores are not usually high quality wires or connections. I'm kind of fanatical about quality, so have always used Ancor marine wires and FTZ heavy duty power lugs with the special FTZ crimper, though they are probably overkill for the usual 200Amp system (and expensive, unless you're redoing your entire electrical system, which I was at the time).

My suggestion would be to try a local marine store or service shop. Boating standards are high and strict, and regulated. Which RV industry is not. Some local store may be able to make the short cable for you and attach the lugs, and will probably do a decent job. Make sure to decide where you're placing the shunt, and then figure on the cable length while keeping in mind needing to move that drawer in and out, and how the cable will bend. My guess would be more like 18-24" than 12".

Oh, and note that at least in my case the battery negative terminal was 5/16", while the shunt was M10 like yours and needs a 3/8" lug. I had to make a new cable after my first one was using 5/16" lugs on both sides.

A good site for learning plenty about boat and RV electrical systems and wiring and such is MarineHowTo.com. The guy that created it is a professional marine guy with many years, and in my opinion knows a lot. I've also purchased various parts from him, he has decent pricing and I like to patronize him, seeing as I've gotten so much out of his blogging articles.

Chinook009,

I agree with everything the other guys have written.

There was a time when I wanted to redo most of the 12 volt system on my Albin Vega 27 sailboat, but dollars were relatively few. I had been a shipyard marine electrician previously, and I found I could get good inboard service from large welding cable, with the lugs installed with dielectric grease, and covered with heatshrink. The silicone grease keeps oxygen away from the exposed copper, and I wrote in ink, the identity of the cable on white heatshrink before heat gunning it. I used Anchor cable, for the tinned strands, in the bilge and up the mast, where it was really wet and salty. My result was a lot stouter and with less voltage drop than the original. (The factory in Sweden had used untinned conductors in the first place anyway.)

I must admit that I did the same on my Chinook when I upgraded. The 500 amp shunt is at the bottom left of the breadboard, PWM solar controller in the middle. The + 12VDC lead to everything else is out of view behind the bunk frame tubing. I posted other photos here earlier. Two 125 AH AGM batteries are inside the coach, to the left, very nearby. Roly

Thanks Guys.
Well, I think I have this basically figured out - in terms of the how to/config - what's what and what goes where stuff.
Funny enough, as I was looking into the Neg. cable I need online to connect from the batter peg to the Shunt and I when all deep on the details (been burned soooo many times not knowing what you don't know till you know it - and now you're stuck!) and decided to figure out the lug sizes needed on the cable. Too simple to just order a 1/0 cable for this purpose - just too simple. Got out the micrometer and figured exactly that out - 5/16 (battery side) to 3/8 (shunt side). Found Battery Cables USA https://www.batterycablesusa.com/online where they let you select wire gauge, color, length and the connector size on each end - pretty slick! $15 delivered.
When that cable arrives and the rain stops I'm going to get this done.
Basically, kill the power, remove the cables/connection from the Neg side of the battery, pin that to the correct side on the shunt, install the new cable from the Neg of the battery to the other side of the shunt, install the little red cable from the shunt port on the circuit board to the Pos terminal on the battery, mount the shunt and done!
At least that's how this plays out in my mind...
Thanks Again - keep you posted.

Chinook009, Your "shunt" install would normally be done to monitor the House bank of batteries for current ( amps) flowing in/out of the House bank. On some of my boat installs, where there are LOTS of negatives and positives involved. I have used high amps rated buss bars on both the positive and negative wires, then in the case of the negative one wire to the shunt and the other side to the battery terminal. It really cleans up the install.
Now would be the time to figure out where all the loads are getting power and sort any out if they should be re-routed since your trying to measure the House batteries. For instance the chassis stereo, you would expect to be wired to the Start battery ( + and - ). Where the coach stereo should be wired to the House battery. Also many find out the coach stereo has a slight draw ( even turned OFF ) but enough to drawn down the House battery. But with your new shunt install your going to see all these loads showing up on the monitor, tough part is identifying them one by one. You actually will have fun with the project.