Battery Monitor and Solar Panel Wiring

Basil48192 · March 2021

I finally pulled the trigger on two, 6V AGM batteries that I will install this weekend. I also have a new Victron battery monitor, factory solar and a second, suitcase solar panel. I think I'm clear on wiring, but want to make sure. My plan is to:
-Remove the factory ground wire (looks like 10 Ga) from the existing negative battery post and connect it to the 'load' side of the shunt. I do not plan on running a new wire from the terminal box under the tongue unless I need additional length.
-Connect a new wire from the 'battery' side of the shunt to the new negative battery post.
-Reconnect the factory solar wires directly to the new battery positive and negative posts (not to the shunt).
-Connect the new suitcase solar wires from the controller to the new battery positive and negative posts (not to the shunt). I will include a fuse holder in the positive wire.

Does this seem correct?
Thank you in advance!

Sharon_is_SAM · March 2021

For your solar charging to reflect in real time on the battery monitor, the negative wire from the solar controllers needs to come after the load side of the shunt.

Basil48192 · March 2021

Thank you. So, I think you're saying I can connect the negative wire from the solar panels to the battery side of the shunt or directly to the negative post of the battery.

Millie_on_the_move · March 2021

The negative battery terminal post should be the only thing connected to the "battery" side of the shunt. Your solar panel negative wire should connect to the "load" side of the shunt. If you connect the solar panel negative straight to the battery terminal, the shunt can't monitor solar charging

Sharon_is_SAM · March 2021

No. Connect the factory solar negative wire to the far side of the shunt (opposite the battery side). We connected ours at the ground terminal in the junction box under the tongue. I think you can just connect it to the terminal on the load side of the shunt if your shunt is in close proximity to the battery. Our shunt was buried inside the TaB, so the junction box ground was the easier route.

Basil48192 · March 2021

@Millie_on_the_move, @Sharon_is_SAM, Thank you both! I saw wiring diagrams both ways so I wasn't sure.

Bclarke · March 2021

I installed two lithium this past weekend which went well ... and this coming weekend I will install the Victron Smart Shunt. I have to admit I am a bit confused by it all. This will make for great entertainment!

Basil48192 · March 2021

@Bclarke, Now I have 'battery envy'! I went with 2, 6V AGM.

Denny16 · March 2021

Installing the Smar Shunt is very simple. Remove the negative wire/s from your negative terminal on the battery. Take,these wires and put them on the Load side of the shunt. Connect thenShunt red positive wire to the battery positive terminal or positive terminal buss. When this is done, reconnect the ground black wire between the shunt and battery. If you have solar panels, cover them or wait until dusk/dark to make the electrical connections.
cheers

Basil48192 · March 2021

@Denny16, Thank you! Waiting for my battery box to arrive and hope to finish everything this weekend.

druthazer · August 2021

@Sharon_is_SAM Victron Smart 75 15 upgrade question. For my 2017 320s.
I previously installed dual Renogy 100 panels and their PWM controller. Routed wires down the side & directly into the tub where I mounted the controller. Wired directly to battery.
Want to upgrade to a new Victron smart controller but their instructions call the DC load to be wired separately from the battery.
Unclear if I need to run some additional wire or can I just wire to the battery that also goes to the load and to the Ac to DC converter / battery charger when plugged in. I currently have the old PWM controller wired directly to the dual batteries and it works fine.

Basil48192 · August 2021

@druthazer. I hope I'm understanding your question correctly. Are you mounting the new controller in the tub as well? I mounted my Victron controller in the tub and wired the positive directly to the dual batteries (through a fuse). I added a 4-lug connector for all of the negative connections...just to clean things up. This has been working fine. I hope this helps!

Image: https://us.v-cdn.net/5021717/uploads/editor/g1/vuhub5pmjcrp.jpg

ColoradoJon · August 2021

@druthazer - you do not have to wire to the Victron DC load terminals. Go ahead and wire directly to the battery. There is an advantage of using the Victron load terminals though - the Victron controller will shut off the load if your battery charge level gets too low so you don't damage your batteries from too deep of a discharge.

Sharon_is_SAM · August 2021

@druthazer - I agree with ColoradoJon. Just simply swap out the PWM controller for the new smart controller.

druthazer · August 2021

@Sharon_is_SAM, @ColoradoJon. Wow, thanks for clarifying... this is what I was thinking but hearing confirmation is so helpful.
Do you also have & recommend a shunt be added? I have seen the threds about the cheaper one as well as Victron. Seems like victron will integrate directly into the app. though more expensive than the chinese one with a wired meter. Nice to not have to run wires through the t@b...
I do check voltage on the standard installed instrument panel regularly and do not have large loads or use an inverter to ac. I do have a small automotive inverter but have never found need to use it.

In case needed, I also have a portable solar panel and 300w solar generator that we could use if rv batteries are drained too low so we can use our CPAPs on DC with heat/humidity turned off.

We also usually alternate few days disbursed and elect / amenities. Getting ready for a full month out to Tetons & Yellowstone from VA in couple weeks(mostly with electricity but a few boondock nites scattered while traveling). Getting ready for Arizona in Feb-March timeframe where we are likely to do more disbursed & alternate pattern.
Happy RVing.
Love our T@b .
Maybe see you at Tabizona? Bob & Dianne

ColoradoJon · August 2021

I have the Victron BMV-712 monitor and shunt, but it is expensive (approx. $220 with shunt). I went with the Victron because it has built in bluetooth for simple viewing on my phone.

Bogart Engineering makes the Trimetric TM-2030-RV or TM-2030-A monitor which is a little cheaper. Both the Victron and Trimetric are excellent meters.

These monitor actually amp usage and are much more accurate than simple voltage meters.

Definitely get a monitor if you have CPAP needs. My wife uses a Inogen oxygen concentrator and its great to know where our battery state is!

scaup · August 2021

I have no experience with DC so be kind.......

What is the purpose of a shunt? The internet says it provides a low resistance path around another part of the circuit. What is the shunt "shunting" around?

I just installed a larger box for the battery/propane tank and have plenty of room now for two 6v batteries. Why can't I just wire 2 6v batteries in series as a replacement for the 12v and let it go at that?

Thanks for setting me straight.

ColoradoJon · August 2021

@scaup - The shunt that is used for these battery monitors measures the current (Amps) passing through it. When you know the current going in and out of your batteries, and the maximum capacity of your battery, you can more accurately measure your power consumption and the battery's state of charge.

You absolutely can wire two 6V batteries together in series. This is exactly I and many others on this forum have done. I chose to add a battery monitor and shunt so that I can accurately gauge the battery state of charge at any given time.

scaup · August 2021

So the shunt basically diverts a little bit of the current into the battery monitors so the monitors can measure the power consumption and state of the batteries?

Sharon_is_SAM · August 2021

@druthazer - as ColoradoJon noted, voltage is not the best way to actively monitor battery state of charge because it is a moving target. Shunted systems are amp counters. Victron products are nice because you can network them with the Victron controller. Having said that, there are forum members who are very happy with less expensive brands - even Renogy has a nice shunted monitor.

Sharon_is_SAM · August 2021

@scaup - correct. The shunted monitors provide the most accurate method to actively monitor battery state of charge. Depending on how you camp (always an electric hook up and/or very limited boondocking) you may not feel the need to monitor as closely. Keep in mind that it is a right of passage to kill your first battery(s), but proper monitoring helps to prevent this.

scaup · August 2021

If you just connect 2 6v batteries in series, are they still charged by the tow vehicle and by shore power as the current 12v battery is charged now?

Does the factory installed battery voltage monitor (the one above the sink in the 320) still work?

What are the advantages of the shunt monitor discussed above over the factory voltage monitor?

We have Zamp solar panels. Will they charge the 2 6v batteries when connected to one of the 6v batteries that is in series with the other 6v battery?

Thanks

Sharon_is_SAM · August 2021

@scaup -
1. Your 2 batteries will still charge by the TV 7 pin as long as you have a charge wire installed and your TV is capable. Some newer TVs limit the available charge sent back to the TaB.

2. The factory installed voltage monitor will still work.

3. As noted above, voltage is not an accurate way to monitor battery SOC. The advantage of using a shunted monitor is to be able to know your true SOC. To use voltage as an indicator, you must disconnect all loads and rest the battery up to 24 hours according to some resources.

4. Solar panels will charge the 6 volt batteries. Do you have a solar port to plug in the cable or are you using alligator clips?

Here is a picture of 2 batteries in series and how you should attach a charger. Same applies to the wires that come off the solar charge controller. These are 12v batteries, but the same applies to 6v batteries.

ChrisFix · August 2021

scaup said:

If you just connect 2 6v batteries in series, are they still charged by the tow vehicle and by shore power as the current 12v battery is charged now?

Two 6V batteries in series creates a 12V battery as far as all your systems and calculations go.
More or less forget that it is two 6V batteries once they are connected in series you can think of it as one 12V battery.
The important thing to remember is that on this new 'virtual' 12V battery, the negative and positive terminals are the ones on the battery that aren't interconnected with the two batteries.
So use the negative terminal that isn't intercconnected on one battery, and the positive terminal that isn't interconnected on the other battery - this ensures all power flows through both batteries.

pthomas745 · August 2021

@scaup The basic "voltage readers", either the SeeLevel/KIB monitor, a hand held multimeter, or even the Victron app with the basic voltage readout, all suffer from the "rested" battery issue. You cannot get a correct reading for a battery while it is "in use", meaning when it is being charged, or when it is being discharged. For the Tab, the battery switch should be off, and charging sources disconnected. (Which means those with installed solar should wait until dark to monitor their voltage "state of charge."

This "rested battery" situation drove me crazy for a year. Every time I hit the SeeLevel it would be showing some low state of charge, so I just figured my solar was overrated and the battery too small, or whatever. Then I discovered the "rested" battery issue, bought a multimeter, and learned to measure my battery with the switch off. Eureka! I was doing much better on power than I imagined. This took a year to figure out! I eventually bought a Victron shunt after two more years, and, as much as I like binge watching it, I bet I can survive with just my multimeter just fine. Experience with how much power you "actually" use takes time to sink in.

The shunt advantage is how it tells you exactly how many precious amp hours you have taken from your battery. If you are running a 2 way fridge or a CPAP, etc, then I think the shunt type monitor is essential.

Here is a "rested battery" example from my Victron. On the left, the trailer battery is on, and I'm running the fan at half speed, solar not connected. The "voltage" is giving me the "false" reading of 12.09, which would indicate that I have reached my limit of how much battery power I can use. On the right, the battery switch is off, and I've waited 12 minutes of "resting" time for the battery. 12.46......which is about 80 or 90 percent of my battery charge.

Image: https://us.v-cdn.net/5021717/uploads/editor/t5/y81nqdi1rip9.jpg

elbolillo · August 2021

Basil48192 said:

@druthazer. I hope I'm understanding your question correctly. Are you mounting the new controller in the tub as well? I mounted my Victron controller in the tub and wired the positive directly to the dual batteries (through a fuse). I added a 4-lug connector for all of the negative connections...just to clean things up. This has been working fine. I hope this helps!

I like your setup. I did some thing similar for my Tab 320.

Basil48192 · August 2021

Looks great!

druthazer · September 2021

@Basil48192. We put shunt insise a collapsable silicon food storade container inside the blue plastic tub.... very wet. See photo. From Amazon,
CARTINTS Set of 3 Collapsible Food Storage Containers Collapsible Silicone Bowls, Silicone Lunch Containers with Airtight Lids, Microwave and Freezer Safe, 500ml.

.

We tore up the bottom of the silicon container putting wires thru but filled with silicon bath sealant... Not neat but very functional. Bolted the shunt thru bottom of container directly to the plastic tub. Note dual size 24 deep cycle batteries. Not expensive from Batteries Plus. I avoided dual purpose marine batteries because they are also designed as starting batteries rather than dedicated deep cycle. We dont care about CCA cold cranking amps.

pthomas745 · September 2021

One of the things I learned about when arranging my shunt in a box were these: "Gland nuts". Drill a hole in the box, arrange the nut, thread the wire in, and lock it down. Not completely waterproof, I don't think, but it was easy to seal it off with a little silicone. I used them on my Solar Controller Tupperware Container, also.

https://www.amazon.com/TUPARKA-Waterproof-Adjustable-Connectors-Plastic/dp/B07KFCGFYF/ref=pd_sbs_4/143-6304957-8877728?pd_rd_w=wm1ru&pf_rd_p=0f56f70f-21e6-4d11-bb4a-bcdb928a3c5a&pf_rd_r=394PX9SMD415KKFDJDAK&pd_rd_r=9b44b3cd-e5f4-4069-9e7a-1570b12adfe1&pd_rd_wg=303NV&pd_rd_i=B07KFCGFYF&psc=1

Horigan · September 2021

elbolillo said:

Basil48192 said:

@druthazer. I hope I'm understanding your question correctly. Are you mounting the new controller in the tub as well? I mounted my Victron controller in the tub and wired the positive directly to the dual batteries (through a fuse). I added a 4-lug connector for all of the negative connections...just to clean things up. This has been working fine. I hope this helps!I like your setup. I did some thing similar for my Tab 320.

@elbolillo
I don't believe you should be covering and sealing your Victron controller as shown in your picture. I recall the instructions say to install vertically, as you've done, and ensure there is clearance above the unit to convective cooling air flow. With your set up it may overheat and shut down.

elbolillo · September 2021

Horigan said:

elbolillo said:

Basil48192 said:

@druthazer. I hope I'm understanding your question correctly. Are you mounting the new controller in the tub as well? I mounted my Victron controller in the tub and wired the positive directly to the dual batteries (through a fuse). I added a 4-lug connector for all of the negative connections...just to clean things up. This has been working fine. I hope this helps!I like your setup. I did some thing similar for my Tab 320.

@elbolillo
I don't believe you should be covering and sealing your Victron controller as shown in your picture. I recall the instructions say to install vertically, as you've done, and ensure there is clearance above the unit to convective cooling air flow. With your set up it may overheat and shut down.

The cover is open on the bottom so as to allow airflow and prevent overheating.

Howdy, Stranger!

Quick Links

Categories

Battery Monitor and Solar Panel Wiring

Comments