Solar panels/ Battery/Victron general questions from newbie

Ninabean

Ok so as someone stated in other posts the T@ b 400 has a life long learning curve.  I have addressed 2 other problem in this forum and resolved my issues with the knowledgeable input of members. I am now onto learning about the solar factory installed system and understanding the Victron app readout and programming of the app per my  installed batteries.  Questions:
1.  Are the batteries on the 2019 T@b installed by NuCamp?
2.  If so what voltage, size and how many are there?
3. I have the Victron app but clueless to understanding it.  Any resources to review for it?
4.  BVM-712?? What is the advantage of having it installed?  I know nothing about solar or electric jargon and what it means.  How would it help me.?
Gosh I know this is a lot to ask but I really want to understand how to use my solar package effectively and maintain it for efficient use. There was nothing in my new buyer packet about the panels and just a very tiny hard to read booklet on the Victron.

Sharon_is_SAM

The factory installs the batteries.  I think they are installing two 6 volts.  220 amps.  The Victron 712 is a battery monitor,  It gives you a real State of Charge vs guesstimating using a volt meter (which is how we all started).

There is a steep learning curve with solar.  

Regarding programming the charge controller:
https://tab-rv.vanillacommunity.com/discussion/8537/programming-victron-solar-controller

Solar charge controller basics
https://www.solar-electric.com/learning-center/batteries-and-charging/solar-charge-controller-basics.html

Downloads here:
https://www.victronenergy.com/solar-charge-controllers/smartsolar-mppt-75-10-75-15-100-15-100-20

Ninabean

@Sharon_is_SAM. Thank you for your response. I appreciate knowing what kind of battery I have now. I definitely will check out the attached links and hopefully get the Victron set up to monitor my battery appropriately.

pthomas745

I'm not sure which Victron app you have, but  I found this page had a good summary of the Victron's battery monitoring displays. 

https://faroutride.com/victron-review/?fbclid=IwAR0S300K9ZY-56b-WoMT-9KFW6f3fA-LVt9MlfdN4roBTNceRj6j9Kaneig

I know it sounds a bit overwhelming now, but you will be surprised how routine your solar will become.  Just put the panels in the sun.  As long as it is wired together properly, it will...just work.  You will be able to watch it work with on your phone and see your battery status anytime you want. 

Everyone has questions about solar at first, and there are plenty of answers here, so don't hesitate to ask.

And, honestly, I think the people who have solar "just installed" have an advantage.  No endless reading of the internet rocket scientists who want to babble about voltage drop and MPPT vs PWM and the NHL and NBA!

Ninabean

@pthomas745 thank you for the reassurance!  I will check out your link and review it but you are right about all the rocket science babble.  Mind boggling!  I do know what NHL (National Hockey League) and NBA (National Basketball Association) stand for but like Solar Energy know little about the games. 🤣 

pthomas745

I guess my point is that having the solar installed gets people over the hump of "what is the right combination of stuff to buy."  It can be a baffling experience by itself.  And the new fangled Victron monitors add a whole new level to the learning curve.  But they are extremely useful.  I put in a Victron monitor a few months ago and binged watched that thing on my phone for a week.  It is just so cool.

Oldcootcamper

Here's one of the things I "think" I learned as I am a newbie to both RVing and Solar -the Tab 400 being both my first RV and first foray into Solar. 

I agree that with the factory installed Solar it just seems to work.  But in reading through a few things I realized that the APP that you link to with your phone does not directly give you the battery "State of Charge".  You have to infer it from battery voltage unless you installed, or knew to have NuCamp or your dealer install, a battery monitor. The MPPT 75/15is not a monitor, it's a charge controller.  NuCamp doesn't automatically provide a monitor (other than the one on the instrumental panel which you should definitely not use).  These monitors tell you exactly if the battery is 100% charged, 90% charged etc.  I was unaware of this.

Below is a screen shot of what my app looked like one day.  Note that the Battery voltage read 13.88 (I have the dual 6v AGM batteries referenced above).  13.88 translates to a fully charged battery.  I understand that anything 12.80 or above is fully charged (The controller protects against overcharging too I guess).  Also, I've read different voltages refer to different SOC. In some cases they say it's fully charged at 12.62 volts

But how do you know at what voltage your battery drops to the dreaded 50% level?  (To confuse thing more I've read in some places you can let our AGM battery get to 20% charged)  The chart below, which was the most conservative I've found, says if the volts are less than 12.30, you're below the 50% mark. 

Lastly, I've also read that the inverter is often tied directly to the battery and by passes the charge controller  and is always drawing power and this is not ever registered by the App. So in reality, the volt reading might be slightly high - meaning the battery SOC is slightly overstated.

So, I've purchased the Victron 712 battery monitor to give an accurate SOC.  But, apparently installation in the Tab400 is not going to be easy. They essentially built the RV around the battery casing, meaning I'm going to have to take apart part of the bed to get to the battery compartment.  Oh, and I don't know  anything about wiring - but will give it a try and hopefully not blow anything up or strip any screws when I take my bed apart etc. etc.

If anyone seems something in here that's wrong, please correct. I'm a Newbie just trying to figure this all out as well!

Edited for inappropriate language—Verna, T@B Admin

Oldcootcamper

sorry, doesn't look like the pics I tried to upload worked

ScottG

Oldcootcamper said:

...

Below is a screen shot of what my app looked like one day.  Note that the Battery voltage read 13.88 (I have the dual 6v AGM batteries referenced above).  13.88 translates to a fully charged battery.  I understand that anything 12.80 or above is fully charged (The controller protects against overcharging too I guess).  Also, I've read different voltages refer to different SOC. In some cases they say it's fully charged at 12.62 volts.

...

I can't answer most of your questions, by I think that 13.88V represents the charging voltage the solar controller is sending to the battery, not the actual state of the battery itself.

A similar thing happens when the T@B is plugged into shore power. In that case, the measured voltage reflects the output of the converter.

To get a true measure of battery voltage the battery should be disconnected from any charging sources or loads, and should have sat for several hours  after charging to allow any surface charge (which will cause an erroneously high reading) to dissipate.

jkjenn

The key is which stage of charging your battery is in. Per your screen shot, you are in float and your voltage rating is normal.

This article might help you underatand: https://www.batterystuff.com/blog/3-stages-of-smart-chargers.html

Oldcootcamper

Thanks all

RCB

Monitoring battery voltage is a pain, and to install a high tech monitor is expensive. I get a fairly close voltage reading from the 12v outlet. I use a 12v plug with the wires cut off to 8” and the ends protected  with crimp on connectors; then use my voltmeter to check the voltage by inserting the meters probes into the end of the connector.

Sharon_is_SAM

@RCB, I can’t quite picture what you are doing.  Why not use a meter designed to fit into the TaB 12 v socket?  

RCB

I should add that if there is any solar input the readings are not of any use. So I measure when I get up and before the sun is on the panels.
sharon, I bought one of those - about $15 but found it not very accurate when compared to my $250 meter. May I should try a different one.

JEB

RCB said:

I should add that if there is any solar input the readings are not of any use. So I measure when I get up and before the sun is on the panels.
sharon, I bought one of those - about $15 but found it not very accurate when compared to my $250 meter. May I should try a different one.

Sure, if you're using a high-end Fluke multimeter or something like that, you can  expect greater accuracy.  But you can still get by with the Innova pretty easily.  Take a measurement with your multimeter.  Then immediately take another reading with the Innova under identical conditions.  That should give you a ballpark estimate as to how far off the Innova is.  Then use the Innova for convenience, making the mental adjustment for the delta.

Sharon_is_SAM

I understand your set up now.  Thanks.  You are still only getting an indirect measurement of the battery SOC.  But if it's working for you, cool!  

ScottG

I use the plug-in Innova model, and also sometimes use the MC4 connectors for my modular solar controller to take measurements directly at the battery in the same manner as RCB described. When I've compared measurements from both devices they are virtually identical--though I admit I'm only using a $100 Fluke meter.  :-)

I also find that with only base DC operating loads (i.e. fridge running on propane, CO/propane monitor, and LED indicators) and no charging input, the Innova voltage is very close to the voltage measured at the battery when fully disconnected. Sure, if I turn on a light or a fan or the water pump, that voltage is no longer "accurate" and the colorful lights twinkle like a July 4th celebration, but I don't really need to know my battery SOC every second of every day in real time. It's a battery--if it's settled in at a good charge before I turn on a light, it's still going to have a good charge two (or five, or even thirty) minutes later when I turn it off.

@Ninabean, getting back to your original post I maintain that if tech gizmos are your thing and you want to drop $200+ for another electronic display--or if you are camping under particular circumstances that demand such a precise level of battery information--the Victron 712 (or similar) is probably for you. However, if you just want to go camping and are willing to invest a little patience in becoming a "battery whisperer" I agree with JEB that you can get by pretty easily with a simpler, more economical option.

pthomas745

For two years I worked with my battery like Scott.  I read Jkjenn's blog about battery management, and printed out copies of the spreadsheet that described the amp hour usage of everything electrical in the trailer. I learned that a good idea of state of charge can only be made on a rested battery.   I used an Innova.  I learned the many ways how a multimeter is useful.  Every time I switched something on, I made little computations in my head about how many amps are being used.  I have a 100 watt panel, and as long as the sun was out, I never had any issues with power in the Tab.  I don't thing people realize how hard it is to use up 35 amp hours with the trailer's equipment. 

I got a Victron 712 a few months ago, and after several trips, my power behaviors haven't changed.  I still have a good idea in my head about how many amps I've used, and the Victron is already confirming my guesses.  The big difference for me is the displays showing me the solar panel's voltage readings, etc.  I think I could easily get along with the "basic" controller display.  As Jenn pointed out, seeing "Float" in the display is telling you your battery is charged.....

jkjenn

RCB said:

Monitoring battery voltage is a pain, and to install a high tech monitor is expensive. I get a fairly close voltage reading from the 12v outlet. I use a 12v plug with the wires cut off to 8” and the ends protected  with crimp on connectors; then use my voltmeter to check the voltage by inserting the meters probes into the end of the connector.

You are getting a fairly close reading of your current voltage and not your state of charge with your method. A lot of folks are OK with getting their current voltage, some of us need more.

It all boils down to how high your need to know an accurate read is and how much effort you want that to be on a reoccurring  basis.

Awca12a

@Ninabean
Have you downloaded the Unofficial 400 Users Guide  from the manuals section?
All of these questions are answered there in some detail. 

Ninabean

Yes  @Awca12a I have downloaded that wonderful guide and am reading so much of it.  I am trying to take notes too but my lack of electrical/solar knowledge keep me from truly understanding the concept. I have become more comfortable with the readings on the Victron app and all the advice from forum members. I feel my solar system is working properly.  Your guide has been printed off and bound and Constant reference made to it.  I do appreciate the work that was  put into it. 😊

Awca12a

Oldcootcamper said:

Here's one of the things I "think" I learned as I am a newbie to both RVing and Solar -the Tab 400 being both my first RV and first foray into Solar. 

I agree that with the factory installed Solar it just seems to work.  But in reading through a few things I realized that the APP that you link to with your phone does not directly give you the battery "State of Charge".  You have to infer it from battery voltage unless you installed, or knew to have NuCamp or your dealer install, a battery monitor. The MPPT 75/15is not a monitor, it's a charge controller.  NuCamp doesn't automatically provide a monitor (other than the one on the instrumental panel which you should definitely not use).  These monitors tell you exactly if the battery is 100% charged, 90% charged etc.  I was unaware of this.

Below is a screen shot of what my app looked like one day.  Note that the Battery voltage read 13.88 (I have the dual 6v AGM batteries referenced above).  13.88 translates to a fully charged battery.  I understand that anything 12.80 or above is fully charged (The controller protects against overcharging too I guess).  Also, I've read different voltages refer to different SOC. In some cases they say it's fully charged at 12.62 volts

But how do you know at what voltage your battery drops to the dreaded 50% level?  (To confuse thing more I've read in some places you can let our AGM battery get to 20% charged)  The chart below, which was the most conservative I've found, says if the volts are less than 12.30, you're below the 50% mark. 

Lastly, I've also read that the inverter is often tied directly to the battery and by passes the charge controller  and is always drawing power and this is not ever registered by the App. So in reality, the volt reading might be slightly high - meaning the battery SOC is slightly overstated.

So, I've purchased the Victron 712 battery monitor to give an accurate SOC.  But, apparently installation in the Tab400 is not going to be easy. They essentially built the RV around the battery casing, meaning I'm going to have to take apart part of the bed to get to the battery compartment.  Oh, and I don't know  anything about wiring - but will give it a try and hopefully not blow anything up or strip any screws when I take my bed apart etc. etc.

If anyone seems something in here that's wrong, please correct. I'm a Newbie just trying to figure this all out as well!

Edited for inappropriate language—Verna, T@B Admin

You would be well served to install the BMV712 shunt and that isn’t a very difficult task as the power block just outside the battery terminal let’s you easily interrupt the ground before the battery as it’s the last point where grounds come together.  If you want the temperature sensor as well then you have to open the battery housing and endure all that it involves.

I didn’t install the temp sensor yet and have been satisfied with the results but will hook it up when and if I ever need to access the batteries directly.  If you don’t know anything about wiring then I’d think twice about doing this as it requires a hydraulic crimper to make the shunt cabling.   Your auto mechanic is well equipped to install this for you and I’d let him do this.  

If nuCamp is listening, this is a classic value add opportunity to sell a field installable kit to tap into the factory power block using pre crimped cable taps, an enclosure with pre installed strain reliefs and a one page instruction set.  Anyone wanting the optional display mounted by the KIB monitors can also add that fairly easily as the factory conveniently  provided an empty conduit in that area.  

That said, I feel like John Adams in 1776 regarding the factory responding to actual user experiences like this.  “Is anybody out there?  Does anybody see what I see?  Is anybody listening?”    Factory is leaving so many up sell opportunities on the table while at the same time frustrating their user base.  Amazing. 

falcon1970

@Awca12a
As usual, you and I seem to think a lot alike!
As best I can tell, the temperature sensor is only needed if you are charging with solar.  The temp helps the solar controller know what to do.  That said, I installed the temp sensor in anticipation of the future--maybe.
You can usually find a 004 gauge battery cable at auto parts stores that come already terminated.  I had to drill the end out a little though.

@Oldcootcamper
My factory installed inverter has an on-off button located on that angled panel under the counter at the foot of the bed.  Unless that is on the single outlet powered by the inverter has no power.  I don't think an inverter would draw any battery power unless there is a load on the inverter--although I may be in error about that.

N7SHG_Ham

@falcon1970 yes the inverter does draw some power when on, even without an AC load.