Shunt and Battery Monitor

[buckland]

As part of the LiFePo4 battery install in the Eagle I thought it would be good to have a monitor (though not a Trimetric) to see what is happening in realtime. The new set up will have 2 solar panels (160 W on the roof and a Flex portable 100 W ). The roof panel is wired to the battery box as is the portable via a exterior wall plug. These will pigtailed to the Victron MPPT 100 / 20 Controller which has bluetooth (to iPhone).
I built the Rando Lithium battery to replace the two AGM batteries. There is a Blue Seas battery separator.

I would like to wire the shunt in the battery box and then replace my old voltmeter monitor with the new battery monitor which is in the cabinet front with the other FWC gauges.

My question is:
Is the shunt installed in the positive and negative lines coming out of the Victron Controller LOAD ? And then continuing on to the Camper DC fuse box? Or is it in-between the battery and the Controller?

 

[rando]

The shunt should be installed on the negative line to the battery, close to the battery. However, if you are using the load terminals on the Victron Solar controller, you will already get the current information through the Victron App and the MPPT display (if you have it) so the a current meter won't give you ay extra information.

 

[buckland]

Thanks... the saved me extra work. So the app display will have the load usage when installed. That’s nice.
I guess I gotta start removing the AGM batteries and get at the install of the new battery.

 

[ntsqd]

Seems like adding the shunt should make the amperage readings more precise?

 

[Vic Harder]

i would add the shunt. load connection only shows amps out. victron would have no way of telling SOC without it

 

[rando]

I this just a current meter, or an actual current counting state of charge monitor?

If it is an actual integrating state of charge monitor it could be useful, although I am not convinced the cheap-o ones aren't more confusing than beneficial as they don't re-sync them selves and thus the integrated errors can be terrible after some time and give you completely false numbers.

If it is just a current meter, the Victron has you covered.

 

[buckland]

I guess if I have them I might as well use them. I do intend to use the load terminals on the Victron. I am still unclear (gee how unusual!) as to wiring the shunt. As Rando says real close to battery (8" cable should do) Negative post.... then, not sure if the shunt load connection is is in the line to the Victron load ?

For those interested (on a basic level of grogging this stuff).... Here is the unit I bought from a suggestion on WTW as well as a poor video of use.

This is the spec sheet:
PZEM-051 LCD DC VOLT / AMP / WATT METER

 

[roverjohn]

I'm with Rando on this one and see no point in adding that shunt for any number of reasons.

I do have a question though. Why do you think having instant access to info on your phone will make any difference at all? BT has minimal range so can't you just look at the controller if you need that info? You're adding a parasitic drain where one is not needed.

BTW: I don't think your controllers MPPT function will have any way to know that two dissimilar panels are wired together so you may not get optimal MPPT functionality.

 

[buckland]

Well... the Victron MPPT 100 20 does not have a screen or monitor, nothing to look at. The iPhone app is the monitor.
Blue tooth power usage is next to zero in power consumption.
The extra portable panel is only used when the camper is in the shade. More amps is better than no amps.
What are some of the, any number of reasons, for not having a shunt?

Attached find the company's hook up instructions for different set ups.
I am assuming the battery set up would be the one to choose?

 

[roverjohn]

I guess I misread Rando's post about the displayed info. Still if you are going to use an app why not use the Victron app or purchase whatever display they sell if there is one? Or just skip both. The best way to see SOC is to measure battery voltage at no load and you don't need an app or a display to check it. Just a good voltmeter. It's a very easy thing to do. Also, there really is no need to keep in constant contact with that sort of info. You either have enough juice to last the night or you don't. So maybe look at SOC once when the sun goes down and plan accordingly or just waste less or produce more. Your panels will make a finite amount of power ea day. Why use any of it to create data that really isn't that useful when you think about it?
I'm the sort that spends most of time with my phone off when I'm outdoors. I also switch off things that are not serving a useful purpose at that moment. Even the green led on my USB charging station bugged me enough that the whole thing is switched off when I'm not charging something.
I still haven't heard why this is some sort of critical info that anyone needs to monitor regularly.
Also, BT power consumption may be close to zero however it's not zero and when the data might be useful is when you have the least available power to spare.

I like things simple and Rando's suggestion to skip the shunt is simpler so I +1ed it.

 

[buckland]

Thanks for your thoughts on that. I am learning what I can from all patient enough to explain. BTW those usb lights bother me too. I like a dark camper and real quiet.
With the new lithium battery I’d like to learn a bit how it handles load and charge. More for learning. Once I am confident ... I’ll forget about it and have s beer. The phone definitely is off. Not one to want interruption in the boonies.

 

[LAWNMOWERMAN]

I have the Victron app on my tablet not my phone and I love geeking out on the data.I have a Trimetric also and to get a true view of battery current the neg side of the controller must go to the input side of the shunt and the other side to the neg side of the battery.My setup is a Victron 100-30 and 2-100 amp Battleborn batteries and 2 100 watt solar panels.I have a Norcold 12 volt fridge and a 50 qt. ARB chest that I use as a freezer set at 5 degrees.Both freezer and fridge have been running for 1 month straight and I have not seen the batteries go below 13.1 volts.

 

[buckland]

That is all good info... details of what's there and what it is consuming. I like data ( retired math teacher) just for the fun of seeing the day solar gain and then seeing what i need energ-wise to do the basics I need. Understanding what's happening behind the scenes gives me enjoyment in understanding why. Being an electrical beginner was at first daunting and then some small things started to click...slowly..... I am getting, what many already take as granted, and that is the logic behind it all.... once I understood the electrical fundamentals .... all the puzzle pieces started to mean something.
I tried to just jump in and get a job done.... without frying everything... then it got to making it better and got into new project ideas.
This WTW forum has been incredibly informative in a wonderfully accepting way... folks are real good.

 

[Vic Harder]

Regarding the shunt, this is for your Victron BMV, right?

 

[buckland]

Victron MPPT 100 / 20 Controller.

Here are the four ways to wire the shunt.... I think I need the last one (#4) so that I am monitoring the camper load.
The other would be #3 which monitors the battery usage .

 

[buckland]

Threw dull care away and decided to wire shunt for battery. I was able, using table top clips to mount the controller vertically. I first mounted it on site scrap walnut and rabbeted the edges so the clip would fit. Mounted the clips the box and the controller on a board slides into the clips, snug on the wall of the battery box. The shunt wires go from battery box on top of the water tank to the counter cabinet to the small shunt monitor....seems to be spot on to the Victron app. I have to admit I have learned a lot from the patient folks willing to help out on WTW. There is NO WAY I would have attempted this project without their guidance. Everything is installed. I turned on the fridge and fan to see the load. It really is cool to see what each appliance draws. And to see how the solar panel is doing. I will now plug in the portable 100 (roof is 160) and see how that adds to the picture.

Caring for this LiFePo4 battery will need to be investigated. I know, when storing the camper in the barn for the long cold winter I won't have to plug in the battery. just draw down the voltage and let it sit at 12V. I also need to find out how the FWC shore power plug in will affect the lithium battery. I assume it will work.

 

[Vic Harder]

Victron MPPT 100 / 20 Controller.

Here are the four ways to wire the shunt.... I think I need the last one (#4) so that I am monitoring the camper load.
The other would be #3 which monitors the battery usage .

OK, now I get why the opinions on shunt yes/no varied. I assumed it was the shunt for a Victron BMV.

 

[Happyjax]

Threw dull care away and decided to wire shunt for battery. I was able, using table top clips to mount the controller vertically. I first mounted it on site scrap walnut and rabbeted the edges so the clip would fit. Mounted the clips the box and the controller on a board slides into the clips, snug on the wall of the battery box. The shunt wires go from battery box on top of the water tank to the counter cabinet to the small shunt monitor....seems to be spot on to the Victron app. I have to admit I have learned a lot from the patient folks willing to help out on WTW. There is NO WAY I would have attempted this project without their guidance. Everything is installed. I turned on the fridge and fan to see the load. It really is cool to see what each appliance draws. And to see how the solar panel is doing. I will now plug in the portable 100 (roof is 160) and see how that adds to the picture.

Caring for this LiFePo4 battery will need to be investigated. I know, when storing the camper in the barn for the long cold winter I won't have to plug in the battery. just draw down the voltage and let it sit at 12V. I also need to find out how the FWC shore power plug in will affect the lithium battery. I assume it will work.

Buckland,

I am curious where you got the 12V level for storing your LifeP04?

During my research I have understood that 50% is a good storage level for LifeP04.

Now 12V is 50% for an AGM but not a Lithium. Lithium holds it's voltage through the usage cycle.

When I received my Renogy 50AH LifeP04 I checked it's voltage. It was at 13.1.

I charged it for 4 hours at 5-6 AH's before it stopped taking juice. It had gulped down about 25AH's or 50%.

You might want to check on that voltage number for storage.

I am also new to this so claim no expertise just lots of study.....

Hope this is helpful

 

[buckland]

Thanks I too am learning as I go. The 120 cells I got I soldered together into packs of 30 (parallel) and then connected in series into 4 packs to make the 13 V battery. I had to balance the whole thing and then put it on the solar charger/controller ... sort of w/o much aforethought and hoped it would charge up and it did.
In winter here I will drain it down to 2.8 volts in each cell pack so around 11. 2 V for storage

 

[Happyjax]

Well if you built it you know it better than I do

I just didn't have the kahunas to build my own yet...... maybe next one though both Renogy and Battle Born make it so easy and I do love easy sometimes

Good luck and I will be following so I can learn more!