Victron battery monitor

Tundra57

I have a tab 400 with factory solar and twin 6v batteries. I can get battery info from the Vicron solar controller.

I notice some tabbers have gotten an additional Vicron or similar battery monitor.

What are the advantages of this, considering they are around $300? I know terminal voltage is not a good indicator of capacity but it suits me at the moment.

ScottG

I'm sure others will chime in with more details, but basically these devices use sophisticated circuitry to monitor your power usage and assess and report the real-time state of charge of your batteries. If you have complicated power needs or are a technology/information junkie (and there's nothing wrong with that) you might consider this a necessity, but otherwise you can likely get by just fine with terminal voltage and a few "battery whispering" skills.

If you're really interested but don't want to part with that much coin, there are some cheap $30-40 knockoffs that have gotten good reviews. I've considered buying one myself just to play with, but so far other projects keep taking precedent. 

DougH

And for $29, this is still meeting my needs. I have all the positive terminal wires (the solar power input and inverter output) squeezed into the sensor, and it does a good job keeping track of my Ah remaining. 

     https://www.amazon.com/dp/B07B4CWKRJ

BrianZ

If the question is not actually rhetorical, I can offer my first trip report which shows screens from both devices for comparison..
https://tab-rv.vanillacommunity.com/discussion/7926/boondocking-our-first-experience-documented/p1

While the Victron charge controller can provide some recharging-based historical data, the Victron monitor can, at a quick glance, tell you the remaining battery capacity right now & how many Amp-Hours used since last full charge and since the beginning of a trip (or last reset).  Moreover, this feedback can be a valuable tool for learning how much power you use from day-to-day, and allows you to see the battery-depletion effects of using various appliances, so you can better manage & conserve.  If you've got enough solar capacity & good sun, then monitoring is less critical.  However, if battery capacity, solar capacity, or sunlight is limited or electrical demand increases, then monitoring becomes a more valuable planning tool for avoiding a depleted battery.

I think of the battery monitor like the battery level equivalent of checking the holding tank levels on the SeeLevel monitor to find out how much you've used/got left.  For comparison, I wonder how much it would cost to add a SeeLevel system to tanks without it?

Afterthought..
How much battery power and solar power would one need to install in a T@B for spending the winter boondocking in the desert southwest versus in Alaska?  And would you do either one without a battery monitor?

TNOutback

What Brian said X2. Camping in the east/southeast, you’ll deal more with trees/shade and less consistent sun for solar charging, so more accurate monitoring helps preserve the life of your batteries and know how far one can go on a charge.  I especially think this is important on multi-day boondocking trips with the 12V refrigerator in use.

MuttonChops

ScottG said:

. . . there are some cheap $30-40 knockoffs that have gotten good reviews. . . .

@Tundra57 ;  I have installed one of the China shunt style units.  Not as fancy as a Victron, maybe not as useful, but low price      Have not decided if it is worth having.

Both the shunt and display add to T@B baseline current draw.

Basic wiring in my 320S Tub

Tundra57

Mmmmmm interesting.

Tundra57

For the moment I think I'll just use a.cheapo voltmeter with ammeter shunt.

Cbusguy

The big selling point of the Victron shunt, beyond blue tooth and smart phone app,  is that it talks to the the solar charge controller and has the ability to make adjustments to the battery charge.    

I have done a bit of research and cannot locate any information on the interaction of the devices and any factual information on how or if it modifies battery charge current.     I have seen additional info populate in their app from other devices but nothing definitive showing changes in charge current or battery state.

I have a $30 battery shunt on my workshop solar and it works just fine.   It wires in exactly the same as the victron.   

@MuttonChops Not as useful?   the main difference is you need to leave your seat to look at it.    It provides the exact same information.    

MuttonChops

MuttonChops said:

. . . have installed one of the China shunt style units.  . . .

Well it Died.
5 & 7/8th  months into the 6-month warranty.

The data was helpful . . . but . . . seller has not responded to email/web-page help requests.
Might attempt to  troubleshoot the circuit board but for now it's a low priority.

Tundra57

@MuttonChops, @BrianZ I worked at Duracell with a team generating an equation to give remaining battery capacity in batteries both rechargeable and not. This used current draw, with time, frequency, rest time amongst others.

There were some very clever people working on it.

It proved very difficult to make it accurate. I can only assume that the same is true of the Vicron monitor. It will be very good at monitoring your ins and outs of energy but still cannot, I believe, be wholly accurate for life left.

My question was not rhetorical, but I was interested to see if they were accurate enough in a practical environment to be useful. You Tabbers out there can give real reviews as opposed to a paper only sales pitch.

Marceline

FWIW Victron is going to roll out a shunt that processes battery data and sends it directly to the Victron app. It will be a stand-alone device without a separate display. 

jkjenn

Marceline said:

FWIW Victron is going to roll out a shunt that processes battery data and sends it directly to the Victron app. It will be a stand-alone device without a separate display. 

Thanks! Good news!

To the original question, it all depends on your needs. Do you do extensive dry camping? You might want to consider one. Do you mainly camp at state parks with electric or RV parks? Probably unnecessary.

I believe I was the first T@b owner to install a Victron. I went with it because I was going to be working FT in my T@b while boondocking and needed to be sure I could power my laptop. I now consider it essential for dry camping because I am never in wonder about the true status of my battery.

BrianZ

@Cbusguy, I'm glad your shunt works for you, but I have doubts that it provides the same information as the Victron battery monitor.  You already mentioned one selling point - that the Victron reports live data to the solar charge controller, so it can deliver the appropriate voltage/current.  Though Victron may not have explained it detail how it uses this data, I have seen in the display when it wirelessly reports the battery temperature via bluetooth to the SCC.  It is a known fact that a battery's state of charge, as indicated by voltage measurement, must be adjusted for temperature, relative to the normal reference point at 80°F.  Indeed, my Victron shunt has a dual wire lead connected to the battery positive terminal that both powers the shunt/monitor and has a built-in temperature sensor.  See this page about temp correction..
http://all-about-lead-acid-batteries.capnfatz.com/all-about-lead-acid-batteries/lead-acid-battery-maintenance/battery-voltmeter-soc-temperature-correction/
So, I would have to ask, when you use a voltage measurement to infer what your battery's state of charge is, do you adjust the measured value up/down as appropriate for each 10° change above/below 80°?  And air temp is not good enough - it needs to be read on the battery teminal itself.

Great perspective, @Tundra57, and I would agree that it can be difficult to be accurate, but to answer your question, I also believe that Victron is the best thing available & certainly accurate enough to be very useful in practice.  I was not totally convinced until I did a test by letting our T@B's electronic's background "phamperage" slowly consume the battery.  It predicted something like 19 days remaining at the current rate of discharge.  I had also found a reference with equations for doing the math, which I shared elsewhere on this forum - will have to look.  It was a bit intimidating, but after slogging through it, I got the same time prediction, then low & behold, my low battery alarm on the monitor went off also on the predicted day.  I was amazed, but convinced.

There's something else I learned about a battery's rated Amp-Hour capacity that is of very practical use & requires a bit of thought.  Whether you can actually get the rated amount of amp-hours from your battery depends on how you use it.  That is to say, the rate of discharge comes into play, and you will not be able to power a 4-amp refrigerator for as long as a lower wattage device.  My test mentioned above consumed only milliamps, so the battery was able to continue at that rate for a long time.  But if it had been a frig running, it would have quit when there was still significant Amp-Hours of capacity left (for powering lower demand devices).  Battery chemistry comes into play too, so recovery time may be an issue.  The AH are there, but whether you can make use of them all for a given purpose may depend.

Tundra57

@BrianZ were you in my battery class lol?

Yes discharge rate is important in all batteries as they have a voltage drop proportion to discharge rate. So you may find a high drain device can't run but a low drain device can still use up those last electrons. Lithium batteries are good at this as their voltage drop is less so even with a high drain device you can suck more power out before low battery is indicated.

jkjenn

@BrianZ shares some great, relevant information. Also, if drawing a higher amperage, particularly if you get to higher levels (microwave, for example), expect the battery life of a lead acid or AGM to depreciate more quickly. 

ginsbuj

The Victron app that connects to the factory installed controller (https://www.victronenergy.com/solar-charge-controllers/smartsolar-mppt-75-10-75-15-100-15-100-20 in my 2019 320 gives you the ability in settings to adjust to the battery of choice. I will be installing a Battleborn lithium tomorrow and with this app I can also set parameters suggested by Battleborn.   

CrabTab

OK, we are ready to submit and install a real battery monitor instead of using the KIB panel and my trusty multi-meter to determine state of charge. There is simply too much usage/live data we don't have about our system.

Trying to plan this out before ordering. Can I tap off the cables inside the cabin, or should I run lines directly to the battery for some reason?

NHCraig

jkjenn said:

Marceline said:

FWIW Victron is going to roll out a shunt that processes battery data and sends it directly to the Victron app. It will be a stand-alone device without a separate display. 

Thanks! Good news!

To the original question, it all depends on your needs. Do you do extensive dry camping? You might want to consider one. Do you mainly camp at state parks with electric or RV parks? Probably unnecessary.

I believe I was the first T@b owner to install a Victron. I went with it because I was going to be working FT in my T@b while boondocking and needed to be sure I could power my laptop. I now consider it essential for dry camping because I am never in wonder about the true status of my battery.

That is good news.  I was going to install one this spring, but I'll wait for that to avoid snaking the wire to the display!

Marceline

NHCraig said:

jkjenn said:

Marceline said:

FWIW Victron is going to roll out a shunt that processes battery data and sends it directly to the Victron app. It will be a stand-alone device without a separate display. 

Thanks! Good news!

To the original question, it all depends on your needs. Do you do extensive dry camping? You might want to consider one. Do you mainly camp at state parks with electric or RV parks? Probably unnecessary.

I believe I was the first T@b owner to install a Victron. I went with it because I was going to be working FT in my T@b while boondocking and needed to be sure I could power my laptop. I now consider it essential for dry camping because I am never in wonder about the true status of my battery.

That is good news.  I was going to install one this spring, but I'll wait for that to avoid snaking the wire to the display!

Yes. That was my issue, too. I'm working with a US distributor to get one as soon as possible and will let people know how it works out. It will probably be early April.

Cbusguy

@BrianZ  In my research the only interaction based on the interconnected victron devices was the temperature sensor allows the solar charge controller to charge more accurately based on temperatures taken, if memory serves,   Hourly.    I believe the victron solar charger without the temp monitor only checks the temperature once every 24 hours and bases the charge rate on that,  a bad thing that is why I added the temp module to my 320.    Beyond that I cannot find any documentation on the interaction of the 712 and the solar charge controller.   

If you have a link or any other documentation please share,  I enjoy the reads and to have the latest information.   I am sure the rest of the forum would appreciate it as well.

Depending on the el cheapo shunt they absolutely provide the same basic information.    Real time amp flow + or -,   and the total amp hours in the battery.     What is missing is the ability to link to a computer or blue tooth app and any history feature.     

Bottom line is all you need to know is how many amp hours are in the battery and what your current state is either charging or discharging.  Both do that.

@CrabTab If you are using the 712,   I didnt bother to mount the display in the trailer living space but to the battery box in the trailer tongue storage box.    I simply use the victron app to check my battery state......probably saved 4-6 hours on the install and drilling holes on the interior of the trailer.  I did mount it in a weather tight box I had....

pthomas745

I left the display inside the waterproof box that sits just outside the battery box.  All I needed was a much shorter "data" cable. The Bluetooth app is more than adequate, eliminates the need to run that long cable, and allows for binge watching your battery while you sit next to the camper.

ChanW

Like @pthomas745 suggests, binge watching the monitor is a gas... er, electrifying!

I too put the monitor in a waterproof box inside the battery box.

pthomas745

Let's see what happens when I plug this in!

Ooooooohhhhh!  So much fun!

CrabTab

Thanks for the insights @Cbusguy, @pthomas745 and @ChanW.

I now understand that the shunt needs to be close to the battery. I'll wait a few weeks to see what develops with the model @Marceline wrote about.

Can't wait to live stream data though! Perhaps I'll mirror my phone on the television, buy a hookah and charge admission to sit in 'the lounge' and watch. 

jkjenn

Alarms, the ability to add relays, and a significant historical data capability within the app are also advantages of the Victron monitor. In addition, they keep upgrading what they can do via firmware updates.

Cbusguy

As you have seen there isn't one best, right answer.     The answer lays with camping style, personal choice, budget and confidence.  I just need to see current charge in the battery.   

The rest of it well ........    Shrugs

BrianZ

@Cbusguy, you're right - those are all important aspects to keep in perspective.  I have to admit that my desire for accuracy, reliability & detail about battery charge status is out of line with our typical camping style, but I do prefer to be well prepared for any situation as much as possible & the freedom that allows. 

I only wish I was as obsessive about the battery in our tow vehicle, which I rarely check (it gets professional maintenance every 6 months though).  I recently found it dead - like 1.5 volts on the Fluke multimeter.  The cells all had good fluid levels, so I thought I'd use the NOCO Genius 7200 charger to recharge it; but, the normal mode will not work below 7 volts.  So the trick was to put it on the 13.6V Supply Mode for about an hour to get the voltage up high enough to then do a complete recharge overnight using the normal mode. 

Now the TV battery is back to its normal self, but how did it get so dead after sitting for just a few weeks & it's only 2 years old?  After looking, I found that I had left my OBDII bluetooth reader plugged into the car's computer port.  I had used it on the last trip for monitoring transmission temp & forgot to remove it, so figure it must have still been consuming some milliamps.

BrianZ

@Cbusguy, you had asked for documentation, and I did come across some things that addresses the communications between Victron's battery monitor & solar charge controller..
https://www.victronenergy.com/live/victronconnect:ve-smart-networking

The SCC uses both battery temp and voltage to adjust its charging parameters to account for voltage being reduced at colder temps and when voltage is decreased by resistance in cables.  Here is a screenshot of my Victron wireless network in action..

And below is from my battery's data sheet, showing the temperature compensation to be used. 

It's listed as 5mV "per cell", so I multiplied it by 6 to get the 30mV per °C entered into the Victron SCC app settings below..


I should point out that this doesn't require the battery monitor, as Victron also has a standalone Temp Sensor with built-in bluetooth that can attach just to the battery to send temp to the SCC (see video in link above).
That said, I should also point out the following pages from the Victron BMV-712 battery monitor manual showing another benefit of using the shunt's auxiliary port for temp monitoring for the purpose of adjusting battery capacity, which decreases with temp..

And here is my setting in the monitor app for using that temp coefficient..

I guess those who have dual 6V battery setups & want to use the monitor's aux input for reading the midpoint voltage between batteries, then one could get the stand-alone bluetooth temp sensor to mount on the battery for temp compensation of battery capacity and SCC charging voltage.

And if your brain isn't saturated yet, another aspect I wanted to point out is that the Victron monitor allows you to use your battery specs to calculate & enter a custom Peukert Exponent to more precisely adjust the state of charge to more realistically allow for higher discharge currents than the standard, if you want.  They suggest leaving it set at 1.25, but using our battery data sheet & example in the Victron manual, I calculated 1.19 for ours.
Here's my calculations with their example..

NOTE:  I used the "Ln" function on my scientific calculator, not the "Log" key to calculate the numbers below (eg, enter 20, then press the Ln key to get 3).

So, you might ask, "What difference does this setting make on what the battery monitor is showing as my state of charge"? 
Well, I can show you an example of what was displayed under the exact same conditions by simply changing the Peukert setting..

At the default setting (1.25) at left, it showed 80% SOC after 11 days of background discharge (200+ millivolts of electronics).

And by changing the value to 1.12 (arbitrary), it decreased to 74%.  I wrote in between my guestimate of 77% if I had tried my calculated Peukert value of 1.19, because it's about halfway between.  So, the lower value would give a more conservative reading (meaning you probably have more power left than shown, if you haven't or won't actually been using any high amperage devices).

Sorry if this is TMI, but if it makes you want to Peukert, then I've accomplished my goal.  😉
On the other hand, somebody asked for more info.

PS:  Almost forgot, for whomever was going to install lithium batteries, you may want to consider installing a temp sensor (either the stand-alone bluetooth one, or a Victron BMV monitor with auxillary sensor), so that you can set a low temp battery cutoff in the SCC settings, if needed to avoid charging when temps are freezing.

Cbusguy

@BrianZ very nice and thank you.   

Reading the docs in the link,  mostly it is temp,  interestingly they use it to control tail amperage,   which looks like the top up current during float.    So it does do a bit more than I thought.   In reading it looks like the biggest benefit is for Lead Acid chemistrys.    

Battleborn, Lion and renogy, Name brand,  have bms's built in that have been proven functional with low and hi temp cutoffs.     THe victron temp cut off comes into play with the no name LIPOFE batterys from ebay, amazon or aliexpress,  many of those have failed youtube reviews.


Laughing at the noco genius charger......I have one also and the way it works is irritating.     I end up using my 30 year old 15 amp Schumacher more often than not.     

jameskuzman

Marceline said:

FWIW Victron is going to roll out a shunt that processes battery data and sends it directly to the Victron app. It will be a stand-alone device without a separate display. 

Now THAT'S something I'd be interested in. The display is handy, but you want it in a convenient remote location, it means a wire to run and a hole to drill. I'd rather use the app, which actually brings some nice additional functionality to the table. 

Jim