Smartgauge vs Mastervolt Easyview-5 vs Simarine Pico

[CatNewBee]

This is not rocket science any way. Any battery decent computer can do the trick. The shunt measures the current. Some devices also measure the voltage too. The logic is in the computer.

It counts all the time the current per second and the direction of the flow. Measuring the Voltage on top and knowing the capacity and chemistry (Peukert factor) it can guess the SoC at any time. There is a drift in the calculation over time, but reaching the full state of the battery - the counters get re-set. The estimation of time is easy, you know the SoC and the total capacity, so you can calculate for the actual current the remaining time.

You measure usualy at the battery minus pole because you want to know details about the battery. the outgoing in ingoing current is always a summary of all currents in the system, that means summ of all appliances, that draw current (-) summ of all sources that provide current. the difference is either charged into the battery or is drawn off the battery.

If you want details about a specific branch, you need a separate shunt there. For solar: add a shunt for solar: after connecting all controllers to a point place the shunt between battery and that point. You will measure at all time how many Amps the solar is delivering to the system, consumed either by the battery or other running appliances. This current is not always the maximum current your solar system can provide any way. it is the current that is consumed from your solar installation. If the batteries are full and no appliances are on, the current will be near zero - no matter how the sun is shining.

[noelex 77]

Originally Posted by CatNewBee

This is not rocket science any way. Any battery decent computer can do the trick.

That is a very good basic explanation of a simple battery monitor, but there are potentially a lot more complexities that can be applied to make these meters more accurate.

For example, there needs to be a component for battery efficiency. You cannot put in 10AHrs then draw out 10 AHrs and remain at the same SOC. Some of the energy is lost, mostly as heat.

A battery monitor could chose to ignore this effect, or incorporate a simple fixed ratio. A more sophisticated monitor will use a variable ratio depending on battery type. More advanced again is to incorporate a variable ratio based on battery type and on voltage. As the charging voltage is increased, battery efficiency drops. More advanced again would be take these factors into account but "learn" from every cycle when the SOC reaches 100%. Battery efficiency decreases with age so the ability to adjust this parameter with time and automatically calibrate the battery efficiency results in a more accurate instrument.

The above is only a simple look at how just one parameter might be treated by different monitors of varying complexity, but the message is the most accurate battery monitor will be a sophisticated device. It should not be assumed that all monitors will give similar results.

One of the difficulties is when building advanced battery monitors, companies are naturally reluctant to reveal exactly what algorithms are incorporated. This makes comparing the features of different models difficult.

[Kenomac]

Originally Posted by CatNewBee

This is not rocket science any way. Any battery decent computer can do the trick. The shunt measures the current. Some devices also measure the voltage too. The logic is in the computer.

Didn't Apollo 13 have an issue with their batteries following the oxygen tank explosion? Necessitating the need to carefully monitor their power consumption....

[zboss]

My Mastervolt shunt reads .06-.08 volts less than my Smartgauge (which matches my voltmeter directly at the batteries) even though the wiring is 2/0 gauge and less than 4 feet. When I contacted my ABYC installer and Mastervolt they did not have an answer as to why that would be.

[CatNewBee]

That's true, batteries age with each cycle. Also the capacity depends on the current flow and the temperature too. The efficiency of storing the Amps varies by chemistry, some of the energy is converted to heat. You can measure the used capacity or the absorbed amperage at a given time, but you cannot reproduce 100% the result on the next cycle.

All battery monitor systems are "smart" guessing devices. But for average Joe this is good enough to estimate how much power is approximately available.

Also a real world usage pattern differs every time / day. A constant current discharge is very rare. Usually a "dumb" monitor panel that shows in a graphic display 10% steps of SoC is good enough for every day use. The exact current / voltage and usage statistics are more for the nerdy user who wants to tweek the system. Most battery monitors deliver such data sufficiently accurate.

Most people are just stunned by all the data available at the screen, charged Ah, kWh, discharged Ah, kWh, A, V, Capacity, Time left, used energy / charge / discharge during last hour, last day, last week, last month; deepest discharge last 30 days, maximum charge / discharge current last 30 days and so on.

Usually the user is overwhelmed by the data and cannot interpret the values because he does not think about the complexity of the system and the relations between voltage, amperes and watt. most often there are several sources (battery charger, generator, alternator, solar, wind generator), several consumer of energy and also the batteries with their state of charge and internal resistance.

A current only flows if there is a difference in voltage between source and destination. I have seen many guys starting to rip off their solar panels assuming they are dead because they measure only 5A charging current having a solar installation that can deliver 50A. This can be fixed easy, just turn on a inverter and put a decent load on for a while, then you'll got your 50A charging current off the solar system back .

What I am saying, measuring exactly is only half of the task, you should understand what are you actually measuring, where are you measuring it and why the results are what they are. Exact measurement does not provide a single Ah more on capacity anyway. Some times the value of an really "exact" battery computer is far overestimated compared to a simpler model.

[john61ct]

Originally Posted by zboss

My Mastervolt shunt reads .06-.08 volts less than my Smartgauge (which matches my voltmeter directly at the batteries) even though the wiring is 2/0 gauge and less than 4 feet. When I contacted my ABYC installer and Mastervolt they did not have an answer as to why that would be.

The answer is that one is wrong by that much, or more likely the actual precise V lies in between.

To get a very precise voltage reading requires equipment that costs hundreds of dollars. And even pro-level tools like that need to be periodically re-calibrated to maintain their accuracy.

Get a pro in if you don't want to make the investment yourself.

BTW every connection point, terminator or device in a circuit will introduce some measurable voltage drop.

That is why top-notch charging devices have a dedicated voltage (and temp) sensing wire, separate from the heavy output wire.

[noelex 77]

Originally Posted by zboss

My Mastervolt shunt reads .06-.08 volts less than my Smartgauge (which matches my voltmeter directly at the batteries) even though the wiring is 2/0 gauge and less than 4 feet. When I contacted my ABYC installer and Mastervolt they did not have an answer as to why that would be.

One of my pet peeves is battery monitors that do not read voltage correctly and this is with accounting for voltage drop in the wiring. Many have significant errors.

There is no excuse on a battery monitor. On other equipment a small error in displaying voltage is more understandable, but my new Zeus 3 is 0.3v out and my previous Simrad plotter was reading 0.4v wrong. Surely manufacturers can do better.

It was pleasing to see my new Pico was spot on. Interestingly, you can calibrate most of the sensor readings on the Pico to adjust for any consistent errors, but surprisingly not for voltage. I presume they must be confident the voltage display is accurate and don't want this calibrated incorrectly by the user.

[Paul Elliott]

Originally Posted by Kenomac

Then why do the voltage measurements on the Smartgauge vary wildly all over the place when loads are placed on the system when compared to the readings off the Magnetronic dedicated shunt or my Fluke Voltmeter? I'm thinking it's due to the Smartgauge taking readings off just a couple of batteries as opposed to the other two taking readings off the shunt.

"Why do the voltage measurements on the Smartgauge vary wildly all over the place?"

I don't know, but this has nothing to do with the Smartgauge "only measuring volts" (or not, as I believe). And why would taking readings off the shunt improve the accuracy of a battery voltage measurement? Is your Smartgauge connected directly to the battery terminals?

Anyway, it sounds like the Smartgauge doesn't fit your system or meet your requirements. That's fine with me. It didn't meet mine either, and I didn't bother to replace mine when it failed. I just think that if we discuss the Smartgauge we should be correct about what it is doing (as best we can, given the secretive nature of the manufacturer).

If anyone is interested, I put this in the panel where my Smartgauge used to be (see attachmment). I have three 100W solar panels, each with it own Genasun GV-10 MPPT controller. It's more of a science project than a vital piece of gear, but I've been curious about how my panels actually perform (they're on top of the dodger, so they have big shading problems). With this monitor I can measure individual panel voltage / current, and the combined output of the three MPPT controllers. I still have my Link-2000 battery voltage / current monitor which I do find very useful. It would have been nice to have a digital link for logging, etc, but I wanted to keep it simple enough that I would actually finish the project.

I used Front Panel Express (Front Panel Express: Front Panel Design Software and CAD Conversion Service: Home) to design and fabricate the panel. I like them.

[Kenomac]

Paul,

The Smartgauge is hooked up directly to the battery terminals as I was instructed to do so by the installation manual.

[Paul Elliott]

[re: erratic voltage readings from Smartgauge]

Originally Posted by Kenomac

Paul,

The Smartgauge is hooked up directly to the battery terminals as I was instructed to do so by the installation manual.

Interesting. I don't know why the Smartgauge should be giving wildly different voltage readings compared to any other voltmeter similarily attached to the batteries. Perhaps your other meters are attached to the ground side of the shunt? But even that difference should be less than 0.05V or so.

Not having a schematic, or even a block diagram of the Smartgauge, I suppose all we can do is speculate.

By the way, that Pico gear is beautiful. If I were starting from scratch I would consider it. But, honestly, the way I use my boat it doesn't really require this level of sophistication. It mostly sits in the slip with solar panels keeping the AGMs topped off. I very occasionally do a month or two of passagemaking and cruising. I've got 4 8D Lifeline AGM batteries as my main bank (plus a start battery) and after 15 years they still do quite well. I do a load test every year or two and the capacity remains more than adequate. If I were full-time cruising my needs might be different.

[john61ct]

> If anyone is interested, I put this in the panel

Niiice

[noelex 77]

Originally Posted by Paul Elliott

I used Front Panel Express (Front Panel Express: Front Panel Design Software and CAD Conversion Service: Home) to design and fabricate the panel.

Nice installation Paul.

Knowing how much power has been put back into the batteries is important. One limitation of devices such as the Smartgauge is that they don't provide any information of current in and out, let alone cumulative totals.

If you are reasonably electronically savvy, meters such as Paul has shown are not expensive and can provide this missing information. However, it takes some care to acheive a professional result as Paul has done.

[Paul Elliott]

Originally Posted by noelex 77

However, it takes some care to achieve a professional result as Paul has done.

Please don't look behind the panel! It's kind of a rats-nest at the moment.

Here's the schematic (attached). In addition the the breaker at the MPPT output there are also per-panel breakers (not shown on the schematic). All these breakers aren't strictly necessary because I have one at my power distribution panel that connects to the MPPT / monitor panel. I just figured that I would be experimenting (playing) with the system so I added the breakers for convenience. Switches would have been just as good, but I had the DC breakers handy. I'm losing a bit of power in the monitoring shunts, but it appears that I more than make up for it by going to independent MPPT controllers.

Here are the V/I monitors I used:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

These are not precision devices. The least-significant digit on the small round units may be off by one or two. But it's good enough for my needs.

[john61ct]

I'd be a bit wary about the meters interfering with the MPPT optimization.

Not that much of that's going on with such low voltage panels?

[Paul Elliott]

Originally Posted by john61ct

I'd be a bit wary about the meters interfering with the MPPT optimization.

Not that much of that's going on with such low voltage panels?

The little meters only introduce a very small series resistance, probably less than my wires to the panels. I don't see how they would interfere with the optimization, other than introducing a small amount of extra loss. And there is certainly MPPT optimization going on, compared to a simple non-MPPT controller. I've seen and measured it.