Smartgauge w/ 3 batterys

[Paul L]

Originally Posted by john61ct

Direct from Chris:

SmartGauge does and will display the charge status during charging. It cannot do this to better than a guaranteed accuracy of 10%. We state this on the website because we are honest. In practice 2 or 3% is usually the achieved figure but we cannot guarantee this.

Amp hours counters can be out by *much* more than this during recharge. Several hundred amp hours adrift after just 5 or 6 cycles is *not* exaggerated speculation. It is fact. I have been involved in the supply, manufacture and design of amp hours counters for over 15 years, it is a *very* well known problem within the industry.

My own Link 2000R is setup perfectly yet during recharge it is not uncommon to see a recharge from, say, - 200 amp hours up to -30 amp hours, then the counter reset to zero because the Link has detected the charge parameters being met. This equates to an error at the end of the charge cycle of over 15%


Smartbank battery management

Skip to the last page to skip a lot of very familiar posts based on overly skeptical ignorance 8-)

Where on the website? + or - 10% or is it + or - 5%?

[john61ct]

I provided a link to the original source forum thread, and stated skip to the end.

Total 10% range of error, not 10'% in either direction so take the "actual" SoC, within 10% of that.

Note the equipment time and skills required to set up the "more accurate" benchmark to measure against is prohibitively daunting.

[john61ct]

Please trim quotes guys and gals?

Originally Posted by Bleemus

One merely needs to go to the manual . . .

Excellent, but could you maybe clean up the line breaks?

[john61ct]

Originally Posted by Paul L

The thing is you go to their site and get what really sounds like

As I explained, it's not "their site", it's an historical artifact that's been preserved because it contains a lot of very valuable information.

It seems you feel entitled to be spoon fed everything you're looking for.

Get out there and google! Start at the websites of the companies that actually own the rights to device now, Merlin and Balmar. Then Maine Sail's reviews. . .

To me, a company that doesn't bother doing much marketing but their product keeps selling well for decades is more trustworthy than one with all the color PDF brochures.

[Paul L]

Originally Posted by john61ct

As I explained, it's not "their site", it's an historical artifact that's been preserved because it contains a lot of very valuable information.

It seems you feel entitled to be spoon fed everything you're looking for.

Get out there and google! Start at the websites of the companies that actually own the rights to device now, Merlin and Balmar. Then Maine Sail's reviews. . .

To me, a company that doesn't bother doing much marketing but their product keeps selling well for decades is more trustworthy than one with all the color PDF brochures.

Don't get all defensive and in a huff. If I tried to support some point of view with statistics that were numbers with unknown units and signs, you would be all over it. The site I was reading from is:
SmartGauge Electronics - Homepage
It has some pretty marketing sounding words:

For the benefit of the unitiated or those with a suspicious mind "Computer modelling" is now a very widely understood technology. It is used extensively throughout every industry in existence and is well developed. There probably isn't a single technical field in existence that does not use computer modelling in one form or another.

[john61ct]

Seems very matter of fact to me, at the time concept was not yet mainstream.

And I'm quite calm thanks.

[Exile]

Originally Posted by john61ct

I provided a link to the original source forum thread, and stated skip to the end.

I did so and read Chris Gibson's entire post (and none of the critiques), the main gist of which was to explain why the SG remedies the problems inherent with coulomb counters when used by the non-techy crowd. I get all that, and do not doubt the performance or accuracy of the SG except for some acknowledged limitations during charging.

What I found interesting, however, were Gibson's comments about how the SG was developed mainly for non-techies who don't understand or do not want to take the time to properly calibrate & re-calibrate their counters. I get that too. But what seems missing from Gibson's explanation -- and frankly yours -- is why simply understanding how to read a VM to determine approx. 50 & 100% SoC, or any point in btwn. for that matter, is not an adequate substitute for the end goal of not prematurely killing your batteries?

It's already been accepted that it doesn't matter much in the long run whether you recharge at 49, 50, 53 or 55%, or whether you prefer to recharge at 70, 72 or 75%, or whether you should keep your genset running until the batts. are at 80, 82 or 85% (or x mins. past start of absorption phase). So why, other than a techy interest or personal preference with more actual (or perceived) precision, does the SG improve upon an educated reading of a VM?

Again, let's assume that the SG does as advertised, as confirmed by Maine Sail's testing and as reported by a lot of knowledgeable boaters on this forum. And again, I can probably understand some benefit in owning one, especially if away from shore power for extended periods. But that's not really the issue being "debated."

Instead, can you simply tell us why a SG is not a generally redundant system for accurately monitoring SoC? You're obviously enthused by this relatively new technology, but as a practical matter does it accomplish anything more than an old school VM?

[john61ct]

The best I can say at the moment is, IMO for a bank in use Voltage does not correlate to SoC accurately enough to be useful.

To the extent 20-hour load tests are regularly performed and a well-calibrated charge source resets the AH counter at 100% Full(almost) every cycle, then I would use a 702-BMV for the extra data, and if strapped for cash could perhaps save up for the SG later on, as the ideal is to have both.

If I were truly poor, and the bank flooded and easily accessible, I suppose I would go back to the dark ages and use Specific Gravity.

But trying to use voltage is to me like trying to truly assess my beloved's mood from telegrams.

[Exile]

Originally Posted by john61ct

The best I can say at the moment is, IMO for a bank in use Voltage does not correlate to SoC accurately enough to be useful.

To the extent 20-hour load tests are regularly performed and a well-calibrated charge source resets the AH counter at 100% Full(almost) every cycle, then I would use a 702-BMV for the extra data, and if strapped for cash could perhaps save up for the SG later on, as the ideal is to have both.

If I were truly poor, and the bank flooded and easily accessible, I suppose I would go back to the dark ages and use Specific Gravity.

But trying to use voltage is to me like trying to truly assess my beloved's mood from telegrams.

Well, I don't want to beat a dead horse at this point but would only say that, based on my admittedly limited experience & knowledge base, I don't understand why a VM used as Rod & others have discussed is not "accurate enough" for the intended use, namely trying to maximize battery life given the limitations onboard a cruising boat. With a very expensive set of Lifeline batts., I was initially quite excited about the SG, but I'd now have to say it's on the "nice-to-have-but-not-necessary" list. But I certainly could be missing something.

[Dockhead]

Originally Posted by Bleemus

Need to comment on this as it seems to be perpetuated throughout the thread. SmartGauge is accurate while charging to less than 10% inaccuracy. Its is not "useless" or "totally inaccurate". Thank you and carry on.

Not in my experience. Just one data point -- one SmartGauge, one boat -- but mine has no clue whatsoever, and needs time with no charging and also for surface charge to come off, before it figures out where we are. It will adjust itself by 20% or more.

So the words "useless" and "totally inaccurate" actually well describe the behavior of my particular SmartGauge, on my particular boat with regard to measuring SOC while charging is going on.

[Dockhead]

Originally Posted by Exile

Well, I don't want to beat a dead horse at this point but would only say that, based on my admittedly limited experience & knowledge base, I don't understand why a VM used as Rod & others have discussed is not "accurate enough" for the intended use, namely trying to maximize battery life given the limitations onboard a cruising boat. With a very expensive set of Lifeline batts., I was initially quite excited about the SG, but I'd now have to say it's on the "nice-to-have-but-not-necessary" list. But I certainly could be missing something.

I have used a simple voltmeter for decades, and have done a lot of checking against specific gravity. I used amp-counting meters (Link, then Victron) for years also, and checked them. During the first year or so I had my SmartGauge, I did more checking against specific gravity.

With my particular battery bank (large 24v bank of flooded Trojans) and my particular boat, voltage readings were no less accurate than any other method, including the SmartGauge, provided you use voltage reading in the right conditions -- small loads only, no charging going on, and no surface charge.

YMMV, of course, but I am surprised to hear anyone think that reading voltage is like "mood telegrams". Maybe it's different with non-flooded batteries. What did you do before battery monitors were invented? I only saw a battery monitor first time in the late '90's; before that, everyone used voltage and I don't think we got less life out of our battery banks than we do today.

[conachair]

Originally Posted by Dockhead

What's the best way to get voltage data into the computer? I've seen USB data loggers that would do it, but they cost a lot more than a pint at the Jolly Sailor.

Easiest - get a raspberry pi

But on windows ...
4 channel ADC is this one, about a fiver on ebay. https://www.adafruit.com/product/1085
Easy on the Pi as openplotter is set up for this chip and converts the readings into signalK or something like XDR sentence in NMEA as well.
Windows maybe best way would be a board like this -
https://www.adafruit.com/product/2264

Then I just use node red as it's the most friendly for cut and paste pretend programmers like me

I store it all in a database but you could just as easy use a csv text file.

Also very cheap to add thermometers - ds18b20, I have one on the engine head which gets converted into NMEA water temp message so it's always visible in the opencpn dashboard.

So bit more fiddly with windows but lots help in google, once it's done it's done

Then if you have a web connection it's simple to program node-red to send an email or tweet if the battery voltage or whatever gets low, though means leaving the computer fired up.

PS:
Another way would be over wifi with a little esp8266 board sending out data as raw numbers or nmea over UDP. Might actually be less involved than direct, if I ever get round to having a play I'll post the results.

[Dockhead]

Originally Posted by conachair

Easiest - get a raspberry pi

But on windows ...
4 channel ADC is this one, about a fiver on ebay. https://www.adafruit.com/product/1085
Easy on the Pi as openplotter is set up for this chip and converts the readings into signalK or something like XDR sentence in NMEA as well.
Windows maybe best way would be a board like this -
https://www.adafruit.com/product/2264

Then I just use node red as it's the most friendly for cut and paste pretend programmers like me

I store it all in a database but you could just as easy use a csv text file.

Also very cheap to add thermometers - ds18b20, I have one on the engine head which gets converted into NMEA water temp message so it's always visible in the opencpn dashboard.

So bit more fiddly with windows but lots help in google, once it's done it's done

Then if you have a web connection it's simple to program node-red to send an email or tweet if the battery voltage or whatever gets low, though means leaving the computer fired up.

PS:
Another way would be over wifi with a little esp8266 board sending out data as raw numbers or nmea over UDP. Might actually be less involved than direct, if I ever get round to having a play I'll post the results.

Whew!

[Bleemus]

Originally Posted by john61ct

Please trim quotes guys and gals?

Excellent, but could you maybe clean up the line breaks?

Sorry about the line breaks. That was a cut and paste from a PDF on an Android tablet. At least nobody can claim that I doctored it in any way!

[ramblinrod]

Originally Posted by Dockhead

Not in my experience. Just one data point -- one SmartGauge, one boat -- but mine has no clue whatsoever, and needs time with no charging and also for surface charge to come off, before it figures out where we are. It will adjust itself by 20% or more.

So the words "useless" and "totally inaccurate" actually well describe the behavior of my particular SmartGauge, on my particular boat with regard to measuring SOC while charging is going on.

2 data points.

My friend, the one I was considering developing the Raspberry Pi battery monitor / analyzer with, reported that his Smart Gauge "doesn't have a clue what is going on when charging". He is a pretty rational, logical guy. I don't believe he would have said this if it was out by the supposed 10% accuracy, which I understand to be +/-10% of full scale (100%).

One of the issues I have with the Smart Gauge marketing hype, is that they shed their product in the best light, and others in the worst possible.

They make it sound like a direct and comprehensive comparison between their technology and the rest of the market. It isn't. And it is certainly not by an independent 3rd party.

Where the SG literature says it can be out by a mere 10%, that is for the current instantaneous reading, so if (% of full scale but not clear) it should be 75%, it could be 65% or 85%.

I don't know about you, but to me that is huge. If it were truly 75% but read 85%, on a 1000 A-hr bank with a 100 A charger, that would mean shutting down the charging system over (because its not 100% efficient) an hour early, if no solar, this PSOC over and over again is going to definitely hurt this bank.

Look at it the other way, if it were truly 85% but reads 75%, that means running the charging system over an hour longer. Lets say 1.2 x 365 = 438 hours per year. Likely 1/10 the life of the generator or a cost of about $1500 per year.

Now lets look at the Smart Gauge claims about coulomb counters.

It is not talking about apples to apples comparison.

For Smart Gauge, they focus on instantaneous SOC.

For others, they focus on accumulated A-hrs.

Not the same thing folks, not the same thing at all.

The Smart Gauge does not even report accumulated A-hrs, it can't. It is not smart enough.

What is the difference in instantaneous SOC for both systems?

The answer is, that a properly programmed and calibrated amp counter, is capable of reporting instantaneous SOC more accurately, PERIOD. (And way more accurate while charging.)

As long as the amp counter is brought up to 100% charge regularly, and the bank capacity is accurately programmed, it has a much better change of being more accurate.

Does one need to perform a tedious 20 hour capacity test constantly?

No. Just estimate A-hr capacity at +5% the first year, and -5% each subsequent year. That should be close enough, especially for quality batteries that will meet their published specs. If you don't have quality batteries capable of meeting specs, why the heck waste your time with this stuff?

It is true that an amp counter can get out of sync counting A-hrs if it is not maintained properly, but alas THE SMART GAUGE IS NOT EVEN IN THE AMP COUNTING GAME.

Do not be fooled by BS and marketing hype.