Merlin Smartgauge specifications and accuracy

[Graham.m]

The suggestion is that people put their faith in a box that has doggy quality issues; that does not have the ability to tell when the capacity of the battery has died to the replacement point; that cannot tell when the batteries are fully charged; that cannot give a voltage reading to two decimal places, is to me not a good one.

 

Now while this maybe OK for someone who is a leisure boater, like you, where the boat goes out for a week or two cruising but spends the majority of its time in a marina connected to a shoreline charging the batteries fully. How about the live a board who spend their time off grid.

 

I would suggest that for live-a-boards, like the young man recently, who was recommended by experts on this forum to buy a gauge, supplied defective; who replaced batteries probably because the advice from this forum using the gauge information. Surely these people need something that will tell them what is going on with their batteries, how much charge is going into their batteries, when charging when the current drops to a low enough level that they can say their batteries are fully charged etc. Their batteries are their main source of power. I believe they need an amp measuring battery monitor.

 

You are comfortably off, and what is pocket money to you is a lot of money to a fair percentage of the live-a-board boater.

 

As to the suggestion of connecting a known load and clamp meters, there is a world of ordinary people who if they were into to doing such things would have an amp measuring battery monitor anyway.

 

As for costs, for what it does the gauge is expensive at £120 while the BMV700 for example is £124.

 

What battery monitoring/measuring equipment you have on your boats or easily available?

[nicknorman]

The suggestion is that people put their faith in a box that has doggy quality issues

We may have found one that is way out of calibration but I think we have yet to find one that pants, slobbers, farts stinkily, shits on the towpath, and shakes itself over you after its fallen in.

Edited January 14, 2016 by nicknorman

[nicknorman]

Oh did you want a sensible answer? I'll resort to laptop and red ink!

 

 

The suggestion is that people put their faith in a box that has doggy quality issues; that does not have the ability to tell when the capacity of the battery has died to the replacement point; This is completely incorrect. With a Smartgauge it is very obvious when a battery bank needs replacing. The SoC indication starts to fall quicker, with resultant lower SoC readings in the morning, and when the morning SoC becomes unacceptably low it is time to take action. In fact it is the AH-counting gauge that fails to tell the user when the batteries need replacing, happily still reporting 80% SoC when the batteries are in fact flat. that cannot tell when the batteries are fully charged As I've mentioned several times but you choose to ignore, there is no such thing as "fully charged". The smartgauge makes a reasonable approximation to what many people would consider fully charged. You repeatedly fail to indicate what you consider to be fully charged, and why. That of course is because you know that there is no such definition; that cannot give a voltage reading to two decimal places, It is not a voltmeter. If you want a voltmeter, get one. They are not expensive. The whole point of the smartgauge is that it is a battery fuel gauge for dummies who don't even know what voltage is. is to me not a good one.

 

Now while this maybe OK for someone who is a leisure boater, like you, where the boat goes out for a week or two cruising but spends the majority of its time in a marina connected to a shoreline charging the batteries fully. How about the live a board who spend their time off grid. It's ideal for them because it tells them when and for how long to charge, and also lets them know whether their usage is reasonable proportion of the current battery capacity.

 

I would suggest that for live-a-boards, like the young man recently, who was recommended by experts on this forum to buy a gauge, supplied defective; who replaced batteries probably because the advice from this forum using the gauge information. This isn't a sentence so I can't respond. Surely these people need something that will tell them what is going on with their batteries, how much charge is going into their batteries, when charging when the current drops to a low enough level that they can say their batteries are fully charged etc. Some folk, me included, like to know the current going in and out. But there are lots of folk who don't know and don't care what current is. They just want a battery fuel gauge. Their batteries are their main source of power. Lots of such people have no monitoring at all. I believe they need an amp measuring battery monitor. You keep saying this, but without any justification. The AH gauge tells them the current, which can be useful, but it doesn't tell them the SoC unless they know the current battery capacity, which they don't. So if it just tells them the current they would surely be better off with an ammeter.

 

You are comfortably off, and what is pocket money to you is a lot of money to a fair percentage of the live-a-board boater.

 

As to the suggestion of connecting a known load and clamp meters, there is a world of ordinary people who if they were into to doing such things would have an amp measuring battery monitor anyway.

 

As for costs, for what it does the gauge is expensive at £120 while the BMV700 for example is £124. The former tells them the actual SoC, how their batteries are doing health-wise. The latter gives a fictitious SoC and tells them the current, doesn't tell them the health of their batteries. Although having both as I do is useful, if I could only have one I would have a smartgauge.

 

What battery monitoring/measuring equipment you have on your boats or easily available? I have a smartgauge, a Mastervolt Mastershunt and of course the ubiquitous UT203 clamp-meter. I'm lucky! So as I have said repeatedly I know how accurate the smartgauge is because I know the current battery capacity and I can watch the SoC of the mastershunt and the Smartgauge tracking down together. They are within a few % but of course the Mastershunt and Masterview Easy panels between them cost around £500 whereas the smartgauge is around £120

 

 

Anyway these arguments are pretty futile. You are talking from a position of not having lived with a smartgauge, and you have an irrational dislike of it. I on the other hand have 4 years experience with one, and the means to compare it with other ways of measuring SoC. I am never going to move to your point of view, and I very much doubt that any reason, logic or evidence will persuade you to change your position, so why are we bothering?

 

One final thought, I recall you refused to mention the name of a marina that you felt had given you poor service on the grounds that they might sue. On the other hand you are quite happy to repeatedly and irrationally slag off a bit of equipment that you are not familiar with, seemingly not worried that Merlin might come after to you. Why the difference in attitude?

Edited January 14, 2016 by nicknorman

[Graham.m]

 

One final thought, I recall you refused to mention the name of a marina that you felt had given you poor service on the grounds that they might sue.

 

 

I am sorry I have never said that

[nicknorman]

 

I am sorry I have never said that

Do you recall refusing to name the marina? Perhaps there was another reason? But if you don't recall it, I suppose I'll have to trawl through CWDF to prove the point, not sure I can be bothered.

 

Edit: I found it. Mis-remembered a bit, actually you were warning me about "dissing" a marina. You didn't mention the word "suing" but that was the implication:

 

http://www.canalworld.net/forums/index.php?showtopic=79846&p=1719497

Edited January 14, 2016 by nicknorman

[Paul C]

Given that now we have the possibility of a bunch of dodgy smartgauges which are miscalibrated out there, I can't see it as the "golden egg" of a simple device which involves connecting 2 wires and that's it. You'd need to at least satisfy yourself that its calibrated reasonably well. Comparison of the voltage it reports with a cheap DVM is a start, but......leads to the issue summarised as:

 

"Man with one watch knows time. Man with 2 watches never knows time".

 

Given that an amp-hour counter is about the same price, AND that it gives the advantage of a current flow, AND that the fact that it needs a bit more understanding of what's going on is countered by the user spending a little time learning/understanding about electricity, I'd still recommend this.

 

At the end of the day the smartgauge is a glorified voltmeter with an algorithm we're expected to trust that provides SoC, of which the details are closed-source.

[Graham.m]

Do you recall refusing to name the marina? Perhaps there was another reason? But if you don't recall it, I suppose I'll have to trawl through CWDF to prove the point, not sure I can be bothered.

 

Trawl away as I never said that

Given that now we have the possibility of a bunch of dodgy smartgauges which are miscalibrated out there, I can't see it as the "golden egg" of a simple device which involves connecting 2 wires and that's it. You'd need to at least satisfy yourself that its calibrated reasonably well. Comparison of the voltage it reports with a cheap DVM is a start, but......leads to the issue summarised as:

 

"Man with one watch knows time. Man with 2 watches never knows time".

 

Given that an amp-hour counter is about the same price, AND that it gives the advantage of a current flow, AND that the fact that it needs a bit more understanding of what's going on is countered by the user spending a little time learning/understanding about electricity, I'd still recommend this.

 

At the end of the day the smartgauge is a glorified voltmeter with an algorithm we're expected to trust that provides SoC, of which the details are closed-source.

 

I wish I had your ability with words nicely put and said in a few line what I tried to say in many

[nicknorman]

 

Trawl away as I never said that

 

I wish I had your ability with words nicely put and said in a few line what I tried to say in many

See my edit, but the point remains that you seemed to be concerned about a minor case of "dissing" a marina - but in fact you seemed to be concerned for me, rather than yourself. That seems inconsistent with your resolute attack on Merlin.

[nicknorman]

Given that now we have the possibility of a bunch of dodgy smartgauges which are miscalibrated out there, I can't see it as the "golden egg" of a simple device which involves connecting 2 wires and that's it. You'd need to at least satisfy yourself that its calibrated reasonably well. Comparison of the voltage it reports with a cheap DVM is a start, but......leads to the issue summarised as:

 

"Man with one watch knows time. Man with 2 watches never knows time".

 

Given that an amp-hour counter is about the same price, AND that it gives the advantage of a current flow, AND that the fact that it needs a bit more understanding of what's going on is countered by the user spending a little time learning/understanding about electricity, I'd still recommend this.

 

At the end of the day the smartgauge is a glorified voltmeter with an algorithm we're expected to trust that provides SoC, of which the details are closed-source.

Yea well the failure to calibrate the voltage properly is a bit of a blow for the cause! Tony contacted Gibbo who has given the production guys at Merlin a roasting, but that probably doesn't help a potentially faulty batch that is out there at distributors. Just for clarity the only calibration is the voltage, since that's all it measures. IF the voltage is correct (within 0.5%) then the SoC will be correct, there is nothing else to calibrate.

The smartgauge is a glorified voltmeter with an algorithm that we (that have them) trust because we see the evidence every day. Well those of us that have ones that are properly calibrated anyway!

 

I come back to my friends who phoned me up when the lights went dim whilst their AH-counting gauge still showed 80%. They are typical users, not much clue about electricity or batteries, they just like boating. If they had had a smartgauge instead it would have become apparent long before, that their batteries were dying.

 

If you are an expert, you don't need any gauges. You can get the SoC from hydrometer readings, rested voltage readings, and know when to stop charging based on an ammeter.

 

If you are a dummy, the Smartgauge is the best option. It tells you when to start charging and when to stop charging and when to replace the batteries. These are the only decisions you need to make, the rest is just floral.

 

An AH gauge gives some interesting information but I would question what decisions you make based on its readings? When to stop charging - yes, but an ammeter would have given you that. But not anything else. It only tells you when you should consider charging if your batteries are in as-new condition, and how many folk's batteries are like that?

You squirm at the Smartgauge's algorithm but as an engineer you will know what integration errors are. An AH gauge works out its SoC based on integration and as such the error accumulates with time and has no limit. Such gauges only become tenable because when you fully recharge they reset to 100%. If you don't fully recharge at each cycle, the SoC reading rapidly deviates from reality even if your batteries are in as-new condition due to the vaguaries of CEF etc

 

By contrast the SG doesn't use integration with its cumulative errors, in fact quite the reverse since the errors reduce with time as the system fine tunes its parameters for your particular installation.

 

Edited January 14, 2016 by nicknorman

[Graham.m]

Do you recall refusing to name the marina? Perhaps there was another reason? But if you don't recall it, I suppose I'll have to trawl through CWDF to prove the point, not sure I can be bothered.

 

Edit: I found it. Mis-remembered a bit, actually you were warning me about "dissing" a marina. You didn't mention the word "suing" but that was the implication:

 

http://www.canalworld.net/forums/index.php?showtopic=79846&p=1719497

 

I am sorry where was I warning you about "dissing" a marine. Think you have totally misread

[nicknorman]

 

I am sorry where was I warning you about "dissing" a marine. Think you have totally misread

"Now as they are one of the best boatyards on the canals with qualified staff, are you suggesting they do not know their job, may I suggest you think carefully as many people know where my boat goes for work."

 

What does that mean then?

 

Anyway, it's not really relevant to the topic. My point if you prefer is "aren't you a bit concerned that you could be libelling Merlin" Although I agree that in reality the worst that is likely to happen is that Dan gets hassle from them to remove it. IMO there is nothing wrong with dissing a product but you have to have evidence. Making the point that one or two have left the factory out of cal is fine because its true, the rest of it is just a product of your bias.

[Paul C]

Yea well the failure to calibrate the voltage properly is a bit of a blow for the cause! Tony contacted Gibbo who has given the production guys at Merlin a roasting, but that probably doesn't help a potentially faulty batch that is out there at distributors. Just for clarity the only calibration is the voltage, since that's all it measures. IF the voltage is correct (within 0.5%) then the SoC will be correct, there is nothing else to calibrate.

The smartgauge is a glorified voltmeter with an algorithm that we (that have them) trust because we see the evidence every day. Well those of us that have ones that are properly calibrated anyway!

 

I come back to my friends who phoned me up when the lights went dim whilst their AH-counting gauge still showed 80%. They are typical users, not much clue about electricity or batteries, they just like boating. If they had had a smartgauge instead it would have become apparent long before, that their batteries were dying.

 

If you are an expert, you don't need any gauges. You can get the SoC from hydrometer readings, rested voltage readings, and know when to stop charging based on an ammeter.

 

If you are a dummy, the Smartgauge is the best option. It tells you when to start charging and when to stop charging and when to replace the batteries. These are the only decisions you need to make, the rest is just floral.

 

An AH gauge gives some interesting information but I would question what decisions you make based on its readings? When to stop charging - yes, but an ammeter would have given you that. But not anything else. It only tells you when you should consider charging if your batteries are in as-new condition, and how many folk's batteries are like that?

You squirm at the Smartgauge's algorithm but as an engineer you will know what integration errors are. An AH gauge works out its SoC based on integration and as such the error accumulates with time and has no limit. Such gauges only become tenable because when you fully recharge they reset to 100%. If you don't fully recharge at each cycle, the SoC reading rapidly deviates from reality even if your batteries are in as-new condition due to the vaguaries of CEF etc

 

 

I'd prefer to educate the dummy (your word not mine) then they can decide where to spend their hard-earned on (they might choose Smartgauge). Once educated, the ability to measure current as well as voltage offers a useful cross-check on stuff.

[nicknorman]

 

I'd prefer to educate the dummy (your word not mine) then they can decide where to spend their hard-earned on (they might choose Smartgauge). Once educated, the ability to measure current as well as voltage offers a useful cross-check on stuff.

That's fine but you can lead a horse to water... and anyway why should you force people to know the nuts and bolts when they don't need to. Next you'll be telling us that we all need to go on a MySQL course!

[Paul C]

That's fine but you can lead a horse to water... and anyway why should you force people to know the nuts and bolts when they don't need to. Next you'll be telling us that we all need to go on a MySQL course!

 

How does "prefer to educate" get interpreted as "force"?

 

Also, I'm not sure they don't need to know. They might not want to know. Its their choice, their loss if they don't understand what's going on. The internet is here, the information is in the public domain etc.

[Graham.m]

See my edit, but the point remains that you seemed to be concerned about a minor case of "dissing" a marina - but in fact you seemed to be concerned for me, rather than yourself. That seems inconsistent with your resolute attack on Merlin.

 

I think my previous post deal with yours

 

This all started with me trying to find some solid information about the gauge. You and you cohorts indicated that it was perfect and when I asked for solid information from the manufacturer I was told it is better than 1% but no link to a solid manufacturer spec. Now after weeks of arguing a spec finally appears, Interesting that Merlin could not be bothered to send it to me when I emailed them,

 

You seem to be playing this as if there has only been 1 gauge out of spec, that does not appear to be the case from information I have read and and been told there are a few out there, how many who knows. I If I had not gone up, I do wonder what you would be telling Tommy today when he said the batteries are not lasting and the gauge just keep falling.

 

I do wonder if the you have an interest in the gauge.

Edited January 14, 2016 by Graham.m

[WotEver]

Tony contacted Gibbo who has given the production guys at Merlin a roasting, but that probably doesn't help a potentially faulty batch that is out there at distributors.

 

I am hopeful that I may have more on this in due course.

 

The smartgauge is a glorified voltmeter with an algorithm that we (that have them) trust because we see the evidence every day.

 

This is the point that I keep trying to make. Graham writes post after post dissing the SmartGauge, denying that it has published specs and stating that it cannot work. Meanwhile dozens (hundreds?) of SmartGauge users on here read what he's posting and think "what IS he going on about?"

[Loafer]

 

I think my previous post deal with yours

 

This all started with me trying to find some solid information about the gauge. You and you cohorts indicated that it was perfect and when I asked for solid information from the manufacturer I was told it is better than 1% but no link to a solid manufacturer spec. Now after weeks of arguing a spec finally appears, Interesting that Merlin could not be bothered to send it to me when I emailed them,

 

You seem to be playing this as if there has only been 1 gauge out of spec, that does not appear to be the case from information I have read and and been told there are a few out there, how many who knows. I If I had not gone up, I do wonder what you would be telling Tommy today when he said the batteries are not lasting and the gauge just keep falling.

 

I do wonder if the you have an interest in the gauge.

 

By then, they WOULD have been lasting, because he had begun to charge them properly in accordance with 'advice on this forum', and have since then improved massively, with or without any gauge indication. It would have been obvious to anyone, following a few question-and answer posts to Tommy, what to tell him.

[nicknorman]

I think my previous post deal with yours

 

This all started with me trying to find some solid information about the gauge. You and you cohorts indicated that it was perfect and when I asked for solid information from the manufacturer I was told it is better than 1% but no link to a solid manufacturer spec. Now after weeks of arguing a spec finally appears, Interesting that Merlin could not be bothered to send it to me when I emailed them,

 

You seem to be playing this as if there has only been 1 gauge out of spec, that does not appear to be the case from information I have read and and been told there are a few out there, how many who knows. I If I had not gone up, I do wonder what you would be telling Tommy today when he said the batteries are not lasting and the gauge just keep falling.

 

I do wonder if the you have an interest in the gauge.

Yes I think there are a few marginally out of spec, but only one that we know of that is way out. Don't get me wrong, I'm not trying to gloss over this problem but if you get one that is properly calibrated (which is pretty easy to check) it is very good at what it does, and it seems a shame to lose the usefulness of an otherwise great product for this one problem, I was going to say minor problem but of course it is not really a minor problem, but it is one that is easily detected and rectified.

 

Anyway, you now have your solid information about the claimed accuracy, figures which are corroborated by the many of us that have the gauge.

 

Yes we are all glad that you took the trouble to go and see Tommy. We had been suggesting that he get a hydrometer and / or Clampmeter for some time but he hadn't done so by the time you visited. Thus we had only the information provided to go on, from a bit of equipment that turned out to be faulty.

 

All that is very unfortunate but does not detract from the fact that a properly calibrated gauge is a very good device.

 

Yes I do have an interest in the gauge, but only because I consider it to be the best device for most "non-expert" people, whereas AH-counting gauges apcan be very misleading. I can assure you that if I had some sort of financial interest in it I would make sure it didn't leave the factory mis-calibrated!

[Graham.m]

I am hopeful that I may have more on this in due course.

 

 

This is the point that I keep trying to make. Graham writes post after post dissing the SmartGauge, denying that it has published specs and stating that it cannot work. Meanwhile dozens (hundreds?) of SmartGauge users on here read what he's posting and think "what IS he going on about?"

 

Simple questions

Why weeks ago when asked could you not produce that manufacturer's spec ?

Why was I told that it was 1% accurate when I knew it could not be, I am suspicious at 5%?

Why was there an attempt to deny that it could be a gauge problem subsequent to my visit to Tommy?

 

Basically what I am going on about is that this is not a golden egg and has what I see as problems. I think this has been hyped up on this forum to a level where anyone disagrees is a bug that must be squashed

[nicknorman]

How does "prefer to educate" get interpreted as "force"?

 

Also, I'm not sure they don't need to know. They might not want to know. Its their choice, their loss if they don't understand what's going on. The internet is here, the information is in the public domain etc.

Maybe you went to a different school from me! Anyway the point is that I am like you, I want to know all these things and find it very odd that there are all these people out there who can't tell an amp from a volt, let alone an amp from an amphour. But they are blissful in their ignorance and are probably riveted by things we would find dull and pointless. C'est la vie. Trouble is they are in the majority!

 

For these people, the Smartgauge is ideal.

 

And just to mention it is people like you and Graham who don't see the point of the Smartgauge - ie people who don't have one. People who do have one don't come on here clamouring that it's rubbish. Doesn't that tell you something?

[WotEver]

 

Simple questions

Why weeks ago when asked could you not produce that manufacturer's spec ?

Why was I told that it was 1% accurate when I knew it could not be

1. I gave you at least three links to specs of and independent reviews of SmartGauge many weeks ago. You chose to ignore them all saying "they're not on Merlin's site". So what? They were the exact same specs as Merlin have.

 

2. It is better than 1% accurate. It's accurate to within 0.05V (on a properly calibrated unit). That's about 0.4%.

 

Tony

[nicknorman]

Simple questions

Why weeks ago when asked could you not produce that manufacturer's spec ?

Why was I told that it was 1% accurate when I knew it could not be, I am suspicious at 5%?

Why was there an attempt to deny that it could be a gauge problem subsequent to my visit to Tommy?

 

Basically what I am going on about is that this is not a golden egg and has what I see as problems. I think this has been hyped up on this forum to a level where anyone disagrees is a bug that must be squashed

So it's my fault that you couldn't be bothered to type "Merlin Smartgauge specifications" into Google? You were the one who wanted to find it, I already knew from experience that it was accurate enough for the job. And don't forget you implied that your favourite BMV did publish accuracy figures when in fact they don't and can't. Which is a complete reversal of the facts.

 

I'm not sure who said it was 1% accurate, not me. I think I said it was accurate to within a few % for SoC, which you can take to be 2 or 3. Of course that isn't the max possible error, just the typical error I've observed in 4 years of use.

 

For tommy's problem we had one bit of kit to go on. It might have been a DVM, in fact it was a Smartgauge. Yes it mislead us but no more than if it had been a faulty DVM or any other bit of faulty kit. When trying to diagnose by remote control and with limited information, mistakes arise.

 

Regarding your penultimate sentence it is not a golden egg but it does its job very well although a few examples have a problem with calibration. What other problems does it have IYO? It is not a question of bug-squashing because you disagree, it is a question of refuting your claims when they are baseless.

Edited January 14, 2016 by nicknorman

[Graham.m]

 

By then, they WOULD have been lasting, because he had begun to charge them properly in accordance with 'advice on this forum', and have since then improved massively, with or without any gauge indication. It would have been obvious to anyone, following a few question-and answer posts to Tommy, what to tell him.

 

His batteries were at were over 90% when I arrived yet the gauge showed 73% after charging the previous day to a lower tail current.

I really do not understand why it had not been picked up sooner, I was aware there was something wrong and knew it was not a stray drain and did not believe it was the batteries, which is why I offered to go up.

 

No I am sorry I seem to remember it was being suggested that it was the batteries. There is too much reliance put in the gauge

[WotEver]

The official word from the Head of Engineering at Merlin in response to "What's going on?":

I have not received the first one (or indeed any) back so I can't really comment. I will let you know what I find if and when I receive a faulty one

And yes Graham, I have his permission to post that.

 

Tony

[nicknorman]

There is too much reliance put in the gauge

There was in that specific case, but then there wasn't anything else to go on. Over the years there have been loads and loads of threads with people complaining that their Smartgauge is not reading what they think it should. In every case it has eventually transpired that the gauge was correct and there was something wrong with the the batteries, the charging, the load or whatever. This is why we were inclined to believe the gauge, but in this one case it transpired that it was wrong.