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My third SmartGauge...


MtB

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On 18/06/2018 at 23:44, Mike the Boilerman said:

Ok I've connected up the new one and it is reading about 0.05v high. Close enough to be useful straight from the box.

 

WAY better than my other two which are 0.4V high and 0.3V low.

 

Well done Merlin!!!!

I've enjoyed following this thread, such fun.

But I'm a simple soul who knows nowt about electrikery so tell me what the problem really is.

If you know a gauge is reading 0.4V high then why not take 0.4V off the reading each time you view it?  Provided the error is consistent does it really matter?

I had a clock that gained 10 mins each day but was never late for an appointment.

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1 minute ago, Bro said:

I've enjoyed following this thread, such fun.

But I'm a simple soul who knows nowt about electrikery so tell me what the problem really is.

If you know a gauge is reading 0.4V high then why not take 0.4V off the reading each time you view it?  Provided the error is consistent does it really matter?

I had a clock that gained 10 mins each day but was never late for an appointment.

Cos it effects the % readout on the smartgauge by a big margin. The % figure being its main benefit 

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5 minutes ago, Bro said:

I've enjoyed following this thread, such fun.

But I'm a simple soul who knows nowt about electrikery so tell me what the problem really is.

If you know a gauge is reading 0.4V high then why not take 0.4V off the reading each time you view it?  Provided the error is consistent does it really matter?

I had a clock that gained 10 mins each day but was never late for an appointment.

The whole point of a SmartGauge is it tries to use various clever algorithms to convert an exact voltage at the battery bank into the state of charge thereof.

 

If wrongly calibrated for volts, the state of charge reading cannot be relied upon, and the device is not doing "what it says on the tin".

You can buy things that give the wrong answer for far less than £120!

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2 minutes ago, rusty69 said:

Cos it effects the % readout on the smartgauge by a big margin. The % figure being its main benefit 

Thanks Rusty for putting me straight.  Clearly there is more to this than a gauge that is misreading.  I really ought not take part in conversations about matters I don't understand.

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2 minutes ago, Bro said:

Thanks Rusty for putting me straight.  Clearly there is more to this than a gauge that is misreading.  I really ought not take part in conversations about matters I don't understand.

Course you should. I do it all the time:)

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4 minutes ago, alan_fincher said:

The whole point of a SmartGauge is it tries to use various clever algorithms to convert an exact voltage at the battery bank into the state of charge thereof.

 

If wrongly calibrated for volts, the state of charge reading cannot be relied upon, and the device is not doing "what it says on the tin".

You can buy things that give the wrong answer for far less than £120!

I am now a little wiser.  technical isn't it.

So tell me, how do I know if my Smartgauge is reading correctly?  Bearing in mind I can just about read a voltmeter, what checks can I run?

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9 minutes ago, Bro said:

I am now a little wiser.  technical isn't it.

So tell me, how do I know if my Smartgauge is reading correctly?  Bearing in mind I can just about read a voltmeter, what checks can I run?

Now you're asking the right questions. 

 

You need a calibrated  voltmeter of the correct accuracy. +/- 0.3% or better iirc

Edited by rusty69
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Just now, Bro said:

I am now a little wiser.  technical isn't it.

So tell me, how do I know if my Smartgauge is reading correctly?  Bearing in mind I can just about read a voltmeter, what checks can I run?

The only way I am aware of is to beg steal or borrow a voltmeter that is known to be calibrtaed to a high degree of accuracy, and to measure the voltage at yout battery bank, connecting directly to it, (as the SmartGauge should be).  If volts on Smartgauge equals volts on known "highly accurate voltmeter", then its fine, if they don't then don't trust smartgauge.

You can do the same check with a cheapy multi-meter from a DIY store but when they disagree, you will not now which is wrong. (or if they do agree, whether both are correct, or both are wrong).

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2 minutes ago, Bro said:

I am now a little wiser.  technical isn't it.

So tell me, how do I know if my Smartgauge is reading correctly?  Bearing in mind I can just about read a voltmeter, what checks can I run?

A big advantage of the Smartgage is that it just works, the only setting up is telling it the battery type. Other instruments require all sorts of settings and periodic resets, plus a need to know how the battery capacity is falling with age.

 

The only snag is that a few smartgages have left the factory with an incorrect internal calibration. You can check this using a reasonable quality voltmeter, if the voltage reads correctly then the Smartgage state of charge will be correct.

 

...........Dave

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Gentlemen, I thank you.

I will indeed try to find a super dooper voltmeter and do as you say.  'Twill be interesting to see the result.

Silly me, I've been using Smart gauge for say 5 years and simply assumed it was telling the truth (though, to be fair,  haven't had any battery problems).

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2 minutes ago, Bro said:

Gentlemen, I thank you.

I will indeed try to find a super dooper voltmeter and do as you say.  'Twill be interesting to see the result.

Silly me, I've been using Smart gauge for say 5 years and simply assumed it was telling the truth (though, to be fair,  haven't had any battery problems).

The fun begins when they don't match:)

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55 minutes ago, Bro said:

Gentlemen, I thank you.

I will indeed try to find a super dooper voltmeter and do as you say.  'Twill be interesting to see the result.

Silly me, I've been using Smart gauge for say 5 years and simply assumed it was telling the truth (though, to be fair,  haven't had any battery problems).

In that case, be happy. Whatever you are doing, it's working, so chill (if you can find some shade :giggles:).

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2 hours ago, Bro said:

Gentlemen, I thank you.

I will indeed try to find a super dooper voltmeter and do as you say.  'Twill be interesting to see the result.

Silly me, I've been using Smart gauge for say 5 years and simply assumed it was telling the truth (though, to be fair,  haven't had any battery problems).

Then I would assume that it belongs to the 99.999% of them that just ‘work’. 

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26 minutes ago, WotEver said:

Then I would assume that it belongs to the 99.999% of them that just ‘work’. 

 

As I purchased two six months apart and both turned out to be WAY out of calibration, it is reasonable to surmise Merlin were churning out faulty gauges for six months. Probably a good deal more.

 

All fixed now. Instead, the new ones are bar stewards to factory reset :banghead:

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On 01/07/2018 at 18:39, alan_fincher said:

The whole point of a SmartGauge is it tries to use various clever algorithms to convert an exact voltage at the battery bank into the state of charge thereof.

 

If wrongly calibrated for volts, the state of charge reading cannot be relied upon, and the device is not doing "what it says on the tin".

You can buy things that give the wrong answer for far less than £120!

I wonder if what you say is really representative of how a SmartGauge works. These units do not measure anything but the battery voltage. They they cannot infer SoC from just the voltage at a point in time as you would also need to measure the battery temperature. The algorithm must therefore calculate SoC from the changes in voltage over time. Consequently,a fixed error will not matter, its much the same as operating the battery at a different temperature.

 

Now if the error is varying over time than that would indeed make a difference.

 

Perhaps one day the algorithm will be published and then we will know how it works?

 

 

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18 minutes ago, jonesthenuke said:

I wonder if what you say is really representative of how a SmartGauge works. These units do not measure anything but the battery voltage. They they cannot infer SoC from just the voltage at a point in time as you would also need to measure the battery temperature. The algorithm must therefore calculate SoC from the changes in voltage over time. Consequently,a fixed error will not matter, its much the same as operating the battery at a different temperature.

 

Now if the error is varying over time than that would indeed make a difference.

 

Perhaps one day the algorithm will be published and then we will know how it works?

 

 

Voltage change compared to change in various charging algorithms, initially it chooses the nearest match and as time passes and the voltage change more closely follows another algorithm it opts for that one and so on and so on. Of course there's other stuff going on, lots of info can be gleaned from voltage other than just the level. 

 

In other words it makes a series of educated guesses, each guess getting more accurate. It's never 100% accurate but nearer than any other gadget, that was my description years ago and Gibbo said that was the best he'd heard. 

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35 minutes ago, jonesthenuke said:

The algorithm must therefore calculate SoC from the changes in voltage over time. Consequently,a fixed error will not matter,

 

Well that's wrong I'm afraid. If a fixed error (as two of my smartgauges have) will not matter as you say, they would they both read the same SoC when connected to the same battery.

 

My two differed by about 20% until I properly calibrated one.  Now one is correct and the other under-reads by about 10%.

Edited by Mike the Boilerman
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47 minutes ago, jonesthenuke said:

a fixed error will not matter...

Unfortunately, as Mike quite correctly observes, a fixed error of more than about 0.05V will indeed matter. 

 

I’ll lay good money on the assertion that the algorithms will never be published. 

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7 minutes ago, WotEver said:

I’ll lay good money on the assertion that the algorithms will never be published. 

I made the mistake of publishing the DumbGauge algorithm (display a random number and put A/Hr at the end) and sales collapsed. ?

 

Jen

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15 minutes ago, Jen-in-Wellies said:

I made the mistake of publishing the DumbGauge algorithm (display a random number and put A/Hr at the end) and sales collapsed. ?

 

Jen

Gibbo got a SmartGauge returned once - totally non-functional. Someone had tried to extract the contents of the PROM and killed it by doing so. This was years ago, well before he sold it to Merlin.  

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On 01/07/2018 at 18:56, dmr said:

A big advantage of the Smartgage is that it just works, the only setting up is telling it the battery type. Other instruments require all sorts of settings and periodic resets, plus a need to know how the battery capacity is falling with age.

 

The only snag is that a few smartgages have left the factory with an incorrect internal calibration. You can check this using a reasonable quality voltmeter, if the voltage reads correctly then the Smartgage state of charge will be correct.

 

...........Dave

Unless you have solar or charging.  So not really a good solution this day n age.

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6 minutes ago, Robbo said:

Unless you have solar or charging.  So not really a good solution this day n age.

Its always been said, by the anti Smartgage faction, that they don't work with solar, but I thought somebody did some tests in real life scenarios and concluded that it was adequate??? Smartgage is an instrument for monitoring battery state during discharge so its not really fair to criticise its inaccuracy during charge.

Smartgage is not particularly good at telling when the batteries are fully charged, its purpose is to tell when they are part discharged or very discharged and I suggest it will do this even if solar is fitted.

Ive only got a little bit of solar by modern standards but my Smartgage gives sensible results.

 

Has your Smartgage given poor results with your solar installation?

 

..............Dave

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Trouble is people with solar need to get up very early at this time of year to read the Smartguage before it gets light - they don't want to. Perhaps they should fit a switch in the panel to controller line so they don't have to but then they sacrifice some solar while they wait for the Smartgage to sort itself out.

Edited by Tony Brooks
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