Do you have a SmartGauge?

[rusty69]

Just now, tomsk said:

I understand this.

I do not understand his reticence in contacting the supplier for resolution though, at all.

Dunno, maybe out of warranty or he can't be arsed. 

[MtB]

On 10/04/2017 at 13:01, tomsk said:

I have had a look and am now fairly convinced that Mike is either managing a concerted kamikaze campaign against the SG, railing at its uselessness at what it claims to be its USP (a spectacular volte-face if so), or he has indeed gone potty.

Either way I still feel sending them back for full refund/calibration or chucking them in the cut and getting on with life would be a better use of his time.

 

1) I want to understand in close detail what is going on with my batteries. This is why I persist. As a non-technician I wouldn't expect you to understand my inquisitive nature as a technician.

2) I don't need to send them back for re-calibration, I can do it myself.

3) I think visitors to CWF need to know the weaknesses of a Smartgauge as well as its strengths. I would feel lost without mine so I'm not sending it back. If Merlin turn out to be that bothered enough about it I'm sure they can drive down to Devizes to me. I don't see why the customer should be doing all the legwork.

[WotEver]

6 minutes ago, Mike the Boilerman said:

If Merlin turn out to be that bothered enough about it I'm sure they can drive down to Devizes to me.

Do they know you? Have you contacted them about it?

[mark99]

Got a Victron BMV 501 and that gives me a lot of info. Whether good or not don't know but last battery bank lasted 8 years.

[rusty69]

I've just checked mine. It appears to read 0.1 Volt higher than my xantrex and dvm. 

Still, it's not a fancy voltmeter but a state of charge meter. 

Edited April 10, 2017 by rusty69

[tomsk]

6 minutes ago, Mike the Boilerman said:

 

1) I want to understand in close detail what is going on with my batteries. This is why I persist. As a non-technician I wouldn't expect you to understand my inquisitive nature as a technician.

2) I don't need to send them back for re-calibration, I can do it myself.

3) I think visitors to CWF need to know the weaknesses of a Smartgauge as well as its strengths. I would feel lost without mine so I'm not sending it back. If Merlin turn out to be that bothered enough about it I'm sure they can drive down to Devizes to me. I don't see why the customer should be doing all the legwork.

1) You seem to be making sweeping generalisations and chasing moonbeams in one fell swoop Mike.

2) If SG's are leaving the workshop poorly calibrated then the manufacturer needs to be informed to implement corrective action, anyone seriously concerned regarding 'visitors need to know' would contact the supplier demanding meaningful resolution, perhaps posting here advising any progress made and manufacturer co-operation.

3) Have you contacted Merlin? Do you really expect Merlin to travel down to you on a whim? What legwork?

This is getting beyond weird.

 

 

 

[rusty69]

1 hour ago, Mike the Boilerman said:

2) I don't need to send them back for re-calibration, I can do it myself.

As the Smartgauge clearly doesn't just measure voltage, what is involved in recalibration? 

[nicknorman]

1 hour ago, rusty69 said:

I've just checked mine. It appears to read 0.1 Volt higher than my xantrex and dvm. 

Still, it's not a fancy voltmeter but a state of charge meter. 

However, if the voltage reading is out, the SoC indication will be out too.

And yes it does just measure voltage. It is what it does with that voltage reading that is the "smart" bit.

[rusty69]

7 minutes ago, nicknorman said:

However, if the voltage reading is out, the SoC indication will be out too.

And yes it does just measure voltage. It is what it does with that voltage reading that is the "smart" bit.

Agreed. 

Are you sure. Mr Gibson implies a lot more than voltage can be measured with two wires. 

[WotEver]

27 minutes ago, rusty69 said:

Agreed. 

Are you sure. Mr Gibson implies a lot more than voltage can be measured with two wires. 

Nobody 'knows' but we're all pretty sure. 

[nicknorman]

37 minutes ago, rusty69 said:

Agreed. 

Are you sure. Mr Gibson implies a lot more than voltage can be measured with two wires. 

He did and he is right, but he was also careful not to say that the SG necessarily did. Have a look at the circuitry. I have.

[cuthound]

4 hours ago, Mike the Boilerman said:

The trouble with a voltmeter is the reading is meaningless unless the battery is rested for an hour or two before taking the reading. 

You can either wait an hour or two for the surface charge to disperse naturally, or you can force it to disperse by putting the tunnel light for 10 minutes and then taking a voltage reading.

[IanD]

From what's been disclosed about SmartGauge it's clear that all it measures is battery terminal voltage, everything then depends on clever processing of the readings together with knowledge about how different batteries behave during charge and discharge.

Yes in theory you *could* measure other things like battery impedance by sourcing/sinking current, but to do this you'd need thick low-resistance connections which SmartGauge doesn't require, so it can't be doing this.

What I don't understand is why any units are supplied with such big voltage calibration errors, even using standard components and low-cost test equipment it's easy to set a voltage reading to 0.1% accuracy or better and maintain this over time -- assuming it's properly designed for stability in the first place (e.g. using stable digital voltage dividers instead of mechanical variable resistors). An error of hundreds of millivolts in 12V is inexcusable...

Edited April 10, 2017 by IanD

[nicknorman]

9 minutes ago, IanD said:

What I don't understand is why any units are supplied with such big voltage calibration errors, even using standard components and low-cost test equipment it's easy to set a voltage reading to 0.1% accuracy or better and maintain this over time -- assuming it's properly designed for stability in the first place (e.g. using stable digital voltage dividers instead of mechanical variable resistors). An error of hundreds of millivolts in 12V is inexcusable...

The SG's circuitry is pretty stable over time and has virtually zero temperature co-efficient. However it needs to be set up correctly in the first place (by means of storing values in the microprocessor's memory, rather than twiddling trimpots) and for some inexplicable reason, this currently seems beyond the wit of the manufacturers.

[WotEver]

13 minutes ago, IanD said:

... assuming it's properly designed for stability in the first place...

Nick recently commented that after he tweaked his (a couple of years ago?) it has remained rock solid stable. 

Its simply a (lack of) calibration at the factory. 

Cross-posted. 

[rusty69]

So,for those of us who are not in a position to return the Smartgauge for calibration, is there an option or are we stuck with it? 

[MtB]

On 10/04/2017 at 18:00, rusty69 said:

So,for those of us who are not in a position to return the Smartgauge for calibration, is there an option or are we stuck with it? 

 

Ah so you have one out of calibration too eh?

[alan_fincher]

How can you recalibrate one yourself?

I have just bought my first one, and it neither looked like it could/should be opened, nor was there anywhere I noticed that looked like it would allow a potentiometer to be "twiddled".

I'm, not sure I have an accurate enough voltmeter on board to compare to, but you have prompted me to try what I do have access to here on the boat.

[rusty69]

22 minutes ago, Mike the Boilerman said:

 

Ah so you have one out of calibration too eh?

I'm not sure as yet. 

[WotEver]

16 minutes ago, alan_fincher said:

... nor was there anywhere I noticed that looked like it would allow a potentiometer to be "twiddled".

Nor is that how it's done

[blackrose]

9 hours ago, WotEver said:

If you do, and if it's a recent purchase, have you ever checked its voltage accuracy?

it appears from anecdotal reports that since Merlin took over production the calibration of some (many? all?) units leaves something to be desired. They should display the battery voltage with an accuracy of 0.05V. We've seen reports here of 0.3V high, 0.3V low, and recently 0.5V high. Tommy Leyland had one which was nearly 1V out and caused him many problems. 

What were these SGs checked against?

I've checked mine against a calibrated Fluke multimeter and it's spot on. Also matches my BEP DC battery monitor, although the latter only goes to 1 decimal place.

Edited April 10, 2017 by blackrose

[WotEver]

Just now, blackrose said:

What were these SGs being calibrated against?

I've checked mine against a calibrated Fluke multimeter and it's spot on. Also matches my BEP DC battery monitor, although the latter only goes to 1 decimal place.

Great that yours is spot on. I've not tested any myself (other than the one I possess which is pretty old and currently unused) so I have no personal experience of any being out of spec. Hence my post said 'check it if you can' and 'if it's out of spec...'. 

I'm truly pleased to see you state that yours is spot on - that's as it should be.

[alan_fincher]

Quick check on my newly purchased one.....

Smartguage 12.55V

Multimeter 12.57, but latter only quoted as +/- .8% + 1 digit.

[nicknorman]

21 minutes ago, alan_fincher said:

Quick check on my newly purchased one.....

Smartguage 12.55V

Multimeter 12.57, but latter only quoted as +/- .8% + 1 digit.

That is fine then, well within spec ASSUMING your multimeter is correct!

[nicknorman]

2 hours ago, rusty69 said:

So,for those of us who are not in a position to return the Smartgauge for calibration, is there an option or are we stuck with it? 

Yes there is. I would say that the best option is to return the SG to the supplier for a replacement that is within spec. The user calibration function has a couple of problems, one is that the user cal is lost after a factory reset. Although it can always be done again I suppose. More importantly, what are you going to calibrate it against? Cheap multimeters look accurate because they have lots of decimal places, but in reality often aren't. And multimeters whose batteries are close to expiring can be ludicrously inaccurate.