SmartGuage

[blackrose]

Has anyone actually bought one of these things and would you recommend it?

 

http://www.smartgauge.co.uk/selector.html

 

(I'm just thinking about the smartguage, not the smartbank)

Edited September 23, 2006 by blackrose

[GUMPY]

Has anyone actually bought one of these things and would you recommend it?

 

http://www.smartgauge.co.uk/selector.html

 

(I'm just thinking about the smartguage, not the smartbank)

 

Strangely enough I have one

It makes battery monitoring real simple you dont need to know the size of the bank and subtract what you have used just look and so long as its above 50% you are OK.

Hasnt really changed how I run my system but I worry less as I can see its still above 50%.

I tried to confuse it by running the tumble dryer off the inverter whilst boating which gives me a net loss from the batteries of 50Ah ( TD draws 100A alternator is 50A) it came up with the correct answer, after a couple of hours boating and drying my 400Ah battery bank had dropped from 75-50%.

It doesnt always get to 100% it levels off at 94%charged however that could be my charging system

Its a small unit 90x60x25mm the only downside is that as mine is an early one it has no mounting brackets so its fixed to the wall with DS tape.

Other than that it does what it says.

What it will do is control external relays according to voltage so if you havent got a system linking your alternators to charge the domestic bank at a higher rate it should be possible to do this (ask Chris at SG).

 

 

Would I buy another one?

I am about to for the 12v system (first one is on the 24v system)

 

Hope this helps

 

 

J

Edited September 23, 2006 by idleness

[blackrose]

Thanks, was it easy to fit?

[NB Willawaw]

The smartguage is easier to fit than a AH counter - it just needs two wires directly from the batt terminals on a single bank. Its a kind of smart voltmeter that calculates remaining battery energy in percent terms.

Good for letting you know when your batteries are getting low.

 

P.S If you want to measure two banks, just make sure they have the same common earth point.

Edited September 23, 2006 by NB Willawaw

[blackrose]

Thanks

[stuart]

I've got one 2. Works okay and is nice and simple to fit. Tells you all you really need to know on a day-to-day basis. ie. how much power is left in batteries!

[GUMPY]

The smartguage is easier to fit than a AH counter - it just needs two wires directly from the batt terminals on a single bank. Its a kind of smart voltmeter that calculates remaining battery energy in percent terms.

Good for letting you know when your batteries are getting low.

 

P.S If you want to measure two banks, just make sure they have the same common earth point.

 

Indeed its very easy just make sure you put a fuse at the battery end on bothe live feeds

The battery banks should have a common neutral as they should be bonded to the hull along with the AC earth.

 

J

[David Schweizer]

Is it me, or am I missing something? this Smartgauge sounds as if it is just a Voltmeter with percentage calibrations instead of the conventuional Volts Calibrations. A bit like those stupid charge meters that were popular in the 1960's, which just told you whether you were charging or discharging your batteries, by means of red and green calibrations, They were just Ammeters with a different calibration.

 

A conventional Votmeter will do exactly the same and tell you whether the batteries need re-charging just as easily. Furthermore it will will probably cost far less.

[Guest]

Is it me, or am I missing something? this Smartgauge sounds as if it is just a Voltmeter with percentage calibrations instead of the conventuional Volts Calibrations. A bit like those stupid charge meters that were popular in the 1960's, which just told you whether you were charging or discharging your batteries, by means of red and green calibrations, They were just Ammeters with a different calibration.

 

A conventional Votmeter will do exactly the same and tell you whether the batteries need re-charging just as easily. Furthermore it will will probably cost far less.

Must admit I use a simple lab. type voltmeter. It cost me a pint and has served me well. Not sure about the Smartgauge 'cause I have never had one. Time will tell.

[GUMPY]

Is it me, or am I missing something? this Smartgauge sounds as if it is just a Voltmeter with percentage calibrations instead of the conventuional Volts Calibrations. A bit like those stupid charge meters that were popular in the 1960's, which just told you whether you were charging or discharging your batteries, by means of red and green calibrations, They were just Ammeters with a different calibration.

 

A conventional Votmeter will do exactly the same and tell you whether the batteries need re-charging just as easily. Furthermore it will will probably cost far less.

 

A brief synopsis is as follows:

As I understand it how it works is this.

It samples the battery voltage 8 times a second and compares that to "maps" of battery types stored in its memory. These maps are adaptable so it "learns" the characteristics of your setup.

Chris did go into more detail but I can’t find the email that it was in.

It is certainly more accurate than a voltmeter as you dont have to let the system "rest" before taking a reading.

 

J

[John Orentas]

I haven't read the full Smartgauge write up but if it is similar to the one I looked at some time ago it works by calculation rather than measurement.

 

It simply does the sums comparing input to output. Why else when you first commission the unit are you asked to enter the existing state of the batteries. If it was as good as it claims to be it would not need to be told.

 

But having said that it is not without value though personally I would prefer an ammeter and a voltmeter.

[Guest]

A brief synopsis is as follows:

As I understand it how it works is this.

It samples the battery voltage 8 times a second and compares that to "maps" of battery types stored in its memory. These maps are adaptable so it "learns" the characteristics of your setup.

Chris did go into more detail but I can’t find the email that it was in.

It is certainly more accurate than a voltmeter as you dont have to let the system "rest" before taking a reading.

 

J

I think Chris posted about this once? I can't find it. Certainly a voltmeter can show a healthy voltage, and then after a few minutes off charge, an unhealthy one. I think it is referred to as a surface voltage. Not so bad once you know but can be misleading.

 

Found the explanation:

 

Ok. As requested I'm here :-)

 

What specific questions do people have?

 

I'd like to make a few statements firstly though.

 

Obviously I'm not about to disclose how SmartGauge works. Anyone who asks me to is being rather unreasonable. 3 years research and a huge amount of money went into the design. I'm not about to give that away.

 

To state that 2 wires can only measure voltage is completely incorrect. To the layman voltage possibly is the only measurment that can be made. To an engineer there are a whole host of other measurements to be got down 2 wires.

 

SmartGauge does not measure battery current. Whilst battery current (in and out) can be an extremely useful piece of information it does not show the state of charge of the batteries. Attempts to calculate the state of charge of the batteries by integrating battery current over time have been made. This is what amp hours counters do. For most people amp hours counters do not work. This isn't speculation. It is a fact.

 

Some people can use amp hours counters very successfully. SmartGauge isn't aimed at those people. It is aimed at people who either cannot use one or cannot be bothered using one. The fact is that amp hours counters can and do run out of synchronisation with the batteries. Once this has happened, they are effectively useless.

 

SmartGauge *does* utilise Peukert's Law. It is a rather large part of the algorithm. But it calculates the required parameters itself. This allows the figures to be automatically adjusted as the batteries age. This does not happen with amp hours counters.

 

SmartGauge incorporates a voltmeter. But it is not *just* a voltmeter. It is far more.

 

I will be more than happy to answer any questions. Except "how does it work" !

 

Gibbo

 

PS Just to be pedantic...... In actual fact *most* electrical gauges actually measure current!

PPS The name is Gibson :-)

[GUMPY]

I haven't read the full Smartgauge write up but if it is similar to the one I looked at some time ago it works by calculation rather than measurement.

 

It simply does the sums comparing input to output. Why else when you first commission the unit are you asked to enter the existing state of the batteries. If it was as good as it claims to be it would not need to be told.

 

It doesn't need to be told, in fact the instructions say connect it and caarry on your charging discharging as normal. After a few charge/discharge cycles it will have "calibrated" itself.

 

J

[anhar]

Hi John

 

I've looked into the SmartGauge. Idleness is correct, it doesn't need to be told the initial charge state of the batteries. The only thing it needs to be told upon installation is the battery type, selecting from a choice of six such as lead wet cell, gell, AGM etc.

 

According to the instructions, the initial set up assumes a default charge level of 75%. You can then set the level manually if you know it, though most people won't I assume. Otherwise, the device then works out the charge level itself after two or three discharge/charge cycles. Note that it can monitor two separate battery banks which is the typical set up on most narrowboats.

 

Thus it is far more than just a voltmeter. It does show voltage but the primary additional feature is the percentage charge state of two battery banks and other points such as low charge warning etc. Additionally it can be used to control their SmartBank split charging device which they claim is far superior to other split charge control systems. But that is an add-on, not compulsory.

 

At £150 it is not cheap but my feeling is that it is quite useful for people who want to know and enjoy finding out what is happening to their batteries. Not an essential piece of kit but interesting to have, and delivering more information than a voltmeter or a voltmeter plus an ammeter, the critical difference being the percentage charge indicator for each of the two banks.

 

regards

Steve

Edited September 25, 2006 by anhar

[blackrose]

A conventional Votmeter will do exactly the same and tell you whether the batteries need re-charging just as easily. Furthermore it will will probably cost far less.

 

Yes, but a voltmeter will only give you an accurate reading if there has been no charging or discharging of the batteries for 24 hours.

Edited September 25, 2006 by blackrose

[Noah]

I’ve always been happy with voltmeter/ammeter to give me a good indication of state-of-charge. Just a few seconds of mental arithmetic and I know how many Amp hours I’ve got left before I need to run the engine again. Immediately after charging, if I want a more accurate interpretation of voltmeter reading, I first remove the surface charge from the batteries by spinning the starter for a few seconds. Admittedly, I don’t have high electrical demands on my boat so I don’t need to monitor large banks that would be required for bowthrusters, 3kW inverters etc. Then, I can see the justification of more elaborate battery monitoring, but I prefer to keep my boat simple. Now, where did I put my hydrometer and safety specs!

 

Noah

[Guest]

Could there be some clue here as to how the Smartgauge works? Mainly the How Intelligent Battery Monitors Work section.

 

http://www.maxim-ic.com/appnotes.cfm/appnote_number/3168

Edited September 25, 2006 by Guest

[DHutch]

I have to admitt, i dont like the stuff written on the website.

- Ats very "salesmanish", a lot of it is very wooly, and in places its simply rubbish.

 

I also simply cant understand how how it manges to do anything other than read battery volts, with just two cables, one to each termial.

- And therefore i fail to understand how it can do anything more than a voltmeter.

 

And at £150, id far rather stick with a decent ammeter and voltmeter, safe in the knowlage that if worst comes to worse, i can buy an whole new battery bank with the money i saved!

 

 

Daniel

[blackrose]

I have to admitt, i dont like the stuff written on the website.

- Ats very "salesmanish", a lot of it is very wooly, and in places its simply rubbish.

 

I also simply cant understand how how it manges to do anything other than read battery volts, with just two cables, one to each termial.

- And therefore i fail to understand how it can do anything more than a voltmeter.

 

And at £150, id far rather stick with a decent ammeter and voltmeter, safe in the knowlage that if worst comes to worse, i can buy an whole new battery bank with the money i saved!

Daniel

 

 

What is it exactly that you think is rubbish on the website Daniel? I thought the technical stuff on the website made a lot of sense, but then my knowledge of 12v electrics is very basic. I think the smartguage calculates volts & available amp/hours minus surface charge. Is that possible with voltmeter & ammeter?

 

There are some other monitors around which are even more expensive. I don't really understand the difference between these and the smartguage apart from shunts vs. shuntless designs (not that I can claim to know what that means either!)

 

http://www.power-store.com/view-item.asp?itemid=954&id=160&

 

http://www.power-store.com/view-item.asp?itemid=1263&id=160&

[Callum]

I also simply cant understand how how it manges to do anything other than read battery volts, with just two cables, one to each termial.

- And therefore i fail to understand how it can do anything more than a voltmeter.

 

Consider an electronic multimeter Daniel. With two cables they can measure voltage AND also resistance. Since V=IR it follows that you can then calculate the current.

 

So now consider the Smart guage. If I understand it correctly, it is effectively connected across the battery bank. Lets assume that it alternates between measuring the voltage across the battery and it's resistance. It can thus calculate the net current through the battery.

 

From the website we know it uses Puekert's law, which provides a relationship between the net current draw, time the current is/can be flowing and the effective capacity of the battery. So I'm guessing that perhaps these calculations are intergrated over time to get an approximation of the battery capacity and/or the calculated values, or perhaps more likely their rate of change, relate to other known characteristics of the battery to give an indication of the state of charge. For example the website mentions in the FAQs that use is made of the 'transitional characteristic' of the battery between charging and discharging to calibrate the guage. I don't personally know what this characteristic is but clearly there are various battery characteristics that can be combined (e.g. the "algorithms" repeatedly mentioned on the website) to provide an indication of the battery charge.

 

I'm not claiming to know exactly how it works or whether it is any more or less accurate than other methods of monitoring batteries but it does seem perfectly plausible.

[alan_fincher]

Consider an electronic multimeter Daniel. With two cables they can measure voltage AND also resistance. Since V=IR it follows that you can then calculate the current.

 

So now consider the Smart guage. If I understand it correctly, it is effectively connected across the battery bank. Lets assume that it alternates between measuring the voltage across the battery and it's resistance. It can thus calculate the net current through the battery.

I'm sorry Callum, I simply don't think that explanation holds water.

 

If you have an electronic multimeter, try setting it to a resistance range, and then putting it across your battery bank......

 

Well actually, I wouldn't, unless it has sufficient internal protection to stop it coming to any harm

 

Unless I'm missing something, a multimeter measures resistance by using it's own internal battery power source to push a current through whatever it's connected to.

 

If you try measuring the resistance of something that has already got it's own voltage across it, (which a battery bank certainly has!), I fail to see how it can work.

 

I do accept that the SmartGauge can do more than a voltmeter can, but I don't think there is any way that with 2 wires connected across the 12 volts, you can actually measure current being drawn from the batteries directly.

 

If I'm wrong, I'll not be offended if someone tells me why, but I was an electronics test engineer in a previous life, and I don't think the basic physics of electronics has changed since then, even if the measuring gear has got a whole lot more sophisticated.

 

Alan.

[Guest]

I do not pretend to understand electronics today. The valve was still commonplace when I last dealt with electronics. What I can say is that electronics have moved on slightly, and the boffins at my workplace tell me, in layman's terms, that much data can be transmitted down a pair of wires by a microprocessor. I do not pretend to understand what the hell they meant, but the words digital and sampling were in there. I can understand that voltage and temperature (important in calculations) could easily be measured down one pair of wires. I am sure somebody on the forum who knows about the new generation of electronics can put a dinosaur like me straight on this?

[anhar]

...If I'm wrong, I'll not be offended if someone tells me why, but I was an electronics test engineer in a previous life, and I don't think the basic physics of electronics has changed since then, even if the measuring gear has got a whole lot more sophisticated.

Alan.

Hi Alan

 

So are you and others who say they don't understand how the SmartGauge works really claiming that because you don't understand, that therefore it cannot work? If so, what do you think it is showing?

 

regards

Steve

Edited September 26, 2006 by anhar

[GUMPY]

I do accept that the SmartGauge can do more than a voltmeter can, but I don't think there is any way that with 2 wires connected across the 12 volts, you can actually measure current being drawn from the batteries directly.

 

It doesn' measure current in the way an ammeter does it doesnt need to.

I did have a personal mail from Chris explaining how it worked but I cant find it.

What people need to understand is that thare are other ways of measuring battery capacity than just with an ammeter.

 

As for the people that say I dont understand it therfore it cant work.........................

 

 

 

J

[Guest]

Consider an electronic multimeter Daniel. With two cables they can measure voltage AND also resistance. Since V=IR it follows that you can then calculate the current.

 

So now consider the Smart guage. If I understand it correctly, it is effectively connected across the battery bank. Lets assume that it alternates between measuring the voltage across the battery and it's resistance. It can thus calculate the net current through the battery.

 

From the website we know it uses Puekert's law, which provides a relationship between the net current draw, time the current is/can be flowing and the effective capacity of the battery. So I'm guessing that perhaps these calculations are intergrated over time to get an approximation of the battery capacity and/or the calculated values, or perhaps more likely their rate of change, relate to other known characteristics of the battery to give an indication of the state of charge. For example the website mentions in the FAQs that use is made of the 'transitional characteristic' of the battery between charging and discharging to calibrate the guage. I don't personally know what this characteristic is but clearly there are various battery characteristics that can be combined (e.g. the "algorithms" repeatedly mentioned on the website) to provide an indication of the battery charge.

 

I'm not claiming to know exactly how it works or whether it is any more or less accurate than other methods of monitoring batteries but it does seem perfectly plausible.

Don't quote formulas Callum, especially ohm's law I got thrown to the lions for doing that a while ago