Smartgauge ponderings

[Nickhlx]

Interesting findings !

 

Is the display adjustable in some easy way ? I have a calibrated Multimeter and wanted to adjust the display to read as accurately as the resolution will permit....

 

(( I don't want to get into having to try to change SMD resistors though !)

 

Nick

[nicknorman]

Interesting findings !

 

Is the display adjustable in some easy way ? I have a calibrated Multimeter and wanted to adjust the display to read as accurately as the resolution will permit....

 

(( I don't want to get into having to try to change SMD resistors though !)

 

Nick

There are no trimpots etc. so any adjustment / calibration must be done in software. There is an RJ45 - type connetor, and another connector, one or both of which I guess is a test/calibration connector.

[Albion]

There are no trimpots etc. so any adjustment / calibration must be done in software. There is an RJ45 - type connetor, and another connector, one or both of which I guess is a test/calibration connector.

Isn't the RJ45 for a connection to the SmartBank split charge relay controller IIRC?

Roger

[nicknorman]

Isn't the RJ45 for a connection to the SmartBank split charge relay controller IIRC?

Roger

Yes you are probably right, I don't have a SB. However its not to say that the RJ45 might not be dual purpose if its just a communication port. There still remains the other test connector which I note seems to mostly be connected direct to microcontroller leads.

Edited January 25, 2013 by nicknorman

[Nickhlx]

There are no trimpots etc. so any adjustment / calibration must be done in software. There is an RJ45 - type connetor, and another connector, one or both of which I guess is a test/calibration connector.

 

Thanks for that

 

Nick

[jonathanA]

so £150 for a not very good voltmeter , attached to a very clever bit of software...

 

a fool and his money....

 

sorry couldn't resist - appreciate that for some people SG is the best thing since sliced bread, but for me personlly I'd sooner spend the money on something else

[Grace and Favour]

so £150 for a not very good voltmeter , attached to a very clever bit of software...

 

a fool and his money....

 

sorry couldn't resist - appreciate that for some people SG is the best thing since sliced bread, but for me personlly I'd sooner spend the money on something else

 

I know some folk whom spend (much more than) £150 every month on cannabis, and suffer with the cold weather and malnutrition

 

And your point is?

[Chris Pink]

I know some folk whom spend (much more than) £150 every month on cannabis, and suffer with the cold weather and malnutrition

 

And your point is?

 

I never tried smoking the Smartgauge maybe that's where I went wrong.

 

And your point is?

[jonathanA]

I know some folk whom spend (much more than) £150 every month on cannabis, and suffer with the cold weather and malnutrition

 

And your point is?

 

no point what so ever !!!!

 

just a bit of light hearted banter, and i tied to make that obvious but obviously failed....

 

sorry if you feel I've somehow offended those who choose to buy SG, honestly I could not care less, its not for me and I am entirely comfortable with that, just as I understand those for whom its an absolute must and entirely respect their choice.

[nicknorman]

no point what so ever !!!!

 

just a bit of light hearted banter, and i tied to make that obvious but obviously failed....

 

sorry if you feel I've somehow offended those who choose to buy SG, honestly I could not care less, its not for me and I am entirely comfortable with that, just as I understand those for whom its an absolute must and entirely respect their choice.

As you say, its not for you, but it is a good purchase for many people who want an easy fit, read and forget system to tell them how their bats are doing.

[BruceinSanity]

As you say, its not for you, but it is a good purchase for many people who want an easy fit, read and forget system to tell them how their bats are doing.

 

I heard an excellent talk from Steve Roe of the Derbyshire Bat Conservation Group last night, but he didn't mention the SmartGauge…

 

 

OK, OK, I'm going.

[nicknorman]

I heard an excellent talk from Steve Roe of the Derbyshire Bat Conservation Group last night, but he didn't mention the SmartGauge…

 

 

OK, OK, I'm going.

I didn't mention the ultrasonic transducer on the circuit board - with the correct button-pressing combination it can be used to send out bat feeding calls - they then come flocking round to see what is going on and this allows you to check that they are all OK.

[Nickhlx]

I didn't mention the ultrasonic transducer on the circuit board - with the correct button-pressing combination it can be used to send out bat feeding calls - they then come flocking round to see what is going on and this allows you to check that they are all OK.

 

No it doesn't

[smileypete]

Someone sent me a pic of the Smartguage PCB and it does indeed look like it takes voltage readings only and nothing else. So having said a few times it must use conductance, it's humble pie for me! (yum!)

 

Still, kudos for Gibbo for designing a decent batt monitor thats smart and sophisticated enough to just work from voltage readings alone, also for Nick for testing it out and finding out more about the secret of how it works.

 

cheers, Pete.

~smpt~

[nicknorman]

So back to the question of whether it under-reads for low battery temperatures ( I think we can see it will do, at least for moderate to high discharge rates due to slowness of chemical reaction) I shall get my coolbox and a battery out, and start testing...

[smileypete]

There's a table in The Battery FAQ for voltage vs temp:

 

http://jgdarden.com/batteryfaq/carfaq4.htm#ocv_soc

 

I guess the batt recovers more slowly after a load is removed, which might affect the Smartguage reading. Maybe the only way to tell for sure is do a full discharge test and see what SG reports at the halfway point.

 

Found a chart of temp vs capacity which might help (ETA the numbers on it seem to have been shifted down a bit):

 

 

cheers, Pete.

~smpt~

Edited January 25, 2013 by smileypete

[Paul C]

I always gave Gibbo the benefit of the doubt, and assumed it was more sophisticated than simply a clever voltmeter with some algorithms converting this to % SoC.

 

The solar thing - it would be useless if it gave false readings during (solar) charging - I'd want to see (for example) 70% SOC in the morning, and after little electricity use on the boat (a few blips of the water pump, radio, etc) something like 85% in the evening. If its only 10% accurate, thats no use - solar charging is slow and long, compared to alternator + running engine.

 

To the person with no worries using it on his 960W solar setup - that's a lot of solar! Not surprised you're able to keep yours charged. I've invested in a more realistic (and affordable) amount of panels, and in any case don't have the roof space to add (much) more.

 

The reason I've not gotten one is

 

1) there's a promise of a Mk2 version - it was promised in November, but is now on hold....with no date. I don't want to be buying a Mk1 then find next week, there's a better one out there.

2) If it does use some kind of exclusive technology, I'm suspicious why it isn't publicised and marketed as such. After all, if I were buying a car and one of them had (for example) 8V, and the other 16V, I bet there's a 16V badge on the car and the brochure plugs its technical stuff.

[nicknorman]

There's a table in The Battery FAQ for voltage vs temp:

 

http://jgdarden.com/batteryfaq/carfaq4.htm#ocv_soc

 

I guess the batt recovers more slowly after a load is removed, which might affect the Smartguage reading. Maybe the only way to tell for sure is do a full discharge test and see what SG reports at the halfway point.

 

Found a chart of temp vs capacity which might help (ETA the numbers on it seem to have been shifted down a bit):

 

 

cheers, Pete.

~smpt~

The difficulty is defining what exactly the capacity is. If you stick with a fixed end pont (full discharge) you will reach that earlier when the bat is cold. But then perhaps if you stop discharging and go away for a while, the chemical reactions catch up and you find you can further discharge.

 

I suppose what is really relevant is, if the capacity (definition as above) is temporarily reduced at low temperature, is it OK to go below 50%? Yes we all know that 50% is no magic number, just a ballpark good idea, but if we discharge to say 40% on a cold day, then warm the battery and leave it to recover, might we find that it is now actually at 50%. Or to put it another way, if we cycle a battery to distruction down to 50% when warm, or 40 when cold, which will have the longer life? Tricky...

 

I always gave Gibbo the benefit of the doubt, and assumed it was more sophisticated than simply a clever voltmeter with some algorithms converting this to % SoC.

 

Yes but that is quite sophistocated! To give a reasonable value for SoC just from d voltage /dt etc is clever. I certainly wouldnt like to try to design it!

[Paul C]

True.....but I can look at a voltmeter, know what good and bad is, look at it again in 5 minutes/half an hour, kinda know how much power a radio, or a microwave oven, or a bunch of lights, or the telly consumes, know that running stuff and looking at volts lowers it slightly, know that during charging it goes up, etc etc and kinda get an idea in my head of whether my batteries are about to die, or are alright, or are happily more or less fully charged. The £150 in my pocket (or spent on something else) is a nice feeling....

[GUMPY]

True.....but I can look at a voltmeter, know what good and bad is, look at it again in 5 minutes/half an hour, kinda know how much power a radio, or a microwave oven, or a bunch of lights, or the telly consumes, know that running stuff and looking at volts lowers it slightly, know that during charging it goes up, etc etc and kinda get an idea in my head of whether my batteries are about to die, or are alright, or are happily more or less fully charged. The £150 in my pocket (or spent on something else) is a nice feeling....

I used to use a voltmeter and do it that way, when I trialled the SG I was getting 50% more use from each charge as I was being pessamistic with my voltage view.

[nb Innisfree]

The difficulty is defining what exactly the capacity is. If you stick with a fixed end pont (full discharge) you will reach that earlier when the bat is cold. But then perhaps if you stop discharging and go away for a while, the chemical reactions catch up and you find you can further discharge.

 

I suppose what is really relevant is, if the capacity (definition as above) is temporarily reduced at low temperature, is it OK to go below 50%? Yes we all know that 50% is no magic number, just a ballpark good idea, but if we discharge to say 40% on a cold day, then warm the battery and leave it to recover, might we find that it is now actually at 50%. Or to put it another way, if we cycle a battery to distruction down to 50% when warm, or 40 when cold, which will have the longer life? Tricky...

 

 

Yes but that is quite sophistocated! To give a reasonable value for SoC just from d voltage /dt etc is clever. I certainly wouldnt like to try to design it!

 

I think a lot of people underestimate just how much testing and measuring went in to the algorithms. I reckon 10% inspiration 90% perspiration.

[dmr]

I always gave Gibbo the benefit of the doubt, and assumed it was more sophisticated than simply a clever voltmeter with some algorithms converting this to % SoC.

 

 

 

This is an odd way to look at it????

Smartgage works and many people think its great (myself included). So because we now possibly know a bit more about how it works (or actually about techniques it does not use) does this make it less good? and does it make Gibbo any less clever?.

I think deducing state of charge from voltage alone is very clever! I could have a shot at designing a machine to measure complex impedance spectra...but I could not design a smartgage!!

And producing an analog-digital instrument, with display, in relatively small numbers, for £150 is also clever...Smartguage is very good value.

We have all got to conditioned by cheap Chinese consumer electronics that is cheap because they sell ten million!

 

.........Dave

[Ralph Claydon]

Sorry to butt in,

Can anyone tell me how a layman can check to see if the smartgauge is giving the correct SOC readings?

Also how do you know that it is not faulty?

I had one installed by Dave Reynolds last year and quit frankly it does not make any sense to me!

 

 

Any help would be most appreciated.

[nicknorman]

Sorry to butt in,

Can anyone tell me how a layman can check to see if the smartgauge is giving the correct SOC readings?

Also how do you know that it is not faulty?

I had one installed by Dave Reynolds last year and quit frankly it does not make any sense to me!

 

 

Any help would be most appreciated.

If the voltage reading on the SG is correct, chances are it is working correctly. If you give us some more information about why/how it is not making any sense to you, and whether it used to be OK but is only now confusing you, we might be able to offer suggestions...

 

It is of course possible to install it incorrectly, the best way to do that would be to not connect it directly to the battery terminals. That would result in it not working properly.

[Tony Brooks]

Sorry to butt in,

Can anyone tell me how a layman can check to see if the smartgauge is giving the correct SOC readings?

Also how do you know that it is not faulty?

I had one installed by Dave Reynolds last year and quit frankly it does not make any sense to me!

 

 

Any help would be most appreciated.

 

 

I think that the best you can do would be to compare it with hydrometer readings. Given enough time for batteries to stand I suppose you could do the same with volatge readings but that would require best part of 24 hours with the batteries doing absolutely nothing so may not be practical.

 

How old is your battery bank and what is your discharge and charging regime?

 

 

The SG tells (more or less) the truth about the degree of charge or discharge BUT, and this is what a lot of people do not read/understand, if you have sulphated batteries that are in otherwise good condition it will tell the absolute truth. Foe example 100Ah battery 50% sulphated gives a true capacity of 50Ah so the SG will say 100% when the battery has 50Ah inside it NOT when it gets to 100Ah which it never could.

 

I also understand that Gibbo has said that once the capacity drops below 50% then it becomes less reliable.

 

Finally I think we have established that solar charging at long, low rates may cause it to be less accurate.

 

A number of us on here use a combination of voltage and current readings over 24 hour periods to assess the state of charge of our batteries but it does require an accurate voltmeter and ammeter.

Edited January 29, 2013 by Tony Brooks