Balmar SmartGuage

[Rusty123]

Anyone have experience with Balmar's SmartGuage, particularly as it compares to battery monitors like the Victron?

Although Balmar (and perhaps other companies) sell it, it appears to be manufactured in the UK by a company called, oddly enough, "SmartGuage", which also makes a number of other interesting battery-related electrical devices.

Haven't seen their stuff mentioned much (if at all) in the forums.

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

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

[Dockhead]

I have to say that I have always found the arguments on the Smartgauge site to be very persuasive. I have been using a regular Victron monitor for a few years, and have long abandoned the amp/hour counter as a measure of state of charge. In favor of watching the voltage, which, interpreted with some feeling, seems like a better measure.

That Balmar is selling them looks like another vote of confidence. I might just buy one of these.

[Strait Shooter]

Originally Posted by Dockhead

interpreted with some feeling, I might just buy one of these.

I have to say, I may buy one as well, and even though I really need to leave the house for work, I would love to hear about the feely interpretation approach to gauge reading.

Peace out

[djmarchand]

I have used both battery monitors: the Xantrex kind and just monitoring battery resting voltage to keep tabs on my batteries. I agree with the previous poster, if you know what you are doing, monitoring just voltage works.

I would wait until late in the afternoon when the solar panel output had dropped to the point that it was just balancing the minimal house loads and the net was only a few amps. Then I would check the voltage. I could cross check it against real state of charge from SG readings of the flooded cell batteries. The voltage always indicated more discharge than actual but within 10-15%. So I became comfortable with the voltage reading and stopped checking SG.

David

[Maine Sail]

As I understand it the Smart Gauge was initially developed for military use and put through the ringer by Enersys. Enersys is an independent battery manufacturer who make the ArmaSafe military TPPL batteries. They also are the inventors of the Optima batteries and the manufacturers and patent holders of the TPPL AGM technology found in their line of Odyssey batteries.

Their in-house testing shows it to perform very well. I was initially very, very skeptical, as I usually am, so I want to do my own testing to see how it works.

If it does work as they say, and as Enersys says it does, then it is a slam dunk on traditional Ah counters. On thing about them is they are far easier to install. Still, many boaters like to see current and the SG does not show current just SoC and SoH...

I still think a well calibrated and manually synched batt mon, like the BMV-600, is a great tool and they are less than half the cost of a Smart Gauge. The problem with traditional Ah counting is that it requires human intervention. If the SG works as they say plug it in and let her rip..

I have one on order that I plan to test in LiFePO4. Unfortunately the folks at Smart Gauge have not answered my emails and even Balmar has tried for me but the questions have gone unanswered about the compatibility between a SG and LiFeP04.

I plan to test one over the winter on LiFeP04 and will then move on to lead.........

[goboatingnow]

I would be very interested in your testing of this product MaineSail. The algorithm for matching voltage to SOC for a battery under load is quite complex, and it would be interesting to see how Smartgauge would work.

Unless they have a specific profile for Li, I can't see it performing well

Dave

[FlyingCloud1937]

It'll be interesting to see how this plays out with Midtronics. They were successful in killing BatteryBug do to patent infringement.

BatteryBug worked as the SmartGuage, it was an excellent little device, and under $90.00 USD

Now we'll see if Midtronics goes after Balmar, now that it is the US Shore Importer.

Lloyd

Here is a link to
Midtronics ING-100 Battery Management System

Originally Posted by Maine Sail

As I understand it the Smart Gauge was initially developed for military use and put through the ringer by Enersys. Enersys is an independent battery manufacturer who make the ArmaSafe military TPPL batteries. They also are the inventors of the Optima batteries and the manufacturers and patent holders of the TPPL AGM technology found in their line of Odyssey batteries.

Their in-house testing shows it to perform very well. I was initially very, very skeptical, as I usually am, so I want to do my own testing to see how it works.

If it does work as they say, and as Enersys says it does, then it is a slam dunk on traditional Ah counters. On thing about them is they are far easier to install. Still, many boaters like to see current and the SG does not show current just SoC and SoH...

I still think a well calibrated and manually synched batt mon, like the BMV-600, is a great tool and they are less than half the cost of a Smart Gauge. The problem with traditional Ah counting is that it requires human intervention. If the SG works as they say plug it in and let her rip..

I have one on order that I plan to test in LiFePO4. Unfortunately the folks at Smart Gauge have not answered my emails and even Balmar has tried for me but the questions have gone unanswered about the compatibility between a SG and LiFeP04.

I plan to test one over the winter on LiFeP04 and will then move on to lead.........

[kentobin]

SmartGauge battery monitor anyone?

From link:
I understand the methods they use (voltage/battery AC impedance ESR to derive a SG that equates to SOC) and it works to a point but for a solar energy monitor you really need a current monitor (shunt/hall sensor) to tune your system loads. The energy source model works better in a static charge/discharge usage pattern.

Last edited by nsaspook; April 8th, 2011 at 16:23 PDT.

[sailinglegend]

I have a SmartGauge AND a good BEP battery monitor. I bought the SmartGauge because the BEP was becoming more and more inaccurate, up to 50%!!!! SmartGauge is not "snake oil", it does work, and it works much better than than the BEP now that my 10 years old Lifeline AGMs are losing some capacity.

If you search this forum there are lots of posts on SmartGauge, but lets try and make this a SmartGauge only post!

Why and how does SmartGauge work?
Nobody knows!!!!!
But the SmartGuage doesn't use a shunt - it monitors the battery voltage 1100 times a second - if you were doing that you would get a pretty good idea what you batteries were doing! It learns you battery status and becomes more accurate the more it "learns". You only have to tell it what type your batteries are, not their capacity, and it uses complicated algorithms to determine the State of Charge.

Why shunt Battery Monitors aren't accurate"
As useful as shunt battery monitors are, keeping the displayed Ah capacity and the actual capacity synchronised is one major problem with them.

There are many complicated reasons for this The battery parameters have to be correctly input to the software on installation. The capacity of the bank has to be entered. Peukerts constant for the batteries being used has to be entered. Also an accurate charging Ah count is affected by the “efficiency” of the battery at accepting charge. Wet cells may be only 75% efficient whereas AGMs may be 98%. If all these values are not input correctly it will upset the Ah count accuracy. Batteries also have a self-discharge up to about 10% per month which the battery monitor cannot detect.

All of these values change as the batteries age. This can introduce large errors.

Auto Re-Sync
To increase their accuracy the Ah count must be reset to 100% when the bank is 100% charged.

The manufacturers Auto Re-sync default value may be set for example at a charging current below 5 amps for 5 minutes at a voltage above 13.5 volts. These values are usually much too conservative, but they do want the battery monitor to reset earlier rather than never.

Ideally the proper values should be set so that the current is about 0.5 % of the battery capacity C at the battery absorption voltage of about 14.4 volts. This voltage/current is impossible to achieve as all regulators will have reset to a float voltage much lower than this long before the current has reduced to 0.5% of C.

"Reset Gotchya”
There is also a problem with solar panels that sometimes may not deliver a high enough current but may meet the Auto Re-sync voltage values. This will prematurely re-set the battery to 100%. This feature can be disabled completely by setting the reset voltage at something like 16 volts – which it should never reach. Then the Battery Monitor can be reset manually when the batteries are known to be fully charged.

Battery Monitor Installation Problems
Another big problem with battery monitors is that the shunt needed to measure the current is often installed incorrectly. It must be as close to the battery as possibly – usually on the negative post – and a new bus bar must be installed immediately after the shunt to take all the negative cables. All other battery negative cables MUST go via this bus bar. Often extra equipment is added at a later date and the installer may well have followed the installations instructions to the letter and installed the new equipment “directly to the battery”, but not to the shunt bus bar.

The starter battery negative must also be connected to the bus bar, not to a service battery negative terminal. This error is probably one of the major causes of battery monitors not reading the charging amps.

With all these problems the military finally demanded more accurate battery monitors - so enter the SmartGuage. Nobody believed it could work, including the man who finally bought the company, MD at Merlin Equipment UK. Tests by Enersys who make Optima batteries found it to be unbelievably accurate.

It is so simple to install. Its downside is that it doesn't measure current so a separate cheap digital ammeter/Ah counter should also be installed, just to keep an eye on all the systems.

The only problem I have found with it is that it shows 100% a bit too early - well before the a current of 0.5% of Capacity at >14.2 volts. As soon as it goes "off charge" it will correct itself. You'll see it drop from say 100% to 96%.

[FlyingCloud1937]

It lacks one thing to be truly accurate. It does not know what the battery temps are. So it can only give you a snap shot.

A battery operating on a low discharge at 50 F is not going to have the same capacity as when it operates at 80 F.

I have seen the battery temp rise during re-charge of the same 50 F discharge voltage, and by the time it hits absorption the battery is now near 70 F. A 20 F temp rise, SmartGuage is attempting to determine SPG by it logarithm, but lacking temp correction.

We all know, to make an accurate SPG reading with a Hydrometer we need to temp correct it. Same with voltage, and bat temp has a direct relation to it's internal resistance.

So there is no way for it to be accurate under these circumstances.

Lloyd

Originally Posted by sailinglegend

I have a SmartGauge AND a good BEP battery monitor. I bought the SmartGauge because the BEP was becoming more and more inaccurate, up to 50%!!!! SmartGauge is not "snake oil", it does work, and it works much better than than the BEP now that my 10 years old Lifeline AGMs are losing some capacity.

If you search this forum there are lots of posts on SmartGauge, but lets try and make this a SmartGauge only post!

Why and how does SmartGauge work?
Nobody knows!!!!!
But the SmartGuage doesn't use a shunt - it monitors the battery voltage 1100 times a second - if you were doing that you would get a pretty good idea what you batteries were doing! It learns you battery status and becomes more accurate the more it "learns". You only have to tell it what type your batteries are, not their capacity, and it uses complicated algorithms to determine the State of Charge.

Why shunt Battery Monitors aren't accurate"
As useful as shunt battery monitors are, keeping the displayed Ah capacity and the actual capacity synchronised is one major problem with them.

There are many complicated reasons for this The battery parameters have to be correctly input to the software on installation. The capacity of the bank has to be entered. Peukerts constant for the batteries being used has to be entered. Also an accurate charging Ah count is affected by the “efficiency” of the battery at accepting charge. Wet cells may be only 75% efficient whereas AGMs may be 98%. If all these values are not input correctly it will upset the Ah count accuracy. Batteries also have a self-discharge up to about 10% per month which the battery monitor cannot detect.

All of these values change as the batteries age. This can introduce large errors.

Auto Re-Sync
To increase their accuracy the Ah count must be reset to 100% when the bank is 100% charged.

The manufacturers Auto Re-sync default value may be set for example at a charging current below 5 amps for 5 minutes at a voltage above 13.5 volts. These values are usually much too conservative, but they do want the battery monitor to reset earlier rather than never.

Ideally the proper values should be set so that the current is about 0.5 % of the battery capacity C at the battery absorption voltage of about 14.4 volts. This voltage/current is impossible to achieve as all regulators will have reset to a float voltage much lower than this long before the current has reduced to 0.5% of C.

"Reset Gotchya”
There is also a problem with solar panels that sometimes may not deliver a high enough current but may meet the Auto Re-sync voltage values. This will prematurely re-set the battery to 100%. This feature can be disabled completely by setting the reset voltage at something like 16 volts – which it should never reach. Then the Battery Monitor can be reset manually when the batteries are known to be fully charged.

Battery Monitor Installation Problems
Another big problem with battery monitors is that the shunt needed to measure the current is often installed incorrectly. It must be as close to the battery as possibly – usually on the negative post – and a new bus bar must be installed immediately after the shunt to take all the negative cables. All other battery negative cables MUST go via this bus bar. Often extra equipment is added at a later date and the installer may well have followed the installations instructions to the letter and installed the new equipment “directly to the battery”, but not to the shunt bus bar.

The starter battery negative must also be connected to the bus bar, not to a service battery negative terminal. This error is probably one of the major causes of battery monitors not reading the charging amps.

With all these problems the military finally demanded more accurate battery monitors - so enter the SmartGuage. Nobody believed it could work, including the man who finally bought the company, MD at Merlin Equipment UK. Tests by Enersys who make Optima batteries found it to be unbelievably accurate.

It is so simple to install. Its downside is that it doesn't measure current so a separate cheap digital ammeter/Ah counter should also be installed, just to keep an eye on all the systems.

The only problem I have found with it is that it shows 100% a bit too early - well before the a current of 0.5% of Capacity at >14.2 volts. As soon as it goes "off charge" it will correct itself. You'll see it drop from say 100% to 96%.

[sailinglegend]

Originally Posted by FlyingCloud1937

It lacks one thing to be truly accurate. It does not know what the battery temps are. So it can only give you a snap shot.

Be clear about one thing on SmartGauge it doesn't know the Ah capacity of the battery it only tells you % SoC of the battery at any moment in time. Battery temperature is only one thing which will determine the rise and fall of the voltage, so I suspect that temperature will not affect SmartGauge accuracy very much. As soon as an abnormal load or charge is removed SmartGauge will settle and correct any errors.

If it is only 95% accurate that is till a lot lot better than my BEP battery monitor has become. I have spent two years trying to re-programme the different parameters and now with SmartGauge I am getting a better match. I know from "off load", "off charge" voltages that Smatgauge is working much much better than the BEP.

[d design]

Best way to find soc is with a hydrometer. I have a bep monitor and it has been very good. However the amps reading keeps drifting off zero.. Grrr! Might be caused by back emf from something.

[Albro359]

Hydrometers don't work well with AGM batteries.
Temperature is needed to know the true SOC of a battery.
As the battery is being charged it warms up.... as a previous poster said, the voltage reading at cold represents a different SOC to when its warm.
Smart Gauge only measures volts....only 2 wires, no shunt, can't measure anything but volts.
So it has some smarts inside so it knows the charge/ discharge profile for different battery types .... I used to have that on a piece of paper for my AGMs on Diva and just a voltmeter and compared the two...didn't take long to remember.

[btrayfors]

I've never been a fan of "battery monitors", though I've used and installed a number of them on clients' boats.

Problem is, they take "human intervention" as MaineSail and SailingLegend have said. I find that most clients don't have the knowledge or inclination to provide what is necessary to ensure that their battery monitors yield accurate information.

BTW, thanks to SailingLegend for an excellent overall summary.

Like Dockhead and DJMarchand said, monitoring just voltage works very well, if you know your boat and have some understanding of DC circuits and battery behavior. That's what I have done on my own boat for many years, and I find it more than adequate.

OTOH, the SmartGuage is a very interesting device, and if I can find one for a reasonable price I'd sure like to try it out.

And, it probably wouldn't hurt to repeat what has become my mantra:

DON'T FORGET THAT SOC AND SG DO NOT EQUAL BATTERY CAPACITY REMAINING.

They're quite different. You can have a very high state of charge (and SG) in a battery which hasn't enough residual capacity to start your engine!

Bill

[sailinglegend]

Originally Posted by d design

Best way to find soc is with a hydrometer.....

This is another controversial subject in the “electrickery game”, and is another good reason why SmartGauge is much simpler and much easy to use.

Measuring SG of an open wet lead acid battery accurately may be a difficult and time consuming procedure, but unless the battery is healthy they may not be the best method because the SG reading gets lower as the battery ages.

The SG of each cell at a 100% SOC should be 1.265 or higher. If the cells in the battery are not equal then an average of all cells has to be made. If individual cells are lower it means their Ah capacity is reduced due to sulfation. A value of 30 points between cells indicates that the battery should be equalized.

For accurate results the SG must only be taken when the cells have been topped up with distilled water and then only after the batteries have been charged, this stirs up the electrolyte to give a true SG reading for each cell. The SG reading must only be taken when the charged battery has been allowed to rest with no charge or discharge for several hours, the temperature of the battery must be measured and compensation has to be applied to all readings. All this is not very practical on a typical cruising boat, so the potential for errors can give poor results.

If the battery is known to be fully charged because it has been on shorepower for a couple of days the SG readings taken then will represent 100% charged. If these are all lower than the readings when the batteries were new that indicates they have lost some of their Ah capacity. Every time the battery is discharged and charged again these SG values will reduce slightly.