Anyone using the Balmar Smartguage?

[gregmchugh]

Anyone aware of info from anyone using the Balmar Smartguage battery meter in an RV?

Someone on the Roadtrek Owners Group was looking for actual experiences before buying one...

http://www.balmar.net/?page_id=15245

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

[markopolo]

I've never used one but they do seem to get positive reviews. This page - SmartGauge Electronics - SmartGauge compared to Amp Hours Counters - is worth reading.

It is worth noting that the SmartGauge is a voltage meter and a state of charge meter. That's all as far as I can tell. It won't show how many amps the furnace or a light bulb uses for example. It doesn't show you the amps out or the amps in.

From the Smartgauge site:

These are the main problems with amp hours counters (there are many more). In effect they are useless for monitoring the state of charge of deep cycle batteries. We may have given the impression we do not like them and see no use for them. This could not be further from the truth. The engineer who designed the SmartGauge uses one on his own boat. But for completely different purposes.

The main problems they list with AH counters are unfortunately a compilation of problems from a variety of different brand AH counters. Some of the problems they list do not apply to all AH counters.

If you just want to know SOC and voltage then it's probably a good choice. It is noted that accuracy can be off while charging.

The great thing about AH counters is that knowing what the amps in are allows you stop bulk charging from a generator or alternator when it is no longer the best or most economical or effective way to charge. That's when you let your solar setup take over for example.

[eric1514]

$320 at West Marine? Not for that price.

[booster]

Originally Posted by markopolo

I've never used one but they do seem to get positive reviews. This page - SmartGauge Electronics - SmartGauge compared to Amp Hours Counters - is worth reading.

It is worth noting that the SmartGauge is a voltage meter and a state of charge meter. That's all as far as I can tell. It won't show how many amps the furnace or a light bulb uses for example. It doesn't show you the amps out or the amps in.

From the Smartgauge site:

The main problems they list with AH counters are unfortunately a compilation of problems from a variety of different brand AH counters. Some of the problems they list do not apply to all AH counters.

If you just want to know SOC and voltage then it's probably a good choice. It is noted that accuracy can be off while charging.

The great thing about AH counters is that knowing what the amps in are allows you stop bulk charging from a generator or alternator when it is no longer the best or most economical or effective way to charge. That's when you let your solar setup take over for example.

I did some more reading today to try to get a feel for what they are doing, and as I mentioned in the other thread, it does look like they only have voltage and battery type to go by, and all rest of the calculation is algorithm. They make a big deal about how many calculations they make, but I really don't get impressed by that kind of stuff as it is how accurate the data is, and how relevant the calculations are in relation to what you are trying to that actually count. That hype is a negative to me (maybe unjustly, but it is). They have to be taking the voltage change over very small increments of time and determining how much state of charge that change would cause by using it to determine a load in % of capacity. They then add all those up to get a composite SOC. All this is well and good, if the algorithm is accurate for the load calculation based on the the voltage change. It is also a moving target as the voltage will also change with load, which can be highly variable. What I would question would be that within a battery type (which is what you set) you can get widely disparate voltage drops at the same % of capacity load. We saw a very large difference between our GC2 wet cells and our 12v wet cells, even though they were all Trojan and allegedly the same chemistry. The setting in the Smartgauge would be same for both, so it gives me pause in what the results would be. Use a marine starting "deep cycle" and it would be even more mismatched, I think.

In the literature they make a big deal about how they never get back to 100% full because of wear and tear, which I think is just covering for the fact that it doesn't work out that way. I seriously doubt they can measure the loss of capacity of a battery that will take 1000 or more cycles to go down 20%, when they list their accuracy at 10%.

Their statements about Peukert, from what we have discussed and seen here on the forum, appear to be totally incorrect. They plainly say that more total power is removed from a battery at high discharge rates compared to lower rates, and that they have that in the algorithm. As we have discussed, the rate only applies at the end of a total discharge test to 10.5 volts and Peukert is really all about voltage drop and not total available energy in the battery. Watts will always be the same. Bogart has all of this in their literature, so it is not unknown by any stretch. If they are reducing SOC left based on the rate that you have discharged to that point, they will get the incorrect state of charge compared to how much energy is actually left in the batteries. This would be a very big deal for those who use inverters to run high power things like microwaves, but most of the time are very low power users (this would include the way we use our system).

Smartgauge also talks about the need for a calibration or reference point, and infer it happens at fully charged, which makes sense as they would see the voltage stabilize and quit changing. I would assume they adjust the algorithm based on how the charge cycle matched the discharge cycle for that total cycle. This is similar to what folks like Magnum do if you have the charge efficiency set to automatic, where they adjust the charge efficiency setting each full recharge cycle. This is another one of those things that works well if the discharges are relatively the same each time, but gets more and more inaccurate if the discharge depths change a bunch. Do 80% down one day, and 20% the next, and you will be way off on charge efficiency (they actually average the previous cycles I think, so a bit exaggerated an example). I think the same thing would happen with the Smartgauge.

I guess the bottom line, It think, is a choice between what kind of inaccuracy you are the most comfortable with, as both the Smartgauge and normal monitor have some built in inaccuracies. What follows is a best case for both.

A Trimetric type, shunt based, monitor will accurately tell you how many amp hours you have used, and based on recharge amps will accurately tell you when the battery is full. But, you will not know how many amp hours of capacity you have left if the battery has aged (this is the big Smartgauge selling point). To know that, you would need to do a drawdown test occasionally to redetermine actual capacity.

With the Smartgauge, if it does what is claimed, you will accurately know the SOC % of the batteries, but you will not know how many amp hours they had in the first place, or after degrading, so you are pretty much in the same position of not knowing how much battery amp hours you have left.

Six of one, half dozen of the other, I think.

I will add that I have no, zero, none, first hand knowledge of the Smartgauge in the real world, so this is all based on claims, speculation, and what I have seen in regular monitors and charger setups. I know that the normal monitors can be a bit intimidating for casual users, and the Smartgauge may address the issues with them. Ease of use and simplicity often give great reviews for products that are less accurate than complicated ones. For those that want more information, as well as the gold standard, amp based, recharge calibration and reset, I think the Smartgauge would come in second. Of course you opinions may be totally different

I hope someone gets on and lets us know what the find out using it!

[gregmchugh]

I agree that they seem to playing it very close to the vest in terms of what they are actually doing but if it actually does a reasonable job using just voltage measurements and a lot of software to process the data they have an advantage that they rightly don't want to have duplicated by someone else at a much lower price point. Who knows, they may have a fancy Kalman filter estimation algorithm that manages to pull meaningful data from very noisy measurements.

There is speculation by some that they may actually be injecting small AC voltages into the battery and reading the response in order to characterize the battery in more detail but who knows if that has any basis.

Bottom line, if it works as advertised and gives an accurate estimate of state of charge during the discharge period then it would be good enough for many users who want something simple that doesn't require any technical understanding of what is going on.

[cruising7388]

Originally Posted by booster

I did some more reading today to try to get a feel for what they are doing, and as I mentioned in the other thread, it does look like they only have voltage and battery type to go by, and all rest of the calculation is algorithm. They make a big deal about how many calculations they make, but I really don't get impressed by that kind of stuff as it is how accurate the data is, and how relevant the calculations are in relation to what you are trying to that actually count. That hype is a negative to me (maybe unjustly, but it is). They have to be taking the voltage change over very small increments of time and determining how much state of charge that change would cause by using it to determine a load in % of capacity. They then add all those up to get a composite SOC. All this is well and good, if the algorithm is accurate for the load calculation based on the the voltage change. It is also a moving target as the voltage will also change with load, which can be highly variable. What I would question would be that within a battery type (which is what you set) you can get widely disparate voltage drops at the same % of capacity load. We saw a very large difference between our GC2 wet cells and our 12v wet cells, even though they were all Trojan and allegedly the same chemistry. The setting in the Smartgauge would be same for both, so it gives me pause in what the results would be. Use a marine starting "deep cycle" and it would be even more mismatched, I think.

In the literature they make a big deal about how they never get back to 100% full because of wear and tear, which I think is just covering for the fact that it doesn't work out that way. I seriously doubt they can measure the loss of capacity of a battery that will take 1000 or more cycles to go down 20%, when they list their accuracy at 10%.

Their statements about Peukert, from what we have discussed and seen here on the forum, appear to be totally incorrect. They plainly say that more total power is removed from a battery at high discharge rates compared to lower rates, and that they have that in the algorithm. As we have discussed, the rate only applies at the end of a total discharge test to 10.5 volts and Peukert is really all about voltage drop and not total available energy in the battery. Watts will always be the same. Bogart has all of this in their literature, so it is not unknown by any stretch. If they are reducing SOC left based on the rate that you have discharged to that point, they will get the incorrect state of charge compared to how much energy is actually left in the batteries. This would be a very big deal for those who use inverters to run high power things like microwaves, but most of the time are very low power users (this would include the way we use our system).

Smartgauge also talks about the need for a calibration or reference point, and infer it happens at fully charged, which makes sense as they would see the voltage stabilize and quit changing. I would assume they adjust the algorithm based on how the charge cycle matched the discharge cycle for that total cycle. This is similar to what folks like Magnum do if you have the charge efficiency set to automatic, where they adjust the charge efficiency setting each full recharge cycle. This is another one of those things that works well if the discharges are relatively the same each time, but gets more and more inaccurate if the discharge depths change a bunch. Do 80% down one day, and 20% the next, and you will be way off on charge efficiency (they actually average the previous cycles I think, so a bit exaggerated an example). I think the same thing would happen with the Smartgauge.

I guess the bottom line, It think, is a choice between what kind of inaccuracy you are the most comfortable with, as both the Smartgauge and normal monitor have some built in inaccuracies. What follows is a best case for both.

A Trimetric type, shunt based, monitor will accurately tell you how many amp hours you have used, and based on recharge amps will accurately tell you when the battery is full. But, you will not know how many amp hours of capacity you have left if the battery has aged (this is the big Smartgauge selling point). To know that, you would need to do a drawdown test occasionally to redetermine actual capacity.

With the Smartgauge, if it does what is claimed, you will accurately know the SOC % of the batteries, but you will not know how many amp hours they had in the first place, or after degrading, so you are pretty much in the same position of not knowing how much battery amp hours you have left.

Six of one, half dozen of the other, I think.

I will add that I have no, zero, none, first hand knowledge of the Smartgauge in the real world, so this is all based on claims, speculation, and what I have seen in regular monitors and charger setups. I know that the normal monitors can be a bit intimidating for casual users, and the Smartgauge may address the issues with them. Ease of use and simplicity often give great reviews for products that are less accurate than complicated ones. For those that want more information, as well as the gold standard, amp based, recharge calibration and reset, I think the Smartgauge would come in second. Of course you opinions may be totally different

I hope someone gets on and lets us know what the find out using it!

If memory serves, the marketing literature indicates that the meter is not usable for lithium battery setups.

[booster]

Originally Posted by cruising7388

If memory serves, the marketing literature indicates that the meter is not usable for lithium battery setups.

You are correct, it does say that. Probably because of the very low voltage change as the batteries discharge?

[gregmchugh]

Originally Posted by cruising7388

If memory serves, the marketing literature indicates that the meter is not usable for lithium battery setups.

Page 9 and 10 describe the various types of lead acid batteries that are available for configuring the meter, no configuration for lithium.

Given the extensive variety of lead acid batteries, I would expect the battery models used by the meter are the level of the battery chemistry not a higher level model normally seen in chargers and shunt based battery monitors.

http://www.balmar.net/wp-content/upl...44-SG-1224.pdf

[gregmchugh]

Originally Posted by eric1514

$320 at West Marine? Not for that price.

I think the price reflects the fact that the initial markets for this technology have been the defense and marine markets. I expect the price to the defense industry is significantly higher than the $400 list price and the $400 list price may not be that high when you compare it to other high end marine equipment from Victron and others. The Victron battery monitor is not expensive but other Victron stuff is typically high priced reflecting the reliability and ruggedness required in the commercial marine market.

[Arlo]

Am I correct that the Smartguage could potentially work in the 24v Etrek setup, which is not compatible with a shunt-based meter?

[gregmchugh]

I don't think it will work with that setup with 2 batteries under the hood and 6 in the rear. As I recall there are separate grounds for the two sets of batteries. A call to Balmar would verify it.

[booster]

A bit older thread, but some other discussions have pointed out some things that should probably be here also, in case someone looks here.

Re the Smartgauge and Peukert discussed earlier. Smartgauge says this in their literature:

1. Firstly, there is the problem of a certain Mr Peukert (see Peukert's Equation). Peukert's equation quantifies how heavier discharges actually remove more power from the batteries than a simple "Amps X Time" calculation would show. What this means for the amp hours counter is that, assuming the example given above worked, then doubling the discharge current would give erroneous results.
For instance, discharging at 20 amps for one hour from a 100Ahr battery, the amp hours counter would have accumulated -20Ahrs. However, according to Peukert's equation the true figure would be much higher. Around 30 amps with a typical Peukert's exponent for a deep cycle battery. So now, after one hour of dishcharge at 20 amps, the amp hours counter reads -20Ahrs but in actual fact the battery is at -30Ahrs. When the charger is switched on (the same 10 amp charger as before), after 2 hours the amp hour counter will have accumulated 20 amps total charge so will be reading 0Ahrs, indicating that the batteries are full. In actual fact the batteries are at minus 10Ahrs.

From the discussion here, it would appear that this is totally inaccurate. It really doesn't matter how fast you discharge the 20 amp hours in the example. The battery will always have the same amount left in it. If you recharge the 20 amp hours after the whatever discharge rate use, it will take 20 amp hours plus whatever the charge efficiency of the batteries is in all cases. If they have this built in to their algorithm, they will not be giving accurate results.

[markopolo]

Similar observation here: Battery charging/alternators tech info

[markopolo]

The key factor in making sure a lead acid battery is fully charged is ending amps. Booster has been patiently explaining this to us for a long time now.

It really is that simple. I like to see it down to one amp in or less but some batteries may not go that low.

[booster]

I really like this kind of discussion, which can "inspire" a much closer look at some of the literature, tests, and personal experience that people have. The Smartgauge is no exception to that, and it is interesting.

What it looks like to me is that the user information for the Smartgauge is very positive, with users saying it is very accurate. Of course they got the Smartgauge because they don't know their state of charge accurately, so there is little reference for that determination. They don't, however, wind up with dead or quickly failed batteries, so the Smartgauge is probably doing pretty well. It runs primarily on voltage, it appears, so it would be pretty easy to make it on the safe side.

I have read a lot of what I could find on independent testing of the Smartgauge and it also is pretty positive. The testers run into the same issues as the users in having a proven, accurate, reference for SOC, and wind up using repeated capacity tests, amp hour counters, well controlled amp based charging, and very importantly fixed discharge rates. The fixed discharge rates, and the repeated capacity tests which take the batteries dead, are way off from real world use, so could skew results. Of course this affects only the reference SOC, not the Smartgauge. It would be interesting to see how the Smartgauge reacts to the highly varied loads that many of us have, which can be from a few tenths of an amp, to several hundred amps. Of interest is that the controlled tests showed fairly large inaccuracies on the recharge side, with the Smartgauge saying the batteries were full substantially early. If you were controlling your charging based on what the Smartgauge tells you, the batteries would be chronically undercharged. If you had a amp based transition charger doing the recharge, it would not be an issue.

From all this, the Smartgauge is likely to give decent information about SOC, and certainly be better than idiot lights, or unmodified voltage that has loads on. I would guess it could be accurate in the same range as a rested voltage, which isn't all that bad, and plenty good enough for what most people do. The biggest thing, I think, is that it is very easy for the non tech folks to use, even though it doesn't really tell you have much power you have left in real terms because you don't know the capacity that the % is based on. It is also very expensive and doesn't allow you to see amps which can be very useful.

Of the biggest concerns to me with Smartgauge have to do with their tech literature, as mentioned earlier. There is so much inaccurate information there, supposedly written by the inventor of the Smartgauge, that it makes the claims of performance immediately suspect. It is hard to understand how there can be that many inaccuracies in the literature, and still have the unit be extremely advanced and technically sound.

As has been mentioned many times, the downside of Smartgauge is the same as the upside, in that it tells you SOC. You don't know what you capacity was when you started discharging, so you don't know how much you have used or how much you have left in amp hours or watts. To be able to know the capacity, you would have to do a drawdown test occasionally, which would be tough because you wouldn't have a ammeter in the circuit. This is similar to what Smartgauge says is so bad about a shunt based monitor's accuracy, but they really both have the about the same shortcoming in this manner. Which would rather know, a % of an unknown capacity, or how many amp hours you have taken out of an unknown capacity? Both have the problem of you not knowing how many amp hours you can still use, unless you have tested the capacity recently.

[booster]

I will throw this out here, as it kind of can apply to both the Smartgauge and the shunt based monitors. As mentioned above, having the correct battery capacity is the critical piece of information you need to have, but I really don't like draw down capacity tests, as they take the battery all the way to 10.5 volts (under some load) which isn't really good for the battery.

We still have batteries that are fairly new and with very few cycles on them, so they will probably be a good long term test setup, as we can repeat the test as the batteries age.

I think what may work, to periodically check your battery capacity, would be to do a drawdown test at the 20hr amps rate, to whatever voltage the Lifeline chart says the voltage should read with that amp draw and the batteries at 50% SOC. At that point, you can look at AH used to get there, and just double it for the actual battery capacity at the 20 hr rate. If you then disconnect the batteries from all loads and let them rest for 4+ hours, Iyou should be able to check their rested voltage against that Lifeline chart to see what the SOC is. Hopefully, both state SOC will be the same (within reason), or close to each other, to confirm accuracy, but we will see about that. I don't know which would be considered the most accurate method.

You should be able to do the same procedure with the Smartgauge, and just use a good clamp on ammeter and voltmeter. I don't think being a little bit off on the 20hr rate amps would be significant error in the overall results.

Once you know actual capacity, both types of meter get much more useful. At that point the shunt based meter gains a bit of advantage because you can program in the right capacity.