I have 4 180w solar panels. 2 of the panels are on the bimini each ran through their own Victron 75/15 controller and 2 Inverness the davits hooked up in series ran through a Victron 100/20 controller. They all run to a blue sea 5025 fuse block and then to the batteries. When my Balmar smartgauge hits 90 percent they go into float and the gauge will not get to 100 unless I run the engine. Do I need each of them separate to the batteries or is the smartgauge not giving me a good reading?
Solar
- Thread starter Southpaw
- Start date
The Smartgauge is probably giving you the correct reading. It takes a long time to go from 90% SOC to 100% SOC.
Some controllers and regulators have a time limited absorption phase. Not sure about the Victron, but I would check the manuals to see if there is a time limit. Another factor might be the time of day, there may not be enough sunlight to drive the panels to a higher voltage.
Some controllers and regulators have a time limited absorption phase. Not sure about the Victron, but I would check the manuals to see if there is a time limit. Another factor might be the time of day, there may not be enough sunlight to drive the panels to a higher voltage.
I have the absorption set at a max of six hours. Even when there was no big draw on the batteries after a couple of days when I would go down to the boat the smartgauge would read 96 percent. I thought this was just because I just installed the smartgauge and it needed a couple of draw downs to learn the batteries.
The SG is not - it's hard to use the correct word here - reliable, useful, dependable, accurate ??? when using solar.
It is all of those words when discharging.
Maine Sail has mentioned this many times:
Quote from: ChrisOB on April 17, 2018, 09:10:28 PM
Also, don’t expect the ‘smart’ gauge to work well with a solar setup, it’s a marketing gig. Use a victron and check your resting voltage at midnight. Save yourself a few hundred bucks.
Reply from Maine Sail:
I have lots of these out there working extremely well with solar. You really only need to know your SOC once or twice per day and you'll know that once the sun goes down and before the sun comes up. After that you may see a 10% +/- discrepancy. Still much better than the accuracy of the majority of Ah counters I come across..
It is all of those words when discharging.
Maine Sail has mentioned this many times:
Quote from: ChrisOB on April 17, 2018, 09:10:28 PM
Also, don’t expect the ‘smart’ gauge to work well with a solar setup, it’s a marketing gig. Use a victron and check your resting voltage at midnight. Save yourself a few hundred bucks.
Reply from Maine Sail:
I have lots of these out there working extremely well with solar. You really only need to know your SOC once or twice per day and you'll know that once the sun goes down and before the sun comes up. After that you may see a 10% +/- discrepancy. Still much better than the accuracy of the majority of Ah counters I come across..
Interesting thread and comments. I wonder if the issue for the SG is the different charging profiles from solar, alternator, and battery charger. The differences might be confusing the SG.
No and Yes at the same time.
The SG is not good when charging sources are present. Most people off the dock and shorepower without solar can see what's happening using the SG all the time because their batteries are being DIScharged.
With solar working all day, even without sun out, the system is being CHARGed all the time, when the SG doesn't work so well.
It's that simple. Nothing to do with profiles or anything else.
Dave and others, I don't have a SG, but I do a LOT of reading.
Most of us know about Maine Sail and his excellent reputation. He tested and sells SGs. On his website he says this about them:
During Charging:
It means that I did see the Smart Gauge get a bit confused when the bank was being charged. It can’t really track the capacity of a battery charger now can it…? However we are only talking about 10-12% variation from the Ah counters during charging, and not a huge deal when you consider how simple this battery monitoring unit is. Another issue with tracking SOC during charging is charge efficiency variations, so it was much easier to do this testing on the discharge side of the equation.
As soon as the charge source was discontinued, the Smart Gauge fairly quickly identified the accurate SOC of the bank, and was back within approx 2% – 3% of the two painstakingly calibrated Ah counters.
This question keeps coming up, over & over again, from people with solar on this and other boating forums. Why folks can't either get the message (it's been years) or go to "The Source" i.e., Maine Sail, is beyond me. Heck, the people asking the questions have already BOUGHT the darned things. Why are they asking? Oh, wait, for many other basic issues how many times do we need to suggest RTFM? [Brian, F still stands for Funny]
I'm pretty sure this issue isn't covered in the SG "manual" but MS sure covered it and many folks found out about it from him. I'll leave it up to an owner of one to see if they mention it.Maine Sail wrote this on our C34 website last week or so in response to a comment about solar and SG:
I have lots of these out there working extremely well with solar. You really only need to know your SOC once or twice per day and you'll know that once the sun goes down and before the sun comes up. After that you may see a 10% +/- discrepancy. Still much better than the accuracy of the majority of Ah counters I come across...
Last edited:
Stu,
The SG uses an algorithm to calculate SOC based on some 400+ data points. The algorithm is of course proprietary, but we can deduce that some of the data points involve voltage and time. From the SmartGuage website (the original one, not Balmar's) http://www.smartgauge.co.uk/sgadesc.html
http://www.smartgauge.co.uk/limits.html
Consider 3 different scenarios, the one constant being a sudden increase in current demand such as a refrigerator starting up.
1. There is no charging source, so the battery voltage drops.
2. There is a charging source, that has less capacity than the refer draws, say 20 amp charge source, but a 30 amp draw. There is a voltage drop, but not as deep as in #1.
3. There is a charging source that can supply both the refer draw and continue charging the battery, say a 50 amp charger with a 30 amp draw. There is no voltage drop.
The SG has no idea what the current draw and supplies are, but does know that voltages are changing in each scenario. To the SG, the voltage changes will appear random and that information will get fed back in to the modeling and the algorithm. The more the charging sources vary and the more the demand varies the more random the results. The SG tries to compensate for this by high sampling rates, which is why it becomes more accurate over time.
So the simplistic answer is that the SG doesn't work so well with solar. The better answer is that because of the algorithm that calculates SOC relies on voltage and time and cannot measure current, it will be less accurate while being charged than while resting or being discharged. Thus, once the charging source has been disconnected (by turning a switch or the sun going down) the SG can better calculate the SOC based on both a "standard rate of voltage decay for batteries of a specific type" and the installed battery's historical rate of decay
The SG uses an algorithm to calculate SOC based on some 400+ data points. The algorithm is of course proprietary, but we can deduce that some of the data points involve voltage and time. From the SmartGuage website (the original one, not Balmar's) http://www.smartgauge.co.uk/sgadesc.html
As MS notes, the SG can't measure capacity, however, it seems likely that it can track voltage variations over time at the battery and from there it can calculate the SOC. Since the algorithms are self-correcting, they will become more accurate is the conditions are stable, i.e., if charge and discharge rates are relatively constant. SG acknowledges this; when there are high rates of discharge the calculated SOG may not be accurate.
http://www.smartgauge.co.uk/limits.html
When the data becomes more erratic, then the SG's accuracy is going to be affected. As a result, the SG will become "confused" and take more time to sort things out. Which is essentially what MS and I both said in slightly different terms.
Consider 3 different scenarios, the one constant being a sudden increase in current demand such as a refrigerator starting up.
1. There is no charging source, so the battery voltage drops.
2. There is a charging source, that has less capacity than the refer draws, say 20 amp charge source, but a 30 amp draw. There is a voltage drop, but not as deep as in #1.
3. There is a charging source that can supply both the refer draw and continue charging the battery, say a 50 amp charger with a 30 amp draw. There is no voltage drop.
The SG has no idea what the current draw and supplies are, but does know that voltages are changing in each scenario. To the SG, the voltage changes will appear random and that information will get fed back in to the modeling and the algorithm. The more the charging sources vary and the more the demand varies the more random the results. The SG tries to compensate for this by high sampling rates, which is why it becomes more accurate over time.
The SG likely measures the voltage decay after charging and uses this to calculate the SOC. In a real life situation, what happens during solar charging late in the day? The controller may maintain an absorption voltage, but be unable to supply an appropriate level of current. The SG only sees the voltage and knows nothing about the current supplied. We don't know how that affects the algorithm.
So the simplistic answer is that the SG doesn't work so well with solar. The better answer is that because of the algorithm that calculates SOC relies on voltage and time and cannot measure current, it will be less accurate while being charged than while resting or being discharged. Thus, once the charging source has been disconnected (by turning a switch or the sun going down) the SG can better calculate the SOC based on both a "standard rate of voltage decay for batteries of a specific type" and the installed battery's historical rate of decay
Dave,
You should be paid for that thoughtful, useful and reasonable presentation. It's one of the best I've yet read about how the SG works [or may work]. And, as you said, it's a proprietary algorithm that no one knows about. Since we all "may" guess as to what it's doing, 'cuz the inventor ain't sayin', your description makes the most sense.
Thanks.
You should be paid for that thoughtful, useful and reasonable presentation. It's one of the best I've yet read about how the SG works [or may work]. And, as you said, it's a proprietary algorithm that no one knows about. Since we all "may" guess as to what it's doing, 'cuz the inventor ain't sayin', your description makes the most sense.
Thanks.
Stu, Thanks. I'll PM you with the address to send the check.
At it's core, the algorithm is likely a regression formula, something like
SOC = (a mess of variables) +/- an error term. An elaborate form of that formula you learned in high school algebra, y = mx +/- b.
Digging into the Balmar Manual and the original tech info, we can be pretty sure that they are measuring voltage and time. After that they incorporate the Peukert formula and probably have a table of standard values for different types of batteries. For example, there is probably a formula or table of values for how long it takes for a FLA battery to return to its resting voltage from various charging voltages. There is probably another table or formula that calculates the age of the battery or how much capacity is lost over time and that is factored into the equation.
The algorithm then calculates the SOC and a few milliseconds later calculates it again and compares the two. And then modifies some variable to account for the difference and repeats, and repeats, and repeats... Each time moving closer to the "real SOC value."
The process is probably not that dissimilar to the statistical processes that social scientists, medical researchers, agricultural researchers, and quality control researchers use; a not so simple factor analysis and multivariate analysis. Same sort of math. I once dove into this pool, nearly drowned in the process.
So, about that check......