Smart Battery Monitor?

[McGinnis]

Would the Blueseas VSM not cover these bases? It's what we had on our Ericson 38 and we're able to monitor quite literally everything.

https://www.bluesea.com/products/1801/Vessel_Systems_Monitor_VSM_422

[Dockhead]

Originally Posted by conachair

How does monitoring the voltage tell you when the batteries are charged without knowledge of the current going in?
The voltage will sit constant for hours at absorption before that batteries are charged?

And that's the whole problem!


The way I do it:

I just know that with my particular charger, it takes about 3 hours to get from the start of the absorption cycle to 85% charged, which is where I generally stop if I'm using the generator.


I guess that it would be possible to combine the SmartGauge technology with some analysis of current going in, to estimate SOC achieved during charging.

Basically since the SmartGauge technology knows extremely well what the SOC is on discharge, you could have it "learn" time and current during charging vs SOC achieved. So after a number of cycles, the device would be able to anticipate what will be when the charger is shut down, even in the middle of the cycle.

The same "learning" process would keep the device reading correctly as the batteries age. Would be cool. SmartGauge II.

[Dockhead]

Originally Posted by sailinglegend

I have been giving you facts direct from the owner of the Smartgauge brand who I know very well - Jason Hortop MD of Merlin Equipment.



This is incorrect - as pointed out by another poster - but Smartgauge does more than just read voltage which is why you do need a heavier gauge wire. Please read the Smartgauge manual.


This is also incorrect see this link:

Battery State of Charge Determination

One quote from here on Voltage Vs SOC tables:

Estimation Accuracy of SOC Estimates Based on Look Up Tables

"Manufacturer's claims of SOC accuracy of better than 5% are typical but this seems hard to justify considering the factors outlined here and errors may diverge even more as the cells grow older."

Also see the Lifeline AGM manual :

Under SOC % Vs OCV Tables page 28:

"The voltages are approximate and give an indication of a battery at rest. As the battery ages these voltage measurements will be lower."

One final fact - The M1 Abrahams tank has just had major upgrades to its battery monitoring equipment by Merlin (US) based on the Smartgauge technology, which is now 10 years old.

For the avoidance of doubt, I want to drill into the "facts" presented here -- since I have been accused of "denying" them.

1. SmartGauge uses heavier wire.

So what? Not even any theory is offered, as to why, much less any fact.


2. "Manufacturer's claims of SOC accuracy of better than 5% are typical but this seems hard to justify"

This is not about voltage and lookup tables -- it's about amp-counting battery monitors. Completely irrelevant to the question of how SmartGauge works and whether or not it is better than using a lookup table.


3. "The voltages are approximate and give an indication of a battery at rest. As the battery ages these voltage measurements will be lower."

This is something I did not know. Now we see one possible reason why SmartGauge might be using impedence spectroscopy -- IF it does. Impedence spectroscopy is apparently not practical for determining SOC (see: http://batteryuniversity.com/learn/a...ate_of_charge; you need a large load of exact amperage), but this technique works extremely well for determining age and remaining capacity of batteries. I have an expensive Argus battery analyzer which uses this technique. It could be that SmartGauge uses this to come up with a correction for cell age, and if so that would be cool and perhaps actually useful.

But in any case -- the open circuit voltages vary little enough over the life of at least an open circuit battery, that this technique works well. I have used it on Trojan batteries both at the end of their lives and new ones, and got more or less equal results vs. specific gravity. So within the margin of error of SG readings, probably.


As a "fact", again -- this tells us nothing about SmartGauge. Not even any hypothesis is offered, about how SmartGauge overcomes the cell aging problem, IF it does.


4. SmartGauge technology is used in new Abrams tanks.

So what? And Victron monitors (which I have and consider to be useless) are used in new Oysters. These are not "facts" which have even the slightest relevance to the question.

[conachair]

Originally Posted by Dockhead

And that's the whole problem!

Thus the comment somewhere about getting a system to get your batteries back to full charge every day before messing about with to the nearest 1% monitors.
Then with the money saved in trashed batteries get something

[Dockhead]

Originally Posted by conachair

Thus the comment somewhere about getting a system to get your batteries back to full charge every day before messing about with to the nearest 1% monitors.
Then with the money saved in trashed batteries get something

Absolutely

I've said it before -- we have to ask ourselves -- how much accuracy do we need in this, and how do we incorporate what we know, into how we manage our batteries.

The reason why I hate amp-counting battery monitors is because they give a totally false idea of WHAT you know about what's going on with your batteries. You don't know at all, what you don't know, but you are led to think that you do.

We don't really need to know to any great degree of accuracy, what SOC we have achieved with any given generator run. Knowing this approximately is perfectly OK in the real, practical world.

We don't really need to know to any huge degree of accuracy, what SOC we are down to, when discharging -- we just need to be warned when the SOC is down to a level which is dangerous to our batteries. We need to be sure that this warning doesn't come too late, but if it comes a little early that's not a big problem.

But accuracy during discharge is usable, even if it is not critical, because it may allow us to use a bit more capacity of the bank without damaging the batteries.

As I interpret it, what all this means is:

1. Amp-counting monitors are altogether the wrong tool for the job.

2. SmartGauge does well, that thing which is important, and is very convenient.

3. Simple voltage reading, even if it were significantly less accurate (but my tests show it is not), is plenty good enough, because it CANNOT give you an error in the wrong direction. All errors (from having too much voltage sag for example due to reading with too much load on) are in a harmless direction.

[sailinglegend]

Originally Posted by Dockhead

For the avoidance of doubt, I want to drill into the "facts" presented here -- since I have been accused of "denying" them.

1. SmartGauge uses heavier wire.

So what? Not even any theory is offered, as to why, much less any fact.....

The BALMAR manual tells you why:

"Smartgauge uses just two wires to monitor the battery. Through these wires, we use proprietary test
methods to generate data. This data is then compared to detailed computerized battery models.
Smartgauge compares real world data with those models to generate information on the battery’s state
of charge. In independent testing Smartgauge was found to be within 5% accuracy at all times.


2. "Manufacturer's claims of SOC accuracy of better than 5% are typical but this seems hard to justify"

This is not about voltage and lookup tables -- it's about amp-cnounting battery monitors. Completely irrelevant to the question of how SmartGauge works and whether or not it is better than using a lookup table.....[/QUOTE]

The heading for this quote is:

Estimation Accuracy of SOC Estimates Based on Look Up Tables.

You just don't read theses links properly and rant and rave that they are irrelevant!

3. "The voltages are approximate and give an indication of a battery at rest. As the battery ages these voltage measurements will be lower."

This is something I did not know. Now we see one possible reason why SmartGauge might be using impedence spectroscopy -- IF it does.....[/QUOTE]

Hurrah,

4. SmartGauge technology is used in new Abrams tanks.

So what? [/QUOTE]

If it didn't work they wouldn't be using it, nor would other service vehicles around the world!

Another fact - there will never be Smartgauge II with a shunt because they say you don't need one. So many people install shunts I ncorrectly anyway, Smart gauge is easy to install which is why it always works.

[Dockhead]

Originally Posted by sailinglegend

The BALMAR manual tells you why:

"Smartgauge uses just two wires to monitor the battery. Through these wires, we use proprietary test
methods to generate data. This data is then compared to detailed computerized battery models.
Smartgauge compares real world data with those models to generate information on the battery’s state
of charge. In independent testing Smartgauge was found to be within 5% accuracy at all times.


2. "Manufacturer's claims of SOC accuracy of better than 5% are typical but this seems hard to justify"

This is not about voltage and lookup tables -- it's about amp-cnounting battery monitors. Completely irrelevant to the question of how SmartGauge works and whether or not it is better than using a lookup table....

The heading for this quote is:

Estimation Accuracy of SOC Estimates Based on Look Up Tables.

You just don't read theses links properly and rant and rave that they are irrelevant!

3. "The voltages are approximate and give an indication of a battery at rest. As the battery ages these voltage measurements will be lower."

This is something I did not know. Now we see one possible reason why SmartGauge might be using impedence spectroscopy -- IF it does.....

Hurrah,

4. SmartGauge technology is used in new Abrams tanks.

So what?

If it didn't work they wouldn't be using it, nor would other service vehicles around the world!

Another fact - there will never be Smartgauge II with a shunt because they say you don't need one. So many people install shunts I ncorrectly anyway, Smart gauge is easy to install which is why it always works.

Ho hum. I like SmartGauge -- you like SmartGauge. This frenzy of hostility against any criticism of the device, even by someone who likes and recommends it, reminds me of Bolsheviks slaughtering their own kind in the '20's and '30's. I don't think this kind of fanaticism will do anything to win anyone over.

I still say that not a single actual fact has been offered here.

"Proprietary test methods generate data." This is just hype. What methods? What data? Used in what way? This is just an invitation to believe in PFM.

Concerning the link about "Estimation Accuracy of SOC Estimates Based on Look Up Tables." You should read the links you post, and not just put them up and call it done. This chapter is about COLUMB COUNTING -- i.e., amp counting. There is more than one kind of Look Up Table, and this has nothing whatsoever to do with evaluating SOC using voltage, as I wrote.

Concerning Abram tanks -- total irrelevance. We are asked to assume that you use Abram tanks like we use our boats (false), and that we can rest assured that the choice of this device by the Defense Department proves that this is the right choice for us (false). Far more persuasive is the choice of Victron by Oyster -- because the use is the same, and the Oyster guys are high quality engineers from our field. But they chose the Victron -- everyone makes mistakes.


And the last thing I especially love, and which characterizes this discussion --

"There will never be a SmartGauge II with a shunt because they say you don't need one." ROTFLMAO! I think it's not even necessary to comment on that "fact".

[a64pilot]

Only way I know of to tell if your bank is fully charged is to watch its acceptance rate at absorption voltage, for my Lifeline bank that is 1/2 percent of capacity I think or 3.3 amps for my 660 AH bank.
So I know if I have a 15 amp load on the bank, when my battery charger gets to 18.3 amps at absorption voltage, my bank is at 100% and its time to go into float. So you have to know three things, rate of charge, voltage and rate of discharge.
In my case I have a shunt that tells me rate of discharge, both of my chargers tell me voltage and rate of charge, so that is all three things.
Voltage will only give you an idea as to SOC during discharge only when there is no charging occurring and if you use the chart for resting voltage to determine SOC, then that will be conservative. You may not be using all the available power, but you will not go deeper than your target SOC, most use 50%.
But during charging, all a voltmeter will tell you is if your at acceptance of float voltage, or if your current limited at the beginning of the charge cycle

[a64pilot]

FWIW, the Abrams tank is actually used in a very similar manner as our boats.
They are often used on a screen line where their mission is observation with FLIR, this uses electricity and being a turbine engine, they use a tremendous amount of fuel idling, so they shut down and run off of batteries, before I retired they were installing small Diesel generators in the Abrams to run all the electronics with the turbine shut down.
They call them APU's or auxiliary power units.
Knowing your SOC in your bank on an Abrams may be way more important than knowing it in a cruising boat, unlikely someone will sneak up and shoot me in my boat if I let the bank get depleted, but if bad guys are coming and you can't start the tank, you may be in a world of hurt.

[Dockhead]

Originally Posted by a64pilot

Only way I know of to tell if your bank is fully charged is to watch its acceptance rate at absorption voltage, for my Lifeline bank that is 1/2 percent of capacity I think or 3.3 amps for my 660 AH bank.
So I know if I have a 15 amp load on the bank, when my battery charger gets to 18.3 amps at absorption voltage, my bank is at 100% and its time to go into float. So you have to know three things, rate of charge, voltage and rate of discharge.
In my case I have a shunt that tells me rate of discharge, both of my chargers tell me voltage and rate of charge, so that is all three things.
Voltage will only give you an idea as to SOC during discharge only when there is no charging occurring and if you use the chart for resting voltage to determine SOC, then that will be conservative. You may not be using all the available power, but you will not go deeper than your target SOC, most use 50%.
But during charging, all a voltmeter will tell you is if your at acceptance of float voltage, or if your current limited at the beginning of the charge cycle

Indeed!

And that's exactly what's behind my idea for SmartGauge II -- you could do an awful lot, know an awful lot, by calculating the acceptance rate or charging current vs voltage. During charging, that should tell you exactly where you've gotten to. The device could cross-check its calculations against SOC measured by voltage during discharge, and "learn".

Not that we are in such desperate need of such information, but if you wanted to make the perfect battery monitor, I think you need current.


Smart operators like you are able to know an awful lot just by eyeballing the current. I am not able to measure charge/discharge current directly (no shunt), but I do measure AC current going into the charger, which is a reasonable proxy if there are no heavy loads on.

[Dockhead]

A couple of my posts have been edited removing references to one of us as a "fan boy".

This was not at all intended to be offensive, so I apologize for any offense which might have been taken.

In any case, it detracts from the force of any argument, to argue against the PERSON (by characterizing the person, for example), as opposed to the substance of the argument, even if it's done politely, and I should have known better.

[Dockhead]

Originally Posted by a64pilot

FWIW, the Abrams tank is actually used in a very similar manner as our boats.
They are often used on a screen line where their mission is observation with FLIR, this uses electricity and being a turbine engine, they use a tremendous amount of fuel idling, so they shut down and run off of batteries, before I retired they were installing small Diesel generators in the Abrams to run all the electronics with the turbine shut down.
They call them APU's or auxiliary power units.
Knowing your SOC in your bank on an Abrams may be way more important than knowing it in a cruising boat, unlikely someone will sneak up and shoot me in my boat if I let the bank get depleted, but if bad guys are coming and you can't start the tank, you may be in a world of hurt.

That's very interesting. I had forgotten for a moment that the M1 has a turbine engine.

But if they have APU's, and use them while on the kind of duty you described, then why is it critical for them to know battery SOC?

Concerning your last sentence -- surely they have separate start and house banks?


I'm surprised that they are using diesel generators as APU's -- with their budgets, wouldn't fuel cells make more sense? Surely they will care an awful lot about being detected from sound.

[a64pilot]

They were installing APU's when I retired, but didn't have them before, and I am sure that once in a blue moon the APU goes down, then what do you do, take the tank out of service? Operational readiness rates are sort of a very Holy thing in the Military, I doubt they are deadlining a tank cause the generator doesn't work, then there is the noise level of an APU.
Observation posts are called LP/OP which is listening post / observation post. A running APU takes listening out of the equation, and your ears are very important in the dark.
I don't know, but suspect they don't have a "house bank", I don't even know if they are lead acid batteries. I'd suspect by now that they are not, but they may be.
Aircraft forever ago went to Nickel Metal Hydride batteries, but when they all got APU's we went to what we called SLAB batteries, sealed lead acid, the NIMH batteries were a royal pain to maintain, SLABs you toss when they die and stick in a new one.

The M1 tank is a computerized/ electrical machine, where the M60 was mechanical.
We called Tankers DAT's for dumb*** Tankers, when they got M1's we started calling them CDATS, the C being computerized of course.
Lose electrical power and maybe the Commanders 50 cal will shoot, but I doubt anything else will, and you couldn't even call for help.

I bet a fuel call that makes the power required may not exist, I'd guess you have to have 5KW or more to run a tank, but that is a guess

[Dockhead]

Originally Posted by a64pilot

. . .I bet a fuel call that makes the power required may not exist, I'd guess you have to have 5KW or more to run a tank, but that is a guess

If you need 5kW to run them, then they sure as heck are not running them on battery power the way we run our boats at anchor.

If that's the case, then they are totally dependent on the APU's.

[conachair]

Originally Posted by sailinglegend

Another fact - there will never be Smartgauge II with a shunt because they say you don't need one. So many people install shunts I ncorrectly anyway, Smart gauge is easy to install which is why it always works.

Pity really, I would be seriously tempted if it had an amp counter, it would be a tempting one stop device then, as it is it's maybe perfect for day sailors etc but for living off the grid it doesn't do enough to warent either the budget or nav table panel space.