Balmar SG-200 Battery Monitor

[Maine Sail]

Originally Posted by a64pilot

.
However if I didn’t very often charge to a real 100% SOC, I assume it would stray further and further from actual SOC.

Not just the Ah counter but also your battery from PSOC cycling "walk down"...

Originally Posted by a64pilot

I just use it to see what my consumption is in AH, and use the SG reading first thing in the morning to see what my SOC really is.

Excellent..

Originally Posted by a64pilot

I just looked, I can set charge efficiency, however I don’t know what to set it to?
Maybe start at 95% and see what happens? Or leave in auto?

The LINK series monitors and the older Vicron BMV-501 (Identical to the Xantrex XBM) could auto calculate for charge efficiency. The newer Victron BMV's rely on you programming the CEF.


Let's say you program a 90% charge efficiency. On the count down (discharging) it is 1Ah out to -1Ah displayed. On the count up it is 1Ah in to .9Ah counted/displayed or a 10% reduction of delivered Ah's on the count up. Pretty obvious why PSOC cycling throws such a hook into the calculations...

The problem with this is when you charge only in bulk (eg: 50% SOC to 80% etc.), which can easily be 98-99%+ efficient, and you've subtracted 10% (or what ever your CEF is set for) your displayed -Ah figure is no longer accurate.

In other words if you charged for an hour and delivered 100Ah worth of energy to the battery, at a 99% bulk charge efficiency, your actual displayed Ah capacity is now skewed by the CEF count up calculation. Repeat, repeat etc...

The CEF calculation in these units count on you returning to 100% SOC for a total charge efficiency close to what you program it for.

Unfortunately with LA batteries charge efficiency is not at all linear. It is very efficient at low SOC and horribly inefficient at high SOC. Sure the total efficiency might be 90% but that is for a full charge cycle, not the partial cycles many cruisers do..

Also, at low charge rates, solar etc., the battery can charge more efficiently than it does at high charge rates.

[a64pilot]

Attached picture is from my Magnum BMK manual.
There is an auto setting, and I’m using it, now.
Interestingly it seems now that I’m out cruising and cycling my batteries, the bank seems to have gained a little capacity.
I strive to achieve a full charge every day, which takes a couple of hours of generator time on top of my Solar, generator starting early in the morning, before Solar is doing anything.
I have a 660 AH Lifeline bank, and with the battery monitor programmed to a bank size of 650 AH, first thing in the morning both my Smart Gauge and the monitor agree within one or two percent. I rarely discharge below 75% SOC and usually only to 80% SOC. Bank is three years old, I think.
When they drift apart more than four or so percent I’ll equalize.
Lifeline manual recommends an equalization whenever a drop in capacity is noticed, but doesn’t tell you how to recognize that, so I’m making this up on my own.
Also interestingly Lifeline in their manual also publish a SOC voltage chart when the bank is at different loads, my bank seems to run consistently .3 VDC higher than the chart, not sure of the significance of that.

[Paul L]

Originally Posted by a64pilot

.......
When they drift apart more than four or so percent I’ll equalize.
Lifeline manual recommends an equalization whenever a drop in capacity is noticed, but doesn’t tell you how to recognize that, so I’m making this up on my own.
.....

You have two devices that have semi-independent errors in their readings. Neither device has a better than something like +/-5% accuracy outside a lab environment. So I don't see how a difference of 4% can be a reliable indicator.

[witzgall]

Originally Posted by john61ct

Chris,

Could you help us come up with a single term for

"the special things done by the SG200 to calculate SoC"

in other words **in addition to** coulomb-counting,

so we do not need to reference others' products' technology in discussing how the SG200 is different and more accurate.

Without a lot of excess verbiage like "sophisticated proprietary mathematical algorithms comparing to internal database of known chemistries"

Say for example we called it

"AC impedance spectrography" (just an example)

So one could say something like

"The result of the usual AH counting technology, is compared or integrated with the results of the proprietary */AC impedance spectrography/* side, to not only provide a very accurate SoC measurement, but also - uniquely - a State of Health percentage estimate of remaining AH capacity at the 20-hour discharge rate"

?

We call it "Active Impedance Compensation."
Chris

[rgleason]

So this formula is for a rather inaccurate conversion of Reserve Capacity a manufacturer provided number.
Isn't there any way to calculate ah used from the data provided?

[Maine Sail]

Originally Posted by rgleason

So this formula is for a rather inaccurate conversion of Reserve Capacity a manufacturer provided number.

Yes...

Isn't there any way to calculate ah used from the data provided?

Take for example the battery we have on the test bench right now.

2016 Trojan Rated at 130Ah
SOC Tracking within 1-2% accuracy
SOH currently tracking within 1.5% accuracy showing 81% = 103.5Ah (actual SOH =79.6%)

If we know the SOH is about 80% this means it is a 104 Ah battery not 130Ah..

If the SOC says 50% then we know we’ve used just about 52Ah’s....

The best part about the SG200 is that the longer it remains connected the more accurate it becomes. The whole point of adding the SOH feature is so you don’t need to conduct a 20 hour test...

[john61ct]

Originally Posted by witzgall

We call it "Active Impedance Compensation."
Chris

Thanks, that's exactly the phrase I used back in October, so must have picked it up from the Panbo interview.

[john61ct]

Originally Posted by Maine Sail

SOC Tracking within 1-2% accuracy
SOH currently tracking within 1.5% accuracy

If anywhere near that accurate

in general for a wide range of battery types and usage patterns

those are revolutionary, game-changing numbers.

How is your benchmark measured for SoC, observed AH counting?

Does that level of SoC accuracy hold during charging, and / or while drawing down at both high and low fractional-C rates?

[Delfin]

Originally Posted by witzgall

We call it "Active Impedance Compensation."
Chris

I've seen it alleged elsewhere by one person that Balmar reverse engineered this functionality from the SmartGauge. This made zero sense to me and sounded libelous, since the SmartGauge doesn't measure current consumption or acceptance and that is what Active Impedance Compensation is supposed to make more accurate.

Do I understand this correctly?

[john61ct]

The "SmartGauge - like functionality" is the referent I was looking for a label for.

As you say SG did no coulomb-counting, nor does that term have anything to do with it, so I have no idea why you would associate the two.

What the SG200 does uniquely is combine and integrate the results of those two completely separate methodologies in realtime, to achieve greater and more consistent accuracy.

And also uniquely, its SoH calculations.

No aspersions were implied by using the term reverse engineering. Doing so has nothing to do with legal issues, and even if it did, afaic it would be none of our business.

[sailinglegend]

Originally Posted by john61ct

.....What the SG200 does uniquely is combine and integrate the results of those two completely separate methodologies in realtime, to achieve greater and more consistent accuracy.

And also uniquely, its SoH calculations.

There is nothing 'unique' with the SG200. Merlin, the owners of Smartgauge, have been doing this for years commercially with their Data Cell II technology that is used to calculate SoH and SoC to the greater accuracy demanded by the military.

[rgleason]

I hope this thread will remain a cordial, investigation into the differences from other devices and the reporting of the capabilities of the new SG200. Thankyou. There is a lot to learn.

Sailing Legend can you please explain how that can be when there is no shunt with Smartgauge?

[john61ct]

The DataCell II does have a shunt, very different product from SmartGauge.

http://www.merlinpowersystems.com/pr...-data-cell-ii/

[sailinglegend]

Originally Posted by john61ct

The DataCell II does have a shunt, very different product from SmartGauge....]

Data Cell II is Smartgauge technology with a shunt. I have discussed this personally with the Merlin boss James Hortop. They actually set the Smartgauge to 0% when the battery Ah capacity is down to 50% so there is always more in the tank in an emergency for dumb MOD (Ministry of Defence) crew who don't understand that 50% is empty.

So Data Cell II is exactly like the SG200, but much more expensive, so please check your facts before criticising other posts!

[john61ct]

Nothing in your post contradicts what I wrote.

And I criticised no post.