Balmar SG-200 Battery Monitor

[a64pilot]

You can pretty easily determine Capacity / SOH in a lead acid bank with an amp counter and an old style Smart Gauge.
This morning my amp counter said we used 158 AH, and my SG said we were at 74%.
Dividing 158 by .26 gives 607 or so, meaning my 660 AH bank has approximately 607 AH capacity.

One trick is to only use the SOC that the SG displays first thing in the morning before any charging, as it appears that SOC displayed may lag behind actual during charging.

[conachair]

Originally Posted by a64pilot

You can pretty easily determine Capacity / SOH in a lead acid bank with an amp counter and an old style Smart Gauge.
This morning my amp counter said we used 158 AH, and my SG said we were at 74%.
Dividing 158 by .26 gives 607 or so, meaning my 660 AH bank has approximately 607 AH capacity.

One trick is to only use the SOC that the SG displays first thing in the morning before any charging, as it appears that SOC displayed may lag behind actual during charging.

Talked me into it, just ordered one - 99UKP Could be one of the more practical ways to get a fairly accurate handle on how your batteries are really doing for liveaboard cruisers.

That would be an interesting test for someone with lots of test kit, water bath and experience to do

Just how accurate could you get ?

[sailinglegend]

Originally Posted by nebster

Reference to post by john61ct

You seem very confused about what "SOH" means on an SG200.

Thanks for you excellent postings trying to correct some very confusing and misleading ideas on here from john61ct who probably has never seen an 'original' Merlin Smartgauge or even the new Balmar SG200. Many on here believe he probably doesn't even have a boat, or an RV as he refuse to fill in his profile. The site should make this compulsory before you can post.

Originally Posted by nebster

Reference to post by john61ct

...You might want to go back and review some of your latest posts in this thread, because I think you are confused -- and then you confuse us, because we can't figure out what you're writing.... so another thing you might try is (a) downloading the manual and reading it, or (b) buying one and hooking it up and trying it. We'd all be the better for it

I have been back over this thread and I think john61ct would be well advised to follow this advice and go back and read all his posts again and see exactly why the likes of Mainesail are forced into posting comments like these:

Originally Posted by Maine Sail

.....John why do you enter discussions acting as an expert, chronically using absolute statements, when you have little knowledge or practical experience of what you are actually discussing? What you just said above is about as gobbledygook as I have read in a while, it does not even make sense.....

My 2 cents worth on this thread so far is that there are so many errors and confusions here because none of us know exactly what the Merlin Smartgauge or the Balmar SG200 is really doing. Maybe we should close this thread and let those with the systems give their actual feedback on another thread.

My last thoughts:

In 13 years the Merlin Smartgauge never published any firmware updates for new battery types, and yet it has been proved to be extremely accurate, even with the changes in battery technologies since then. This is because the algorithm is 'learning' the characteristics and usage of the batteries.

I think the SG200 uses the same 'kind' of mathematical algorithm to produce an SoC value that is probably as accurate as the Merlin Smartgauge. I don't believe the SG200 Ah counting shunt helps the accuracy of the SoC calculations because too many of the shunts will have been installed incorrectly. That is why Merlin Smartgauge refused to add a shunt to their system. Balmar even compounded this problem with their original RevA and RevB manuals which showed the incorrect wiring of the Starter battery. This would have stopped counting amps when the House Battery was being charged by the alternator.

Often other charging sources or loads may be incorrectly installed at a later date so that they do not go through the Shunt, this will give big errors in the Ah count. These historical differences may show the SoH to be going up as well as down over time may well lead to software updates which could give advice like "ERROR-charging sources have been installed incorrectly, or "ERROR - a new load is not being read by the SG20 shunt". This would be a fantastic and is maybe one of their promised future features.

If Balmar don't keep pushing ahead with this then others like Victron would be mad not to follow with SmartGauges of their own.

[Delfin]

Originally Posted by a64pilot

You can pretty easily determine Capacity / SOH in a lead acid bank with an amp counter and an old style Smart Gauge.
This morning my amp counter said we used 158 AH, and my SG said we were at 74%.
Dividing 158 by .26 gives 607 or so, meaning my 660 AH bank has approximately 607 AH capacity.

One trick is to only use the SOC that the SG displays first thing in the morning before any charging, as it appears that SOC displayed may lag behind actual during charging.

The SG200 calculates what the SmartGuage does (SoC), plus SoH. Owning both, it's unclear to me where the market for the SmartGuage is post release of the SG200.

[a64pilot]

Originally Posted by Delfin

The SG200 calculates what the SmartGuage does (SoC), plus SoH. Owning both, it's unclear to me where the market for the SmartGuage is post release of the SG200.

Only thing that would drive me to purchase one of the newer ones as I have the old one is a Lithium battery bank.
I don’t believe the old one works at all with Lithium, but I think the new one does.

Now the new one does come with a lot more bells and whistles and is I’m sure better, but the old one does everything I need it to do, for me.

[a64pilot]

Originally Posted by conachair

Just how accurate could you get ?

My mentor as a fixed wing test pilot kept telling me that “perfection was the enemy of good enough” meaning that often all you need is good enough. For example do you really need to know oil pressure and engine temp to single digits? Not really, and giving such detailed data often causes confusion, people read more into something than they should, and just because a gauge indicates single digits, is it accurate to single digits?

Me, knowing about what my banks capacity is good enough, I use that to determine when I should equalize.
Close is good enough for me.

[conachair]

Originally Posted by a64pilot

My mentor as a fixed wing test pilot kept telling me that “perfection was the enemy of good enough” meaning that often all you need is good enough. For example do you really need to know oil pressure and engine temp to single digits? Not really, and giving such detailed data often causes confusion, people read more into something than they should, and just because a gauge indicates single digits, is it accurate to single digits?

Me, knowing about what my banks capacity is good enough, I use that to determine when I should equalize.
Close is good enough for me.

To an extent...

Good fun trying to tune out any noise you can though. ISTM knowing what it's like compared to what it was like 6 months ago would be more helpful than compared to some objective industry figures. Certainly for liveaboard on the hook cruisers, batts do seem to tend to fall off the edge a bit when they fail. Knowing that might be soon could be gold dust before setting off across another ocean. I can log amps/voltage/temperature as well which could be interesting, maybe see how close your peukerts number is? Somehow..

[john61ct]

Originally Posted by nebster

You seem very confused about what "SOH" means on an SG200.



SOH is just {SG200-computed-capacity} divided by {a capacity someone typed in when they set up the SG200}.

Yes I agree and have zero confusion about that.

The inaccuracy of using the mfg rating nameplate value for the latter variable is an issue but not one specific to SG200, true for any unit that asks for that input from the user. SmartGauge managed without it, and IMO as an historical data point it should only be relevant to SoH, not SoC,


> The calculated capacity (the numerator above) is as accurate as SG200's black-box learning algorithm can be, which is to say, we have no idea without just observing how it behaves in real life. It might be very accurate, or wildly inaccurate, or somewhere in between.

Yes that is true. That is why IMO the user should be able to set the top 100% point, once, rarely, often or never, as they prefer. Not to have any impact on the SoH calculation, but to see the SoC% count down from 100%, that representing the actual max-Full point of the batt at **this** point in time.


If 100% SoC indeed is left representing a charge point that the batt can never get to, so the readout can never show higher than say 88%

and it's not been confirmed yet that is the case

then sure there may be Reasons, but I personally would see that as a design flaw.

Part of keeping a coulometer-based gauge accurate has always been the user needs to feed a new "actual Ah" capacity number as SoH declines, ideally based on a load test.

If SG200's estimate SoH proves accurate, then that requirement is eliminated, load testing is no longer required, and the frequent 100% reset is also redundant.

But again IMO, it should at least be **possible** to set the SG200 to indicate 100% SoC when the bank is as Full as it can get without overcharging.

Once the actual SoH has declined, i.e. total Ah capacity is lower, then each SoC % increment should represent a proportionally lower number of Ah.

Example: 100Ah actual usable capacity when new, from 10.5V 0% to 100Ah 100% each percentage point 1% represented 1.0Ah.

Now SoH is 90%, 0% is still 10.5V, but 100% readout is now 90Ah above that, each percentage point 1% now represents 0.9Ah.

That is how every SoC meter afaik has ever worked, and IMO that is how I would like SG200 to work.

I do not want anyone to try to convince me otherwise, if that's the way it is I can accept it, so be it. But I'd be surprised.

[rgleason]

This is a good discussion. Here's another particular question about the SG200
2 - T105 FLA in series
1 - SG200
Fully charged to 100%SOC 100%SOH
No load or attachments.

2 days down to 90%SOC
5 days down to 88%SOC 12.8v Clamp meter 12.88v 0.4amps on shunt red wire to + battery.

Should this be expected?

Does the SG200 use power? Yes of course. How much?
The screen probably uses the most power, it turns off.
Then how much does it use?
Is this load significant enough to cause the drop from 100% to 88%?
Is this kind of drop normal for FLA standing in storage basically?

The batteries still are at 12.8v.

[Delfin]

Originally Posted by rgleason

This is a good discussion. Here's another particular question about the SG200
2 - T105 FLA in series
1 - SG200
Fully charged to 100%SOC 100%SOH
No load or attachments.

2 days down to 90%SOC
5 days down to 88%SOC 12.8v Clamp meter 12.88v 0.4amps on shunt red wire to + battery.

Should this be expected?

Does the SG200 use power? Yes of course. How much?
The screen probably uses the most power, it turns off.
Then how much does it use?
Is this load significant enough to cause the drop from 100% to 88%?
Is this kind of drop normal for FLA standing in storage basically?

The batteries still are at 12.8v.

It is supposed to draw 10 mA in sleep mode, so yours is quite a bit higher. I'll check my draw later today and let you know what I am seeing.

If your bank is 225 Ah, and the draw is .4 amps the 90% after 2 days seems to pencil out, but the 88% after 3 more days not so much.

[sailah]

Originally Posted by rgleason

This is a good discussion. Here's another particular question about the SG200
2 - T105 FLA in series
1 - SG200
Fully charged to 100%SOC 100%SOH
No load or attachments.

2 days down to 90%SOC
5 days down to 88%SOC 12.8v Clamp meter 12.88v 0.4amps on shunt red wire to + battery.

Should this be expected?

Does the SG200 use power? Yes of course. How much?
The screen probably uses the most power, it turns off.
Then how much does it use?
Is this load significant enough to cause the drop from 100% to 88%?
Is this kind of drop normal for FLA standing in storage basically?

The batteries still are at 12.8v.

Are you reading the amp draw with the gauge, or clamp ammeter? Depending on the meter, it may not be accurate enough for low amps. When I have everything shut off and no loads, I'm not seeing anything on gauge. 0.4A is a pretty decent parasitic load that you can't account for. I haven't checked with actual inline ammeter but I shouldn't see much load at all other than stereo memory and SG200 screen. But that won't be 0.4A.

I'll leave my shorepower off and no loads for the next couple days and see what I get for SoC since our banks are pretty similar.

[lateral]

Originally Posted by rgleason

This is a good discussion. Here's another particular question about the SG200
2 - T105 FLA in series
1 - SG200
Fully charged to 100%SOC 100%SOH
No load or attachments.

2 days down to 90%SOC
5 days down to 88%SOC 12.8v Clamp meter 12.88v 0.4amps on shunt red wire to + battery.

Should this be expected?

Does the SG200 use power? Yes of course. How much?
The screen probably uses the most power, it turns off.
Then how much does it use?
Is this load significant enough to cause the drop from 100% to 88%?
Is this kind of drop normal for FLA standing in storage basically?

The batteries still are at 12.8v.

How many cycles have you done?
Were they below 75% & back to 100%?
Just curious as going through this stage now.

[rgleason]

I have done 2-3 deeper cycles and several smaller ones due to winter storage basically. I need to get a bigger inverter to put a 10amp load on for awhile and do a good drawdown or three.


I should record this better too. I used the clampmeter on the red wire to the batt+ post to measure the amps.

[Wood]

Originally Posted by rgleason

This is a good discussion. Here's another particular question about the SG200
2 - T105 FLA in series
1 - SG200
Fully charged to 100%SOC 100%SOH
No load or attachments.

2 days down to 90%SOC
5 days down to 88%SOC 12.8v Clamp meter 12.88v 0.4amps on shunt red wire to + battery.

Should this be expected?

Does the SG200 use power? Yes of course. How much?
The screen probably uses the most power, it turns off.
Then how much does it use?
Is this load significant enough to cause the drop from 100% to 88%?
Is this kind of drop normal for FLA standing in storage basically?

The batteries still are at 12.8v.

Irony is still on the hard. The SG200 is connected to 6 235AH older Crown @ 12v. They have been basically float charged all winter. I drew them down ~ 200AH a couple of times. But this was not controlled or to determine capacity.

After a day's work last week I shut off all power and battery switches. SG200 was reading 0.0 Amps, 12.8v, 100% SOC, 100% SOH.

About 12 hours later I returned. 0.0 Amps, 12.7 volts, 75% SOC, 100% SOH. I fired up the charger and they took 20 amps or so for a few minutes to get to 15v [temp compensation]. Absorption lasted less than an hour. When they went to float acceptance was 5amps.

Next time I'll be there is Saturday. Curious what I will find.

I'm just chalking this up to SG200 learning curve.

[rgleason]

Originally Posted by Wood

I'm just chalking this up to SG200 learning curve.

I am guessing that the SG200 when woken up needs to figure out what has happened when asleep. So initially SOH%100 and SOC%100.


Do you know if, when the system has been quiet a long time with no charger attached, what the measured amp drawdown is?