Balmar SG-200 Battery Monitor

[noelex 77]

Originally Posted by SVHarmonie

I have to say, I am baffelled why a measurement of Amp-hours is important to people. If you trust the SOC %, and you REALLY wanted to know the Amp-hours used, just multiply...

The biggest problem is that the % display often only has two significant figures. In my case the steps are therefore in 6 AHr jumps. This is too coarse. It is enough to know the state of the battery, but not enough to know if an intermittent or variable load is producing a net gain or loss.

Ignoring the resolution problem, while the mental arithmetic to derive the AHr deficit is not difficult, we don’t know the assumed battery capacity, so it is impossible to calculate accurately. Personally I find AHr deficit to be the more useful number and it seems strange not to offer this as an option for people that feel the same way.

The Balmar has some excuse in that the AHr deficit would need to derived from the %SOC, introducing a further source of error. The opposite is true of most battery monitors: the AHr deficit will always be the more accurate information.

[sailinglegend]

Originally Posted by SVHarmonie

I have to say, I am baffelled why a measurement of Amp-hours is important to people. If you trust the SOC %, and you REALLY wanted to know the Amp-hours used, just multiply.....

I totally agree....

There was a very short thread called Amp-Hour counting started by Balmar Product Manager Witzgall on 7th April 2020 @https://www.cruisersforum.com/forums/f14/amp-hour-counting-232505.html

He asked:

One of the most requested features for a future update of the SG200 is amp-hour counting. We are getting ready to work on this for the next release. I would like to solicit some feedback and help in understanding what people want, how they use what the have now (If another vendor's product) and what they would like to have.

You responded to Witzgall and so did I but I'm afraid my long posting killed the thread, but I still think it is worth seeing what he was planning and maybe this SG 200 thread will keep the discussion going - and hopefully explain to readers why Ah counting is so inaccurate.

Let me add here a short clip from my posting:

[QUOTE=sailinglegend;3119810]
I’m a little confused as to why your are attempting to add Amp hour readings to your SG-200 when you already know that all shunt based Battery Monitors are inaccurate when Ah counting - which is why the original SmartGauge was invented in the first place.

I refer to your own post on the bloated Balmar SG-200 Battery Monitor thread.

[QUOTE=witzgall;3111261]
Originally Posted by witzgall
...When choosing the data to show on the SG200, we purposely omitted AH remaining, or Ah consumed, and similar counters. This was not a blind decision, there is some reasoning behind this. For instance, in our testing, showing AH remaining can be misleading, often quite so.

Chris

So why did you changed your mind Chris and why didn't you keep that thread going?

I'm a great believer in Balmar products and the original Merlin SmartGauge which I have had for 14 years.

[mlydon]

My apologies - the reading i was discuasing was actually the hours remaining, not the percentage. Latest firmware says they have adjusted all battery chemistriea to reporr hkurs remaining is to 50%. I would prefer to be able to set rhar ro choice... Such as 30 hrs remaining until 30% as opposed to 50%

And id like to see ah used just to assure myself the SOC% was accurate, or at least fully understood. If i had a 75% soh and a 75‰ soc on a 400ah bank, how many ah do i actually have to play with, if you see what i mean...

Matt

[Peeew]

For me the main reason for wanting amp hours used (hopefully per 24 hour period or setable time frame) is for planning purposes. Upgrading batteries, solar etc is a lot easier with hard data on what I use rather than estimate.
But, the new update went well and I had never tried naming my devices before. So far the system is stable and seems to work well. Waiting to get through a few learning cycles now and see what I get.

[witzgall]

We will be adding the ability for a user to change the discharge floor in a forthcoming release.

AH remaining too, which I think is what you were also asking for. It will part of the amp hour counter when we get that added in.

Chris

Originally Posted by mlydon

My apologies - the reading i was discuasing was actually the hours remaining, not the percentage. Latest firmware says they have adjusted all battery chemistriea to reporr hkurs remaining is to 50%. I would prefer to be able to set rhar ro choice... Such as 30 hrs remaining until 30% as opposed to 50%

And id like to see ah used just to assure myself the SOC% was accurate, or at least fully understood. If i had a 75% soh and a 75‰ soc on a 400ah bank, how many ah do i actually have to play with, if you see what i mean...

Matt

[lateral]

Major change to SOC on my 464Ahr FLA's with latest FW, much more accurate.

[Peeew]

I’ve been through a few charge discharge cycles since I updated. Still showing 72% SOC and 100% SOH when fully topped up. Hoping to see better numbers soon.

[lateral]

So its reaching 1%C amps and still showing 72%?
Mine was dead on 100% when I hit the configered
tail with previous FW.
But the SOC dropped off a cliff with no load after a week.
Hoping this cycle will be to spec.

[Peeew]

Yes close to 1% anyway. I’m going to try shutting off my solar and run the batteries well down and then let it sit on shore power charger for a day or two and see if that educates it. I’ve been wondering if perhaps my solar charger programming is fouling up the learning so far. But at least the communication glitches were fixed on this update. When the amphours used becomes available I think the additional info will be helpful.

[mikedefieslife]

Originally Posted by SVHarmonie

I have to say, I am baffelled why a measurement of Amp-hours is important to people. If you trust the SOC %, and you REALLY wanted to know the Amp-hours used, just multiply...

I am pretty sure if you actually read your manual you will see that 0% SOC is actually 0% SOC. Why would you want it to be anything else?

Probably because the SOC on battery monitors is well reported to be wildly inaccurate for lithium LiFePO4 batteries, and also for all chemistries whilst there is any load or charge on the batteries. With coulomb counting if everything is setup correctly you get a much more accurate figure as to where your batteries are.

[two-rocks]

“Much more accurate” for coulomb counting depends on some variables that can be not-so-accurate.

My state of charge for a 300ah LiFePO4 bank has been very good, maybe even better than very good.

I like the device, but purchased it before the LiFePO4 bank....and was planning on lead acid. The device has had some hiccups that I find less than desirable. Had I known a LiFePO4 bank was in the works i would have paired the system with a victron monitor. (I already have lots of very reliable victron gear)

[lateral]

Yes, the Victron 712 offers data logging, which for me is appealing.
Just shows market hype, awards etc, before user proof isn't the way to judge a product.

[Peeew]

I ran my bank of batteries again down to a 50% reading on the SG200. Then I left it on shore power charger overnight. Now it shows 82% and floating while taking 0.45 amps. Seems like a full charge to me. Should it still need more cycles? Is it possibly really only at 82% with this low absorption? The bank is 5x 116 amphour G31 Firefly batteries and using two Cristec 40 chargers.

[SVHarmonie]

Originally Posted by Peeew

I ran my bank of batteries again down to a 50% reading on the SG200. Then I left it on shore power charger overnight. Now it shows 82% and floating while taking 0.45 amps. Seems like a full charge to me. Should it still need more cycles? Is it possibly really only at 82% with this low absorption? The bank is 5x 116 amphour G31 Firefly batteries and using two Cristec 40 chargers.

It certainly IS possible, depending on exactly how your battery chargers are deciding to end the absorption phase.

What is your absorption voltage set point? At 82% SOC, a healthy 580 A-hr bank of Firefly batteries should still be able to accept all your chargers can put out not really tapering off until close to 90%SOC...

How many cycles do you have on your SG200 since it was installed or last reset or upgraded? What is your battery capacity set to? How about the charge voltage and taper current?

I would cycle your battery chargers off, and reset them so they start over with bulk. See what happens.

---------------edit-------
I was just about to post an update, when I see that Chris from Balmar beat me to it... What he says. Combine that with what Mainesail posted, and you have the braintrust getting you the answer. Your battery charger is NOT fully charing your batteries. Your SG200 has paid for itself already.

[Maine Sail]

Originally Posted by Peeew

I ran my bank of batteries again down to a 50% reading on the SG200. Then I left it on shore power charger overnight. Now it shows 82% and floating while taking 0.45 amps. Seems like a full charge to me. Should it still need more cycles? Is it possibly really only at 82% with this low absorption? The bank is 5x 116 amphour G31 Firefly batteries and using two Cristec 40 chargers.

Many Cristec chargers drop to float 4 hours after turning on, regardless of what SoC was achieved before dropping to float. If the charger drops to float before absorption is finished the last bit of charge can take days not hours to complete.

If you dropped to 50% this means 290Ah's need to be replaced plus a bit for charge efficiency.

So, 4 hours X 40A = 160Ah, unless you hit absorption, then you would be storing less than 160Ah in the batteries before dropping to float. For this I will assume one 40A charger as we don't know how they are wired or if one charger is sensing the other and shutting down.

290Ah (50% SoC) + 160Ah = 77.6% SoC

Not all chargers are created equal. 82% SoC can be realistic with a charger that drops to float based on an egg-timer type algorithm.