Balmar SG-200 Battery Monitor

[sailah]

Originally Posted by Seaman gagging

Mine has been in place for over a month. So far, the information it is giving seems to be accurate. Installation was not an issue. One stud thread was not machined properly and made the nut very difficult to get on and probably will never come off. I reported it to balmar customer service. I was told they had not heard of the issue and it had to be my fault. Other than that and no blue tooth yet, I would recommend the unit.

The stud issue they know about, i am sure of that. They are using bare stainless and likely galled. I had to hacksaw mine off and switched them to bronze.

[Exile]

Originally Posted by Delfin

I think that is correct. The task this device sets out to accomplish, especially for LFP, seems very complex and the number of variations of chemistry, Ah, charging sources, etc. Is daunting.

In my install, the device is powered directly to the positive terminal of the LFP bank upstream of the BMS, and fused with the supplied inline fuse. The negative directly from the bank is wired 12" away to the shunt with 2 0 copper. The negative distribution part is downstream from the shunt. The amps being consumed, or recharged have been cross checked with the SG200, a clamp on multimeter, and the Link 20. All match. The Link accurately counts Ah used, and whether I am charging at 100 amps from alternator alone, 180 amps from inverter charger plus 3 Sterling chargers, or 280 amps from all of the above I can take the Ah counted by the Link, divide by the charging amps and calculate to within 5 minutes when the batteries acceptance rate will drop below 3%.

If I've made an installation or calibration error, I don't know what it would be.

This sounds exactly how I installed my Victron BM. No, not hard. Also good to hear I can keep my existing BM (which I like) and wire it's shunt downstream from the SG-200 as is recommended. This seems like the best of both worlds -- total consumed amps from the Victron and everything else from the SG-200. I never relied on the SoC reading from the Victron anyway for reasons already discussed. Like others have mentioned, I do find the amp totals helpful in estimating daily usage.

The only installation question I have concerns my SSB which is wired directly to the batteries, and thus obviously upstream from the shunt. I've rarely used the SSB thus far so it hasn't been much of a concern, but could it possibly throw off the SG-200? I'm not concerned about it not counting amps consumed by the SSB, only whether it could somehow throw off SoC & SoH. Wiring a SSB direct to the batts seems to be best practice, but not completely necessary.

[sailinglegend]

Originally Posted by CatNewBee

...JUST MAKE SURE THE NEGATIVE POLE OF The BATTERY HAS ONLY A SINGLE WIRE CONNETED, AND THIS WIRE GOES STRAIGHT TO THE SHUNT....

If it's that simple why has Maine Sail reported so many incorrect shunt-based battery monitor installations??????

With multiple batteries in a bank you have to check each negative stud and make sure they are only common negative wires. So each stud may have one or two negative cables in place!!!

Originally Posted by Exile

...Wiring a SSB direct to the batts seems to be best practice, but not completely necessary....

This is why shunt battery monitors don't read correctly!!!

My SSB takes a small drain to keep the crystal at the correct temperature so that when you switch on it will transmit immediately.

So many installation manuals will say - wire directly to the battery - because high current drains through switches can cause voltage drops.

Problems will also happen later when new kit is installed - either a charger or a load - and the engineer will wire directly to the battery and may not notice the shunt.

[lateral]

I can’t get my head around the sg200 I have yet. Just expected plug & play plus some learning as Rod intimated.
My SOC seems to get more accurate as battery bank discharges. Rested voltage vs SOC.
I still have a feeling the tail amps setting and your “normal” charge tail amps habit have to correlate to get a meaningful SOC..Especially nearing 100%. Maybe algorithms are set up assuming most people only achieve 2-4%C and want to call that 100%? Fuzzy logic?
Once SOH is established, with factory Ahr, it can then count back +_ Ahrs for SOC and time to go with some accuracy.
Dunno.......,but then it’s just an auto coulomb counter.
And it’s supposedly not. Beats me . It’s Winter and not using boat enough.

[john61ct]

Originally Posted by sailinglegend

If it's that simple why has Maine Sail reported so many incorrect shunt-based battery monitor installations??????

He is letting us know that many get it wrong. Not deprecating the basis of the technology, all the BMSs he recommends are indeed shunt based, including selected for his own use, Link Pro, and now SG-200.

Except for Merlin SmartGauge, which has so far been in general most accurate, but only works with lead.

> With multiple batteries in a bank you have to check each negative stud and make sure they are only common negative wires. So each stud may have one or two negative cables in place

Not sure about this nor how relevant, the shunt is located at the negative take off for the bank as one big battery, nothing to do with the intra-bank connections. Which of course have their own needs, but a separate topic.

> This is why shunt battery monitors don't read correctly

For LFP there is no alternative afaik.

Obviously some guesstimate more accurately than others, and that may well vary by battery type or even model.

Originally Posted by lateral

My SOC seems to get more accurate as battery bank discharges

That is as expected, and good news of course

> It’s Winter and not using boat enough

Yes just sitting on Float will not give much data for the learning process to work with.

> I still have a feeling the tail amps setting and your “normal” charge tail amps habit have to correlate to get a meaningful SOC..Especially nearing 100%.

Only relevant to the 100% setpoint. Actually reaching endAmps is important for bank health anyway, and yes also (less critically) should help improve the meter's accuracy.

Just because there is a default setting OOTB, does not mean anything like that is a good setting. All such settings, on all such devices are there to be customized by the user.

By setting it a little earlier (higher) than your charging endAmps target, that just says "I want to see 100% even if my charge cycle only hits 99.8%"

Since source regulators' usual AHT-based stop-charge algorithm has nothing to do with the actual endAmps, at best sometimes, but only if well calibrated by the user,

and as a lead bank ages, it gets harder and harder to hit such a later (lower) endAmps target

the alternative is **never** seeing 100%, which I believe few people would want.

> but then it’s just an auto coulomb counter.
And it’s supposedly not.

A device that is truly **just** an Ah counter costs $40-50 and will never be as accurate as the true BMs.

The fact that SG-200 does sophisticated calculations, combines that coulomb-based methodology with the results of the learning "Active Impedance Compensation" technology that used to be unique to the Merlin SG, **and** offers SoH calculation as well, truly is an amazing leap forward.

I am hopeful / confident that their incremental firmware development over time will improve its accuracy with an ever-expanding universe of battery types and models.

If indeed the inaccuracy reports here are not just the result of insufficient learning data and/or external / installation issues.

[Exile]

Originally Posted by Exile:
...Wiring a SSB direct to the batts seems to be best practice, but not completely necessary....

Originally Posted by sailinglegend

This is why shunt battery monitors don't read correctly!!!

Yes, I understand. But I have a Victron BM that I only use for counting amps & voltage. I don't rely on it for SoC because I'm not confident I can accurately reset it. Thus far I rely on trailing amps to determine when the batts are topped off. Hence my interest in the SG, and perhaps now the SG-200. I have a switch for my SSB so not sure how it could be drawing even minimal amps from the batts when off, but I'll put a meter on it when I'm back onboard. But back to my question, I may be wrong but figured I can manage the add'l amps not recorded by my BM during (infrequent) use of my SSB, but such usage may in fact throw off the more sophisticated SG-200. I honestly don't know.

[Exile]

Originally Posted by john61ct

Except for Merlin SmartGauge, which has so far been in general most accurate, but only works with lead.

According to what people have reported in previous threads, it's only accurate when the batts have been "at rest" for awhile, i.e. no charging sources and little if any draw. This is why a64, for example, recommends relying on its accuracy first thing in the morn (when at anchor that is), i.e. when there's been minimal draw overnight & before the solar or other charging sources have had a chance to go to work. It's difficult to have batts truly at rest on a cruising boat. It sounds like the SG-200 might do a better job compensating for this, but it may still be too early to tell.

> With multiple batteries in a bank you have to check each negative stud and make sure they are only common negative wires. So each stud may have one or two negative cables in place

Not sure about this nor how relevant, the shunt is located at the negative take off for the bank as one big battery, nothing to do with the intra-bank connections. Which of course have their own needs, but a separate topic.

I think what MS and SailingLegend may be cautioning about is that when a bank is comprised of multiple batts, it may be all too easy to confuse the negative cable going to the bus (main distribution point) with what is often a multitude of negative cables running between the batteries themselves. Not always as obvious as it may seem when you're not onboard.

* * *

> I still have a feeling the tail amps setting and your “normal” charge tail amps habit have to correlate to get a meaningful SOC..Especially nearing 100%.

Only relevant to the 100% setpoint. Actually reaching endAmps is important for bank health anyway, and yes also (less critically) should help improve the meter's accuracy.

Just because there is a default setting OOTB, does not mean anything like that is a good setting. All such settings, on all such devices are there to be customized by the user.

By setting it a little earlier (higher) than your charging endAmps target, that just says "I want to see 100% even if my charge cycle only hits 99.8%"

Since source regulators' usual AHT-based stop-charge algorithm has nothing to do with the actual endAmps, at best sometimes, but only if well calibrated by the user,

I'm not sure if you're talking about typical BMs here or the SG-200. I thought the benefit of the latter (and the original SG) was that they didn't rely on user settings to determine SoC(??)

and as a lead bank ages, it gets harder and harder to hit such a later (lower) endAmps target

Maybe it's just me, but I don't understand this one at all. My understanding is that, as a battery ages, it doesn't get harder to achieve the end-amps target, it's just that the target is at a lower % of the batt's total capacity. So whether the batt is (hypothetically) a year old at 95% or two years old at 80%, end-amps remain the same, namely a % of the mfg's rated as opposed to actual capacity. Isn't this the whole point of using end-amps to determine when the batt is topped off, namely because you typically don't know what the capacity actually is??

* * *

A device that is truly **just** an Ah counter costs $40-50 and will never be as accurate as the true BMs.

Again, this is confusing. What is a "true" BM. Do you mean the Victron BMs and maybe simpler devices which simply count amps, or the SG and SG-200?

The fact that SG-200 does sophisticated calculations, combines that coulomb-based methodology with the results of the learning "Active Impedance Compensation" technology that used to be unique to the Merlin SG, **and** offers SoH calculation as well, truly is an amazing leap forward.

IF it works as advertised that is, which is what the feedback we're getting from these threads is helping to determine. You seem to be parroting the marketing info as if it were already fact. I prefer to wait until some more evidence has come in, and maybe until Balmar has completed their new product intro with the promised Bluetooth updating capability.

[john61ct]

Actually I am keeping an open mind either way, but not defaulting to cynical skepticism.

I prefer to be encouragingly optimistic unless the negatives get proven.

No point in discouraging the pioneers, and MS's endorsement carries a lot of weight with me.

Even if it only worked well with LFP, I would consider that a very worthwhile advance in the field.

[lateral]

As much as your charity is admirable it doesn’t compensate the
Frustration of a gauge lying to you.
I still have Kenomac’s “grounded” comment reverberating in my brain after I bought a Sterling SG and sold it without installing.

[john61ct]

What is a Sterling SG? Maybe link to the “grounded” story, do not recall that.

It is important to keep expectations realistic to avoid disappointment.

Being a pioneer is exciting, lets you contribute to the community's knowledge base, but involves a lot of uncertainty and risk.

[Exile]

Originally Posted by john61ct

Actually I am keeping an open mind either way, but not defaulting to cynical skepticism.

I prefer to be encouragingly optimistic unless the negatives get proven.

No point in discouraging the pioneers, and MS's endorsement carries a lot of weight with me.

Even if it only worked well with LFP, I would consider that a very worthwhile advance in the field.

I haven't read anything that could remotely qualify as "cynical skepticism." When it comes to yet another system for a cruising boat, a truly open mind requires neither optimism nor pessimism, only realism. The "pioneers" will only be encouraged or discouraged based on whether their product works as advertised, and people then purchase it or not. I agree that MS' testing & endorsement is a big plus.

[john61ct]

By pioneers, I mean posting members that are customers, the bleeding edge early adopters.

Say the first few hundred detailed reports gathered. . .

[Stu Jackson]

Originally Posted by sailinglegend

If it's that simple why has Maine Sail reported so many incorrect shunt-based battery monitor installations??????
...................................

Very astute observation.


I installed my Link 2000 almost 20 years ago. I, too, had trouble understanding the concept until two things dawned on me.


1. The manuals all kept talking about "load" side and "battery" side. I got confused by the "load" side part, because on the (-) there IS no load, it only goes to the ground (engine). I kept mumbling "WHAT load SIDE?" Until Victron did their excellent manual on the original BVMs with a nice diagram (that Maine Sail continues to have to republish on various boating forums on the internet), I found it confusing and I'm an engineer!


2. Once I understood how shunts work it was easy. Since most books about boat electrical systems use water as analogies for Voltage and Amps (pressure and flow), shunts are just flow meters. Like this: Ammeters & Shunts 101: Ammeters & Shunts 101


The manuals then, as many seem to continue to be, are in too many cases simply horrible.



They should make the guys writing the manuals use the bloody instrument FIRST!

[Stu Jackson]

Originally Posted by john61ct

What is a Sterling SG? Maybe link to the “grounded” story, do not recall that.

It is important to keep expectations realistic to avoid disappointment.

Being a pioneer is exciting, lets you contribute to the community's knowledge base, but involves a lot of uncertainty and risk.

SG would be the original smart gauge, IIRC.


Pioneer? john, when you get one, and use it, why not let us know? Otherwise...? I'm with newhaul.

[Exile]

Originally Posted by Stu Jackson

1. The manuals all kept talking about "load" side and "battery" side. I got confused by the "load" side part, because on the (-) there IS no load, it only goes to the ground (engine). I kept mumbling "WHAT load SIDE?" Until Victron did their excellent manual on the original BVMs with a nice diagram (that Maine Sail continues to have to republish on various boating forums on the internet), I found it confusing and I'm an engineer!

Your comment made me think I misspoke in a previous post when I said the neg cable that attaches to the "load" side of the shunt goes to the distribution busbar. It goes to engine ground as you say, with the pos cable going to the bus. I'm definitely not an engineer, still riding a fairly steep learning curve, and want to avoid learning it wrong. I always welcome any & all corrections.