Odd Smart Gauge Behavior

[a64pilot]

Mine is reading voltage of both banks lower than actual, and I assume because of this, the SOC is incorrect.
I was beginning to get alarmed as it was appearing if my bank had reached the end of its life, but my battery monitor wasn’t agreeing with my Smart Gauge at all.
Then looking at Lifelines chart of SOC while under load showed my bank should be at about 85% or so at 12.55V while the Smart Gauge was showing 61%. SG was showing 12.25 V, my calibrated Fluke and my battery monitor agree within .01 V at 12.55 V.
SG is installed with only its factory wire, with no extensions and since the voltage is incorrect for both banks, I have to assume it’s the ground, but have not cleaned the ground yet.
However I believe I will find it good.
Has anyone seen behavior like this with a Smart Gauge?

[john61ct]

Or you got a faulty unit from the get go.

This helps explain your past negativity about SmartGauge.

Assuming it is a Balmar-marketed one, have you called them? 360-435-6100

[a64pilot]

It’s worked well for a year or two, just got weird recently.
I just got through cleaning and moving the ground, to no avail though.
I haven’t called Balmar, I’m sure it’s out of warranty.

Past negativity? I haven’t been negative I don’t think, not until now anyway. I believe I have defended the thing quite a lot.

[john61ct]

Sorry crossed wires then, someone was talking about issues that made me think theirs was failing.

No harm in calling, they've got a good CS rep. Apparently Dale and Eldon know their stuff, maybe mention the forums and Maine Sail's HowTo site, you never know.

[a64pilot]

OK, seems 99% of the issue was slight corrosion on the fuse blades, I removed and scraped the blades clean, there was slight corrosion on them, put silicone grease on them, reinstalled and did a factory reset on the Smart Gauge.
I’ll likely soon replace the fuse holders with something a little more sealed.
Pretty sure if I had put the silicone grease on from the start, I wouldn’t have had an issue.
However time will tell if it’s fixed, at least it’s reading voltage very closely to actual now.

[Paul L]

Lucky you had a standard battery monitor to monitor your smartgauge

[hzcruiser]

Happy that you found the issue. For the record, did you measure the voltage with the DMM at the same points as the SG ? It sounds as if your batt monitor is connected to a different point?

[a64pilot]

Originally Posted by Paul L

Lucky you had a standard battery monitor to monitor your smartgauge

Well it via tracking amps and battery voltage alerted me to having a problem, the SG was underestimating SOC, which is safe of course.
Both the battery monitor and the SG are connected directly to the banks, Pos and Neg posts. Actually the Neg of both is connected to a bus bar that I made from a piece of solid copper bar 2” wide by .5” thick.
I’m going to replace the fuse holders with sealed ones that I have, the ones supplied are open and subject to corrosion.
I’m surprised as I have an AGM bank, so what was the cause of the light corrosion?

I first had only a SG, but I think to really know what is going on, you need an amp counter too. Turned out to be a good thing cause now I know exactly what is going into or out of the bank, before I had to estimate. I knew how much was being generated and how much approx was being used, subtract the two to determine how much actual charge I was getting. It was close not not nearly as accurate.

Plus with the Magnum BMK, it allows me to set the point the charger drops into float based on measured acceptance rate, for me that is drop into float at 3 amps.
Only really useful when I’m on shorepower of course, but a nice feature.

[pitlaw]

A64, i am curious about your Magnum settings because I think I have the same set up-a Magnum 2000 charger/ inverter, anMe RC 50, an ME bMK and 510amps of Lifeline AGMs. Following the manual I have set the controller for 2 hours of absorb time; chosen the type as AGM 1, set the charge efficiency to auto and max charge rate at 100%. My main concern has been whether or not to manually set the charge efficiency profile, but I dont have the tools to measure the SOC manually. Also, do you use the AGM 1 profile?

On a side note I considered buying a Balmar SC but it seemed redundant, which you have confirmed here. Thanks.

[a64pilot]

I have a 2812 and I think an ME RC 50.
Under set up menu for charger I selected custom and set absorb voltage at 14.3 and float at 13.3
Then one click on the rotary knob (03D)and you set how it trips to float, you have time, SOC and amps you can select, I selected amps and set the end amps to 3.
Charger holds absorption voltage until 3 amps are going into the bank.
You have to have a BMK for this menu selection to show up.

I did not want to select time cause time will almost never be only 2 hours, SOC, I didn’t trust how it calculates SOC.
Lifeline says their battery is full when it is accepting .05 percent of rated capacity, which for my 660 AH bank is 3.3, which rounds to 3.
It can and has taken hours to get to 3 amps, I mean like 5 hours or so, it has also only taken only a few minutes. Time difference is based on SOC of course. If I have been motoring all day and pull into a Marina, then I’m already at 100% SOC, I don’t want the charger to go for hours, if I have sat at anchor overnight, well then it will take hours.

If you have a Smart Gauge, it’s my opinion that you can roughly determine your banks capacity without doing a real load test.
Start at an actual 100% full as in bank only accepting .05% at absorption voltage, then just use the bank until the SG tells you your at or real close to 50% SOC, Read on the RC50 how many AH it took to get to 50%, double that and you have your capacity.
Doing that it seems my three yr old Lifeline bank is real close to a 600 AH bank, which I believe is right in line with where it should be.

Now this is all just my observations, not based on any test equipment, so I could be way off base, but I think it’s close.
So I know now that my safety cut off is 300 AH used.
Also Lifeline publishes an excellent chart that tells you SOC while the bank is being used at a 1 hr to discharge rate, a 20 hour and a 120 hour.
I have that chart cut out and taped beside of my monitor as another way to see where I am at. However I seem to always be at a higher voltage than the chart indicates.
For example right now I’m at 12.80 volts, I believe I am at 87% SOC, however Lifelines chart says that at 90% SOC I should be at 12.65 volts.
So long as I’m above that chart I figure I ought to be OK.

[pitlaw]

Thanks a64. So, i use the AGM1 setting which the manual says is for Lifelines and not custom. I get the right absorb and float amperage. But I will have to reset the time for longer than 2 hours to accomodatenthe times I am below 80% ( arbitrary) soc. Usually I dont get below that unless I am under sail and at anchor.

I take it you leave the efficiency setting on auto. You describe a good way to check capacity by reading the amp used number. I think the Magnum set up with the remote control and battery monitor is powerful in that it gives all the setting you need and too with amp and soc via the monitor. But I dont see many talk about it.

[a64pilot]

You don’t want to use the timer, unless of course you are always st the exact same SOC every time You begin to charge, which no one is.
Use amps to end your absorption phase, that way it will always end at the exact correct time.
Note, since this is only amps going into the battery, it will work. Assuming you have the BMK installed correctly and the shunt is between the bank, and ALL grounds.

Yes, I use Auto, cause I’m sure it’s a moving target, one you can just can’t get perfect, so I’m lazy and take the easy way out and use auto, besides I have two other ways to determine SOC, the chart and the Smart Gauge.
Now you can’t trust the SOC on the BMK either, it will display 100% SOC on my bank, when the bank is still accepting 10 or 12 amps, and it’s not truly 100% charged until that acceptance drops to 3 amps, that can be a couple more hours.

[john61ct]

Another good opportunity for calibration.

If your BM allows input for Peukert coefficient and/or coulombic efficiency, you could tweak those values until it only shows 100% after endAmps is reached.