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missourisailor · 13-08-2017, 15:16

This is a very interesting thread.

While I do have two banks, House and Start, they are only combined when the start battery can't start the engine.
All house draws and charging goes directly to the House bank. The start battery is charged thru a Duo Charge connected to the house bank.

My Smart Gauge has no problem with this set up. Even with 24/7 charging from the different sources.

I attribute this to the fact that the Smart Gauge is not quite a simple volt meter.
Somewhere, and I can't find it now for the life of me, there was a discussion stating that although voltage is one way to determine SoC, the unit actually gets most of it's info from sending high frequency pulses through the battery to determine SoC.

How it does it, is PFM to me.
But on my boat, it works very well.

ramblinrod · 13-08-2017, 16:46

Quote:

Originally Posted by Stu Jackson

Rod, I, too, couldn't find this in the manual. Didn't you say you got it elsewhere from a link? If I missed that link in this topic, I apologize, but could you repost it? Thanks.

Hi Stu, follow the link in post 32.

ramblinrod · 13-08-2017, 17:06

Quote:

Originally Posted by john61ct

Wiring In Series (pro vs con) - Page 4 - Cruisers & Sailing Forums

Significantly different from your misrepresentation and irrelevant to subject.

Will you please try to stay on topic.

ramblinrod · 13-08-2017, 17:15

Quote:

Originally Posted by missourisailor

This is a very interesting thread.

While I do have two banks, House and Start, they are only combined when the start battery can't start the engine.
All house draws and charging goes directly to the House bank. The start battery is charged thru a Duo Charge connected to the house bank.

My Smart Gauge has no problem with this set up. Even with 24/7 charging from the different sources.

I attribute this to the fact that the Smart Gauge is not quite a simple volt meter.
Somewhere, and I can't find it now for the life of me, there was a discussion stating that although voltage is one way to determine SoC, the unit actually gets most of it's info from sending high frequency pulses through the battery to determine SoC.

How it does it, is PFM to me.
But on my boat, it works very well.

This raises an interesting point. If your SM was out by say 30% between normal discharge low and full charge, how would you know?

I liken this to the old adage, "A man with one clock knows exactly what time it is, while the man with two is never sure."

lateral · 13-08-2017, 17:40

Quote:

Originally Posted by ramblinrod

Hi Stu, follow the link in post 32.

I'm not trying to be a PIA but I don't see
THE BALMAR SMART GAUGE IS NOT ACCURATE (not even designed to work accurately) WHEN INSTALLED IN A CIRCUIT WITH A BATTERY COMBINER. anywhere in that link or on the net.

R$ght now I'm trying to ascertain what is fact and what is alternate fact.

Besides, the link in post #32 is the Merlin site not BALMAR.
I looked on the balmar site & couldn't find it either.
http://www.balmar.net/wp-content/upl...-SG-1224-3.pdf

If you mean by the blue statement the SG is not accurate when the combiner is activated
I will buy that....and a SG. But, that doesn't mean it won't work with one in the circuit switched on "non-combined."
Gotta eliminate the cross purpose talk here and get to the nitty gritty.
So, the blue is not a quote, but a partially correct interpretation?

john61ct · 13-08-2017, 17:51

This quote:

"THE BALMAR SMART GAUGE IS NOT ACCURATE (not even designed to work accurately) WHEN INSTALLED IN A CIRCUIT WITH A BATTERY COMBINER."

is **not** present on this page http://www.smartgauge.co.uk/sgvahrs.html

In fact the word "combiner" **only** appears on the SG site on one page, here: http://www.smartgauge.co.uk/sb_faq.html

Which reminds me that with their own combiner, the SmartGauge becomes "SmartBank Advanced", uses it's own voltage sensing to control isolating the House from Starter.

lateral · 13-08-2017, 18:21

Quote:

Originally Posted by ramblinrod

This raises an interesting point. If your SM was out by say 30% between normal discharge low and full charge, how would you know?
"

By the amount of load x time it took to get it there relative to when the batteries were at new spec?

missourisailor · 13-08-2017, 19:10

Quote:

Originally Posted by ramblinrod

This raises an interesting point. If your SM was out by say 30% between normal discharge low and full charge, how would you know?

Let me throw the question right back at you.

How do you know your coulomb counter is accurate?

Did you program in the proper Peukert number?
Did you program the "real" capacity of your bank?
Did you do a 20 hour test on you bank to know the "real" capacity?
What is the manufacturer's tolerance of your shunt?

You, being a battery person, know all of this. You also know they make real differences. Heck, even the resistance of the sense wiring contributes to the equation.

But ask most folks, "When is the last time you recalibrated your counter?"
For most folks, the answer would be..."am I suppose to after the first time?!?!"

So to answer your question....
Without doing a real 20 hour test... I don't know 100% for sure.

EXCEPT...
The Smart Gauge also displays DC Volts. And when it displays 40% give or take, it also reads about 12.25 resting volts.
Which tells me it not the 30% off you're talking about.

john61ct · 13-08-2017, 19:24

Quote:

Originally Posted by ramblinrod

This raises an interesting point. If your SM was out by

Sorry what is an SM supposed to be here?

john61ct · 13-08-2017, 19:29

Quote:

Originally Posted by lateral

So, the blue is not a quote, but a partially correct interpretation?

Unless presented with hard evidence, I'm going with: made up out of whole cloth, by someone with an ax to grind, or suffering from a bad case of Dunning—Kruger (as have/do we all from time to time.)

missourisailor · 14-08-2017, 04:48

Quote:

Originally Posted by john61ct

.... or suffering from a bad case of Dunning—Kruger.

I'll admit, I had to look this one up.

**Dockhead** · 14-08-2017, 05:56

Quote:

Originally Posted by missourisailor

.. . Somewhere, and I can't find it now for the life of me, there was a discussion stating that although voltage is one way to determine SoC, the unit actually gets most of it's info from sending high frequency pulses through the battery to determine SoC.

How it does it, is PFM to me.
But on my boat, it works very well.

Some people have speculated that the SmartGauge uses impedance spectroscopy in addition to smart analysis of voltage, and the designer has dropped some hints to encourage such speculation. But neither the designers nor the makers have revealed even basic details of any such technology, so we don't actually know anything.

What I do know, is this. I have tested my SmartGauge against specific gravity and voltage under a wide range of conditions over a long period of time. It's very accurate when the batteries have no charge source attached and have the surface charge off of them. Otherwise, not.

john61ct · 14-08-2017, 06:10

And VSRs should be set to combine only when?

Ah, when the charge source is active!

ramblinrod · 14-08-2017, 06:30

Quote:

Originally Posted by Stu Jackson

Rod, I, too, couldn't find this in the manual. Didn't you say you got it elsewhere from a link? If I missed that link in this topic, I apologize, but could you repost it? Thanks.

The words in my post are are not in quotation marks, so should not be considered a quote. It is an emphasized declaration of my opinion, with a
link to authoritive information that I believe corroborates it.

Here is a quote from the Smart Gauge website, after a description of how the device calculates (guesses) SOC when charging...

"This is why it is so important to keep SmartGauge permanently connected to one battery bank."

My education, background, and experience in electronic and electrical devices, leads me to believe that if the designer states that it is important to ensure that it is connected to only one bank, that they feel it will not work well if one attempts to monitor multiple banks connected intermittently via a combiner.

I also have a declaration by an owner, (a friend who is an avid sailor, also with education, background, and experience in electrical and electronic systems) that it gets confused when the start battery ACR switches in, and is not accurate when charging sources are connected.

I am not going to go back and reread the Compass Marine review or cite the quotation, but IIRC, that also indicated accuracy suffered when charging sources are connected. If the house bank is charged by solar, this inaccuracy could be occurring 15 hours per day, about 90% of waking hours aboard.

Based on this evidence, I feel confident to conclude that the device is
neither designed to, nor capable of, working well in a circuit with an isolated bank that can be combined, without need of third party independent 300 page lab report.

I feel the designer would not state, "This is why it is so important to keep SmartGauge permanently connected to one battery bank", if it was designed to, and capable of, working well with multiple banks.

It is generally considered bad practice for an intellectual property owner to recommend customers not attempt to use a product as it is intended to be used.