Victron 100/30 voltage measurement

[thomm225]

Originally Posted by Erik Dolson

There are patterns, and then patterns of patterns. The brain is a pattern discovery machine.

I've learned a tremendous amount from this site, and much from posters on this thread. On ocassion I've wondered how those without the necessary resources of time and understanding manage to go boating at all.

To be clear, this discussion has helped me. I've just spent two days hanging from my arch, putting up 1.08 kw of panels (3 x 360 watt). I plan two more for the bimini. I have three Victons with Bluetooth, am contemplating wiring them so I have port-side panels on one (similar shading and insolation), starboard panels on another, and of course a back-up.

Then along the dock comes a guy to tell me he is thrilled with his 200 watts of flexible panels he lays on top of his bimini, sliding from one side to the other with a piece of line. I don't know if I want to spear him or copy him.

Point is, aside from the fun and challenge of understanding details to the nth degree, how much will we save in real dollars (Euros or PoundS) compared the those who DON'T know their Victron is .1V off? And will adjusting for that be significant when compared to all the other factors beyond our control?

I am not trying to be a smart-ass, here. As I said, I've learned and made changes as a result of the forums and received signficant help from those more knowledgeable than me. But I wonder at times about the cost of the greater understanding, as well as the difficulty in measuring gain, proving again I can be a bit compulsive.

This sort of thing is very common especially among engineers and technicians. Most will always over do it and take things to the nth degree.

When it's mentioned that the forest by the road on the way to work looks quite nice in the Fall, a true engineer type will say yes and there are 350 trees in that forest and then give you a breakdown on the quantities of each different type of tree

I see it every day as the manager of tech/engineers while going over the completed paperwork or being put through the long explanation of a fairly simple repair by a tech. (I was/am a tech myself) If I wrote up the monthly tech report summary the way the tech/engineers describe the repairs it would take days on end to put together and be the size of a small book instead of a few pages

I think this natural tendency to over do things especially when technologically related is increased for sailors who's world sort of shrinks down to the boat and it's systems.

It becomes the main thing to think about for these folks.

I've even spent hours monitoring my batteries charging up with my laptop connected to my Victron as the Sun clears the horizon. I'll be moving panels around etc for max wattage, but that's as far as it goes

When my system goes to Float, and reads 13.6 when the default is at 13.8, It doesn't concern me

[john61ct]

The satisfaction of "getting things right" is a good in itself for those who feel well rewarded by it.

Certainly little to do with money.

For those who see these issues only as means to an end, then they should definitely make their own judgment calls about how close to the ideal is "good enough".

[ThereAndBack]

Never let perfection be the enemy of good.

[noelex 77]

Originally Posted by thomm225

When my system goes to Float, and reads 13.6 when the default is at 13.8, It doesn't concern me

There is no need for “concern”. Adjust the voltage set points 0.2v higher. Simple.

Many cruising sailors I meet are frustrated by their lack of electrical power, often just a few minor changes can make a significant difference. These threads are mostly about maximising the electrical performance.

[Paul L]

Originally Posted by thomm225

This sort of thing is very common especially among engineers and technicians. Most will always over do it and take things to the nth degree.

When it's mentioned that the forest by the road on the way to work looks quite nice in the Fall, a true engineer type will say yes and there are 350 trees in that forest and then give you a breakdown on the quantities of each different type of tree

I see it every day as the manager of tech/engineers while going over the completed paperwork or being put through the long explanation of a fairly simple repair by a tech. (I was/am a tech myself) If I wrote up the monthly tech report summary the way the tech/engineers describe the repairs it would take days on end to put together and be the size of a small book instead of a few pages

I think this natural tendency to over do things especially when technologically related is increased for sailors who's world sort of shrinks down to the boat and it's systems.

It becomes the main thing to think about for these folks.

I've even spent hours monitoring my batteries charging up with my laptop connected to my Victron as the Sun clears the horizon. I'll be moving panels around etc for max wattage, but that's as far as it goes

When my system goes to Float, and reads 13.6 when the default is at 13.8, It doesn't concern me

I think what you say is especially true on the forum. Less so when actually out cruising and lots of other issues start to take priority and good-enough begins to feel comfortable and practical.

[thomm225]

Originally Posted by noelex 77

There is no need for “concern”. Adjust the voltage set points 0.2v higher. Simple.

Many cruising sailors I meet are frustrated by their lack of electrical power, often just a few minor changes can make a significant difference. These threads are mostly about maximising the electrical performance.

The point is that there is no need to make an adjustment.

See if you can let a .2 volt voltage reading alone and not make an adjustment. Do you think you could deal with that?

Remember though, I'm a natural tech/engineer also so I know the deal but luckily for me after I was trained for many years in electronics, electrical, and computer systems, I majored in the liberal arts

It was a total eye opener. The people even dressed differently in those buildings

My college was set up so that the buildings identified the school. Psych building, math building, engineering, history, arts, etc

It was quite an education in more way than one......

[snotter]

I had the exact same nuisance problem with both of my 100/30’s. I chalked it up to Victron economizing on quality control. My logic was why would Victron want to spend the money the money on lab grade accuracy on a relatively cheap controller that should be user set up. I upped the voltage and measured output at the battery. I set absorption and float voltage to the published values that Trojan specify for my T1275’s. After a year my batteries seem happy. They never seem to need water. However, in hot or cold weather I rely on my sterling shore charger because they are temperature monitored.

[hzcruiser]

Originally Posted by Erik Dolson

[...]
Point is, aside from the fun and challenge of understanding details to the nth degree, how much will we save in real dollars (Euros or PoundS) compared the those who DON'T know their Victron is .1V off? And will adjusting for that be significant when compared to all the other factors beyond our control?
[...]

I assume you're not expecting one number here, no matter which currency, Erik?

Fine-tuning any system will "just" make it run better, smoother, more efficiently, or, in this case, could extend the life span of the battery bank by some percentage. You pick a number.

If the settings are way out of whack, one can possibly reduce the life of the batts by 50%, hence if your batts cost you $1000, you can save $500.

Here you have your number after all...

If you're a sci-fi fan, the number is 42 instead. And to top it off, make that 42 Amps-per-hour

[hzcruiser]

Originally Posted by snotter

I had the exact same nuisance problem with both of my 100/30’s. I chalked it up to Victron economizing on quality control. My logic was why would Victron want to spend the money the money on lab grade accuracy on a relatively cheap controller that should be user set up.

My new Victron MPPT SCC was off by 5 mV at 12V IIRC. Tested with a calibrated bench DMM.
Having said that, with todays chips like the INA219 you don't need to calibrate each device individually anymore like in the old days. I've been developing marine electronics for a few years now and do occasionally check the accuracy of the measurements and they're either within spec or damaged beyond repair.
However measuring current is a different story...

[Jim Cate]

The point is that there is no need to make an adjustment.

See if you can let a .2 volt voltage reading alone and not make an adjustment. Do you think you could deal with that?

Since you are a highly trained marine electrician what do you think is the result, long term, of having an absorption voltage of 14.6 instead of the 14.8 specified by Trojan? And a float voltage similarly low?

Some folks believe that such undercharging will be detrimental to battery life. I am one of them. What say you, Thomm?

Jim

[john61ct]

umm, that is 14.7+ you meant there right?

Here's Mainesail on when to go higher too

https://forums.sailboatowners.com/in...lation.125392/

[evm1024]

I have to say run it for a while and if there is a problem then look for a "fix". In other words be sure there is a problem. Math is your friend here (expected charging times vs reality).

I do have a fluke meter that was at one time calibrated to a NIST standard. I might have it re-calibrated before I go but why? For me it would be just to have an accurate reference....

But back to if it ain't brok don't fix it. Does the system work for you? Do you need the last 5% out of it?

Just as a side note back when I owned a company and was the chief technical officer I was on site with one of our customers (a 2 million USD contract as I recall) and was working with their COTR (contracting officer's technical rep) and one of the asst attorney generals for some state (it was a litigation support system) - anyway at some point they realized that I was the CTO and complemented me by saying that I sounded like a real person rather than a techie.

The point being don't let the tech pull out of being reasonable. Even with LiFePO4 charging to 3.4, 3.45 or 3.5 VPC will likely result in much the same results. (3.4 to 3.5 is a 100 mV difference) And much the same life given a realistic 80% SOC to 20% SOC limit.

Don't sweat the small stuff - and as a techie I do want to have sub mV accuracy. I will not be obsessive I will not be obsessive, I will not be Obsessive.....

[Jim Cate]

Thanks to all who have responded. I read your comments with interest and appreciate that you have taken the time to respond.

Several have suggested that my two voltmeters are in error and the Victron is correct. I'm certainly aware of that possibility, and that uncertainty was a big part of why I posted the question.

We are transients most of the time, so ordering a voltage standard isn't a convenient solution. I checked with the only electronics vendor (Jaycar) in the area and they don't seem to have such a thing. I'd be happy to have access to one!

However, the error in question is substantial: at least 0.2 volts. So, I just made a improvised check: took nine brand new Energizer alkaline cells from a fresh package, connected them in series and checked their voltage:14.33. The individual cells were all within 0.01 v of the average of 1.5964 v which is right in line with nominal values garnered from the web. If one multiplies the average value by nine we get 14.346 v, a difference of .016 v from the measured value.

While this is a weak substitute for a proper voltage standard, I feel that it suggests that my meter isn't too far off, and that the 0.2+ v discrepancy between the Victron and the meter might well be real.

I'll keep casting about for a lab quality meter or standard... one never knows what one will find in the cruising fleet.

Meanwhile, I'll leave the Victron with manually selected voltages that provide the correct battery values.

Jim

[Jim Cate]

Originally Posted by john61ct

umm, that is 14.7+ you meant there right?

Here's Mainesail on when to go higher too

https://forums.sailboatowners.com/in...lation.125392/

Ooops! Yes, of course 14.xxx

Jim

Now edited to correct values

[Jim Cate]

I have to say run it for a while and if there is a problem then look for a "fix". In other words be sure there is a problem. Math is your friend here (expected charging times vs reality).

My main concern is to limit PSOC as much as possible, given no shore power access. And here, it seems that those voltage differentials do matter. The use of expected charging times as a metric is a bit hard to implement when one has an aged battery bank and a combination of wind and solar as charging sources, neither of which are consistent in charging rate.

So, hitting recommended target voltages and checking tail current to establish a full charge is the method I think I must use.

Jim