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john61ct · 08-12-2018, 03:47

Yes, with enough panelage and a small bank, need to ensure the bank is at 50-60% SoC, and

perhaps still need to add active loads if testing current output.

Yellowjacket · 08-12-2018, 06:51

Quote:

Originally Posted by noelex 77

I think this will prove to be a good solution, but there are reports of problems associated with an intermittent connection, presumably caused by a lack of range from the Bluetooth signal. Perhaps Victron will release a wired version.

One significant drawback is that it makes it more difficult to tell if the controller is maintaining absorption voltage.

Noelex, I don't understand why install of remote temperature and voltage sensing on battery will make it more difficult to tell if controller is maintaining absorption voltage? I've misunderstood something, here.

thomm225 · 08-12-2018, 15:55

Quote:

Originally Posted by Erik Dolson

I'm not an engineer, just mildly OCD with a heavy helping of ADHD.

I spent hours, HOURS, plugging in and unplugging my three panels the other morning trying to figure out why I didn't get 33 percent more juice from the third panel (which ever one it was) when I plugged it in.

Then decided that perhaps the battery could only take so much at a time.

Had I been an engineer, I would have known the answer before I was through with my first cup of coffee, assuming I didn't know the answer before I asked the question.

Not necessarily.

Sometimes engineers go why off base also whereas a technician that is a good troubleshooter can find out the answer quite quickly

A good logician is sometimes much better at figuring out the problem than an engineer because he (the tech) simply troubleshoots without getting too caught up in theory like an engineer would

We have many wannabe engineers here on CF that totally confuse people with their troubleshooting methods and ideas. Troubleshooting is quite different than designing or endless theorizing.

I stated earlier that .2 volts off isn't a problem and that is a true statement, and if you are a trained tech it wouldn't take very long to figure out why.

As stated about 60 posts back, you first need a calibrated meter before you even broach the subject of a voltage being off .2 volts

Mick C · 08-12-2018, 16:47

has anyone mentioned the need to update the firmware on the SmartSolar units. There is a relatively urgent post on the bictron site that talks about updating it to stop errant behaviour and the possibility of device failure. My recommendation is do that ASAP.
Hope this helps.
Mick

**noelex 77** · 09-12-2018, 00:43

Quote:

Originally Posted by Erik Dolson

Noelex, I don't understand why install of remote temperature and voltage sensing on battery will make it more difficult to tell if controller is maintaining absorption voltage? I've misunderstood something, here.

To be in absorption mode the controller should be maintaining the absorption voltage (for example 14.7v). Unfortunately, the Victron solar controllers report they are in “absorption” mode even if the voltage is much lower.

So the only way to know if the controller is really in the absorption phase is to look at the voltage. If the voltage is 14.7 (using the same example) and you have used manual temperature correction, you know the controller is in absorption mode.

If the controller is using automatic temperature correction, the absorption voltage will be adjusted by the controller from the 14.7v that you have set to a new and un-disclosed voltage (although you can calculate what this voltage should be if the battery temperature is reported). The target voltage could be higher or lower depending on the temperature. So if the voltage is reading for example 14.5v, you do not know if the controller is in absorption mode or the voltage is still rising.

The significance of knowing if the controller is in absorption mode is two fold:

1. If the controller is in absorption mode the solar panels are producing more power than the batteries + loads are using. So extra loads can be turned on without slowing the battery charging down. This is the ideal time to run loads such as laptop charging, fuel polishing, watermaker etc.
2. The total time in absorption mode is one of the best indicators of the battery SOC.

So if you are using manual temperature correction you can immediately tell from a simple voltage reading if the solar panels can produce more power than is being used charging the batteries and running loads.

Automatic temperature regulation is normally a very good feature. The better controllers will accurately report the charging state so you do not need the voltage information. However, the Victron controllers do not report the charging state accurately (or even vaguely correctly). Engaging the automatic temperature regulation makes it harder to tell what state the controller is in and if the solar panels are producing more power than can be used. I think most users are still better off with automatic temperature regulation, if this is measured at the batteries, even when using the Victron controllers, but the downside is annoying with this brand of controller.

Yellowjacket · 09-12-2018, 08:24

There are issues on my boat running new wire to the batteries from the panels, so the Victron(s) are in the engine room while the batteries sit on the keel in cold water (near Vancouver Island, CA).

Thus, a large potential temperature difference and possible voltage drop, though the victron is connected to a bus in turn connected to batteries with large, finger-size (#4?) cable.

Solution seemed to be remote sensing, which is why your comment about remote sensing making it more difficult to maintain absorption concerned me.

On reading that portion of the thread again and your followup, I think you were not saying that remote sensing causes the difficulty (aside from bluetooth issues), but that automatic temperature regulation, regardless of where the temperature is taken, is the problem and that manual temperature correction results it better data. And this is why Victron not allowing users to extract what temperature is being used is a difficulty.

Therefore, Victron does not accurately measure voltage (the initiating question), may or may not accurately measure temperature at the battery, does not disclose the algorithm used to adjust voltage for temperature, reports incorrectly the phase (absorption) based on what may or may not be an accurate temperature reading? Is that a correct summation?

I'd really liked my Victron until now. What are the better controllers you mention?

**noelex 77** · 09-12-2018, 09:09

The Victron solar control units have some very good features. They are inexpensive, well made, have great voltage adjustment and very low self consumption.

The downside is they have a very unusual charging algorithm that works very differently from most controllers.

The Victron smart battery sense solves the poor battery temperature regulation that is inherent in the less expensive Victron controllers (sensing the temperature at the controller is not much help), and it does this for a very reasonable price. However, it does highlight that despite the detailed Bluetooth connection it is difficult to know with the Victron controllers the state of the batteries and how much of the solar panel output is being used at any given time.

Controllers like the Midnite and Outback are far more user adjustable, but this sophistication means the self consumption rises significantly.

An interesting question is how a single Midnite or Outback controller wired to multiple panels compares to multiple smaller, less sophisticated Victon controllers devoted to a single panel.

Yellowjacket · 09-12-2018, 09:31

Thank you. That puts trade-offs into perspective.

As mentioned earlier, I've opted for smaller less sphisticated Victrons (75/15) sourced from Amazon, and one larger (100/50) purchased earlier. Only way I can think to accommodate for varying insolation, shading, etc port and starboard.

According to Victron, once Smart Battery Sense is attached to one of two house bank batteries (2 x 12v parallel), all of the Victrons can receive data from that Smart Sense. I wonder now if Smart Sense voltage sensor should be attached at connection where the two batteries become one, but that just shows my lack of knowledge and I'll leave that for now.

Perhaps Victron can be persuaded to do theiir algorithm differently. It could be as simple as a a software update, it could be impossible due to design/build issues.

john61ct · 09-12-2018, 09:47

I think the the issue is pretty insignificant, more abstract than real.

Most owners do not truly rely on their solar, mostly it just helps reduce ICE runtime for a small number of days per year.

A fraction of those that do actually do anything to use the "excess free" panel output, and out of those that do, only a vanishingly tiny number use it for anything very important.

Even setting that aside,

Total "time spent at actual Absorb voltage" is not IMO important information in itself, but simply one means towards the very important goal of "getting the bank to 100% Full".

Making use of "excess free" energy production is a trivial goal in comparison, and should never interfere with getting to Full.

Once you are successfully measuring trailing amps directly, that is both the definitive measure of the Full state and the metric on which turning on a Dump Load to consume excess power should be based, both the timing and the amps current that can be spared, relative to the other concurrent requiring carrying.

Accurate SoC information as a %number then becomes less critical, but if that is desired, can also be derived pretty accurately by meters designed for that purpose, not by guessing based on using "time spent at actual Absorb voltage".

TL;DR If you track trailing amps and SoC during the charge cycle, "actual time spent at Absorb voltage" is not an important metric.

john61ct · 09-12-2018, 09:50

The temp sensor should be attached to a battery case, not to wiring infrastructure.

john61ct · 09-12-2018, 09:52

LFP batteries require neither Absorb time, nor temp compensation.

Temp **protection** may in some use cases be important, but that's a separate topic.

**noelex 77** · 09-12-2018, 10:19

Quote:

Originally Posted by john61ct

I think the the issue is pretty insignificant, more abstract than real.

Most owners do not truly rely on their solar, mostly it just helps reduce ICE runtime for a small number of days per year.

A fraction of those that do actually do anything to use the "excess free" panel output, and out of those that do, only a vanishingly tiny number use it for anything very important.

John, I think you have this backwards.

ICE are noisy, unreliable, add heat, consume fuel etc etc. The nirvana for most cruising sailors is to eliminate the need for ICE input.

This is not always possible, but with availability of cheap, efficient solar panels (and other technologies) the goal is entirely realistic.

You seem convinced that alternative energy can only supplement ICE power. While most yachts have an ICE for propulsion making some contribution inevitable, there are plenty of cruising yachts where the contribution from ICE is minimal.

Yellowjacket · 09-12-2018, 10:43

Quote:

Originally Posted by john61ct

The temp sensor should be attached to a battery case, not to wiring infrastructure.

John, I wasn't clear: the Smart Sene reads both voltage and temperature. The sensor itself would be attatched to the battery case, from which it receives the temperature reading, but the point from which it receives and reports voltage could be at the ends of one battery or the points where two batteries become one in parallel.

Admittedly, I do not know if there would be a difference after confusing myself with possible differences in output of individual 2 volt cells, but in writiing this I think it becomes clear that if I'm reading temp from a battery, I should receive voltage from that battery.