Solar Outback 80 programming Tips

[Dsanduril]

Originally Posted by Pelagic

...until I get around to my own wiring clean-up and proper labeling...

I understand that! Our own boat is much the same way, but I always have more important projects, so I've only addressed the critical safety items much as you. One day....

Once you get the Victron working to recognize the solar you may have a little programming to do on either the Outback or the Victron or both. On the Outback I have extended the absorption phase to the time 'usually' required to get to a current into the battery of 0.5%C - Since the Outback doesn't know how much current is being used by the house loads at the same time as charging it can't be set to end absorption on current, has to be set on time. I can't recall the default, but I do know I had to extend it. I say the time 'usually' required because it does change depending on solar output and how deeply we pulled down the bank (several cloudy days vs. a week of endless sun), so I've selected an average/ballpark time value.

For the Victron, I don't recall if it defaults to an automatic reset of AH or if you have to tell it if you want automatic. That again could be an entire thread on the merits of automatic vs. manual. However, if you elect automatic you'll need to adjust the voltage and current settings so they are in line with the voltage setting you have on the Outback for absorption and the current you want for endAmps. And then of course you want both to match alternator and/or battery charger systems so everything is doing the same thing.

Both are pretty easy adjustments but they do take a little bit of testing/trial-and-error. For instance even at very low currents the Outback and Victron on our boat differ by about 0.07V as to battery voltage measurement. Haven't found an offset I can put in either one to make them read the same, so a little fudging is required.

[Pelagic]

Thanks again, these programing tips from experienced users was the Intent of this thread, until I discovered my Shunt problem.
I am painting the inside liners of our new deck hatches today but will get back to Solar programing and testing tomorrow

[Dulcesuenos]

SOC, from the victron battery monitor is nearly never accurate, not even close.

[Pelagic]

Originally Posted by Dulcesuenos

SOC, from the victron battery monitor is nearly never accurate, not even close.

Why is that?

[Dulcesuenos]

Originally Posted by Pelagic

Why is that?

Peukerts law. I have found on our past 3 boats with victron bmv that they simply do not allow for peukerts law. They also are very innaccurate with their projected "hours available at current discharge rate"
Don't get me wrong, I like seeing the amps in/ out, etc but just because my solar or charger has replaced the 100 amp hours pulled out over night, it does not mean my batteries are 100% as the bmv will show.

[john61ct]

No BM is very accurate. Victron's newer units are as good as any, of the AH counting type.

SmartGauge more so, and easier to use, but doesn't count AH.

[CatNewBee]

you can tweak peukert, absorption voltage tail cuttent etc to tweak the sync point, then the BMV is very accurate counting amps and guessing SOC. It needs to synch when the battery is full, otherwise it may drift over time and became inaccurate.

Just set it that way, that it syncs 30 minutes before the solar charger goes to float, eg 0.1V earlier than the charger, higher tail current. Set the Peukert according to your chemistry.

You wont miss any Ah doing so, because the BMV stays at 100% until the battery starts discharging, from that point it is accurate, you only will see a small jump between 98% and 100% when charging, because of the earlier sync.

[Pelagic]

Originally Posted by Dulcesuenos

Peukerts law. I have found on our past 3 boats with victron bmv that they simply do not allow for peukerts law. They also are very innaccurate with their projected "hours available at current discharge rate"
Don't get me wrong, I like seeing the amps in/ out, etc but just because my solar or charger has replaced the 100 amp hours pulled out over night, it does not mean my batteries are 100% as the bmv will show.

My Victron monitor has the facility to program Peukerts rating for my AGM batteries.

Fullriver in China was very good at providing all the details for setting the Victron monitor to synchronize with the charger

[john61ct]

Even with the most accurate settings and every-cycle resetting, no consumer-grade SoC meter is really all that accurate.

Best you can say is good enough for our purposes.

The Victron line is as good as it gets out of the AH counting category.

[a64pilot]

The BM kit on my Magnum is astonishingly accurate, but that is only because it is reset at least once weekly when the bank really is at 100% SOC. It seems to be more accurate than the Smart Gauge
I think they all start out pretty good, then drift, the longer since a proper reset, the more off they will be.

[Dsanduril]

Originally Posted by CatNewBee

you can tweak peukert, absorption voltage tail cuttent etc to tweak the sync point, then the BMV is very accurate counting amps and guessing SOC. It needs to synch when the battery is full, otherwise it may drift over time and became inaccurate.

Just set it that way, that it syncs 30 minutes before the solar charger goes to float, eg 0.1V earlier than the charger, higher tail current. Set the Peukert according to your chemistry.

You wont miss any Ah doing so, because the BMV stays at 100% until the battery starts discharging, from that point it is accurate, you only will see a small jump between 98% and 100% when charging, because of the earlier sync.

+1, this is my setup. It took me about a month to get Peukert's set correctly on the Victron. It's hard to do when you're living on the batteries, much easier if you can take the load off and charge them fully. I put in the value in the manual, then charged to endAmps at absorption voltage, looked at how many AH the monitor told me were still out (even though batteries at 100% SOC) and used AH in from charger compared to AH in as measured by Victron to estimate an adjustment to Peukert's. After a little trial and error came up with a value that means the Victron AH count gets down to the low single digits about the same time as I reach endAmps on the charge cycle. The Victron is also programmed to reset at that point (I do use the automatic reset).

After setting it up this way on the very rare occasions when I can allow the batteries to rest the Victron is in pretty close agreement with a hydrometer down to about 25%DoD. I don't usually get much lower than that, so have never tested below that point.

[john61ct]

Note these coefficients actually vary depending on current amps and SoC anyway, the CPU in these meters just use the input number as a constant.

[Captain Bill]

Originally Posted by a64pilot

All you need or do is set bulk and absorption voltage to the same value, so that when it drops into absorption, voltage remains unchanged.
I also based on Maine Sails recommendation set my float voltage to to absorption’s levels. In my case, bulk, absorption and float are all 14.4 V

Bulk means current limited, it means that your bank is accepting all that your panels can supply, if you had more power, it would take it.
Absorption is the point at which it becomes voltage limited, your bank can no longer accept 100% of the output of the panels.
Float of course is when the bank is 100% fully charged and is a maintenance voltage.
If Maine Sail is to be believed, its exceedingly unlikely you will ever get there on a cruising boat on Solar alone, it’s not a lack of power, it’s a lack of enough time to dribble in that last few percent of charge is all.

That is a wonderful way to kill a set of AGMs. I know because I recently did just that. There was an obscure setting on my solar controller that was set wrong at the factory and stopped the controller from going into float mode so effectively staying at absorption voltage until the sun got too low.. Since I was barely getting to 100% in the dead of winter it was not a big deal, but by March I was getting to 100% by early afternoon as measured by amps being absorbed at absorption voltage. It took about a month and my batteries fell off a cliff. I woke up one morning to 10.1V. Needless to say this was not good. I talked to the manufacturer and they told me that such a sudden failure is characteristic of electrolyte depletion due to overcharging. They also told me as AGMs age the definition of 100% charge changes. For new batteries it's defined as .5% of the 20 hr amp hour rating or in my case 2.1 amps. For batteries 5 years old it's more like 1% of 4.2 amps. I had never heard this before and no the don't have a published curve for amps in versus age. I had never heard this before. I don't know if Mainesails advice works for FLAs where you can watch your electrolyte levels, but I don't recommend it for AGMs.

[a64pilot]

So you were living aboard when they were killed, or were you gone for an extended time?
Big difference, cause no, if Boat is stored your right it will kill the bank, cause every day your already at 100% SOC

[Captain Bill]

Originally Posted by a64pilot

So you were living aboard when they were killed, or were you gone for an extended time?
Big difference, cause no, if Boat is stored your right it will kill the bank, cause every day your already at 100% SOC

Living aboard.