question

tfage avatar image

Smart shunt settings

451d0a00-30ae-4ea5-a716-a9c3bef81ad5.pngI’m struggling to read/understand the smart shunt, any help is appreciated

It was recently installed along with 4 brand new 110ah sealed lead acid batteries (hankook xv110 dual purpose), then plugged into the mains to ensure 100% charge and synced.

Today it shows I’m at 91% SOC after using 62ah out of my 440, which I calculate as 86% SOC

However when my fridge starts and has been running for 10mins my volts drop to 12.34v, then with fridge off and for 5mins the volts jump back to 12.5v

So….. what reading should I be using?
Percentage seems wrong, Ah used doesn’t seem to match the voltage when in use.

I’m so confused? I don’t want to damage my brand new batteries?

***Batteries are charged by both solar and running the engine and currently battery temp is 5*c

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smartshunt
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2 Answers
tfage avatar image
tfage answered ·


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These are my settings


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JohnC avatar image
JohnC answered ·

Hi @Tfage

The answer is, at least until you gain confidence, to use all your observations.

There's little things, like cold batts under light load not holding up V as much as you expect. But that's a reactivity thing that you'll learn to overlook in winter temps.

Rather than repeat myself, have a look at this fresh thread.. https://community.victronenergy.com/questions/116985/smartshunt-battery-settings.html?childToView=117130#comment-117130

But take care changing settings, you shouldn't do that unless you know why you're doing it. The manual is a good start, even if you have to read it over & over ad infinitum.

What you've described so far is normal, and your SOC reading shows typical behavior. You'll learn to believe it once you understand why, and have had a go at tuning. Try using the Trends graph too, can be fun changing Peukert and watching it recalculate the SOC curve.

But keep asking as you need..

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@JohnC Since SmartShunt settings is one of the most common questions here in the community, maybe someone can pin the linked thread at the top of the page. It's probably the best answer I've ever seen, and it's explained so clearly.

Ta for the kind words @Stefanie

But that was really a one-off instance where the poster's batts were similar to mine. The subject probably warrants a Wiki, but it would be like trying to explain witchcraft. And I didn't make it to Hogwarts. :)

And I've gotta say Victron have done a great job with these monitors. I never believed calculated SOC's were good enough. I grabbed a Smartshunt only to switch my mppt Tail with A, but found my preconceptions crushed.. this is good kit. Despite the witchcraft..


Thanks for your reply, Ive had a good read through the thread, watched the video and read the manual, you’re right in saying I may to do re-read again! So much information


I’ve made a few adjustments to the settings and I’m getting a more realistic SOC, the only thing I’m struggling with is the Peukert exponent as I can’t find any data on my batteries? ‘Hankook XV110’ I haven’t charged my batteries now for 5 days (apart from a few ah the solar has provided) and they still seem happy-ish. What would you suggest I set the Peukert too?


@Tfage

Yeh, i went for a look and returned with the impression those batts are probably rebranded bulk generics. Even Hankook mightn't know.

Given your low drawdown rates, the safe side is to underestimate Peukert, so it will show a pessimistic SOC rather than something that'll give you false confidence. Maybe that 1.09 will be ok, the truth may well lie between there and 1.2. Victron say 1.25, but I suspect that's weighted more towards less reactive batts like gels, and heavy discharge.

What you need to do also then is to set the Charge Efficiency Factor to a value that will bring the SOC back up to near 100% at the same time as your batts reach your chosen Tail. Perfection is when sync occurs just as you hit 100.0% naturally. There's no perfect world here of course, but you can get pretty close if you're patient.

The 80% CEF you show above will be too low, try 90-95%. You can also check your overall round-trip efficiency from the cumulative kWh figures in History. This won't match the set CEF, but I can't explain that..

And never forget that an Ah IN isn't the same as an Ah OUT. Different V usually, so different energy..




I’m learning so much from you, thank you


I’ve adjusted the CEF and today charged the batteries with my alternator for 5.5hrs and managed to capture the exact time the SOC went to 100% (which wasn’t at the set parameters) and then again when all AH had been returned. looking at this I think some tweaks need to be made somewhere? Or does it need a few cycles to settle it?
I ran the engine for a while longer, and the current sat around 5ah for quite a while, so I believe I should monitor this and adjust the tail current slightly?

I feel like I have learnt so much, and yet know so little



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For some reason I can’t add more than one picture

"I feel like I have learnt so much, and yet know so little"

That's what makes you a good student @Tfage , and a pleasure to help out. I'm still learning too. But on with it..

From your newer 'shots I see a V of ~14.2, which isn't a typical Float V. The Tail the batts will accept will be a little higher than what it might be at (say) 13.6V, so make allowances if that's what you do often.

15m for the detection time is likely too high. Little spikes from switching etc can keep resetting this, and sync may never happen. The default 3 min might work, but then you have to be wary of premature syncs under early charge, when Vbat is up, a cloud comes over, and the Amps drop. Sluggish batt response holds Vbat above the set CV and it will sync.

Interesting your Consumed Ah has crept back to zero (or close). Mine does that too, and I wonder if Victron have something in there that adjusts this progressively? I'm not privy to the code they use, and rather prefer to dream that it's because my settings are good.

I like to use the Trends graphs for all this. On a pc, but mightn't suit your phone to stay connected for hours. A single cycle will usually be enough for assessing changes, but the real test is when you haven't reached 100% or synced for a week. Satisfying when a good day arrives and it all comes together within 0.3% SOC. And you can.. that makes for a really good day. :)