question

rzirzi avatar image
rzirzi asked

SmartSolar MPPT 100/15 Float state voltage


We have a problem with brand new Victron SmartSolar MPPT 100/15.

After a night, when new day powering solar panels and Victron SmartSolar

-the SmartSolar is NOT reaching Float Voltage setting. We have to unplug

battery and solar panel – to brigh it back (Float voltage). Why?

Is there any software bug? or We have a broken SmartSolar?

We have a Firmware 1.50

MPPT Controllers
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ejrossouw avatar image ejrossouw commented ·

How many panels? Battery voltage? How are panels connected? Panel VOC? System voltage? Battery type and profile used? You are aware that to start, voltage has to be vbat +5?

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rzirzi avatar image rzirzi ejrossouw commented ·

Two panels, voltage about 70-80V, battery 24V (27,6V), "user defined" battery preset to: Absorption 28,5V, Float: 28V.

It works good....to the night. When new day is powering on Victron charger, the SmartSolar is charging battery: Bulk, Absorption and Float.... with voltage below the Float voltage setting. Why?

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Trina avatar image Trina rzirzi commented ·

In MPPT settings, what is your load output "operation mode" set to?

I have the 100/15 and found playing with different settings in here (especially changing to "battery life" or changing here to custom user modes) changed some other parameters -like my absorption time and lengths and when and how it went into float mode if at all!

So this might be where a float voltage issue could be?

Also when I joined my bmv712 via VEsmart network the MPPT started using the bmv712 values to change when it did things and because my bmv712 was not set up correctly that messed the MPPT up and changed absorb and float times and voltages that I saw. So maybe if part of a network remove it while solving float voltage problem.

Also 70-80v each or together in MPPT reading?

If batteries are overcharged will they still reach wanted float voltage?

Does problem with float voltage happen when no load on system for that day?

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hour avatar image hour Trina commented ·

What did it screw up / what did you change in the BMV to not interfere with the MPPT? In all my reading the MPPT is a standalone thing even paired with a BMV. Voltage over smart network still seems like more trouble than it's worth.

If I show 13.33v on the SmartSolar (charging at say..14 amps), the BMV will show 13.52 (yes paired over smart network, left/rejoined/recreated/many fw updates/over a year of this mystery, temp compensation OFF). If I leave the network on the MPPT it'll show 13.6v. If I rejoin the network the MPPT will slowly taper down to 13.33v again over about a minute. Wherever it's getting that voltage from beats me, everything is closer to the BMV's reading measured anywhere in this compact system. I just went from 14ga to 10ga for MPPT->Battery and there was zero change. My thought was that the BMV reading and MPPT reading was skewed from small wire, too much for it to calculate, so it goes wonky at 13.33v. But yeah, no improvement with 10 gauge (8" wire runs)

TL;DR if there's some magical setting in the BMV that makes this work as intended, let me know. Right now I have absorption set to 13.70v on the SmartSolar and reach 13.8-13.83v daily, on the smartnetwork. I have no idea why some days it goes over. It'd sure be nice to program the SmartSolar absorption to 13.8 and know that it'll cut when the BMV reads 13.8. You know, how everyone assumes these things are supposed to work. I've spent a lot of time camped out with BMV on one screen, SmartSolar on another, watching what happens at the very end to try and hit 13.8 on the nose. I now have all of this logging with a smart BMS just because there was no trusting the MPPT/Smart Network voltage

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Trina avatar image Trina hour commented ·

Well first, Danny's reply below is a good question as 28v for float is a tiny bit high. My interstate gc2's wanted 2.47/cell absorb and 2.2~2.5 float so that's a bit higher than the MPPT defaults.

Second. Both the MPPT and bmv712 work great on their own and mine read exactly same on voltage. I only have my MPPT+bmv share info because the mppt seem to confirm or use the bmv as a second more precise source of info and the bmv would use the MPPT info to adj more accurate the info it needed.

If there's issues with MPPT settings then I would solve that first and don't have then shared for now as the MPPT will take the bmv charge detection time and adjust it's own settings and adaptive response to absorb and float following so if you changed the bmv or it's off slightly...

I found no magic setting. However changing the mppt settings load out operation mode to batterylife made the absorption time fluxuage all over the place based on usage (vs using a set absorption time like on other controllers I have used). That in turn changed my float time and briefly the voltage.

Sounds like you already had in mind the voltage drop and that's not it.

There is a function in the charging parameters (I've only read about it) where a tweaked value can begin this process you are describing where the calculations the MPPT uses can be degraded daily by an incorrect threshold or percentage. It will take Methias' expertise on here to find it or disable any custom settings with a factory reset or stock defaulfts for a day or two then gradually introduce your customizations (after first separating/disabling ant shared info between any devices) -remember you can save your current settings AS a custom preset so you don't lose it!

I would disable all other custom functions, do a factory reset (after backing up my custom profiles) and Re-set up your MPPT.

In lieu of that check your tail end and Re-bulk offset mode and absorption settings under battery expert mode in your custom battery settings and see just how far off they are from the stock ones - you might have mis-set something and not noticed it.

If the problem solved with a few days of stock settings, change things back .

As far as bmv and delays vs MPPT readings... I know you can set the delay in how the bmv reads and responds to data over time right on the battery page so put it at defaults for now.


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hour avatar image hour Trina commented ·

Thanks for the response! Do yours read the exact same voltage when rapid charging? Mine read the same (BMV vs MPPT) without load, but hit it with 5 amps charge and I may see the numbers within 10mv. 15 amps and it could be a 13.33 perceived @ mppt vs ~13.52 at BMV (and smart BMS, and terminals, and other pokey places) I think that's always been the worst, knowing that solar is... unpredictable, so my "calibration" of 13.7v absorption to equal 13.80-82 actual is a wildcard, who knows what my panels will be bringing in at that time/any time.

I'll try to do the factory reset, I believe that's the one thing I've failed to do in all this time. I also have a 100/30 that I never implemented, so I can give it a test with another Smart Solar device and rule that out at least. Forgot I had it... FWIW this used to be a common discussion on these boards, there were probably 10 threads on it a little over a year ago. Some are still to be found, others I cannot, but they never saw resolution. Just the hope that a future firmware update would resolve it. Thanks again!

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Trina avatar image Trina hour commented ·

Wait. WHAT?

I thought you were doing 24v?

Where/why 13.xV on anything?

Oh...yoI've not the OP.

I'n your case I'd save my current settings for both devices, unplug the bmv and do a factory reset on both then set the the MPPT up with defaults to get it working correctly.

There's a parameter if messed with incorrectly in expert battery mode that allows a degrading of these adaptive settings over time. I think it was related to over voltage and overcharging?

Make a new post? Too confusing on another's thread.

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Trina avatar image Trina Trina commented ·

On my way out but just read about it (7.0 in manual) and forget now the link and will have to check back on rest as my bmv went wonky yesterday.

Turn off and unplug everything don't even have the temp wires in the b2 on the shunt while ironing out any MPPT issues seems to help me.


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hour avatar image hour Trina commented ·

Lol, yeah sorry - not OP. Still yet to do a factory reset, but I don't know that your tip on ironing out MPPT issues stand-alone will work here as the issue seems to be how the charge controller is interpreting voltage over the smart network.

Here's a screen shot of both the BMV and MPPT open simultaneously on my computer. Note: the MPPT and BMV voltage will read the same when idling, but when charging like in the picture - oh no.

BMV reads 13.59. Smart BMS (not pictured) reads ~13.59. Poking places with multimeters reads ~13.59. Smart Solar on Smart Network reads 13.42. If I leave the smart network it'll read a bit above the BMV/actual system voltage (say 13.65) - normal, and one of the reasons I bought a BMV - but that number is soo much closer to reality than this 13.42 that's making my absorption setting a very rough approximation.

Expected would be the smart solar displays the BMV voltage it's receiving over the smart network and honors that for absorption settings. Worse, but still acceptable, would be it averages its perceived voltage (say 13.65 versus BMV's 13.59). Absolute worst - me: the smart solar picks some random number that doesn't appear to correlate to anything and actually uses this number for absorption setting.

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3 Answers
rzirzi avatar image
rzirzi answered ·

No none could help me at this forum?, so - where should I ask about it? Is there any Victron support contact possibility?

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klim8skeptic avatar image klim8skeptic ♦ commented ·

What charging state do the leds on the mppt indicate?

Do the batteries reach the bulk/absorb setting?

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Trina avatar image Trina commented ·

Got to give us some system specs or screen shots of your settings and battery page tabs.

Without this,

If you are not getting into float consistently are you certain your batteries are still good?

For 1 day they might seem good but need to have everything be "reset" by unplugging everything and redoing it to appear good again a day later. So that's one possible problem.

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Trina avatar image
Trina answered ·

The victron techs are not on here except 1x or 2x a week so you might have to wait a few days more for a direct response. Sharing specific details also will help the community help you find an answer possibly quicker.


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danny-du-plessis avatar image
danny-du-plessis answered ·

Hi what batteries are you using. Because 28V float is very high for a 24V system.

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