SmartSolar MPPT 150/45 don't go into Float

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Daniel asked Jul 29, '21

SmartSolar MPPT 150/45 don't go into Float

Hey!

I got myself a SmartSolar MPPT 150/45 - TR with the Display option. I switched from my 100/20 to the 150/45 because the smaller one was on its limit.

The problem that I encountering now: The new MPPT doesn't go into float.

It's connected via VE. Smart Network to a SmartBMV 712 and a SmartBatterySense. On the app, the MPPT says it's using external voltage and external Battery current sense from the BMV and Battery Temperature from Battery Sense.

Its also connected to a Raspberry Pi running VenusOS.

Right now, the MPPT is set to a maximum absorption time of 6h and an Absorption Tail Current of 4A. The MPPT as I'm writing this is charging the Battery with 3.1A (MPPT Reading) where 2A go to Battery (BMV Reading)

From my understanding, the MPPT should go into Float if the Absportion time is at max 6h or the Battery Current goes under 4A for one Minute.

Today it started charging with 11.8V and is in absorption for 4 hours.

Typical days are, charging bulk over the day, going to Absorption, Battery Current falls under 4A, and MPPT still in absorption. Then, when I come home and using the energy, it goes back to bulk if the sun is going down. Or if I'm not using Power, the MPPT going straight from Absortion to off.

2 Days ago it once was in float for 20 Minutes then the Sun gone down.

I think it is not good for the battery if it's continuing this. Does someone know an answer to this?

MPPT Controllers BMV Battery Monitor float

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Alexandra ♦ commented · Jul 29, 2021 at 05:52 PM

@Daniel

What battery do you have? you could always change the absorption to a fixed rather than adaptive and lower the hours. Hard to make recommendations if you dont know battery capacity and various other details.

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Daniel Alexandra ♦ commented · Jul 29, 2021 at 09:26 PM

I'm running a 200Ah sealed LeadAcid AGM Battery. Im try to run other Appliances with the Function of the MPPT to switch on the Relay if battery are in Float to Use more Solar Energy.

The faster the MPPT turns to Float on a full battery the better for me.

And it would be nice to know if its a bug in the MPPT Firmware or something else.

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Answer 1 · 2021-08-02T12:58:39Z

Alexandra answered · Aug 02, 2021 at 12:58 PM

@Daniel

From what i can see is it is rebulking everytime a load switches on and drops the voltage under the float voltage.

So it wont stay in float. You could try and dummy it by changing the rebulk offset to a larger figure (not so keen on this one it is agm and best to charge them up and keep them up. or running your float a little higher by about 0.2v or so of battery spec allows it.

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Daniel commented · Aug 02, 2021 at 04:05 PM

Hey Alexandra and @MaxS ,

as i mentioned above, it doesn't even reach the Float state. It charges in absorption all day long until sun goes down and Charge current isn't enough to hold the 14.6V.

Also is this a day where i wasn't home and i didn't switched any load on. Only thing that's running is my Phoenix 12/375 Inverter with a draw of around 5W. Everytime it goes to back to Bulk is when clouds hiding the Sun.

Everything worked fine with my older MPPT 100/20.

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Answer 2 · 2021-08-02T13:12:13Z

maxs answered · Aug 02, 2021 at 01:12 PM

When your battery is old and you draw large current, the voltage drop caused by battery ESR can become very high. Hence, resulting in the effect Alexandra mentioned. Maybe you can check the battery ESR and determine your load current. Or just measure the bat voltage drop when you connected your loads. Then set hysteresis "re-bulk voltage offset" 0.1 / 0.2 V above the dropping.

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Answer 3 · 2021-08-02T14:46:50Z

JohnC answered · Aug 02, 2021 at 02:46 PM

Hi @Daniel

I don't think it's the Re-bulk causing this. Even after rebulk it should drop to Float when the 'System' current gets below the Tail (and Abs V is met). Sometimes that may take just minutes and happen many times over a day.

I suspect the mppt isn't recognising the Tail function. This hasn't been around forever, and might be old firmware in the mppt. What do you have there?

Another possibility is that the mppt isn't getting the system current and using it's own. Would only be relevant if you had separate loads which would keep it above the 4A.

You could test the Tail by raising it to something silly.

In your pics you've cut off the Battery Preset line. Is it a standard one, maybe 'Gel(2)' or suchlike?

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Daniel commented · Aug 02, 2021 at 04:19 PM

Hey JohnC,

this is exactly what I mean. It doesn't recognize the Absorption Tail Current. Firmware is v3.02 and Bootloader v1.07.

I have a couple of loads: one Phoenix 12/375 and some USB devices. When everything is on Standby I have a current of around 1.5 A to 1.7 A over the whole day until I'm coming home from Work.

When I click on the VE.Smart networking Symbol, it says is Configured to use Battery Voltage, Battery Temperature and Battery Current from the VE.Smart network. But the Last days I could see that the MPPT had a Charge Current of around 3.4A so it was below the 4A Tail Current. So it isn't even using its own current. It totally ignores this Funktion.

The Battery Preset is a Custom one. I have an Orbis 200Ah AGM Battery.

It is this one: https://basba.de/orbis-bagm230dc-bordbatterie.html?gclid=CjwKCAjwr56IBhAvEiwA1fuqGoX6jXIFt6P1yA0kh7-nD9z-CzU4JmbUsup6QnkeMKOem9iy1hZAQRoC_jsQAvD_BwE

I even tried to set the Tail Current to 15A when in fact the MPPT only put out 4 A in full sun.

It says me the MPPT ignores this Function nevertheless I tell it to do. It wants to absorb the full time.

One thing I maybe can test, Charging the Battery overnight with my BlueSmart Charger so that the Battery Voltage is fairly high so the absorption time should be shorter.

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maxs Daniel commented · Aug 02, 2021 at 08:25 PM

Hi Daniel,

what is happens when you disable the tail current trigger function and set the maximum absorpotion time as low as possible? Does it switch into float charge mode for a short time after running for the set maximum absorption time?

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JohnC ♦ Daniel commented · Aug 03, 2021 at 06:34 AM

@Daniel

Check your mppt firmware. The firmware you've quoted might be VConnect. I note 1.59 came down for me today, but VConnect may lag a little getting that. As long as it's something recent.

Look to the Battery Preset. I know the Lithium preset ignores the Tail, and if you've modified that then you may have inherited that trait.

Your batts aren't unusual, so try this.. Select a pb preset, 'Gel(2)' would do (I know that doesn't ignore Tail), then Create Preset. You'll be asked to name it, let's say 'User1'. Save that, then Edit it. Enter your preferred data and Save that. (Take care deleting Presets).

You should now have Tail functionality, with User1 listed as the Battery Preset.

If that doesn't work, then I'm calling a firmware bug for that model mppt.. Good luck..

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Answer 4 · 2021-08-04T15:19:33Z

Daniel answered · Aug 04, 2021 at 03:19 PM

@MaxS I have to test this. Right now, it is heavily overcast, and I need more energy than my PV can deliver.

@JohnC What is VConnect? I logged in on my MPPT over the App. Clicked the three points and then Product info. Oh now... VConnect is the Victron Connect app, am I right? Oh my, I'm dumb. I clicked the Update button, and it says that the Firmware is already the newest version. Screenshots below.

I think I did the preset thing over a PB preset, but I think the standard setting when I first time powered it up was lithium, so your theory might be right. I first will Try @MaxS's suggestion by deactivating the Tail current and setting the Absorption time to an hour.

Then I try to make the new preset over the Gel PB Battery.

It might take some time with this weather in Germany here. German Weather Service says overcast with thunder from now until Thursday 4 am. I will then post my findings here.

Oh btw. On my old MPPT, I set the Tailcurrent for fun on another Battery, and it worked.

Thanks for all suggestions by now!

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Daniel commented · Aug 05, 2021 at 07:11 PM

So I was home earlier today and even had some sun to test. I deactivated the Tail Current function and set the MPPT to 1h absorption. After being absorbed for more than one hour with some breaks caused by clouds, I put the absorption time to 10min, where the MPPT directly switched to float.

Then I tried to create a new profile. I first reset the MPPT, put the rotary switch to 0, and in the App, I select preset Gel. Interestingly the app directly switches to custom again. I then set the Voltages and the Tailcurrent to 10A, and Absorption is six h by default. And what did the MPPT do? Nothing. It stayed in Absorption even the Tailcurrent was set to 10A, and the Battery took only 4A.

So I think it's a bug.

It would be nice if someone of the devs of the Firmware could explain what the MPPT watches for to go to float if the current is lower than the tail current is set.

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JohnC ♦ Daniel commented · Aug 06, 2021 at 08:27 AM

@Daniel

I think I've found it. You must have a mppt with both VEDirect and CAN ports. From the firmware changelog..

"v3.04 – 05 March 2021

Released for all models

Bug-fix:

-Fix transition between Absorption and Float states when tail current condition is met."

And it was the only change in that release. I can't link it directly as it's a .docx file, available in VictronProfessional. The latest fw is actually v3.07, so see how you go trying an update.

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Answer 5 · 2021-08-05T19:53:04Z

maxs answered · Aug 05, 2021 at 07:53 PM

Seems to be a software issue probably. But last check I recommand: take a clamp meter (Strommesszange - you are german too) and compare all currents to the software measured currents. Measure plus and minus lines and check that currents are equal in both lines and to the displayed values.

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Daniel commented · Aug 06, 2021 at 07:51 AM

@MaxS So tested it right now, but it is heavily overcast right now. I tried to measure as quickly as possible that solar didn't change so much.

MPPT Pushes in 2A and shows 2,3A

BMV Says I use 3,5A from Battery and measured 3.46A

My loads are 5A from Inverter and around 0.4A to 0.2A from other 12V loads.

So my loads are around 5.3A - MPPT 2.3A is around 3A. 3.3A if I use MPPT Reading. So it seems to be somewhat correct with measuring errors.

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maxs Daniel commented · Aug 06, 2021 at 10:13 AM

Yea seems to be right, so I must admit that cant help you any further. Maybe the v3.04/7 update is the solution

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