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shellyp81 avatar image
shellyp81 asked

Smart Solar Firmware v2.25 Issues - Going to float too early & not keeping up with demands while in float

Hello, sorry for the long post/question but I wanted to give plenty of information upfront in hopes of a resolution.

I have noticed recently (after the recent firmware update v2.25) that my smart solar mppts are now synchronizing with each other and going into float far too early. Also, while in float, they are not covering power usage like they used to. For example, if a refrigerator compressor kicks on, the solar charge controllers are not compensating for the drop and I see a negative draw on the battery bank in the middle of a sunny day at 2 pm at the equator with full sun on all panels. (I have 5 controllers and one BMV712 battery monitor).

I went into each controller and each said it was networked to the other (NEW), along with the BMV712 using the Battery voltage sense and the external current sense from that monitor (as originally installed). This system was working properly with the connection to the BMV.

Now, while in float, the system is only letting current flow from one solar panel. All of the others were seeing good voltage but not sending any current to the battery bank which should not even have been in float yet. (Yes, I am sure they should not have been in float)

First, for each smart solar controller, I went into settings and in the expert mode, I changed the absorption time to 10 hours fixed. That did not overwrite the floating-issue nor the issue with keeping up with usage.

Next, I went in and turned each charger off and then on again to see if they just needed to be reset for the change to take effect....no didn't work

Finally, I un-networked them entirely, they are no longer connected to each other or to the BMV712 and now all controllers are back to absorption. While this is working, I am concerned that they should be still connected to the BMV.

My questions are: Why is the fixed absorption setting not working? Is there some other setting that is overarching and not allowing that setting to take effect?

How can I re-network the BMV without having the float issue return?

Many thanks for any insights,

Michelle

smart solar charging behaviour
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1 Answer
mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi Michelle / @Shellyp81, since you have a BMV connected, the switch from absorption to float is probably due to the Tail current function. That mechanism is still active; even when selecting a fixed absorption time.

More details here: https://www.victronenergy.com/live/victronconnect:mppt-solarchargers#battery_settings


The alternative to disabling the tail current feature is to further lower the threshold; so that it only switches to float once the battery really doesn’t accept any more current - but be careful - too long absorption everyday; especially when only discharged a little bit; is also not good.

Ps. I see now how this can be confusing - we’ll work on clarifying this further in the app.

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shellyp81 avatar image shellyp81 commented ·

Hello mvader,

We're on a sailboat with limited solar panel capacity, so I have a hard time generating enough power to fully charge my bank of batteries in optimal conditions. It's rainy season now and cloudy a lot so I need this system working right. I did realize that the tail current was causing a problem, so I disabled that setting on the chargers. On the BMV I have the tail current set to .5% per Lifeline's user manual. That did not work and the batteries still went to float too soon. So, then I noticed the re-bulk voltage offset setting which I think was causing the issue of not covering my power usage during float. We're still going to float before the battery is fully charged. So then I changed the float voltage to the absorption voltage and I am getting a little better results. But I still have a problem - these controllers are not bringing the batteries up to my voltage settings even though there is enough sun and voltage on the panels, I still have one or two chargers doing nothing when they should and could be doing something. If I turn on our generator, that charger will bring the batteries up to the right charging voltage so I don't think it's the batteries. Pictures below.

First: My original settings were based on Lifeline's user manual for charging in higher temps - I have 800ah AGMs set to Absorption: 14.1, Float: 13.1, Equalize: 15.2 (yes I can equalize per Lifeline recommendations) - I was using the adaptive absorption. So the batteries almost died, we are trying to bring them back up to a full charge, they are recovering but I am noticing several deficiencies with my solar set up during this process.

The settings are currently absorption for 10hrs at 14.1, Float 14.1, Equalize 15.2. Yesterday, I first see that the batteries are in absorption putting in about 12 amps far more than my tail current setting which would be 4 amps. I see this: battery voltage is 13.97, I have not yet hit 14.1v this day & I have two solar panels putting in zero amps (see photo). WHY?

When I saw this I hit the equalize button, the batteries have been undercharged for a few weeks and it's sunny for a change. So they all go to work, but then they never take the batteries up to 15.2, highest I see is 15v with two panels back to doing nothing. (see photo) If I flush the electric toilet, the panels start adding power. Why are we not achieving the correct voltages during absorption and equalize even though there is enough sun? What am I missing?

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shellyp81 avatar image shellyp81 commented ·

Another update: Today I saw the batteries go to float at 12:30pm, the BMV still shows 30 amps to be replaced into the bank. The voltage never reached 14.1 - I took each chargers off of the network and watched the controllers go back to bulk charge and immediately bring the batteries up to 14v. Something is not working properly with the synchronized charging and the connection with the BMV - what other setting might be the issue?

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