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scubasail avatar image
scubasail asked

Victron 100/30 doesn't rise to absorption

Hello,

this new 100/30 is set to "User defined" battery profile with 13.9V absorption for 1 minute and 13.4 V float (equalization not used but set to 14.0V) however every morning it brings the LFP batts from around 13.0V o 13.1V to 13.4V but never tries to get them to 13.9V as can be seen on the graph.

I read in a different post here that it needs a minimum drop of 0.1V for LFP before it rises to absorption. What is the required drop for this "user defined" profile then?




battery charging
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2 Answers
stevecounsell avatar image
stevecounsell answered ·

I’m no expert but maybe the Absorbtion Stage is not long enough. I think I’ve read on this community that absorbtion should be set to 30 minutes and you have it set to 1 minute.

But as I say, I’m no expert.

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scubasail avatar image scubasail commented ·

Thanks Steve, it was deliberately set to 1 minute to effectively turn the absorption phase off, since you don't want that with LFP batts.

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stevecounsell avatar image stevecounsell scubasail commented ·

I’ve misunderstood your question; i thought you were trying to get the MPPT to push absorbtion voltage :)

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mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi, try increasing absorption time; and, measure at the mppt terminals. And check what the mppt itself is measuring; and what state it is in.


I really cant see a reason for it to go from bulk (which normally ends once the voltage has risen to absorption voltage) before it has done so.


I’m not sure what the 0.1V drop is referring to.


Lastly: check temperature compensation.

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scubasail avatar image scubasail commented ·

Thanks for the reply, the graph shows the voltage and current directly at the output of the MPPT terminals as that's where the producer controller is situated. That controller then send the data back to the database and web server.

I can try to increase the absorption time to see if it makes any difference, but if it does, it sounds like there is bug in the firmware, doesn't it?

I haven't touched the compensation setting, but will check that, too.

The 0.1V drop I mentioned was referred to in another thread: It suggests that the bus voltage has to drop by some value first before the MPPT changes from float to bulk mode. Can you confirm that?

Say the batts get fully charged by 11AM, MPPT goes to float, then comes a big load which draws the batts down to, say, 70% SOC by 1PM. At some stage, the MPPT should decide to go back in bulk mode rather than just trying to hold the float voltage, correct?

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mvader (Victron Energy) avatar image mvader (Victron Energy) ♦♦ scubasail commented ·

Hi; no I don’t think there is a bug.


Forget about that 0.1V; I dont know what it is; but know for sure that its not related.


The unit switches from bulk to absorption once voltage has rised to absorption voltage. There are no other conditions.


Unit switches from float to bulk on voltage as well. Search the documentation to find the threshold. Either mppt victronconnect manual or the mppt manual itself.

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Gary Pacey avatar image Gary Pacey scubasail commented ·

You say "the graph shows the voltage and current directly at the output of the MPPT terminals ". Does your measuring equipment connect to the actual terminals of MPPT 100/30? And how do you measure the current coming from the 100/30?

I would suggest the following:

  • Increase the absorption time to 30 minutes
  • Measure the terminal voltage of the 100/30 using a digital voltmeter once the unit is in absorption mode - say every 5 minutes
  • Then measure the voltage at the battery - say every 5 minutes
  • Report the voltages


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