question

kane-1 avatar image
kane-1 asked

Absorption limit 24v, float limit 24v

Multiplus 2 24v + 10 cell battery

One cell broke from the big lead acid battery (3x11 cells), so I had to take one cell out of all and now I have 3x10 cells. I can't combine them to 2x set in because 1 package is slightly different.

I thought it wouldn't be a problem, because I calculated that the voltage would never drop close to the limits of the inverter. In addition, next to the batteries, there are large capacitors to handle the sharpest consumption peaks.

The battery is mostly ESS and I don't use the battery much during the night. Sometimes there are power outages, but they are short, lasting less than a second.

I was surprised when the limit couldn't be lowered enough. Minimum absorption voltage is 24v, minimum float voltage is 24v.

Now I have to monitor when the battery is full, after which I set the ESS charge limiter to 0 watts. Difficult. Can I get the charging to be cut off when the battery SOC is 100%?

Could float limits be lower in future updates?

Multiplus-IIchargervoltagefloatlead-acid
4 comments
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Michelle Konzack avatar image Michelle Konzack commented ·
May I ask you, WHY you where running only 11 cells instead of 12?


A configuration with 10 cells is not supported.


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kane-1 avatar image kane-1 Michelle Konzack commented ·

https://community.victronenergy.com/questions/98914/multiplus-2-24-is-it-possible-to-use-a-22v-battery.html

Because Matthias Lange - DE said it is possible and because I wanted to. I get inexpensive battery packs that usually run out of one cell.

The capacity of the batteries has since increased, but I don't buy new cells because they cost a lot. The battery is otherwise fine.

10 cells would not be a problem, because the voltage does not even drop below 20.6v at any point due to the capacity of the batteries +1200ah




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Michelle Konzack avatar image Michelle Konzack kane-1 commented ·
Right, 11 cells will work, but with 10 you run into trouble.


If Victron would add an option for 18V Batteries (like for 36V), then you can go to the upper limit.


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kane-1 avatar image kane-1 Michelle Konzack commented ·

I have now used 10 cells and ESS Assistant voltage limits adjusted to 20v. The system works well, of course it requires manual monitoring of the charge level so as not to overcharge for too long. The usage is now cyclic and I don't use float at all.

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3 Answers
mvas avatar image
mvas answered ·

You say that, you are surprised that a 24 volt Multiplus will not Float below 24 Volts? There is no 24 Volt (Lead Acid or Lithium) battery that should float below 24 Volts. You are "lucky" that your 11-cell 22 volt battery is supported. Now, you want a 10-cell 20 volt battery to be supported? When another cell fails, will you be asking for a 9-cell 18 volt battery to be supported? Why should Victron redesign their equipment for the abnormal needs, of one person?

You might be able to adjust Absorb mode, to stop at 100% SOC for your 10-cell 20 volt battery and then skip Float. Then go to re-Bulk, as needed.

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kane-1 avatar image
kane-1 answered ·

Of course, I won't go below 10 cells, because the device has certain voltage limits. Due to the size of the battery, there is no problem in terms of use, because I stay well within the voltage limits, I'm sure you get the point. And I'm certainly not the only one who has thought the same thing.

There is no need to go below 20v voltage. And I'm skipping float and using it now in cyclical use.

Your response was quite negative and rude. I hope you haven't done the same to others, because the forum doesn't need that kind of thing.

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mvas avatar image
mvas answered ·

Just buy yourself a small regulated power supply with current limit. Set it to your abnormally low float voltage and set it to your maximum float amps. Connect it to the battery bank. Problem solved.

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