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Alexander Ravencraft avatar image
Alexander Ravencraft asked

Help with Victron Configure Charger Settings

Multiplus C

currently going thru my config of the Multiplus Compact (24/1600).

I already adjusted some settings with help from a distributor, but I'm not happy as there are some unclear values, which I'd be happy to understand.



I plan to charge my LiFePo4 when connected to shore. That can be one day, or 1-2 weeks.

My idea is I don't need to charge to the extreme, as I am on 230V anyway in the charging situation.

Thus, my charging voltage settings are quite low.


LiFePo4 Balancing starts at 27.2 (3.4) end ends at 28.8V (3.6)


My Multiplus Compact float is currently set to 26.4 and absorption to 27.6V.





In The Victron Configure Software, there are some details I don't understand:

https://docs.victronenergy.com/veconfigure.html#charger-settings


Talking about these points:


Charger Settings

4) Lithium.

It seems, when I check this option, I don't have possibilities to adjust the absorption/float voltages, it's greyed out?

I'd like to use Lithium settings, but still adjust voltage values, for me the values are too high, my battery manufacturer suggests to set it lower.


So currently I've unchecked Lithium and adjusted manually.

Not sure if the resulting charge curve is good for LiFEPo4. In my understanding, especially after the absorption is done, it shouldn't hold the voltage any more to protect the LiFePo4 cells from overloading.

So would a "fixed curve" make sense, or what?


5) Storage Mode

How much will the voltage be reduced below float value? I find no values or percentage given in the manual. is there a storage mode for the Multiplus C at all?


11)Battery Type

My battery is a self built 2p8s LiFePo4 220Ah 24V,

So should anything specific be set here at all?

Again: the voltages which are preset for the Lithium mode are too high.


12) Absorption Time

I don t get it. Why will it be limited? Is it the time it stays on full voltage after that voltage has been reached?

Or is it the Time it charges with the Absorption Value, and after this time it goes to Float, even if battery is not full?

If so, where do I set the time it stays on full voltage after it is reached?


Currently set to 1h


13) Repeated absorption interval

I don't get this neither. Why is the loading dependent on an interval, and not on the "Full" status of the LiFePo4 pack?

e.g., the MPPT Smartsolar will load the LifePo4 till it reached the voltage , and eventually swith to float.

So how is this interval setting understood, related to the default loading whenever the battery is not in float or storage mode?


Currently set to 7d


14) Max Absorption Time.

I don't understand. Can u explain?


Currently set to 1h




Explanation to any of these setting values is highly appreciated !

thx

VEConfigure 3multiplus compact
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1 Answer
Kevin Windrem avatar image
Kevin Windrem answered ·

Keep in mind that the absorption phase is used to balance cells in a LFP battery. The voltage needs to be high enough and absorption phase long enough to guarantee the cells are balanced. I suggest using the values specified by your battery manufacturer. Setting absorption voltage too low won't allow cells to balance. Don't second guess their recommendations.

The VE Configure demo allows setting absorption and float voltages and absorption time even with Lithium batteries selected. Same in VictronConnect which you might want to look at -- it's simpler.

There is a good help system in VE Configure. It should answer most of your questions.

You need to select Lithium since this disables temperature compensation which should not be used.

Stoarge Mode isn't used fro Lithium batteries and is disabled at least in the demo. In any case, it should be off.

You should select the Fixed Charge curve. In which case you get a setting to set the Absorption time and not a Maximum Absorption time. This is the time from when the absorption voltage is reached. During absorption, charge current will decrease and eventually reach the "tail current" (which resets the battery SOC to 100% in the battery monitor). The charger switches to the float voltage at the end of absorption time. It is essential that this period is long enough that the cells balance. The battery manufacturer should specify this time.

With no (or minimal) loads on the system, the battery will remain at the float voltage indefinitely. The repeated absorption interval forces the charger to reenter the absorption phase. In the case of lithium batteries, this would trigger the balancing mechanism, so this doesn't need to happen often. If you load the battery, it will reenter bulk then absorption phases due regardless of this period.


Again, check out the help in VE Configure, and/or the manuals for it and VictronConnect

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Alexander Ravencraft avatar image Alexander Ravencraft commented ·
Kevin,

Wow,I didn't expect such an elaborated answer, I really appreciate your effort.


I'll work through your answer and mayhaps come back

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