question

elimac avatar image

How to reset SOC to 100%?

There is one past thread about this issue in which I participated, but it seems the recipes mentioned (and that I've been using) for some reason don't work anymore:

https://community.victronenergy.com/questions/39650/how-do-i-get-soc-to-show-100.html

For the last weeks I never got my system to show 100% again (or 85% for that matter). I've set MPPTs to have absorve voltage higher than what is set on Multiplus, I also made sure the absorption time was higher, but nothing seems to work. Never get to the 85% or whatever is set on the Multi.

I have run out of ideas...

My system is Venus based, no BMV, but no DC loads or charges.

Current Multi Settings are like this:

MPPT vales are what you wish.. tried even with 28.8V in absorption today.

See graph:


Why can't the SOC be recognized as 90% ?

Venus is running 2.60, not since too long ago. Could be something within Venus OS?

I also tried Multi connecting to GRID -> Goes straight to FLOAT, SOC continues at ~30%

This is an old issue... but for the moment, besides trying to figure out the root cause for the system not resetting every day to 85/90%, what I would like to ask now - as a workaround - is how to manually force the system to reset to 100% ?

I used to do the trick of commanding the Multi to Equalize from Grid and then Interrupt -> go to absorption / Float. It used to reset to 85% (that was at the time set). But now even this is not working.


MultiPlus Quattro Inverter ChargerVenus OSSOC
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6 Answers
Mark avatar image
Mark answered ·

Hi @Elimac,

Sorry I did not see your recent updates until now.

1- Yes indeed the Multiplus re-bulk voltage is significantly different when 'Lithium batteries' is the selected 'battery type' (in the charger tab of VEConfigure):

  • Lithium: Re-bulk Voltage = Vfloat - 0.2V (max 13.5V) - for 12V system, multiply by 2 for 24V systems & by 4 for 48V systems
  • Others: Re-bulk Voltage = Vfloat - 1.3V (max 12.9V) - for 12V system, multiply by 2 for 24V systems & by 4 for 48V systems

As you were having this issue I assumed that you were using lead acid type batteries and could not change the 'battery type' setting in VE.Configure to 'Lithium batteries' (since there are also other implications), so did not mention it.

Per my initial answer, you can also force a new charge cycle by restarting the Multiplus.

2- In the current Venus OS, to keep the menus clean/simple, that system information is now under Settings 》System setup 》System Status

However this menu is now hidden and only appears if the access level is set to 'Superuser'.


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Thanks Mark for coming back. However, I still can't find this menu.

Here's what I see in System Setup:

I went into every submenu in Venus OS 2.6 and I never saw any System Status... are you using ESS? I'm not...

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Yes sorry, this menu is now hidden and only appears if the access level is set to 'Superuser'. I have just edited my answer above to include this information.

Hi Mark, I am experiencing similar issues with the SOC and I am trying to find a solution reading several discussions on the forum. I have an Easy Solar 24V, 1600 VA and I recently installed the Cerbo GX. The SOC % is slowly rising day by day, it started at 0% and it is now around 30% although the system seems to bulk correctly and then goes in float. See picture attached ( please note that it is an off grid system, with no loads at the moment)

I have tried to slightly raise the absorption voltage in the MPPT as explained in the manual but nothing has changed. All the parameters seem right but now I have just found your post, I have checked my system and I noticed that neither the " Synchronize VE.Bus SOC with battery" nor the "Solar charger current control" are ON. Shall I put them ON? Why are these into a Superuser mode, could I damage anything if I just try?

Thanks


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elimac avatar image
elimac answered ·

Just confirmed. The problem was the Multiplus was never in Bulk stage. Once I selected Lithium, finally on next cycle it was ok again.

So, in summary, after I added more capacity to battery, the voltage never reached a level low enough - Multiplus always in Float and SOC was incorrect.

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elimac avatar image
elimac answered ·

The answer to this thread might be here:

https://community.victronenergy.com/questions/175/how-do-quattro-and-multiplus-decide-to-switch-from.html


I've changed to Lithium in Multiplus, as it is what I have now. Before I didn't explicitly checked the below option, I just changed Voltage levels to my needs:


But it seems the Multiplus has different thresholds to return to BULK if the checkbox is checked or not. If is checked, it is enough for battery voltage to drop 0.4V (24V system) below Float to restart bulk cycle. If not checked, it will go to bulk only when BAT voltage is V Float -2.6V (again, 24V system).

It would be nice if someone from Victron confims or denies this.


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Mark avatar image
Mark answered ·

What firmware are you running in all devices - are they up to date?

In the Venus device, can you recheck that the Multiplus is selected as the SOC source under Settings → System Setup → Battery monitor?


With an external charge source (solar charger) the Multiplus will not 'reset' the SOC % to the 'SOC when bulk finished' level when the battery voltage is raised above the absorption voltage set in the Multiplus - it will only allow the SOC % keep rising above the 'SOC when bulk finished' level.


To 'reset' the SOC % to the 'SOC when bulk finished' level you need to conduct a charge cycle with the Multiplus.

And to trigger a new charge cycle (with the Multiplus) the battery voltage needs to fall below the 'Restart bulk voltage', which for a 12V system is = Vfloat - 1.3V (max 12.9V), multiply by 2 fro 24V systems and by 4 for 48V systems.

The other option to trigger a new charge cycle with the Multiplus is to simply turn the unit off and then back on.


Long term - if you run off solar regularly and the SOC % is not tracking properly (falling overtime when the battery is actually fully charged) then you need to increase the charge efficiency - I would go direct to 100% and see how it tracks after a proper synchronization. Your batteries may have also lost some capacity over time, so it might also help to lower the capacity a little.

If you want more accurate/better SOC% measurement you really need to add a BMV/smart shunt to the system.

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I've found an important detail.

Today morning I switched Multiplus to GRID. Surprise: its state was still FLOAT.

And I think I know why. In last weeks I have expanded the battery with more cells. And now, the morning voltage is always above 26V whereas in the past it was about 25V.

The float value in Multi is set as 27.5V at the moment. I think it does not recognize that a new cycle as started, in the morning. How to solve this?

octafish avatar image
octafish answered ·

Good thread (newbie here).

So I just installed 600ah Lithium (x3 Superpacks, 200ah each) with Multiplus 12/3000 and 340w Solar w/ Smart MPPT.


Since you guys give great advice, what’s the recommended way to do a full charge/discharge cycle, so as to prolong the life of the battery bank?

Note, I’m using a Simarine Pico display as a Battery Monitor with (1) shunt for loads, (1) shunt for batteries, (1) shunt for solar/chargers, (1) shunt for inverter. It seems to read to correct SOC on the Simarine but it’s not identical to the Multiplus, especially since I activated the MPPT charger.

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elimac avatar image
elimac answered ·

Thanks Mark for your reply (once again you alwasy try to help :)

However, I can't understand why the SOC is being "capped" at 39, 38, 36, 34% .... going lower every day, when the voltage always reaches absorption and higher from Multiplus setting by a good margin. This didn't happen before. I had not had a correct SOC, but I had and approximation. See old SOC calculations from older period:


I always found a way to push up. But now, since some weeks, no way to make it back up. Started descending and never ever again hit the 80-ish % mark. I did not change nothing in Multiplus in September. Only Venus OS was updated.


Coincidently, I cannot find the below options / information anymore in my system. This picture is actually from a topic of yours, Mark:


Has anybody checked if the above is still visible?


EDIT: Multiplus version: 459

MPPT chargers were using latest official release at the time of the drift started.


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