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Multiplus-II State of Charge (SOC) Calculation (Undercharging)

I like to keep my LiFePO4 batteries in a comfortable range of 60%-90% state of charge and the SOC calculation combined with AC disconnect settings are a great way to maintain this with the MP-II (24v/3000/2x120). For my batteries the optimum charge settings to achieve 90% are 27.40v absorption voltage, 1h absorption time and a 26.70v float voltage. Right when the bulk charge hits 27.40v and enters absorption phase, the pack is about 73% charged, so I set "State of charge when bulk finished" to 73.0% in General settings, and it works as expected. The absorption charge tapers off the current a bit for 1 hour, and at the end of the hour the battery is exactly at 90% according to my BMS and verified with a final capacity check using a full charge.

The problem is the SOC calculated by the MP-II jumps from 90% as it should be, straight to 100% right at the end of that absorption phase as it switches over to the float cycle, even though at that lower float voltage of 26.7v, the current immediately drops to 0a. It seems the SOC calculation wants to hit 100% when entering float despite the "State of charge when bulk finished" setting.

Just wondering if there are any workarounds.

alferz asked

0 Answers

MP2, ESS Can not discharge below 19% SOC

Hallo All :)

I'm using the Multiplus II + Cerbo + 3x SOK48V100Ah (16x3.2V LiFePo4) in an ESS setup with AC coupled PV. Batteries are weeks old. Using ESS without battery live only.

I noticed that when I set the lower SOC limit (that triggers ESS#1) below 20%, this limit is never reached. At 17%(with load)-19%(without load) the Multiplus starts charging from grid will 3000W for one or seconds and repeats this after some seconds. Voltage is around 51.2V - 51.8V at that time.

I tried to find a setting in VE.Config & Cerbo without luck. Sustain voltage is set to 48V. Dynamic shutdown is set flat to 48V. Nowhere in the system is this voltage mentioned. The BMS (connected via CAN) anounces no discharge limit, no notification in the Cerbo menu.

When I set the SOC limit to 20%, the ESS#1 is triggered and the battery idles as expected.

I tried to find similar questions in the forum, but only got this one:

https://community.victronenergy.com/questions/109156/ess-low-soc-battery-not-idle.html

which might be a similar problem, but at much lower SOC. I can not discharge that deep.

I even tried to set the grid setpoint above zero, zero, and even at -3500, but with no luck. At about 17% the discharge is interrupted with frequent short charge cycles.

I know that this is not a serious problem, but it really bothers me that I don't understand why this happens.

Sven Ewald asked

0 Answers

Augmentation SOC Battery Life et charge depuis reseau

Bonjour,


petite question suite à constat de la veille...

La base : MP2 + US500 en ESS AC coupled (CERBO, ET112,....).

Apres une journée de moindre ensoleillement, le SOC du battery life à augmenté de 10%, rien d'anormal, sauf qu'après l’arrêt de production des PV le système a tiré 10% du réseau pour remonter le SOC de la Pylontech à la nouvelle valeur.

Aujourd'hui il fait meilleur, donc j'injecte, plutôt dommage d'avoir du coup chargé la batterie la veille depuis le réseau.

Y'aurai t'il une astuce pour ne pas que ce phénomène arrive ?

Du genre avoir un SOC DELTA vis à vis du SOC battery Life qui bloquerai une recharge depuis le réseau, tant que le SOC batterie ne descend pas en dessous du SOC battery life - SOC DELTA ?



krystof69 asked

0 Answers

Battery monitor multiplus: SOC jumping and not accurate

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Hi all


In my setups with a color control connected to a multiplus 12/2000, Victron AGM super cycle 230, MPPT 100/50, i noticed some werid changes in soc. While i only have inverter as load i use the multiplus build in battery monitor . No BMV or smart shunt connected because no need to.


Now and then my SOC seems to change.

While i can control the system by VRM sometimes i have to switch of the inverter to protect from battery drain. While it seems when i set the inverter to off i cant see voltage and amp-usage, i tebd to switch to "charger only" while above mentioned seems visible.



For example:

My battery SOC is 100 % while i charged by generator and solar panel. During midnight battery voltage is.12,9 volts and no amps drawn except multiplus standby amps, around 1 amp.

So SOC seems to be correct. I Leave multiplus on because i need power and slowly battery is draining because of ther is not too much sun and i use more power then solar can breng up.

Battery soc seems to be ok and calculations seem to be in order. After a few days battery SOC reacties 65 percent, Voltage around12,25. While i dont like to damage the batteries and i it is not completely nesacery i turn of inverter and switch to "charger only".

After one hour battery voltage has dropped a bit (also because solar power is less) to 12,15 and battery SOC jumped to 85 percents. 85 percents never matches 12,15 volts, even not without knowing amps drawing.


Build in battery monitor is setup correct with 230 Ah.


Above mentioned happens when i turn inverter off , or to charger only. It seems like build in battery monitor is confused after i switch off inverter?

Is there a solution to this problem?


Best regards and thanks in advance.





heinzie asked
Alexandra commented ·

0 Answers

Désynchronisation du SOC ?

Bonjour la communauté,

j'ai une installation comme présenté sur les schéma. Mon problème est une désynchronisation entre le SOC affiché (63%) et le SOC réel puisque le Multiplus maintient en Float la batterie avec une tension à 53.3V.

J'ai lu sur un autre post une méthode pour réinitialiser le SOC (https://community.victronenergy.com/questions/102985/comment-reinitialiser-le-calcul-du-pourcentage-cha.html) mais je n'arrive pas à le faire sur le GUI. Y a t il une autre méthode (via DVCC) ?

Je précise que je n'ai pas de Shunt mais que j'ai commandé un "Smart Shunt", cependant même dans ce cas il faudra réinitialiser, une procédure qui semble décrite dans le manuel (automatique ou manuel)

Confirmez vous mon analyse ?

merci

laurent

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laurent-2626 asked
laurent-2626 edited ·

0 Answers

VRM - Remote Console can't see SOc Pylontech Force L1

Hello everyone,

I connected a Pylontech Force L1 tot a Victron Cerbo GX.

As soon as the cables are plugged into "BMS Can" I see in the Remote Control Device list a Pylontech battery but the SOC, voltage and Amps are all 0 .

Any ideas why the Cerbo can't display the values?

Thanks in advance.

Regards,

David

davidvm asked

0 Answers

Why would the SOC in my BMS be different to what is in my Victron CGX display?

Hi. I lost AC power this morning at 1.30am. No heavy loads running and the typical ambient draw at night is around 12A so a bit over 100W. The notification was a Voltage Overload error and the house bank inverter state was Fail. Turning the Quattro off and on again cleared the fault.

I have two propulsion banks, port & stbd, each with 2 x 48V/5KW inverters in parallel and a 48V/540Ah battery bank. Typically, I have one of them charging the 12V/900Ah battery bank (that has another quattro, 12V/5KW) and keeping it at float. However, I noticed the 12V bank was at 13.9V at charging at 41A with the display SOC reading 100%. I turned off the propulsion bank to stop the charge and let the 12V house bank get us through the night. All batteries are LiFePO4.

At a more sociable hour this morning, I connected to the BMS (Orion Jr) and looked at the settings, which is when I noticed SOC reading was 84% but the Victron display was 94% (about 8hrs after we lost power and I switched to the house bank). This got me wondering whether the BMS didn't stop the charge because it thought the SOC was much lower than it was despite the voltage being over the float voltage of 13.5V.

This is probably more of an Orion BMS question really (I've emailed Orion already) but I was wondering if anyone else has come across this issue of SOC differences on the Victron display and the BMS and what the solution was.

eyacht asked

0 Answers

SOC not showing on Home page, but does show on detail page

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The SOC and time remaining does not show up on the main screen but does show up on the detail screen

Ross Wendell asked

0 Answers

Multiplus II internal SoC jumps before absorption begins

Hi,

Lately our Multiplus II (12/3000) frequently sets the SoC from like 40% to 80% for no obvious reason.

Batteries are 560 Ah of LiFePO4 cells with Daly SmartBMS (but Multiplus uses its internal battery monitor, no data connection to the BMS). The sudden jump to 80% is most probably from the "State of charge when bulk finished" setting - but the batteries were far away from bulk finished when the jump happened (actually the 30% were correct).

My guess is that the voltage raised over the absorption voltage of 13.80V for a very short period of time (not even visible in VRM portal - voltage was around 13.60-13.70 at the time the jump happened). Maybe it was also just a single false measurement causing the jump? The 80% are then held for a longer period until bulk actually finished, then the SoC is correct again. But if the charge was ended after the jump (e.g. due to cloudy weather), the SoC would remain terribly off...

Anyway - is there a possibility to make "State of charge when bulk finished" less sensitive, like it requires to be in absorption for 10 seconds at least or so? The batteries seem to be healthy, cables are rather oversized, I don't believe there is an electrical issue. The absorption voltage of 13.80V may be a little bit low, but is recommended for the CATL cells, with an absorption time of 2 hrs.


Thanks for any hints!

ips-ad asked

0 Answers

Easy method to manage storage charge for lithium ion battery

Hello all,

Seen a few posts but not any answers around this area. I have a 7.5kWh lithium ion LMO battery being charged by my Multiplus 48/2000 in a boat. I currently have the Multiplus configured with a battery 'storage' profile that floats the batteries at about 40% SoC voltage. I have another 'active' profile in VEconfigure3 that I can upload that charges the batteries to 90% SoC. Is there some way I can control this via my Cerbo's GX Touch? It doesn't look like I can choose battery profiles in VictronConnect via VE.bus dongle (which I do not yet have). Is this something an 'assistant' might help with? It's really just adjusting the absorption and float voltages. Perhaps even a physical switch on Cerbo's DI channel? I don't want to rely on Internet connectivity to do this via VRM and VEconfigure3 on a laptop.

mmsi2022 asked

0 Answers

Reliability SOC VRM

Hello,

we are using a MultiPlus-II VE-buss-ystem connected to a VRM. We also have several meters to measure the consumption.

We have noticed that the the SOC tends to be same irregardless of consumption above a certain threshold. For instance will a consumtion of 5kWh and 6.8kWh throughout the night both yield a SOC of 11% in the morning.

How reliable and accurate are the state of charge estimate (not a direct measurement from what I have heard)?

martin-a-kraft asked
nickdb commented ·

0 Answers

How to use a programmable relay assistant using SOC setting

When I try to configure programmable relay assistant in Multi II to close relay, using SOC level settings, seems that assistant doesn´t use SOC coming from CerboGX using BMS-CAN.

I read post with same issue https://community.victronenergy.com/questions/65651/does-the-soc-assistant-condition-on-the-programmab.html , and tried to use same recommendation , that seemed worked in that case, so I selected "enable battery monitor", because the post says that doing so, SOC will be coming from external meter (in that case BMV) and not from internal SOC calculation, as all internal data will be replaced by the data coming from external control.

Well, I tried to replicate the solution indicated in post and it simply doesn´t work. The only difference I see is that in post SOC was coming from BMV, and inmy case SOC is coming from BMS. But cannot figure out why this could be the difference for my Assistant fails to take true SOC.

Any help to understand how to use SOC coming from BMS in a Multi II assistant ?

Note: Assistant and connections work fine and activate Relay when using other conditions. The problem is where SOC is coming from.

mito asked

0 Answers

Soc not showing for Quatrro 10KVA on Color gx

My system consists of Axitec Li 10s batteries with Quatro 10kva and 250/100 mppts . I have chosen battery monitor as Can-bus BMS selected and inside services I have chosen the following CAN bus profile but still I State of Charge option is showing --- (see pic1)


I am using terminators at VE.CAN port on colorgx and also at the battery end

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solartech12 asked
solartech12 commented ·

0 Answers

Multiplus 5000 SOC estimate with DC current and voltage and passthrough issue

We have 3 phase system using 3xMULTIPLUS 5000 48V/5000/70A together with batteries that are not communicating with Multiplus. The system is controlled via display in ESS mode to setpoint input power of 600 W. When there is low battery voltage and current drops via voltage limit the SOC rises, since the measured current is positive instead negative which in reality is (battery is discharging). DC voltage drifts down as a result of discharging, but SOC is false increasing. The system in bulk mode then decides to go to passthrough mode and stops maintaining minimum battery voltage, voltage due to self discharge keeps droping and SOC increases to 100%. It never resumes bulk charging. Is there anything one can do to fix the current measurement offset. The DC side is measured without external components .

Thank you for the answer.

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evgen-urlep asked
evgen-urlep edited ·

0 Answers

Multiplus 12/3000 low voltage shutdown vs low SOC shutdown - Both triggers active ?

Hi - have a question about the multiplus shutdown configuration and precedence.


If you have DC voltage settings for low voltage shutdown, AND low SOC shutdown, is it safe to assume both settings are active and shutdown may occur based on which ever trigger occurs first ?

SOC will be provided via smart-shunt/BMV to ve.bus as configured on VENUS OS device. Thus it's possible to have the smart-shunt/bmv incorrectly report SOC if the setting "Battery starts synchronized" is turned on; So the battery voltage could be way lower on a somewhat depleted battery yet the bmv SOC says 100%, if you have reset power to the BMV. Thus I'd expect the low voltage triggers to take effect.

Of course we usually try and disable this "start syncronized" setting to prevent misunderstanding true state of charge until the battery has gone through a true charge cycle. Which also begs the question:

If you restart the BMV and it's SOC reading is not available until a full charge has completed, will the inverter just pay attention to the voltages at that point ? I'm assuming a SOC is not presented to the ve.bus/inverter until the full charge has completed.


thanks in advance.

chad-smith asked
abegweit commented ·

0 Answers

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