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conrad-vermeulen avatar image
conrad-vermeulen asked

[SOLVED] MultiPlus-II / Pylontech - 97% max SoC

Good day

I have a site with a Multiplus II and Pylontech batteries (3x US3000C). The batteries are not charging beyond 97%. I have read the FAQ on the Victron - Pylontech battery compatibility page that states this is normal.

https://www.victronenergy.com/live/battery_compatibility:pylontech_phantom#the_battery_won_t_charge_to_100

The problem is when the installation was done the batteries did charge to 100% and after a few firmware updates the 97% problem started. The client is not happy and believes that I "broke" his system.

ESS and DVCC are on. Have tried different ESS modes but no change.


Are there any steps that I can take to get the batteries to charge to 100%?

max-soc.pngSoC graph

batt-volt-curr.pngBattery Voltage and Current

bus-volt-curr.pngVE Bus Voltage and Current

charge-discharge-limits.pngBattery charge and discharge limits

I noticed a large voltage difference between the Battery BMS voltage and the VE Bus. Is this normal? When the voltages were checked with a multimeter they were the same from the battery up to the DC bus, so not sure why there is such a large difference.
voltdiff-bus-bmonitor.pngVoltage difference between DC Bus and Battery

Currently, the plan is to update all the firmware (Multiplus and Pylontech), fully discharge, and recharge the batteries on a standalone charger to reset their SoC hopefully. But I'm not sure either of these will resolve the 97% problem. Any advice or guidance would be greatly appreciated.


Kind regards

Conrad

Multiplus-IIPylontech
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charge-discharge-limits.png (37.5 KiB)
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3 Answers
Albert de Jongh avatar image
Albert de Jongh answered ·

The voltage difference sounds similar to an issue I had recently @Conrad Vermeulen.

Can you check over the last few months when the voltage differences started to grow?

It could well be the same as my issue here: https://community.victronenergy.com/questions/242912/multiplus-ii-483000-measured-voltage-drifting-up-o.html

In my case I disabled vsense using veconfigure to fix this - do you use a vsense cable at all?

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conrad-vermeulen avatar image conrad-vermeulen commented ·
Thank you @Albert de Jongh. Disabling Vsense brought the two voltages together and the battery is charging to the correct voltage now.
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Alexandra avatar image
Alexandra answered ·

@Conrad Vermeulen

What firmware are you running right now? Did you update all the components?

Roll back the firmware, reprogram and check.

If it solves the issue. Then it is firmware. If it does not then it is hardware.

The voltage the battery is requesting (CVL) is way higher than even the ve bus terminal voltage anyway. So should have some tolerance for the terminal reading high.

In DVCC is SVS on?

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Richard Norman avatar image
Richard Norman answered ·

Hi I reckon this is a case of difference in voltage between your MPPT/Multi and the battery BMS, there was an offgrid garage video about this recently, the 97% seems to be that your pylon batteries arent reaching the right voltage to reset to 100% but that your charging service is slowing down and stopping as it thinks it has reached the target voltage.


The Victron Pylontech setup is 52.4v target and the batteries are stopping at 51.31v yet the charger is seeing the target voltage 52.36v. The recommendation in the off-grid video was to enabled Shared Voltage Sense which would tell the charger the battery voltage but this is forced off on pylontech so I would suggest that you try to adjust the target charge voltage in your MPPT/Multi to 1.1v more than the current setup, you can set a fall back in the MPPT via local Victronconect you setup the Multi via the MK3 and see if this resolves your issue, claibrate charging voltage for your voltage drop. Or worth checking that the charger or the MPPT is using the BMS as the controlling party and that they are following the battery info and not their own voltage.

My Solar RS has the following so it follows the BMS voltage and current settings

1701273074269.png

Same in DVCC the Pylontech is the controlling BMS

1701273292498.png

With the setup as above I have the pylontech resetting to 100% as they reach a voltage of 52.27v so your missing percentage is a lack of voltage rise and it would seem that the system is using its own voltage not the BMS voltage.

1701273885493.png


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