MultiPlus 48/8000 throwing low battery Alarm when LiFePo4 Lithium is at 99%

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duncangardiner asked Aug 28, '23

MultiPlus 48/8000 throwing low battery Alarm when LiFePo4 Lithium is at 99%

Hi I have installed 2 x 48v 200A Rosen LiFePo4 Lithium Batteries (Pylontech clones) which is a total of 20Kw of battery storage.

I have based the RS 450/100 MPPT TR charge controller and Victron assistant ESS (I am still grid connected to be able to draw from it at night when its cheaper if I need to) within the MultiPlus charging configurations on 15 cell maths (because my packs are 15 cell packs).

Above is the MMPT charging config

Above is the MultiPlus configuration.

I am running the Victron ESS assistant on the MultiPlus so I can send and draw power to and from the Grid.

The Issue I am having is that in since turning the batteries on and adding the House load (all on the Critical side of the inverters AC out, I have no loads on the grid side of the system). If I then turn off the Grid, and turn off the solar panels, so that only the Batteries are powering my home, which simulates after sundown usage. While switching between the various power sources is seamless. When we are on only battery. The MultiPlus throws a low battery alarm and turns itself off when the Batteries get drawn down to 99% SOC. You either have to switch the grid back on or the solar panels to have the batteries increase their SOC, at which point the Multiplus resets and all is good again.

I must have set something in the MultiPlus' configuration to not allow enough draw from the batteries.

Can anyone point me in the right direction to setting the correct parameters to allow the batteries to be drawn down to 25% or 30% SOC before the inverter switches off.

Kind regards

Duncan

Multiplus-II alarm

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charger.jpg (167.7 KiB)

ess-sustain.jpg (93.1 KiB)

ess-dynamiccutoff.jpg (118.8 KiB)

ess-restart.jpg (94.7 KiB)

inverter.jpg (172.8 KiB)

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nickdb answered · Aug 28, 2023 at 01:29 PM

Your charge settings and cutoff settings are really close to each other.

Looks like it isn't configured correctly.

Pylons are 15 cell batteries, most others are 16 cell with higher voltages.

You need to get the correct parameters from the manufacturer, while it may spoof a pylon BMS it may have different voltage requirements.

Your float voltage is too far off absorb for lithium which is ok for a 15 cell battery but way too low for 16.

This is why proper manufacturer support and testing for an inverter is important.

If the battery is identical to an equivalent pylon then follow the victron/pylon setup guide, but if it is a 16 cell battery best contact the maufacturer's support as it isn't something Victron can assist with.

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duncangardiner commented · Aug 28, 2023 at 02:16 PM

Hi Nick

I agree with your points. However Rosen customer support is rubbish, I have sent many, many emails to them asking for the correct settings and all I got back in return was a test data sheet that has no correlation to the settings I need to apply.

Here are the BMS readings from the batteries taken by me.

Above are the master battery

Then the Slave Battery config.

As you can see they are 15 cell batteries. Which is why I did the absorption and float maths for a 15 cell battery.

Do you have any documentation on a 15 cell PylonTech I can see to make the right changes in my charge controller and inverter?

Kind regards

Duncan

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masterbatteryconfigrealtimemonitoring28aug2023.jpg (382.2 KiB)

masterbatteryconfigparams28aug2023.jpg (386.8 KiB)

slavebatteryconfigparams28aug2023.jpg (384.2 KiB)

slavebatteryconfigrealtimemonitoring28aug2023.jpg (386.3 KiB)

Matthias Lange - DE ♦ duncangardiner commented · Aug 28, 2023 at 02:26 PM

Bad support would be a good reason for me to ditch the battery and send it back.
There also seems to be not datasheet or manual available online for download, a good reason to not buy them in the first place.

Here are the recommended settings for Pylontech:

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

You have a big cell imbalance there.
Also the "balance threshold" seems a bit high to me. Maybe reduce that to 3.45 or 3.40 to start the balancing earlier.

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duncangardiner Matthias Lange - DE ♦ commented · Aug 28, 2023 at 03:14 PM

Cheers @Matthias Lange - DE

This document got me back on track.

Re Rosen Batteries, and their support. Yes I accept that these batteries are a risk. But they were within my budget.

Moving forward I think if I need to upgrade or add more storage Ill go with another Chinese supplier and the new offering from Global Power. Their GP-SR1-PC200-B 51.2V 280Ah 15Kw LifePO4 battery is a much better option than what I have. And the customer support from Global Power is top class.

Anyway it looks like my issue has been resolved.

Thanks again for your input.

Take care

Duncan

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rikhf duncangardiner commented · Aug 29, 2023 at 03:09 AM

That Gobel Power battery is a good choice but keeo in mind that tou cannot combine it with your existing batteries since they are 15s. The GP-SR1-PC200-B is 16s.

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Answer 1 · 2023-09-07T19:10:27Z

pyrorider answered · Sep 07, 2023 at 07:10 PM

A cheap solution that worked for my crappy chinese lifepo4 battery was to buy a SmartShunt for 110€ and use it as battery monitor. The bms still does the protection etc but the smartshunt measures the charged and discharged power, battery voltage and SOC

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MultiPlus 48/8000 throwing low battery Alarm when LiFePo4 Lithium is at 99%

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