MultiPlus 2 "Low Battery warning" with full pack

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kopi-andi asked Jan 22, '23

MultiPlus 2 "Low Battery warning" with full pack

Hey, we've just commissioned a new installation with a Multiplus 2 48/5000. The battery pack is a 16S 280Ah LiFePo4 rack-mount pack from Gobel that is connected over CAN to the Cerbo. The pack has been fully charged by an MPPT before commissioning the MP2 and it shows 52V in the Cerbo. The MP2 has received the newest FW 501 after connecting to the Cerbo as well. Yet, after turning on the MP2 it shows "low battery warning" and flashes the red light after a few seconds. I don't have an MK3 interface and did the firmware upgrade and config updates through VRM. I am planning to use the system as an ESS and have played with a few values already but without success. The default voltage warn levels are already quite low (43V in inverter tab of VEconfigure).

I am attaching a screenshot of the warning in the Cerbo and the current config file.

Any thoughts on this?
Thanks

Andi

Multiplus-II low battery warning

screenshot-from-2023-01-21-19-33-08.png (37.0 KiB)

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Answer 1 · 2023-01-23T03:43:48Z

Harold Lopez answered · Jan 23, 2023 at 03:43 AM

Have you checked the BMS configuration? It could be that you have a wrong comunication protocol or haven't selected the rigth kbps in the BMS system.

I'll try with that.

best of luck.

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kopi-andi commented · Jan 23, 2023 at 08:34 AM

The BMS protocol is correct and it's also pulling the correct values from the battery, see attached screenshots.

I've noticed that when I disconnect the VEbus cable that goes to the Cerbo the MP2 seems to be not issuing the "low-battery" warning. Could it be that it's still pulling a wrong voltage reading from the BMS module despite it being correctly configured?

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screenshot-from-2023-01-23-09-30-28.png (53.3 KiB)

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Answer 2 · 2023-01-23T05:59:46Z

pripp answered · Jan 23, 2023 at 05:59 AM

Did you set the battery capacity correctly in the Multipus setup?
Enable battery monitor in the Multiplus setup, later the SOC from the BMS is used but it seems that the ESS Assistant needs the capacity value.
I had the same problem. I disabled the battery monitor in the Multiplus config after the ESS setup which leads to odd "low battery warnings"

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Answer 3 · 2023-01-23T08:21:21Z

kopi-andi answered · Jan 23, 2023 at 08:21 AM

Thanks for the hints but I believe I have the correct battery monitor settings already, also the capacity is set (both in general and in ESS).

Just seeing now that the cutoff voltage for 0.0005C is quite high. What are the suggested values for those here?

P.S. For some reason I cant upload my config file here.

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Answer 4 · 2023-01-23T08:28:40Z

kopi-andi answered · Jan 23, 2023 at 08:28 AM

Setting cutoff (0.0005c) to 50V in ESS also didn't work (50+1.2V < 52.7V).

When I toggle the power switch of the MP2 I see it in state "inverting" for 1-2 seconds, but then I get the alarm again.

screenshot-from-2023-01-23-09-25-52.png (52.5 KiB)

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Answer 5 · 2023-01-23T08:37:02Z

nickdb answered · Jan 23, 2023 at 08:37 AM

Best you speak to your supplier or battery manufacturer for guidance, they really need to give you the setup procedures for this battery and Victron.

You can review setup guides for supported batteries to give you some tips.

First is to make sure your comms are working and that meaningful info is being received, then make sure DVCC is operational and correctly set.

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Answer 6 · 2023-01-23T08:42:11Z

seb71 answered · Jan 23, 2023 at 08:42 AM

Can you see/check the voltages of individual cells?

The battery BMS might detect low voltage for a single cell (while the battery voltage appears normal).

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Answer 7 · 2023-01-23T09:12:52Z

kopi-andi answered · Jan 23, 2023 at 09:12 AM

> Can you see/check the voltages of individual cells?

I can read the cell voltages from the remote control. Although temperatures seem off, the voltages are ok. No warnings or anything in the BMS.

screenshot-from-2023-01-23-10-09-59.png (30.9 KiB)

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nickdb ♦♦ commented · Jan 23, 2023 at 09:16 AM

The more important metrics is what CVL, CCL and DCL it is sending and what DVCC has been configured to.

Temp values will be wrong because they are not sending it correctly in the CAN broadcast, that does not bode well for compatibility.

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Answer 8 · 2023-01-23T20:13:49Z

kopi-andi answered · Jan 23, 2023 at 08:13 PM

Hey, it seems that after updating/configuring the BMS and setting the cutoff voltages and max charge/discharge currents (see screenshot) the problem disappeared. I didn't change anything else in the MP2 config. The cell voltages in the remote console are still wrong, but correct in VRM - maybe this is a just a display bug? Anyway, thanks for the help and suggestions.

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