SoC difference between Cerbo and BMS

DIY
, , ,
1

Hi, i just installed a 16 cell 48v 306Ah battery with a cerbo GX and Multiplus II 48v 5000VA.
I have JK BMS that gives a SOC of 26% while the smart shunt / VRM shows 100% SOC.
Can anyone help, it must be something in the config.

Screenshot_20250301_103639_BMS
Screenshot_20250301_103639_BMS1080×2340 162 KB

vrm
vrm1088×542 19.5 KB

2

Pls post the settings of the smartshunt.

Most probably rhe settings for charged voltage and tail current are wrong.

3
  1. The linked FAQ will tell you how yo set your SmartShunt, especially charged voltage.

Shunt jumping to 100%

  1. If you have only just started the system and not yet charged it, the SmartShunt counts energy in and out of the battery so at start up it knows nothing about the battery state, it only starts working once the battery has been fully charged for the first time. In the interim you can go into the settings and manually set it to match the BMS.
4

@Ludo and @pwfarnell , thanks for the quick reply! I will check it now. These are the settings i have

Screenshot_20250301_115442
Screenshot_20250301_1154421080×2340 186 KB

5

I think i found it. I manually set the SOC to the same % as the BMS and changed the grid metering to the Multiplus as i don’t have a grid meter yet installed.

Grid
Grid1137×461 21.6 KB

6

Maybe not, it’s back at 100% again, but it is charging.

7

There’s your problem. You shunt has not been set up correctly.

Read the link that @pwfarnell gave you.

8

Set charged voltage to 56, tail current to 1%

Peukert to 1.0

Charge efficiency to 98%

Set your SoC back to 25%

2 Likes
9

Thnx! All good now. I will ready the doc to fully understand all the settings. Thanks a lot!

10

It doesn’t really charge a lot, it’s still on 26%.

Screenshot_20250301_201527_Brave
Screenshot_20250301_201527_Brave1080×2340 181 KB

11

Next stage is to make sure your Multiplus charge settings are correct, it is in bulk, not sure why that should be so limited in charge output. See section 5 of the manual.

https://www.victronenergy.com/media/pg/MultiPlus-II_230V/en/configuration.html

1 Like
12

Can change in this settings what measuremnts to use on VRM

you will may see Multi / SmartBMS / BMS.CAN and the BMS.CAN will may be the most correct.

In the picture bellow the RUiXU is BMS.CAN and is the only one Visible to get correct SoC.

image
image2015×1172 137 KB

1 Like
13

Thanks, great learning curve. I will read and check the settings tomorrow. I’ll be back!

14

I double checked all the settings, but they look fine:

Multi2-1
Multi2-1546×526 57.5 KB

15

They look OK so I am not sure why the charge current was so limited. If there was a poor DC connection then the Multiplus usually goes into absorption or float because the Multiplus sees a higher voltage due to resistance. Perhaps start a second question asking why is my Multiplus charging at such a low rate.

1 Like
16

Thank all fot the support, i created a new topic: New Multiplus II 48v 5000VA setup only slow charges battery