VE.Bus System - MULTIPLUS II Low battery Alarm

DIY
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1

Hi Community

Typical Victron marine set up…
4x 330Ah Smart Lithium, Lynx Distributors, Lynx Smart BMS, Cerbo and Screen, Multiplus II, and all associated other MPPTs (1.2Kw of Solar), Battery Protects and so on.

I am getting an alarm on my Cerbo Touch Screen and an email via VRM - saying VE.Bus System - MULTIPLUS II Low battery Alarm. This happens when I place a load on the batteries, via the Multiplus II, a heavier AC load.

For example -

  • invertor on - only drawing about 150W on AC loads
  • the battery V is showing as about 13.3v and are at 90% SOC.
  • I switch on a load of about 1000W - so now total of 1150W
  • the battery V sags / drops under the load to about 13.15v
  • I get the alarm
  • turn the load off - and the alarm clears.

I can’t see why I am getting this alarm. The V of 13.15v is healthy - no ???

I can’t see where this alarm is set up / configured. I have check the documentation as see it is a pre-set alarm - but what is the trigger voltage ?

Can anyone help ?

Thanks

Tim

2

You can set it in victron connect here.

And ve config here.

You can also get false triggers from DC ripple.

The alarm is being triggered by the inverter so it is the programming there doing it. Not the bms itself

3

Thank you so much LX. I’ve just checked - and the low alarm is set at 13.00v. But the V on the Cerbo Display when I get the alarm is showing 13.15v - so I don’t understand why the alarm.

4

You are using ESS assistant?

5

Shouldn’t be as it is marine.

@Manyata
0.1v is hardly a difference and probably a bit of dc ripple masking the reading there.

You could drop it by 0.2v to 12.8v and see from there.
What is the cut off?

6

I agree, but I’ve seen worse :joy:

7

No - I am nor using ESS.

8

Screenshot 2025-07-02 at 13.10.52
Screenshot 2025-07-02 at 13.10.52880×856 19.4 KB

Current settings above. And this why I am confused. My pre alarm is 12.90 and the V only gets as low as about 13.15v.

Thanks.

9

With victron connect and the mk3 run the load and check the ripple. (Unless you have a DMM and want to do it that way)

It is most likely that. Ypu aren’t getting the ripple alarm, so you could just choose to live with it, or possibly upgrade the wiring.

How to check.

Summary

IMG_20250702_142943
IMG_20250702_1429431080×1478 183 KB

10

Thanks LX

I will check for Ripple.

I have checked for V drop when under load -

  • I placed a load of 100A on the batteries (with an AC load).
  • V at battery terminals was 13.24v
  • 4 x 330Ah batteries in parallel with each wires 95mm2 all the same length (1m)
  • V at Distributor (before Lynx BMS) was 13.21v
  • V at Distributor (after Lynx BMS) was 13.18v
  • 2 wires (2+ve and 2-ve) 95mm2 all same length (70cm)
  • V at Inverter terminals was 13.14v

I’ve checked all terminals are to correct torque - used FLIR camera to check for heat (there is none).

Do you think these V drops under load are healthy and normal ?

I really appreciate your help on this.

Thanks

  • V at the Invertor terminals was 13.14v
11

They look pretty healthy.

2 Likes
12

Thanks LX :grinning_face:

13

Did you manage to check the ripple at that current?