Paul Harms avatar image
Paul Harms asked

VE.Bus overload L1 and High DC Ripple

I have a hybrid system with a Steca AC invertor and a Multiplus II Victron invertor.
Completely off grid

I had Pylontech batteries for 7 years which was replaced 3 months ago with BSL3ATT bateries with exact same KWH rating as the Pylontech system had.(19,2KWH)
Ever since the replacement 2 problems occur.
1. I get VE.Bus overload L1 warnings every so often, sometimes when a pressure, borehole or pool pump starts, sometimes with almost no load at all. All my pumps are on timers so that max load can never go above 4kw

2. The bigger problem, the moment the batteries gets fully charged, the Victron trips/switches off which also switches the Steca off, Victronb restarts after a few seconds, as soon as it is on the Steca starts booting up. As soon as the Steca starts up it trips the Victron again. This happens even if I switch my mains off - no load at all. Only way to get passed it is to switch the panels connected to the Steca off and only run the Victron. Ocassionally this will repeat itself 4-6 times and then the system will get up and run again. More often I have to switch the Steca panels off.
I am worried about damage to the invertors or batteries
Any ideas?

multiplus ve.busripple
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klim8skeptic avatar image klim8skeptic ♦ commented ·

@Paul Harms I had Pylontech batteries for 7 years which was replaced 3 months ago

Myself only being off grid for 5 years with Li batteries, what prompted the replacement of your Pylontech batteries?

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3 Answers
nickdb avatar image
nickdb answered ·

You aren't likely to break anything, the system is doing what it is designed to do, and is protecting itself.

kWh isn't important, it is discharge limits that matter.

What specific BSL's do you have and what DCL is it reporting? Is it lower than your previous battery?

BSL use a pace BMS which has had issues particularly when the battery sizing is a bit too close to inverter requirements.

Have you checked all the necessary settings have been changed for the new batteries?

Double check all the wiring for bad connections.

If all else fails, we will need to see screenshots of VRM charts which shows the BMS CVL/CCL/DCL, min/max cell voltages, battery voltage and current etc.

Off grid systems are much more demanding on batteries so it is important they are properly sized.

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Francois Rossouw avatar image
Francois Rossouw answered ·

I'm posting the screens from the Cerbo as requested.

3 x 6.4kWh 1C BSL Batteries.

Screenshot 2024-03-06 at 15.33.04.pngScreenshot 2024-03-06 at 15.33.28.pngScreenshot 2024-03-06 at 15.55.09.pngScreenshot 2024-03-06 at 15.57.55.png

We used this guide initially:

In our efforts to solve the High DC Voltage I have changed the float voltage on the charger tab down to 54V (instead of 54.8); I have not adjusted the "fall back" values on the MPPTs... which should be overruled by DVCC anyway...

All DC wiring was recently inspected when we installed a new DC Buss bar.

For a little more context to the problem:
The Victron/Steca reboot/trip loop only happens when the batteries are in float (97% and up) and the Steca is producing power.

It does NOT happen if the Steca is turned off

It does NOT happen if the Steca is turned on with no PV input.

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nickdb avatar image nickdb ♦♦ commented ·
Thanks. By pylon standards that is plenty of power.

What size inverter is it?

The high voltage alarms are normal on new installs, annoying but mostly harmless. The BSL's are slow to balance.

54V is too low, but will be ignored anyway. You can only force it lower under DVCC.

Deep discharge cycles can help speed the process up.

What alarms are logged by the multi?

If you use the BMS viewer tool, what is logged by the BMS?

Does the PV inverter respond to frequency shifting, has the factor 1 rule been followed?

It may be that the BMS is rolling over because of overshoots from PV and being in an unbalanced state. That min/max cell voltage from VRM advanced widgets can help show the scale of the problem.

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Francois Rossouw avatar image Francois Rossouw nickdb ♦♦ commented ·

5kVa Multiplus II

Stecagrid 3010

While I agree that High Voltage alarms are normal during a new install, it's been 4 months since install though. I've never had BSL's take this long to balance.

The batteries regularly go down to ~30%

The High Voltage alerts are not coming from the BSL's (That I can see)

(I would expect them to come from the "Battery Monitor" in the logs)

These are what the inverter is logging

VE.Bus System - Inverter DC - Multiplus-II 5kva [276] Overload L1: Warning

VE.Bus System - Inverter DC - Multiplus-II 5kva [276] High DC Voltage

Yes, the Steca inverter does respond to frequency shifts to increase and decrease the power it's delivering.

I have not looked at the status of the individual batteries with BMS tools or similar.

I'll post screenshots of the battery voltages this afternoon when the system is at ~98%

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Alexandra avatar image Alexandra ♦ Francois Rossouw commented ·
Compare ve bus voltage with battery voltage and mppt voltage if you have DC mppts.

Maybe cap the voltage in DVCC.

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Trevor Bird avatar image
Trevor Bird answered ·

Hello @Paul Harms , one of the hints to this issue is the High DC Ripple warning. From my experience the Multiplus cannot tell the difference between High DC Ripple or High DC variation. The High DC ripple indicates a relatively high resistance from the battery to the Multiplus. The result of this is a 100hz ripple on the DC supply voltage feeding the Multiplus in sympathy with the AC waveform being produced by the inverter of the Multiplus.

DC voltage variation is a different thing where the DC voltage presented to the Multiplus varies in a random fashion. I don't think (but I'm not certain) that the high DC Ripple is bandpass limited to only see 100hz ripple rather than seeing DC variation.

From my experience when certain types of Lithium Batteries are fully charged the internal BMS switches in and out to protect the cells internally from overcharging. This appears to vary the output voltage enough to cause the Multiplus to shut down because it interprets the variation wrongly as DC Ripple.

In order to at least isolate this as a reason for the problem is to adjust the absorption voltage lower so the internal BMS doesnt have to shut cells off to avoid overcharging.

This may not optimally charge your batteries but may at least provide a plausible story for what is happening. At least then you can think about how you can fix the problem. I know nothing of the brand of batteries you are using so can make no comment regarding quaility but do know I have had the problem described above with cheap Lithiums installed by others on a boat.

I hope this may help a little to at least isolate the fault.

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Paul Harms avatar image Paul Harms commented ·

@Trevor Bird

This should give you access to my installation,
We have reduced the max charge to 95%, also the charging rate reduced.
I am at my wits end, I cannot leave my house for a day since the tripping does not stop or at least I am worried about damaging the system if it trips multiple times.
Do you think I could leave the Steca on to see if it will stop tripping after a while ?
Thank you for your assistance

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