question

marcmu avatar image
marcmu asked

Multiplus II - Dc Ripple with generator

I built a stand alone system consisting of 1Kwp of solar panels, a Victor mppt charge controller, a Multiplus II and a 16s 48v 176Ah lithium battery pack.

the system has been running for about 12 months and is working great and I'm really happy.

In the last days I tried to connect a Honda ex4000s generator, I made the necessary changes to get the generator working.

Unfortunately, I have noticed that if I switch on the generator I have a DC voltage ripple.


This problem occurs especially when I switch on the generator when the solar panels are also producing current. In this situation you can see on the ccgx that the voltage varies continuously in a few seconds from 51v to 53v, after which the system goes into protection and shuts everything down.

I was able to solve this problem by inserting a relay that disconnects the solar panels when the generator is switched on. after about 20 minutes of operation, the problem occurs again.

The cable cross-section is adequate and all connections are correct and stable.


do you know what could be the problem ? the generator current not clean ?

Multiplus-IIGenerator
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2 Answers
Alexandra avatar image
Alexandra answered ·

@marcmu

DC ripple will cause the weird voltage readings. Since it happens when both solar and PV are charging, I would start with lowering the battery charging current either using DVCC for a system wide setting or lower it in the GRID tab on the multiplus.

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trevor-bird avatar image
trevor-bird answered ·

Hello @marcmu ...So you have had a working system and this is the first time the mains has been connected and the Multiplus charger is working. A couple of issues you may consider.

1. The Multiplus may have a different charger voltage setting to the MPPT controller. If the Multiplus charges with a higher voltage than the MPPT it may cause the BMS of the batteries to become active causing voltage variation.

2. Voltage variation caused by BMS switching can be interpreted by the Multiplus as "DC Ripple" even though it is not really DC Ripple. If it sees the DC Ripple as bad enough it will shut down the Multiplus.

If you read this post it goes through a few thoughts on this topic.

https://community.victronenergy.com/questions/129138/quattro-shutting-down-lithium-batteries.html

I hope this helps,

Trevor


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