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Why is my Multiplus constantly pushing current to my batteries?


cairanvanrooyen

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Recently I had noticed the fan in my Multiplus come on (during no/low load) and went on to try and investigate.

 

The past couple of days I have been monitoring the VictronConnect software and noticed that the batteries seem to have a near constant 9 or 10A pushing onto them for the past couple of days - see screenshot.

 

We have no load in our boat at the moment (12V fridge on low setting), and I have even tried disconnecting all the loads and the 10A remains - it seems the charger is constantly trying to charge the batteries with 10A, even when they were in 'storage mode'. If i isolate the batteries from the Multiplus, the 10A disappears. Does anyone have any suggestions why this might be? Is this normal or not?

 

I have also noticed that the voltage on the software is higher than the stated inputs - for example it shows 13.98V on the batteries despite the input of 13.8V - does anyone know why?

ve.JPG

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Normal reason in cold weather for a Victron to have a higher float voltage than the set float voltage is temperature compensation.

I would lower the float voltage to 13.5v if you are connected 24/7.

 

Eta at 16.17mv/deg C and the batteries at 15 deg C rather than 25deg C then the difference is 0.1617v or pretty much what the victron is telling you

 

 

Edited by Loddon
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1 minute ago, Loddon said:

Normal reason in cold weather for a Victron to have a higher float voltage than the set float voltage is temperature compensation.

I would lower the float voltage to 13.5v if you are connected 24/7.

As for current, how old are the battteries is there a possibility of a failing cell?

 

Great, thanks. I will lower the float voltage as suggested.

 

The unit has now flipped into storage mode and you can see its still pushing 7A or so onto the batters. Is there a similar setting for reducing the storage mode voltage? I cannot seem to find it...

 

The batteries are only a couple of months old - 5 of these

ve2.JPG

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13.37v is fine.

I assume you have the code to allow you into the settings menu.

As for current my solar pushes 6-7amps into the batteries way longer than I think it should,  however if we have been running the engine it doesn't do it, so I have assumed when its doing it the batteries must not be quite fully charged.

 

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Didn't know you had ve config as well as the app, most things can be changed from settings within the app.

I have never used storage mode so can't answer that.

1% of your battery capacity is about 5ah, batteries are said to be fully charged when tail current drops to 1-1.5% of capacity so I wouldn't be overly worrying 

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4 minutes ago, Loddon said:

Didn't know you had ve config as well as the app, most things can be changed from settings within the app.

I have never used storage mode so can't answer that.

1% of your battery capacity is about 5ah, batteries are said to be fully charged when tail current drops to 1-1.5% of capacity so I wouldn't be overly worrying 

So 5 to 7.5A when in storage mode is OK?

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4 minutes ago, Loddon said:

 

1% of your battery capacity is about 5ah, batteries are said to be fully charged when tail current drops to 1-1.5% of capacity so I wouldn't be overly worrying 

I disagree. After batteries have been on charge for a long time, let’s say a day, and the charge voltage is down around 13.3v, I would expect the current to be zero or certainly less than 0.1A. 5A is far too much, something odd going on. I would check the temperature of all the batteries to see if any is slightly warm. Are you sure there are no loads connected directly to the batteries? Absolutely everything should be connected via the shunt. Nothing should be connected directly to the domestic battery negative except the shunt, not even the engine battery negative. 

3 minutes ago, cairanvanrooyen said:

 

So 5 to 7.5A when in storage mode is OK?

No

You could obtain a dc clamp meter etc UNI-T UT203 and check for current flowing into individual batteries.

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The charger is set to adaptive charging, at best this only takes the batteries to about 96%, it can take a very very long time to put the other 4% in at 13.8v.

Before solar I have watched my batteries take days to reach fully charged.

However the warmth check is a good idea just in case.

 

Edited by Loddon
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4 minutes ago, nicknorman said:

I disagree. After batteries have been on charge for a long time, let’s say a day, and the charge voltage is down around 13.3v, I would expect the current to be zero or certainly less than 0.1A. 5A is far too much, something odd going on. I would check the temperature of all the batteries to see if any is slightly warm. Are you sure there are no loads connected directly to the batteries? Absolutely everything should be connected via the shunt. Nothing should be connected directly to the domestic battery negative except the shunt, not even the engine battery negative. 

No

 

The boat is an ex Black Prince by Pinder. There are essentially five direct connections onto the leisure batteries - two feeds to two fuse boards on the boat, one to the Multiplus, a direct fused connection to the bilge pump and a feed from the alternator. We do not have a shunt.

 

Our starter battery negative is connected to the leisure batteries negative - its all common.

 

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I see so you are only using the output data from the Multiplus. That means that absolutely anything on the boat could be taking the current. Yes I know you think everything is turned off, but...

 

I have Mastervolt kit, not Victron, but on the Mastervolt Combi we have, the resolution and accuracy of its built in output current measurement is surprisingly poor. It doesn’t really get below 5.something amps even when the current into the batteries is effectively zero. I think you will need to corroborate what the victron is saying, with some other means of measuring current, such as the clamp meter I mentioned. Just because something is displayed on a shiny digital display, doesn’t mean it’s right!

 

26 minutes ago, cairanvanrooyen said:

 

The boat is an ex Black Prince by Pinder. There are essentially five direct connections onto the leisure batteries - two feeds to two fuse boards on the boat, one to the Multiplus, a direct fused connection to the bilge pump and a feed from the alternator. We do not have a shunt.

 

Our starter battery negative is connected to the leisure batteries negative - its all common.

 

If you don’t have a shunt then obviously it doesn’t particularly matter that all the negatives are connected together.

Edited by nicknorman
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16 minutes ago, MoominPapa said:

Is the alternator warm, by chance?

 

No, its cold

 

17 minutes ago, MoominPapa said:

Then how is the multiplus measuring battery current?

 

I am not sure. The data i am showing you, is from the VictronConnect software, which is installed on my PC. My PC is connected to the MultiPlus via a USB VE.Bus connection.

 

5 minutes ago, nicknorman said:

I see so you are only using the output data from the Multiplus. That means that absolutely anything on the boat could be taking the current. Yes I know you think everything is turned off, but...

 

Yes, only using output from MultiPlus. I think i am going to physically disconnect everything from the battery bank one at a time and see if I can figure out where the current is going.

 

6 minutes ago, nicknorman said:

clamp meter

Ah, dont have one. Only have a tester to measure voltage etc.

 

35 minutes ago, Loddon said:

However the warmth check is a good idea just in case.

 

Batteries all cold - nothing warm. Although i am only using my hands and nothing scientific

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2 minutes ago, cairanvanrooyen said:
 

No, its cold

 

I am not sure. The data i am showing you, is from the VictronConnect software, which is installed on my PC. My PC is connected to the MultiPlus via a USB VE.Bus connection.

 

Yes, only using output from MultiPlus. I think i am going to physically disconnect everything from the battery bank one at a time and see if I can figure out where the current is going.

 

Ah, dont have one. Only have a tester to measure voltage etc.

 

Batteries all cold - nothing warm. Although i am only using my hands and nothing scientific

I would strongly recommend getting a UNI-T UT203 or UT203+, eg

 

https://www.amazon.co.uk/UNI-T-Digital-Current-Backlight-Multimeter/dp/B07XNWPDFQ/ref=sr_1_2?dchild=1&keywords=Ut203&qid=1603273520&sr=8-2&th=1

 

I suspect that the Victron output current parameter may well be lying!

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34 minutes ago, cairanvanrooyen said:

One last simple question - is the hum from the unit normal?

 

I have come to expect it, as the unit it transforming AC to DC. But just wondered if the hum is normal or a sign of malfunction?

I think a gentle hum is normal. As you say, there is a transformer in there reducing mains voltage to something lower, and alternating current creates an alternating magnetic field which physically affects the laminated cores and windings causing them to move slightly, which creates the hum.

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1 hour ago, cairanvanrooyen said:

There is certainly something going on, as its humming gently in the background

If you can't identify what the hum is, then Google now claim to be able to identify the song from just a few bars.

https://variety.com/2020/digital/news/google-hum-whistle-sing-song-search-1234806737/

Could be worth a try!

 

Jen ?

Edited by Jen-in-Wellies
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