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peterbernard avatar image
peterbernard asked

Is this normal? Multiplus 24 | 5000 volts/amps jumping all over the place during charging

I recently purchased a Victron Multiplus 24| 5000 and it is exhibiting some strange behaviour when charging, compared with my previous 24 | 2000.

Specifically, the voltage and current jump around significantly during the bulk and absorption phases. You can see a video I’ve made here, which shows voltage jumping between 27v and 28.8v in large increments every second, and amps jumping from 20a to 3a every second as well.

My previous Multiplus 24 | 2000 exhibited very stable behaviour by comparison. During bulk charging, for example, the voltage would climb slowly and steadily towards 28.8V, at which point it would switch to absorption mode and would hold voltage at 28.8 while steadily decreasing current until it reached around 1 or 2 amps (bank is 510 ah) before switching to float.

In an attempt to eliminate variables I have variously disconnected solar and wind charging, and turned off all DC and AC loads, but this has not made any difference. I have removed the battery temperature sensor as well in case it was faulty. The dip switches are correctly set for AGM, and we have also checked via the console to ensure the correct voltage parameters have been set.

None of these changes have made any difference.

I am wondering if there may be a problem in the installation (it was only installed last month, and has exhibited this problem since), or perhaps there may be a fault with the unit.

Could you please let me know if this behaviour is normal, and if not, what you would recommend we do next?

Many thanks

Peter Bernard

S/V Steel Sappnire

Phuket, Thailand

Multiplus-II
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Elimac avatar image Elimac commented ·

Link not working.

What is your AC input current limit and DC charge current settings?

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peterbernard avatar image peterbernard Elimac commented ·

AC Input current limit is set at 32. Where would I find the DC charge current settings? The charger can produce 120A, and I've seen it producing up to that level on my BMV 600s battery monitor, so I assume it's set up to deliver as much as it can.

Not sure why the link broke - you can see the video at https://www.dropbox.com/s/up5h63qvwo8i5aj/IMG_7766.MOV?dl=0

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klim8skeptic avatar image klim8skeptic ♦ peterbernard commented ·

Are your batteries getting hot? Do they make hissing or bubbling sounds? Are they swelling?

Better post a web link to your batteries.

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peterbernard avatar image peterbernard klim8skeptic ♦ commented ·

No, batteries are sitting at ambient temp (31 Celsius), no probs with them at all

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4 Answers
peterbernard avatar image
peterbernard answered ·

Not sure why the link broke - you can see the video at https://www.dropbox.com/s/up5h63qvwo8i5aj/IMG_7766.MOV?dl=0

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Hi @PeterBernard

do I hear a generator running? if so, try another source like shorepower or a bigger generator.

The only way to really setup well and inspect this is with an MK3-usb cable and a laptop. You'll never regret buying such a cable because of how much easier life is with it ;)

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peterbernard avatar image peterbernard Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Hi Daniel

Thanks for the quick response. Can’t remember if this video was with Genset or shore power, but behaviour is the same with both.

Genset is 7.5kVa, and shore pier was 32a, both more than enough to pump out 120a DC of charging (remember no other draw).

If I had the Mk3-USB cable, what would I look for? I’ve had two different people use one and we’re not able to find the issue....

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ peterbernard commented ·

If you just open VictronConnect or ve.configure and connect to the unit, you can see what it is using on AC side and charging DC, etc. also you can change some settings to see if it helps.

With VictronConnect you can also easily update the unit's firmware, giving you the latest version. when on clean firmware the unit still does strange things (and you can rule out a 'messy' AC supply, then there might be something wrong with it and a local dealer should be able to help you with that.

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peterbernard avatar image peterbernard Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

Hi Daniel

I purchased the Mk3-USB cable, and have been unable to resolve the problem.

The dealer from whom I bought the unit (Octopus electrical in Phuket, Thailand) said he thought it was "messy" AC supply from my genset.

I disagree, based on two factors:

  1. I did not have this problem with my prior 2000W multiplus - it was very stable. My genset is 7.5 kVa, and I am experiencing this problem even when I have no other load.
  2. I have this problem when connected to shorepower too (the dealer said he thought the shore power was also dodgy!)

At the dealer's suggestion, I selected the "Weak AC Power" option on VictronConnect, and while at first that seemed to fix the problem (at the expense of significantly throttling my charging capability), the problem has now returned even with this option selected.

I am now in Sri Lanka and a long way from dealer support. As I sail through the Indian Ocean this year I am going to be very reliant on my Multiplus, so I'd really appreciate your input and support.

Many thanks in advance

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ peterbernard commented ·

Hi @PeterBernard

What firmware version is the Multiplus on now?

can you make a video (screen record?) of the VEConfig window when the V/A fluctuations occur?

If you were close to a dealer, fault finding would be easier: just try another unit with the same settings...but let's try if we can find out things remotely like this.

What would be interesting to see here is the AC-input values when this occurs.

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JohnC avatar image
JohnC answered ·

Hi Peter. Nice ketch. And sorry about Dixie..

That behavior isn't normal, and your installer should be notified.

I'm reluctant to do this, cos I know nought of your relationship with your supplier (whoever it is), but @Paul B is Phuket based and a prolific contributor here. He's with Octopus, and has now been emailed re this post.

I hope you can sort this, but remotely is a big ask.. Good luck.



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peterbernard avatar image peterbernard commented ·

Thanks John.

I bought the unit from Octopus, although had it installed by another provider (AEM), so I’m caught a little between the two.

I’ve already emailed Paul, so hoping he might be able to help.

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Paul B avatar image
Paul B answered ·

Hi Peter

re this item below

2. I have this problem when connected to shorepower too (the dealer said he thought the shore power was also dodgy!)

Thats not quite correct, when I was On site on the boat when you were in phuket the and on shore power the inverter was working correctly with no fluctuations and thus was working fine, You said you had the problem at another marina. and I advised that possibly the reason maybe the Power supply there at that other marina may have had low voltage or unstable or some other issue , but as it was not happening at Boat lagoon at that time when connected to shore power, I could not fault the unit.

You purchased a MK3 unit as you were leaving phuket and thats the last I have herd from you, so if you are still having issues or you have questions then please contact us by email.

Possible issues.

The multiplus 5000 is a much larger unit and thus takes more power and charges more, and you also installed new Lifeline batteries and lots of other stuff yourself or with another installer, and I have no idea as to how these have been installed.

The inverter has been installed in a tight space with limited cooling. this was discussed, with you as well.

Things to check

1. whats the voltage at the Batteries when the charge amps goes up and down

2. where has the Inverters voltage sense wires been installed, (please supply a wiring diagram of the installation and all the connections between the Inverter and the batteries, please include any shunts), also photos of the full installation.

Please also supply a diagram of how the batteries have been wired showing all connections.

you have my email address so you can send that directly to me if you wish or post it here on the forum.




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peterbernard avatar image peterbernard commented ·

Hi Paul

Thanks for the quick follow-up.

I just wanted to clarify a few points you made in your response, so we can eliminate some variables.

We only installed the unit while at Boat Lagoon, so the problems on shore power could only have happened there, and not in another marina. The fluctuations (while on shore power) may not have happened at the time you were on the boat, but when they did happen, it was definitely at Boat Lagoon.

This reinforces that the issue is intermittent - would that imply that it is less likely that it's a wiring issue and points more to the unit itself? Not sure, but food for thought.

With regard to the new battery installation, I think we can rule that out too. They were installed 2 months prior to the new Multiplus, while I was still using the prior Multiplus 2000, which continued to be perfectly stable post battery installation.

The only other changes were the installation of a large solar array. The Multiplus issue was occurring before the solar array was installed, and since it is straightforward to switch off the solar panels, I have been able to confirm that the Multiplus problem exists with or without the solar array.

I'll provide photographs, diagrams that you've requested later today.

In the meantime, thanks again - I really appreciate your help.

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Paul B avatar image Paul B peterbernard commented ·

Peter Its very unlikely that its the inverter/charger, not impossible though, and therefore we need to pin point the cause. once the cause is identified then a solution can be obtained.

So in addition to the diagrams

1. what is the current firmware version, you could try updating that to the latest version. (think we did that as well when you were here and we could not find a fault) anyway it is worth doing as its a possibility, note recheck all setting after you do the firmware update.

2. check the inv/chr voltage reference point. it should be connected to the pos and neg at the batteries directly , and I mean right at the battery terminals. also recheck the vsense connections at the inverter as well, maybe one of them is not fully pressed home.

3. when the charger is charging and preferably at high amps check the voltages at each of the batteries, they should all be the same.

4. then check the voltage at the Inverter charger. ( we are looking for a bad connection somewhere or a bad crimp) thus you may see a different voltage at one point in the chain, if you do and its charging at high amps then that spot will also be hot.

5. after its been charging at high current (SAY AROUND 100 AMPS)for say 15 min. feel all the connections along the cables coming from the inverter/charger and feel to see if any one of them is HOT, if you cant get high charge amps for long enough then do the opposite run the inverter up to a very high load condition this will then draw large amps as well and also then feel for hot spots. check voltages as well

6. Your reference as to the old charger not doing this maybe just that it could not supply large charge amps and therefore you would not see the swings. anyway it gets back to the basic issue we have to find the cause.

7. only do the checks when its giving you the issue, doing the checks without the problem being there will make it very had to pin point the issue. as we have a lot of possible causes.

8. If a spot is hot then find the reason, normally it needs cleaning or its loose (stating the obvious here sorry)


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peterbernard avatar image peterbernard Paul B commented ·

Just wrote a long reply to this, but won't let me submit for some reason. Will try reply as a new answer in case that works

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peterbernard avatar image
peterbernard answered ·

Hi Paul

I started trying to draw an electrical diagram, but was taking too long (I'm leaving for a 7 day passage to the Maldives later today), so have created a video instead - https://www.dropbox.com/s/1u5kk9hfgm6a4u5/img_8132.mov?dl=0

My batteries are 4 x Lifeline 8DL 255ah (new October 2019 as direct replacements for the previous 8 year old set of Lifeline 8DLs. We literally removed and replaced with no changes at all to the connections or system).

They are connected in series and parallel to create a bank of 510ah @ 24v. The only connections on the terminals are for the Voltage sensor and the temp sensors for the multiplus. Immediately after the batteries is a bus bar and the shunt for my BMV.

Firmware on the multiplus is v465 which according to VictronConnect is the latest version.

The voltage sensor is connected to the battery terminals, and the connections at the inverter are tight. I actually tried removing this from the system completely today just to see if that stabilised things, but it didn’t, so I reinstalled it.

I've conducted a full voltage and temperature check today at all key points along the installation, as follows:

  • At the DC connections for the inverter/chargers
  • At the bus bar that the DC cables then go to
  • At the battery switch
  • At the bus bar next to the batteries
  • At the batteries

I've recorded my readings before the test, during high load inversion, and high load charging, and have laid out the results below.

You can download the results of the test at https://www.dropbox.com/s/cd269w0ps3934h2/inverter%3Acharger%20test.xlsx?dl=0

From what I can see, there are no red flags in there.

At the time of the test, we were in bulk charge mode, and so the fluctuation problem was not presenting itself -it only seems to occur during absorption and float mode. During bulk, the amps are steady, and the voltage climbs nice and steadily towards 28.6V (which is where I have it set to switch to absorption).

That means it's impossible to have high charge load during the fluctuations.

Yesterday I conducted a voltage test with high load on the inverter during the absorption phase (Charge current was fluctuating rapidly between 5a and 30 a, and voltage between 27.9 and 28.5) - I didn't do a temp test then, but voltage results were consistent with the results in the table above - (ie a 0.5 V drop between inverter and batteries, but no significant voltage variations at any points along the installation or at the batteries themselves).

With regard to your point 6 above, the fact that this issue only occurs during absorption and float means it's happening at lower charge amps (typically less than 35a), which kind of levels the playing field with the old 2000w inverter/charger and makes me think it's not specifically about the size of the charger.

As noted above, I'm leaving for a 7 day passage later today, sorry, but I'll be able to check in tomorrow as we sail down the Sri Lankan coast to see if you have any further thoughts, and then no internet for a week).

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peterbernard avatar image peterbernard commented ·

It's now 1 hour since the post above, and I've been monitoring this charging run closely. Fluctuation have started again - only once in absorption mode and charging amps below 35 a. Voltage on BMV now rapidly cycling between 27.9 and 28.5V, current cycling between 20 and 30 amps. All temps and voltages through system consistent with the test above (temps actually a little lower as charge current not so high but no red flags anywhere).

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Paul B avatar image Paul B commented ·

Peter there is no cut and dried answer to your issue, and you will need to test it on a stable shore power connection as well, All I can suggest is that when you find a authorized Victron dealer at one of your stops, and you will have to be able to duplicate the issue, and then ask them if they could check the systems out for you (and yes you will have to pay them for there time)


One thing you have not mentioned if you had dont this. is when the charger is charging at high amps for 30 min check all the connections between the charger and the batteries for any warm to hot connections, and repair any of these check all the battery connections as well.


As a diagnostics test to exclude other posable boat systems and connections maybe try the below.

Disconect the DC batteries from the inverter and the vsense reference and put a battery right in front of the inverter and then connect that battery directly to the inverter, so that it is the only device connected to the inverter and then see if you get the same issue when charging that battery, NO fuses no switchs just a pos and neg lead about 1 mtr or less in length for each to the battery them and connect the vsense to the battery. (I would also suggest that the battery you use is at about 60% capacity so that the charger has to fill it on bulk then absorption then float.

Please photo graph the test and write down the test procedure in detail, you should do this on shore power and generator power, also measure the incoming AC volts as well and record this.

another helpful solution is to install a colour control or a GX unit and connect them to the victron VRM so that remote monitoring can be done and a record of the charging could then be seen on the vrm system, also remote support and configuration is also possible, as well,


Another possibility is one faulty battery in the bank, ie one going open circuit then coming back on line, so you could try just one battery connected only and see what happens, then swap to another one, maybe best to do this first before the above procedure.

I know this is some work but its got to be isolated out, if you were here in phuket I would swap in a load unit, but thats not possible.

Paul


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peterbernard avatar image peterbernard Paul B commented ·

Thanks for the reply, Paul.

There's an endless array of tests one could perform, but in the middle of the Indian Ocean it's a little challenging to undertake, nor do I think it's appropriate under the circumstances.

I'm not sure if the approach you're suggesting takes into account any of the data I've been sharing. You've asked me in your most recent reply to do some things that you asked previously, and that I reported back on (eg testing temperatures after running under load, and testing battery voltages under load).

What I'd like to see is some informed speculation on what the problem might be based on the data I've shared, and why, rather than just an ongoing and potentially never-ending list of new things to check.

Specifically:

  • Why does the issue only present itself when charge is less than 35a?
    • Most of what underlies your proposed tests would be worse under higher charge loads (or at the very least still be present at higher charge loads if not actively worse)
  • Other than a fault in the machine what is a reasonable explanation of why the fault might be happening only under lesser load?

This is a new machine, purchased less than 3 months ago, and which has had problems since the day it was installed, after replacing a prior problem-free Victron Multiplus on the same boat, with the same batteries, switches, cabling, generator and shore power.

I only purchased this unit after the one I originally purchased (a second 2000w machine) from your dealership had problems out of the box and could not be switched on.

The problems are consistent and easily replicable.

Can you please do some investigating within the Victron dealer network and head office and let me know if the dealer in Maldives (listed below) is adequately equipped to perform diagnostics and provide a warranty replacement.

Thanks

Peter

Marine Equipments Pvt. Ltd.

M.White Bardy , Ground Floor Kanbaa Aisa Rani Hingun Reg. No: C-808/2006 Male 20339 Maldives+960 3338820

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