question

Albert de Jongh avatar image
Albert de Jongh asked

Multiplus II battery terminal bolt snapped / sheared

I was tightening the negative terminal tonight, using a Gedore 5 - 50 Nm torque wrench set to 10 Nm (the manual says tighten to 12 Nm). The bolt inside the inverter snapped off :-(

And this is what the other half of the bolt looks like - kind of powdery inside?

I am a little bit unhappy, since we have regular power failures in South Africa at the moment, and I have no idea how long this will take to have fixed (the inverter is less than a year old).

Multiplus-II
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6 Answers
Rob Duthie avatar image
Rob Duthie answered ·

Hi

Note these are only 6mm tinned brass bolts, just go an buy another one and fit your self.

Note: 6mm brass bolts torque range from 5 to 8Nm range depending on the friction coefficient.

Regards

Rob D

NZ

3 comments
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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

Only the very first batch of MP-II has M6 bolts. Now they have M8.

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Albert de Jongh avatar image Albert de Jongh commented ·

I don't think I'd even try to replace the bolt - it is behind that little circuit board, and probably also soldered to it or something. I looked from the bottom of the inverter, and can't see how it is kept captive.

I see M.Lange mentioned below M6 vs. M8 bolts - mine has the M6 bolt, and my paper manual says max torque is 11Nm. The manual on the internet says 12Nm (but in brackets behind it M8 bolt). Could easily create some confusion!

And I was even more conservative with the torque wrench at 10Nm.

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Apologies for the inconvenience, but the thing to do in this case is start the warranty claim process.

Please contact your dealer, or fill in the form above. It might be able to be resolved quickly.

That torque setting is the maximum, in the future if you are going to use torque wrenches, find one with a range closer to the target, eg 1-15 Nm. In this case it could be a fault in the metal part, or the low end of the torque wrench. It is much easier to feel the natural point of tightness with a smaller tool.

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Albert de Jongh avatar image Albert de Jongh commented ·

Thank you @Guy Stewart (Victron Community Manager). The inverter has been handed in at the supplier here in Cape Town and they will liaise with Victron to have it resolved. I hope for quick resolution as the inverter keeps my business running during our regular rolling blackouts.

The Multiplus II documentation could perhaps be improved in two ways:

  • Note the actual torque values, not the maximum ones.
  • The manual on the internet is for the latest inverter - hence the max torque there is different to the older version (which I have). It is not immediately obvious that you should be using a different value since the manual is for a "Multiplus II". I have now gone and checked that it does actually specify the HW revision on the second page at the bottom, but it is easy to miss that. Perhaps I am nit-picking :-)
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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ Albert de Jongh commented ·

Point 1- They are the same though, the actual recommended torque is the maximum torque! Any tightening beyond that value is considered overtightened, and risks damage somewhere. Any less, and it could be tighter making a better contact and more secure connection.

I am sympathetic with your second point. All the information is there, but it is easy to overlook the model number variation, and given the significant potential for damage to an M6 tightening to an M8 torque rating, I will consider how we can make the situation clearer in the documentation. I am also open to suggestions...

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koos avatar image koos Guy Stewart (Victron Community Manager) ♦♦ commented ·

Hi Guy, I am finding these posts very frustrating as it feels to me that there are some underlying issues that is not communicated or addressed. I ran into the same problem yesterday fitting new DC cables to a year old Multiplus-II 8k. Following all the training and user guides, I felt it important to follow the instructions of ensuring the terminals are correctly torqued and went ahead and checked AC and DC terminals but managed to snap of two bolts just by using the correct values, which again you highlighted as being important.

img-1778.jpegWhen researching the issue I am finding dozens of posts like these complaining about the same problem. I am also concerned that I have two bolts on the same unit and have never had this problem on any other unit before which again makes me think of a factory defect or if heat could of damaged the bolts.

What really bothers me is I have followed your advice of initiating the warranty process just to be told straight out even before the unit was seen by the dealer that this can only happen because of installer error and will not be covered by warranty. I now have a quote for a 1/3 of the price of a new unit, just to replace this terminal board.

it is very frustrating trying to follow all the instructions as per your training and manuals, then having a problem and be told, but you really shouldn't of followed our guidance and should of just try and feel by hand when it is snug enough.

Why is Victron and its dealers providing conflicting information and why am I being punished for following your instructions?

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ koos commented ·

I installed literally hundreds of MultiPlus of all sizes (and other Victron devices) and never managed to break a bolt or screw.

Using a torque wrench isn't an excuse to turn your brain off and apply more and more torque until it clicks or snapps.

At some point you should ask yourself if you really should apply more torque or stopp and check if there might be something wrong.

Can you make a picture how you adjusted your torque wrench?

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Rob Duthie avatar image Rob Duthie Matthias Lange - DE ♦ commented ·

Hi

You are so spot on with that analogy Matthias

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koos avatar image koos Matthias Lange - DE ♦ commented ·

I am taking some offence to your statement and think you need to check yourself. Common sense is great in a perfect world and a great argument if I were using an oversized torque wrench where I would not feel the point of too much resistance, not so great when using a small torque wrench, set to the correct measurement but still snapping the bolt while barely applying pressure too it. I have also installed many units of different models and makes and have never snapped a bolt either... all of a sudden there is one unit and two bolts snap... after triple checking what I am doing. Again perhaps there is something else wrong. If you cannot add value to the post, keep your comments to yourself.

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Hi @koos,

I hear you, and I get it.

I have just renewed my effort internally to bring more clarity to torque settings in the documentation, both the manuals and the datasheet.

If you are certain you correctly followed the specification, then I would persist with your warranty claim.

My data has the spec as;

MultiPlus-II 8k, 10k, 15k DC M8 bolts 12 Nm
MultiPlus-II 8k, 10k, 15k AC M6 bolts 5.5 Nm

I'll confirm those with R&D to prevent the same issue if there is a mistake.

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koos avatar image koos Guy Stewart (Victron Community Manager) ♦♦ commented ·

How do I persist with the warranty claim? Dealer just said straight out that Victron will not entertain such claims.

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If you have been clear with the dealer that you followed all specifications and would like to request an RMA from Victron, the next step would be to explain the situation in as much detail as possible in a support request here - https://www.victronenergy.com/support

It is very unusual to have two bolts shear off on the same product, it does indicate that they were overtightened. I think that is where the dealer is coming from. If it was only a single bolt, it’s potentially a manufacturing defect, but two is so very rare as to raise a flag.

The fear is that if the manual specification is correct, it is replaced, and your tool isn’t correctly calibrated then the same thing happens again.


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Rob Duthie avatar image
Rob Duthie answered ·

Hi

Is that a brass bolt? if so they have lower torque values anyway than steel bolts, also is the torque wrench being calibrated and checked not a cheapy? as thay can be a long way of in calibrated readings.


Regards

Rob Duthie

NZ

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koos avatar image
koos answered ·

Victron posts torque values of 12Nm for DC terminals and 1.6Nm for AC terminals in the manual

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Rob Duthie avatar image Rob Duthie commented ·

The 1.6Nm is for the AC screw terminals not bolt type as the bigger units have.

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Robert avatar image
Robert answered ·

Hello,

my brand new phoenix had the same Problem.

Victron replaced it without problems.

Best regards Robert


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solarpete avatar image
solarpete answered ·

The picture of the broken M8 bolt does not appear to be brass or copper. Why is the bolt not solid? (having the center filled with some non structural material) The Victron 12Nm torque spec seems very high (even if for a brass solid bolt) compared to the steel grade 4.6 torque spec of 11Nm.

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