question

Albert de Jongh avatar image

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
1581882327254.png (4.6 MiB)
1581882895466.png (731.1 KiB)
2 |3000 characters needed characters left characters exceeded

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
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.

2 comments
2 |3000 characters needed characters left characters exceeded

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

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 :-)

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...

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
2 |3000 characters needed characters left characters exceeded

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

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

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.

Hi Albert

As us kiwis do, we call it the number 8 wire method, just do it!! the inverter is simple in design and construction. Other wise if you stuck out in the boon docks, you can wait for ever.

Note: I do have one myself with 6mm bolts.

Regards

Rob D

NZ