question

john-strein avatar image
john-strein asked

Why no Torque specs from Victron on bolts on their equipment?

I bought a Smart Shunt that has "beefy" M10 bolts for the electrical connections. No where in the manual is there a torque spec for these bolts. Furthermore, a search on this forum reveals others have requested a torque value for this device and other Victron components and not gotten any official responses from the company representatives.

So, given most of these questions were asked a couple years ago I am asking again. What value should I torque these bolts to? There has to be some sort of range that is acceptable. Can anyone answer this question?


SmartShunt
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Unfortunately I can't help. This type of issue highlights the lack of support that is not unusual for Victron. Whenever I ask my local dealer for any info on any product, I'm always told to search or ask on here. As you say, some questions get asked, but never get answered. I'm sure that although my dealer will not give me any advice, if I ever have a problem. I know they will have no problem telling me that I installed/connected whatever it maybe wrong & that it's not covered by any guarantee.
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Probably because not needed. They're supplied with spring washers to stop the nuts undoing. And you should be able to tighten something like this correctly by feel.
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campdaily avatar image campdaily kevgermany ♦♦ ·

I'm afraid that this is a perfect example for the lack of support. "Probably because not needed"?? Is this an official Victron policy, or just your personal opinion? Also using your spring washer theory, would you say. Finger tight is enough? Sorry, but surely you see my point. This in no way answer's the question asked & this is where everyone is supposed to get info from. I'm sure that the two people that have answered were only trying to be helpful, but. One of them refers to a Non-Victron product & the other refers to a completely different Victron product & there is a difference of 6Nm in the answers given. Using Victron is a big investment & correctly installing is a must, so a little bit of help is surely not too much to ask. Do you have any helpful suggestions as to where the OP may get the answer they are looking for?

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I'm not getting into arguments. If someone can't tighten something like this by feel, then they should pay a professional.
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From and engineering standing using the tables for A2 and A4 Stainless fastners with 1.0mm and 1.25mm pitch threads. I would suggest M6 1mm pitch thread nuts dry at 5ft-lbs or 7NM and for M8 1.25mm pitch thread nuts dry 12ft-lbs or 16NM but maybe the 8mm bolts on Victron uquipment are 1mm pitch thread so 14-15 NM would be sufficent. Although I have read somewhere in Victron documentation 14NM for 8mm nuts.

You can convert the figures below in google to ft-lbs or NM depending on what your torque wrench is calibrated in.

screenshot-1.png


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screenshot-1.png (131.7 KiB)
The shunt does not have stainless nuts and bolts. Using these values is guaranteed to strip the threads. See @WKirby reply earlier.
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johnsmith avatar image johnsmith kevgermany ♦♦ ·
The table shows in/lbs, if you can strip a 6mm thread with 7Nm and an 8mm thread with 15Nm then you either have a bolt made of cheese or your torque wrench is poorly cailbrated by atleast 350%.
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We're talking brass, not Steel.
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2 Answers
wkirby avatar image
wkirby answered ·

Sometimes with these components, not even the OEM lists these specifications. Since they are just brass blots, then standard tourque values would apply. M10 brass bolts, 20Nm is a good ballpark.

I did find one OEM who does have the torque values in their datasheet.
Check out a similar sized shunt from muRata (500A/50mV):
1647034366242.png

Seems to agree, with 19-20Nm for a 3/8 inch - which sounds like an American size to me and so would be equivalent to standard M10 size.

Taken from muRata shunt manual here:
https://docs.rs-online.com/18e7/0900766b813bb936.pdf


1647034366242.png (29.9 KiB)
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Ingo avatar image
Ingo answered ·

It might just be an oversight in the SmartShunt documentation but my Quattro manual clearly states the following and might give you an indication of what to use.


1647072665342.png


1647072665342.png (10.3 KiB)
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Hi,


same is stated in my Multiplus-II GX manual.

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The shunt connection is a different size bolt than the DC in on my PMP 3kw/24v inverter/charger so I don't think this applies
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