Looking for some advice on how to proceed here. After considerable reading and coming across this topic several times, I finally invested in torque screwdriver. Like many I was initially surprised at how tight the actual settings were supposed to be, but not mine to question. Anyway, I went through and checked and tightened all my existing Victron components (quite a few) and all was ok. Yesterday I went to install my new IP22 and on installing the first DC+, started tightening, with the end goal of 2.4n-m as per spec. At just under 2 the tension let go and it was apparent the terminal screw had stripped. This is disappointing to say the least for a person who has spent his whole live tightening screw terminals successfully with just a screwdriver and an experienced touch. To now finally concede to using the actual proper technology and having it bite me in the arse, I am highly disappointed.
Normally, it certainly shouldn’t happen that a screw clamp rated for 2.4 Nm strips at >2 Nm. This is likely a manufacturing defect, and you should claim under warranty.
For instance, I once had a Multiplus 1600 where the screw clamp for the negative connection stripped quite quickly while tightening. I returned this Multiplus under warranty, got my money back, and bought a Multiplus 2000. Slightly larger, more power, and a decent bolt/nut connection.
Definitely. It would be considered a defect if it did not take the torque expected.
Wording of the warranty and the reason warranties exist is for this sceanrio.
..
This limited warranty covers defects in materials and workmanship in this product,
Nice torque wrench BTW.
Not casting any aspersions here on your claim (you didn’t reach the max torque) but i have still seen people overtighten with the beep/vibrate one . I was horrified - like did you not hear it screaming at you?
I hear what you are saying though with a hand held basic screw driver as an experienced user you get a feel for how the screw is behaving.
I will just add that tightening the Victron 48V switch to its rated torque should also probably not be attempted.
And with the Lynx busbars, you can clearly see how they’ve evolved because of being not quite able to take the rated torque (the distributor has a plastic slot holding the M10 screw, the Class-T power in has the screw welded or somehow else attached to the busbar. I had the screw-in-plastic let go, but I suspect someone before me tightened it with an impact wrench and not a torque wrench).
I think also sometimes ‘max torque’ is mixed up with ‘what you should torque at’. Just because it says max 14nm doesn’t mean you have to tighten it to 14. 14 is the outer edge of where it should be.
I’m pretty fussy about this so no that didn’t happen. This torque driver has several modes and the one I use is: at 80% of rating it buzzes, at 90% it buzzes more frantically and a yellow led lights up, and at 100% it goes bananas. I typically use the first two as check & balance opportunities - if at 80 or 90% it “feels” too tight I’ll just stop there. But if it feels solid still I’ll go the distance. Also, the torque is constantly being displayed so I have a dynamic reading of where I’m at. That’s how I knew I was at <2 n-m when it stripped.
I know. It was a general conversation with the other poster. Partially related to the issue. Slightly aside. I can clear it out.
Again there is a reason why a warranty exists it for manufacture defects. It will likely be replaced if you haven’t made the head look like chowder.
(Otherwise i would have brought it up incorrect torque already. 2.4nm is reasonable/standard for most small cable entry terminals.im sure you know this already)
Thx, I did not know that. As mentioned earlier, I’m used to working by feel. I only got into the whole subject because of Victron. In another boating forum is a story about a guy burning up 3 MPPTS. Like melted-almost-started-a-fire-on-his-boat kind of thing. A bit serious as you might imagine. Long and short of it was he was not torquing down the connections, but relying on his considerable experience as to what was tight enough. Turns out in this case with this kind of connection (which is universally hated in the boating world) the connections were loosening with vibration and heating/cooling cycles and the loose connection was generating enough heat to melt stuff. As with most forums, MUCH dialogue ensued, some of it on-topic. But the gist was they really do need to be actually properly torqued to a specified number. I’m a tool junkie anyway, and have a fair bit of Victron gear on my boat, and am also quite desirous of not having a fire. So I got the torque screwdriver and proceeded to check all (most?) of my existing connections and then use it for new installs going forward. BTW, almost all of my existing connections were sufficiently tight ie within maybe 3-5% of the specified torque number. And the remainder didn’t require much of a twist to get them there. The one surprise was my Orion XS which took a couple of turns to get there.
One other thing to add is that I now use ferrules a lot. I didn’t before because I didn’t need to in those circumstances. But putting fine stranded wire into a connection that just has a bare screw coming down into the wire and squeezing and tearing it seemed to be a good candidate for finally springing for ferrules and crimpers. I don’t know if or how much that might be related to the above, but just clarifying.
@Daniel , I feel I’m not understanding your question. How else would you torque a screw terminal to a specific setting without a torque screwdriver?
As for calibration, man don’t get me started. Short answer without too much ranting: a middle price-ranged tool can be reasonably expected to - most of the time - be within an acceptable value. In my case above, 20%. But the bigger rant would contain the thought that if this $300 device requires a $1000 (or $5000) tool that must calibrated at some unreasonable frequency at x$’s per calibration (x=lots) and be stored in a temperature and humidity controlled case to preserve its calibration, and so on and so on, then you should NOT BE PERMITTED to sell it to the general public. Your sales should be restricted to General Dynamics or General Electric or Boeing (whoops, that last might not be a good example given all their doors falling off et al).
I still don’t understand what you are saying - you need a torque screwdriver in this situation at least because Victron says you need to torque these screw terminals to a specified value. How would you propose to accomplish that without a torque screwdriver. And as I have some evidence of, the failure to do so correctly is serious.
As far as that significant an error, I was not aware of that. Neither was I aware that calibrating them is a simple process. I will look into it, although if you could share said procedure or a link(s) to info that would help. What I can say is that I did a lot of reading and searching the topic before buying one, including watching several YouTubes of testing various units and satisfied myself that the unit I chose tested very favourably. I even seem to recall a certificate of accuracy but will have to wait until I return to the boat to look for it. BTW, I am well aware the a “certificate of accuracy” from a junk tool supplier isn’t worth the paper it’s printed on, but nonetheless all these little things added up to give me a reasonable confidence it was legit.
A. Victron publishes torque instructions as they have no control over who and with what competency will be following their installation instructions.
Anybody that has held and used tools such as screwdrivers for any period of work time would have a good feel for correct torque.
B. Screwdrivers in particular rely on common sense limits imposed by hand strength, by the strength of the achievable metallurgical driving force and the physical/mechanical strength of the screw material itself (slot, philips).
University of Hard Knocks! - obviously you have recently had a tutorial at that University!
C. Calibration, simple - this can be modified and applied to any torque measurement tool
Go back to first principles.
torque = force/distance
get a pull spring scale
attach a length of solid material to the handle of your torque screwdriver (eg using vice grips etc)
pull scale to the required Nm force at a length of 1 metre.
Thanks @Daniel, appreciate the detailed reply. I will try to avoid a common forum foible of splitting hairs and debating terminology instead of intent, but would say the following: I would say you cannot know what “correct torque” is by feel until you have actually done it ie torqued something down with a tool, felt what it felt like, and then continued in the future just using a screwdriver or wrench and remembering what it felt like. Basically you now have educated hands, and add a bunch of years of experience to boot and I have no disagreement. Or if your intent was that by hand you learn what “tight enough” is, I also agree. That’s my background although not nearly as extensive as yours. Mine started with a farm upbringing which was full of over engineered and overbuilt parts and equipment so we got used to “wrenchin’ ‘er down” pretty good. And stripped a few along the way.
But….I am aware of at least one (possibly more) instance where a Victron component, an MPPT in the case, melted (almost burned) because the screw fitting loosened (as per my post above July 26). The individual involved was also very experienced and I have no doubt that his versions of “tight enough” would have been similar to what I would do. But it was not to actual Victron spec. In this case no tragedy, but I would bet a euro to two that had the boat burned down and peopled killed, you would have insurance companies (and Victron) leaning VERY heavily on the torque requirement. And if it could be determined that it had not been done “correctly” there would additional tragedy with the settlements and blame.
As for calibrating, thanks for the explanation, although it gives me a D’Oh moment Cripes, I know this stuff. Don’t know how I managed to forget basic physics from Uni 40 years ago. Ouch. I will do this in the next few days to determine where my tool actually is.
Ok, did my test. My driver set to 21.24 in-lb (2.4 N-m) pulled 4.7 lbs on a lever arm of 4.5 inches, = 21.15 in-lb. I’m going to conclude that is well within any reasonably expected margin of error. Therefore when the screw stripped at <80% that’s not kosher.
But thanks for the helpful nudge @Daniel777. It was a good memory refresher as well as a jolt of confidence in my tool.
. I was horrified - like did you not hear it screaming at you?
. It was a good memory refresher as well as a jolt of confidence in my tool.