Wire too big for Victron charge controller

[Wotname]

Originally Posted by jordanbigel

This is what I said in post #9 - or rather, I said this is what I have done in the past - and I asked if someone could explain to me why this is not the right approach. I was hoping one of the electrical gurus could explain why this is a bad idea.

So far no one has done that, and obviously you agree this is an acceptable solution.

Is there any counter-argument against this approach?

I concur, it is the right approach. Time the strands until they fit into a 10 AWG uninsulated ferrule. Crimp it using a decent square form crimper, fit some dual wall heat shrink, fit to the Victron unit; job done, sit back and have a beer (or beverage of choice).

There are no downsides, only upsides.

[Wotname]

Originally Posted by GordMay

........... Wire Ferrules, on the other hand, will crimp on the barrel end of the terminal, so the diameter of the connection will be the slightly larger than the actual wire itself.....

Well yes and no...using a ferrule and a square crimper, the overall size of resulting terminal is smaller than using a round bare wire.

We are mostly talking about Victron units in this thread and they use square style clamp plate screw terminals. Multi-stranded marine wire is round. We also know there is lunacy ahead if trying to fit a round peg in a square hole.

Let's look at the cross sectional areas of squares and circles given the Victron square terminal is the governing factor i.e. we can't change that aspect.

10AWG - round form with a conductor cross sectional area of 5.26mm2. The actual cross sectional area for the wire is somewhat larger but I haven't found a suitable reference to determine a hard number as it depends greatly on the number and diameter of the individual strands. So taking into account the air gaps, the actual cross-sectional area is likely to be 5% greater than the conductor cross sectional area. So let's use a circle with an area of 5.26 plus 5% i.e. 5.52mm2. The diameter becomes 2.65 mm. Thus to fit a bare (round) 10AWG wire into a square terminal, the side of the square has to be about 2.65mm.

Now look what happens when the 10AWG is forced into a square cross section. We can use the actual conductor cross sectional area of 5.26mm2 as the air gaps between the individual conductors is removed by the crimping process. The square will have a side 2.29mm. Now add the wall thickness of the ferrule which according to my on-line references varies between 0.15mm and 0.2mm. Taking taking average as 0.175mm, the square form of the resulting wire and ferrule has a side of 2.64mm.

Thus round bare wire and the crimped square ferrule and wire will essentially fit into the same sized square terminal.

I haven't been able to find the actual size of the square terminations used on the 75/15 unit and I don't have one at hand to measure but the Victron data sheet says it will accept a 6mm2 wire. Using the above process, this suggests a square which has side of about 2.8mm.

As Ron C states, some crimpers don't compress the 10AWG ferrule enough to fit the 75/15 and I guess this also depends on the wall thickness of the ferrule used.

The biggest advantage of using a ferrule over a bare wire is the number of times the wire can be removed and refitted with out damage to the conductors. In this instance, the ferrule wins hands down.

You most important point is certainly true -

Originally Posted by GordMay

If it fits, use it.

[s/v Jedi]

Crimped ferrules on AWG 6, 8, 10, 12, 14, 16 and 18 and inserted into DIN rail terminal blocks, showing which sizes fit which blocks comfortably.

These are Dinkle terminal blocks:

DK10N AWG 6 - AWG 20
DK6N AWG 8 - AWG 20
DK4N AWG 10 - AWG 22
DK2.5N AWG 12 - AWG 22

The smaller, the narrower so you can fit more in the same space. There’s a picture showing these sizes installed on a long DIN rail.

Note that these are insulated ferrules. When using the maximum wire diameter for a terminal block, the insulated part is wider than the terminal block so it won’t fit in a row on the DIN rail. You must use un-insulated ferrules in that case. In a pinch, you can cut the insulation off.

Also showing some closeups and applying dielectric grease after crimping. Here I cut the strands just short so that there is room for the grease to protect the ends of the strands.
I later concluded it was too much work for production, so I switched to stripping strands long, push them into the tube with grease, then crimp and then cut them flush. This is about 3-5 times as fast, even when I put that cut end in the tube again to put some grease on the fresh cut ends.

Note that this is the grease I really like because of the plastic tip on the tube. It is more expensive than others and the grease is the same but if you shop around you can find deals.

[s/v Jedi]

Another picture where an uninsulated ferrule is needed simply because the wire insulation doesn’t fit inside an insulated ferrule.

This is an interesting setup, made possible by the new Wago terminal blocks that allow solid as well as stranded wire. I can connect 20 wires together using 5 crimps in a 5-way Wago 221 that is as small as your finger tip. Try that with the old terminal blocks and ring terminals!

[Wotname]

Originally Posted by s/v Jedi

...............
Note that these are insulated ferrules. When using the maximum wire diameter for a terminal block, the insulated part is wider than the terminal block so it won’t fit in a row on the DIN rail. You must use un-insulated ferrules in that case. ...............

Would this style of insulated ferrule work better with the narrow blocks? These 'rectangular' insulated collars are designed so that 2 wires can be crimped into a single ferrule.

[s/v Jedi]

Originally Posted by Wotname

Would this style of insulated ferrule work better with the narrow blocks? These 'rectangular' insulated collars are designed so that 2 wires can be crimped into a single ferrule.

They are still the width of a standard ferrule. There just isn’t room for the plastic part at all. The outer diameter of the wire insulation equals the width of the terminal block.

You can go up a size of the terminal blocks but then of course you’re gonna need more DIN rail length for the same amount of terminals. This may not be a problem, but on boats space is often limited.

It is very nice to mix and match different size terminals on a DIN rail. The rail in my picture has 6 AWG but also 22 AWG

[Senojev]

If you are convinced that 8AWG is the way to go a reduction splice is the best way to go. By the way, on Victron equipment using a screw/pressure plate clamp, they do not recommend ferrules as they consider the clamped connection better directly on the wires with more surface contact. I was told their torque specs are based on no ferrule.

[Wotname]

........ By the way, on Victron equipment using a screw/pressure plate clamp, they do not recommend ferrules as they consider the clamped connection better directly on the wires with more surface contact. .........

Does anyone have a Victron reference supporting this?

I haven't able to find it so far and I wonder if it applies applies more to land based installations where the units are likely to operating closer to their max current limits and where corrosion issues are not so harsh. I think that in a marine environment, the sealing and refitting advantages of ferrules would outweigh the claimed lower resistance of the wire / clamp but I would like to see exactly what Victron says about the issue.

[Statistical]

Originally Posted by Wotname

Does anyone have a Victron reference supporting this?

I haven't able to find it so far and I wonder if it applies applies more to land based installations where the units are likely to operating closer to their max current limits and where corrosion issues are not so harsh. I think that in a marine environment, the sealing and refitting advantages of ferrules would outweigh the claimed lower resistance of the wire / clamp but I would like to see exactly what Victron says about the issue.

I haven't seen anything from victron discouraging use of ferrules. Any plate based screwed down system doesn't require a ferrule as the plate will protect the wire from the screw but that isn't the same as prohibiting it.

As you point out there are advantages beyond connectivity for ferrules. Reduced corrosion, reduced need to retighten the clamp screw, reduced risk of wire damage, reduced risk of wire splaying into adjacent port, etc.

[s/v Jedi]

How it’s done for clean, reliable installation; I know it’s a lot more work than slapping some wires on, but it is required to achieve the results.

[HeinSdL]

Originally Posted by s/v Jedi

How it’s done for clean, reliable installation; I know it’s a lot more work than slapping some wires on, but it is required to achieve the results.

Perfect, Jedi, admirable. But I am also interested in good enough. Referring to the OP, simply reducing the number of strands (obviously removing them carefully and completely) and then clamping in the socket, surely that is good enough?

[Chotu]

We all have an opinion. Here’s mine. Ha ha

Introducing more connections introduces more places for problems and corrosion to occur. The less connections the better in any wiring project

So, trim off some of the strands and slide it right into the connection within the charge controller.

[HeinSdL]

Also, crimping correctly on the various wire sizes is a skill which can be learned but needs practice. Most boat owners making the occasional electronic connection are not likely to have sufficient practice nor the tools & consumables.

I have tried and have been mostly successful in having the required materials on board (incidentally thanks to a Jedi tip) but the amount of different types and sizes of crimps + tools I now possess makes the place feel like a floating hardware store. Ok I exaggerate but it's a lot of stuff to have and I enjoy the process, but just to connect up the occasional charger, or whatever, well, one's got to be a bit pragmatic sometimes.

[s/v Jedi]

Originally Posted by HeinSdL

Perfect, Jedi, admirable. But I am also interested in good enough. Referring to the OP, simply reducing the number of strands (obviously removing them carefully and completely) and then clamping in the socket, surely that is good enough?

Originally Posted by Chotu

We all have an opinion. Here’s mine. Ha ha

Introducing more connections introduces more places for problems and corrosion to occur. The less connections the better in any wiring project

So, trim off some of the strands and slide it right into the connection within the charge controller.

Exactly. My pictures show no splices to different diameters. One wire, with ferrule, straight into the Victron terminals.

But also the wires are all securely bundled so they don’t slap around causing all kinds of trouble. You see four Orion units, all mounted on a single piece of GPO-3 electric grade fiberglass, all specifically designed to fit in one particular spot and ready to mount as a module. That is what it means when Victron states that these should not be mounted on a flammable surface in their installation manual.

What I am trying to say is that while using crimped ferrules is a big step in the right direction, using them doesn’t in itself make the installation “good enough”. A lot needs to be done right in order for it to be good enough for use on a sailboat.

Unfortunately I hardly ever see good installations other than factory new expensive yachts.

[CharlieJ]

#52 & #53:
All accessories provided by Victron have ferrules installed. Further, Victron’s book Wiring Unlimited has this statement;

Use ferrules for all wiring connections, especially when connecting to a screw connector that does not have a cage. If a stranded cable is used without a ferrule the connector screw can pinch on only a few strands, and the turning motion of the screw can even twist and break the strands.

The photo on the right illustrates this. The strands of the top wire have been damaged, and only partial contact was made. The strands of the bottom cable were protected, and full contact was made.