Wire too big for Victron charge controller

[Moo]

Originally Posted by team karst

step down butt: https://www.amazon.com/Pico-2295PT-E.../dp/B004BTDROW

AWG8 is way overkill for this project, btw. THese 3% Voltage drop rules should not be applied to solar panels as it is to end use power feeds.

Correct. You want to drop it even lower than 3%

[Moo]

Originally Posted by team karst

Where is 12vcoming from?
Panels not usually near 12v

I am trying to lead this conversation with leading questions.

Isc and Voc are my next questions. All in an effort to actually provide math driven engineering help.

Plus, the original termination fix has been listed. This follow on work is an effort to help solar installs in the future.

Another btw; my last solar work was in a 75MW field. Capital M! [emoji847]

You obviously didn't design it ! Tea boy?

[Wotname]

Originally Posted by 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.

Thanks CharlieJ, I initially missed the ferrule info in my reading of 'Wiring Unlimited' so I went and had a better look. My version (Rev 06 undated) lacked the photo mentioned however the current on-line version (Rev 01 - 3/2023) does have the photo and more importantly, highly recommends the use of ferrules as well as explaining the torque requirements is to protect the tinned brass screws, not to 'squash' the bare wires sufficiently. From page 27 of https://www.victronenergy.com/upload...ted-pdf-en.pdf

The screws inside electrical connectors are usually made out of tinned brass. When tightening always use the correct torque. Over-tightening might break the screw. See the product manual for the correct torque.
Also, never use rigid cable starts or solder the cable strands together, this will create poor contact inside the screw connector, the wire might come loose, or this creates too much contact resistance. Too much resistance will cause the connector to heat up.
It is highly recommended to use ferrules (also see next section). Ferrules will align the cable strands and keep them together. This will create the optimal contact inside the screw connector.

This should put to bed the above posts suggesting Victron does not support the use of ferrules.

Screenshot -

[Wotname]

I highly recommend the Victron 'Wiring Unlimited' document. It has excellent information for anyone doing their own wiring and perhaps more importantly, it allows the inexperienced to spot poor wiring practices made by shoddy professionals. Far too many 'marine electricians' aren't worth the salt your boat floats in.

Along with Ron Collins (Marine Sail) site mentioned upthread, one can confirm if professional work is truly up to scratch.

From the introduction

Welcome to "Wiring unlimited", a book about electrical wiring systems containing batteries, inverters, chargers and inverter/ chargers.
With this book, we aim to explain the wiring basics of electrical systems. We will explain the importance of "getting it
right" and cover the issues that might result if a system has bad wiring. It also assists electrical installers or users in troubleshooting issues that have arisen from bad wiring so that a correct conclusion can be drawn for the electrical systems they are involved with.
Wiring issues are often a cause of system problems, or they can lead to the underperformance of systems.

https://www.victronenergy.com/upload...ted-pdf-en.pdf

[s/v Jedi]

The Victron Wiring Unlimited booklet is very good. If cruisers would have the knowledge from it and fix their boat electrical systems accordingly, there wouldn’t be much left that can go wrong.

Big items are that it explains the basic laws of electricity. It even shows why you don’t always need a class-T fuse for a LFP battery bank; something that many on CF don’t understand.

It shows why I always promote DC disconnect switches on each inverter/charger, as well as the bypass breaker featuring my diagrams. It even shows the AC isolated “IT” network although for isolation transformers it is limited to just their galvanic protection function, skipping the safety features and possible use for a shore connected IT network.

Highly recommend Wiring Unlimited
(but genuine Anderson connectors have silver plated contacts, not tinned

[Goodxcharly]

A pin terminal sounds like a good idea.

I wouldn’t over think it. Solar panels are rarely working at max out put which your wire is sized for.

My solar install recommended 8/2 wire and I chose 10/2 because I’m a cheapskate which saved me from what you’re going through now and it probably doesn’t make any difference anyway.

Enjoy! the luxuries of solar for a better off grid experience!

[ErnestV]

Trim the wire. The charge controller will not overwhelm the inch, and for the rest of the run you have your full size which is not needed for load but to reduce voltage drop. Nothing sketchy IMHO.

[MVDarlin]

I have wondered about this myself. I have 4 Victron controllers, 3 100x30 and one 75x15. Seems peeling back and trimming a few strands would have the same result as connecting a smaller guage wire, and far less effort.

[skenn_ie]

As it is oversized because of the length/run rather than current capacity, I would work the insulation back a bit, cut off enough strands to get then into the connector, then slide the insulation forward again to cover the ends of the cut strands.

[Statistical]

Originally Posted by MVDarlin

I have wondered about this myself. I have 4 Victron controllers, 3 100x30 and one 75x15. Seems peeling back and trimming a few strands would have the same result as connecting a smaller guage wire, and far less effort.

I know I am in the minority here but I am not a big fan of cutting down wire.

1) It isn't obvious it is done and maybe in the future the wire will be reused for higher current loads.

2) The conductivity between individual strands isn't that great. They are loosely laid in the cable. The assumption is that the entire cable will either be compressed in a lug/ferrule (ideal) or compressed using the screw terminal. When you cut back the cable that isn't the case.

Pin ferule is the right tool here. The second best option would be to install a termination post and transition from 8 AWG to 10 AWG. Some will say this adds resistance but properly crimped connectors should be less than 0.1 mOhm (measuring from wire prior to and after connection). In fact in most cases it will be a lot less than 0.1 mOhm but even being conservative and saying 0.1 mOhm that is the equivalent of about 2" of extra

If one wants to do double duty well it is a good idea to have a PV disconnect switch and/or breaker. Not that common on boats but a good idea. Those tend to have screw terminals supporting a range of cable sizes so an alternate option would be 8 AWG into disconnect and then 10 AWG to the controller.

That being said trimming the cable isn't terrible in this application there are a lot worst things being done on the average boat but I wouldn't do it unless there was no other option and there are other options.

[S/V Serenity]

We had same issue. Easily solved by crimping the wire in a ferrule which, we are finding out, should be done with all wires not terminated in a connector. Actually required in Europe. At any rate ferrule selection and tool fairly inexpensive (like $20 Amazon) and we are sold on them for all loose wires. Check out videos on YouTube.

[skenn_ie]

Pin ferrule or solder joint, while initially not a resistance issue IS an extra opportunity for corrosion and stress fatigue Either way, if you make a particularly structured installation, will require shortening the main wire a little. If you keep a loop, then a wire with "pruned" ends will only require shortening slightly (1/4") to regain full capacity. With high-current connections, I usually crimp gently (with a ratchet crimper), then solder. Tight crimping will prevent the solder from flowing into the wire.
I may have said before, NEVER tin/solder a strand bundle before screw-clamping. The solder will cold-flow and leave a loose connection. Also, never use stainless to carry current, it is OK for clamping against steel, copper, or aluminium.

[Statistical]

Originally Posted by skenn_ie

Pin ferrule or solder joint, while initially not a resistance issue IS an extra opportunity for corrosion and stress fatigue Either way, if you make a particularly structured installation, will require shortening the main wire a little. If you keep a loop, then a wire with "pruned" ends will only require shortening slightly (1/4") to regain full capacity. With high-current connections, I usually crimp gently (with a ratchet crimper), then solder. Tight crimping will prevent the solder from flowing into the wire.
I may have said before, NEVER tin/solder a strand bundle before screw-clamping. The solder will cold-flow and leave a loose connection. Also, never use stainless to carry current, it is OK for clamping against steel, copper, or aluminium.

Solder I agree would be bad in fact solder is pretty universally bad everywhere on a boat. I make an exception for VHF connectors simply because the alternatives are worse.

Ferrules however reduce corrosion because they reduce surface area compressing the wire strands into a solid block via cold welding.

The key is tin plated wiring, tin plated connectors, and good tools for a solid crimp.

[FlyingScot]

The easy answer is to replace with 100/30. Problem solved.

I agree with proper use of tools, wire, ferrules, etc.

For anyone advocating cutting the strands, ABYC says:

11.15.3.1 Wiring conductors shall be designed and installed to make mechanical and electrical joints without damage to the conductors.

That seems pretty clear to me!

Chris

[Chotu]

Originally Posted by FlyingScot

The easy answer is to replace with 100/30. Problem solved.

I agree with proper use of tools, wire, ferrules, etc.

For anyone advocating cutting the strands, ABYC says:

11.15.3.1 Wiring conductors shall be designed and installed to make mechanical and electrical joints without damage to the conductors.

That seems pretty clear to me!

Chris

I don’t know. Sometimes you can follow the rules right into a brick wall.

Thinking is pretty important as well.

For instance, the termination point on the equipment is obviously designed to take a certain size wire and cannot carry a larger wire’s current just because you can find ways to attach one.

So there is no harm in cutting strands to fit. It’s only capable of carrying the current from the number of strands that fit in there anyway.