Wire too big for Victron charge controller

[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.

[CharlieJ]

@MaineSail #13:

R.C.: Great recommendation on the electric torque wrench. Ordered!

[CharlieJ]

@team_karst #16:
Disagree. Why install an expensive PV system and then cheap out on the conductors?

Conductor voltage drop manifests itself as useless heat.

[GordMay]

Originally Posted by Maine Sail

Even with a ferrule 8AWG is not going into a 75/15..

this may help:


https://marinehowto.com/terminating-bare-wire-ends/

https://marinehowto.com/terminating-bare-wire-ends/

It certainly does help. Thanks (as always), RC.

See also: “Out, Out Brief Wiring Terminals!” ~ also by Rod Collins
➥ https://www.practical-sailor.com/mar...ring-terminals

[Statistical]

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.

Voltage drop is lost energy. You are paying to produce useful energy not heat the wires.

The OP can fix this any number of ways which involve going to a smaller cable for the connector:

butt splice
terminal block/stud with ring terminal
circuit breaker or switch supporting both 8 & 10 AWG
etc

Annoying Victron makes the openings a bit too small. This is only an issue on the smaller MPPT.

[team karst]

Every conductor moving current has loss. One can/should do the math to determine the diminishing returns on increasingly more valuable copper costs. You are already seeing install difficulties.
#8 moving 10 Amps is overkill. 15A is the max design value determined by the controller.

[Statistical]

Originally Posted by team karst

Every conductor moving current has loss. One can/should do the math to determine the diminishing returns on increasingly more valuable copper costs. You are already seeing install difficulties.
#8 moving 10 Amps is overkill. 15A is the max design value determined by the controller.

Making absolute statements is silly. Saying 8 AWG is overkill without specifying distance or voltage is just wrong. Resistance is per foot. 8 AWG may be the correct cable for a very long run especially at low voltage.

If the difference between 10 AWG and 8 AWG was 2% voltage drop vs 1.5% voltage drop then yeah 8 AWG was overkill. Without knowing the voltage and distance you don't know that was the case. It could be 10 AWG was >3% voltage drop and 8 AWG brought it under 3%.

Yes maybe the OP miscomputed and 8 AWG is overkill but blanket statements don't help. Regardless he has run the 8 AWG now. Even if it is "overkill" there is no reason to rip it out to put new smaller cable with higher losses in.

[GordMay]

Originally Posted by Statistical

Making absolute statements is silly. Saying 8 AWG is overkill without specifying distance or voltage is just wrong. Resistance is per foot. 8 AWG may be the correct cable for a very long run especially at low voltage...

Indeed.

At 10A, 12V, #8AWG Cu. wire will produce a 3% voltage drop, over a total (pos + neg) run of about 45 feet.
Under the same circumstances, #10 AWG is good for about 30 Ft total.

See ➥ https://getpocket.com/explore/item/h...=pocket-newtab
& ➥ https://www.cruisersforum.com/galler...r&imageuser=79
& ➥ https://www.cruisersforum.com/forums....html#post1256
& ➥ https://www.cruisersforum.com/galler...r&imageuser=79

[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]

[thinwater]

A bloody anchor thread ....


Also, the wire only carries 11 A in theory. In practice, with sun angle, shading, and partially charged batteries, it will spend 90% of its life at 5 amps or even less. You know it. Anything over 7-8 amps is not actually possible, depending on location and installation.

[CharlieJ]

@team_karst #24: You implication is absolutely correct. But the problem that we collectively were trying to solve was how to connect AWG 8 to conductor pockets in the MPPT that will only accommodate AWG 10.

The AWG 8 was an initial condition. The OP wasn't asking us to validate his overall design.

And, BTW, the step down butt you recommended is only a safe, viable option if the OP has a crimping tool that can crimp AWG 8 crimps.

[team karst]

Point taken.

Since we have sortof convinced ourselves that awg10 or even 14 would not suffer overload damage, one could trim enough strands away to fit. Not my first or even second choice tho.

[thomm225]

Here's mine with 14 gauge wire.

I used the 14 gauge because I had it left over from another job years before.

Two panels coming in.

Black wire is for the Victron Connect to my onboard and quite old Toshiba Satellite Laptop Computer.

Plus I can check it on my phone via Bluetooth.

[Wotname]

nash_sailing,

I owe you an apology for inadvertently posting incorrect information. I failed to remember the Victron 75 / 15 has a different sized terminal block to the 100 / 30 unit. The 100 /30 unit (which I had used routinely) accepts 8AWG wire while the 75 / 15 unit only accepts a max wire size of 10AWG. Not that it matters here but the 100 / 30 will accept 6AWG. I should have checked the Victron datashhets rather than relying on my memory

So what would have I done - using small sharp flush cutting side cutters to trim just enough strands from the 8AWG to allow it to fit into a 10AWG ferrule and square crimp it.

Originally Posted by nash_sailing

I know, I’m so annoyed - the wire sizing information was buried so deep in the manual!

Victron publishes all the critical information of their unit in easy to find data sheets. Not helpful to you now but maybe helpful for other readers e.g.

[Wotname]

Originally Posted by GordMay

In my view, a proper wire terminal has a compression clamping plate, that bears against the wire/conductor. The set screw bears against the clamping plate - not the wire.
When the equipment terminal has only a set screw, bearing directly on the wire, a Crimp Pin Terminal (bootlace ferrule), or better yet, a ring/captive spade crimp terminal must be used.
Otherwise, use of the pin terminal is not advantageous. It’s extra (unneeded) work/cost, and adds a small amount of circuit resistance (extra connection) to the circuit.
..........

In my experience, a ferrule (or captive spade terminal) is always advantageous even when using a 'proper' wire terminal i.e. one with a compression clamping plate.

I have yet to see such such (proper) terminal blocks being able to compress bare wires enough to create a gas tight joint. Only by using a good crimp terminal with dual wall heat shrink can a gas tight wire termination be approached. Even if in the unlikely event the actual clamped conductors compress enough to form a solid mass, the remaining conductors immediately adjacent will not. This allows corrosion to form in this section of the wire and then travel down inside the insulation.

Simply allowing bare wires in the clamp area will lead to increased long term corrosion. I am reminded of a saying that goes something like this - "If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"