Wire too big for Victron charge controller

[wkyongae]

Trim wire to desired size. Heat shrink exposed clipped wires and install. Using a reducer could create a failure point if not connected properly.

[Statistical]

Originally Posted by wkyongae

Trim wire to desired size. Heat shrink exposed clipped wires and install. Using a reducer could create a failure point if not connected properly.

So connect it properly. A boat of any decent size has hundreds of connectors the idea that one more is a problem or can't be done wrong strikes me as silly.

Trimming wires may lead to problems down the road in a decade when the OP or whomever he sold the boat to decides to put more panels in parallel is anyone going to remember/know this one wire is trimmed?

That being said it is a relatively minor corner cutting. I am not going to shame the OP if that is the route he goes. God knows most boats have far worse corner cutting. Still pretending the corner cutting is the prefered route is dubious. If one does it they should do it with the mind set that is corner cutting but "good enough" not that it is the prefered action to take.

On a related victron oversizes the connector upper limit on other controllers. 35A & 45A controllers use 6 AWG and larger ones use 2 AWG which is very much oversized but it gives the user that option. It is only the <20A controller with 10 AWG limit.

[CaptainRivet]

Just add a double pole breaker shortly before the MPPT, input your 8 gauge wire and output 12 gauge that fits into your MPPT.
Like this the breaker acts also as interruption switch for maintenance and as cable adapter.

[wkyongae]

Captain has it correctly wired as there should be a breaker right at the charge controller anyway.

[CaptainRivet]

Originally Posted by wkyongae

Captain has it correctly wired as there should be a breaker right at the charge controller anyway.

Exactly, use a 20A breaker which is the correct spec for the 12 gauge wire, then you don't have to add another fuse. The MPPT can do max 15A, so thats fits perfect.
With small panels like that = low voltage and long cable runs its better to put them in series so you have higher voltage and less current on the cable. On a boat i normally advise only parallel the panels due to shading but thats the exception.

[wkyongae]

That low of amp could get by with an AC breaker but myself would prefer a DC breaker just so it's done right.

[Renegde_Sailor]

What matters here is not the gauge of the wire going to the battery, only so much power can come from the controller period.

What I would do is put a pair of bussbars near the controller, one for + one for - and then run your battery cables to them, then run the #10's from the controller to the bussbars.

With #8 you are not going to be able to pull much of a load on your I am assuming 25' one way run. On my boat from the main buss to the batteries is is about 29' so almost a 60' round trip.

My system experiences less than 3% voltage drop running my 3000W inverter at full tilt.

You can also run your alternator and any other charging source to these bussbars.

Over a 50' run as long as the majority of the cable is the #8 that will help.

I have a similar situation on my boat, where my house bank is under my V-berth, but the chargers and controllers are under the cockpit or on the cockpit/cabin bulkhead.



I have two pairs of 2/0 that run from the battery bank to the main buss. Then I bring all my charging sources there to that buss, alternator, solar, inverter/charger it all comes to that buss.



If you are feeding the

[Statistical]

Originally Posted by Renegde_Sailor

What matters here is not the gauge of the wire going to the battery, only so much power can come from the controller period.

The issue in question is on the PV side of the controller.

[s/v Jedi]

Originally Posted by Statistical

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.

I am afraid crimped ferrules do not compress strands into a solid block like crimped lugs do. You only bundle them. This is why I recommend to stick the strands into dielectric grease before crimping.

[Wotname]

Originally Posted by wkyongae

Captain has it correctly wired as there should be a breaker right at the charge controller anyway.

Err...
There is zero need for a breaker at the charge controller; either for the PV side or the battery side .

There should be circuit protection close to the battery and some like to put a switch/breaker near the PV.

[Statistical]

Originally Posted by Wotname

Err...
There is zero need for a breaker at the charge controller; either for the PV side or the battery side .

There should be circuit protection close to the battery and some like to put a switch/breaker near the PV.

Outside of boats PV arrays usually have a PV disconnect in fact in most locations it is mandatory. They are pretty uncommon on boats but then again so were GFCI until recently.

"Zero need" is not correct.

Also circuit protection close to the battery for a charge is next to useless. It means all the wiring from the charger to the battery is unprotected. Power sources should have a fuse/breaker as close to the power SOURCE as possible. In this case the charge controller output.

[Wotname]

Originally Posted by Statistical

....
"Zero need" is not correct.

Also circuit protection close to the battery for a charge is next to useless. It means all the wiring from the charger to the battery is unprotected. Power sources should have a fuse/breaker as close to the power SOURCE as possible. In this case the charge controller output.

I completely disagree. In this case, both the battery and the CC are power sources but the CC is current limited, the battery is not.

The battery is almost unlimited uncontrolled current source. A fuse needs to be placed close to the battery.

The Victron charge controller is a current limited source. Its internal circuit design prevents it from supplying more current than the rated current for the model in question. The wire size is selected to safely carry the max output current thus there is no need to fuse at the CC end.

[Nicholson58]

Originally Posted by Knotical

Feel your pain, this is probably the only situation where oversizing wire gauge is not a good idea.

I have (non-expert) 2 ideas:
1. Crimp and heatshrink a 10 AWG wire to it
2. Use a terminal trip between the 8 & 10

Proper wire size is the way to go. The best you can do is solder the mass of copper and then reduce to fit the terminals. The extra losses in the last half inch
are small.

[Statistical]

Originally Posted by Nicholson58

Proper wire size is the way to go. The best you can do is solder the mass of copper and then reduce to fit the terminals. The extra losses in the last half inch
are small.

God not solder. Just no. There are a half dozen ways to resolve this of various degrees of good. None involve solder.

[noelex 77]

Contrary to popular belief there is sometimes the need to provide circuit protection between the solar controllers and the solar panels in addition to the always mandatory protection between the controller and the batteries.

The basic general rule (with some exceptions) is that three solar panels or above in a string need circuit protection. The reason is to provide protection for the wire within the solar panels. These wires are kept small to minimise the shading of solar cells, but in the event of of fault condition these wires can overheat which is not ideal especially when installed on top of flammable canvas or even fibreglass structures.