Did I miscalculate wire size?

[TrekkerPlanet]

Hey everyone.

I was just testing my camper van's 12v system by generating a 650w load through the inverter (I was charging my EF wave 2). I noticed smell of "melting/burning plastic or rubber" so I went to check all my wires. All the wires were cool to the touch expect for the one that was going from the bus-bar to the BougeRV 1000w inverter. I noticed that the black insulation had peeled back on the red (+) wire going to the inverter. At the bus-bar I have a 125amp MRBF to the inverter using 2 awg cable.

Did I miscalculate the wire size for the inverter? am I using the wrong fuse at the inverter? any advice would be greatly appreciated.

Here's my configuration:
Battery to Battery 4 awg
Batteries to Bus-Bars 1 AWG
Solar panels to mppt to bus-bars 6 awg using breakers and fuses
All 12v things (water pump, lights, usb chargers, etc) have their own separate fuses and connections. All use 12 awg marine grade wire
Have 4-195 eco-worthy bifacial panels on the roof VOC 23.3v each at 10.5a
2 - LiTime 165ah batteries
LiTime 60a mppt

 

[yabert]

2 AWG should be good, but contact is probably bad.
Or you put a washer at the wrong place or some other error.

 

[MisterSandals]

this is a cheap audio breaker and represents a fire hazard. Is it inline/redundant with another breaker right above it?

 

[hybe022]

650w on 12v is ~54A which the 2awg should easily handle.

check for terminations. a crimp or a nut might be just a bit loose.

 

[outboard1196]

How are the crimps on the lugs?

 

[hybe022]

How are the crimps on the lugs?

give it a good tug, it shouldnt budge.

 

[TrekkerPlanet]

this is a cheap audio breaker and represents a fire hazard. Is it inline/redundant with another breaker right above it?

Yes it is, there is a breaker right above it. That break will disconnect everything coming from solar.

 

[TrekkerPlanet]

2 AWG should be good, but contact is probably bad.
Or you put a washer at the wrong place or some other error.

Fuse+lu

How are the crimps on the lugs?

650w on 12v is ~54A which the 2awg should easily handle.

check for terminations. a crimp or a nut might be just a bit loose.

that's what I thought. I went with a higher gauge wire than required on purpose to avoid resistance. I'l go back down to my van and double check the connections.

 

[TrekkerPlanet]

How are the crimps on the lugs?

I'm going to go check on the cabling as soon as I get a chance.

 

[outboard1196]

I'm going to go check on the cabling as soon as I get a chance.

Did you crimp them, if so what did you use?

 

[TM48]

Are you sure it's real copper wire?

 

[TrekkerPlanet]

2 AWG should be good, but contact is probably bad.
Or you put a washer at the wrong place or some other error.

At the bottom, fuse, wire lug, washer, lock washer, nut. Isn't that the order it should go in?

Come to think of it, the fuse itself was emitting heat.

 

[TrekkerPlanet]

Did you crimp them, if so what did you use?

Didn't crimp them, bought from amazon.

 

[TrekkerPlanet]

Are you sure it's real copper wire?

The description had 100% copper wire. The real way to find out would be for me to cut into the wire and see.

 

[Koyaanisqatsi]

Clean connections. Make sure your lugs and other contact surfaces are bright and shiny, and free of dirt and fingerprints. Clean mating surfaces with superfine scotchbrite and then wipe down with alcohol wipes. Then make sure you use a torque wrench to tighten everything.

 

[outboard1196]

Didn't crimp them, bought from amazon.

What brand or link to ad?

 

[740GLE]

At the bottom, fuse, wire lug, washer, lock washer, nut. Isn't that the order it should go in?

Come to think of it, the fuse itself was emitting heat.

What brand MRBF? Cheap ones are cheap you know.

Can you get a close up picture of the connections?

You could try and remove the MRBF from the bus bar and go direct lug and see there is heat generated.

 

[outboard1196]

What brand MRBF? Cheap ones are cheap you know.

Can you get a close up picture of the connections?

You could try and remove the MRBF from the bus bar and go direct lug and see there is heat generated.

Yeah, only use bussman / bluesea holder and fuses.
Don't trust any no name fuse.

 

[TrekkerPlanet]

What brand or link to ad?

 

[yabert]

At the bottom, fuse, wire lug, washer, lock washer, nut.

That good.
Seem like the lug crimp is probably your problem. If no, contact between fuse lug and busbar.

BTW, your pictures with all those arrows/marks are really handy to easily understand

 

[TrekkerPlanet]

What brand MRBF? Cheap ones are cheap you know.

Can you get a close up picture of the connections?

You could try and remove the MRBF from the bus bar and go direct lug and see there is heat generated.

I am going to bypass the MRBF and see if the same thing happens.

 

[TrekkerPlanet]

That good.
Seem like the lug crimp is probably your problem. If no, contact between fuse lug and busbar.

BTW, your pictures with all those arrows/marks are really handy to easily understand

They've always said, a picture is a 1000 words. A lot easier to visualize than to verbalize

 

[740GLE]

I am going to bypass the MRBF and see if the same thing happens.

Do the 200a MRBF of the battery get hot?

Also I see you have a 3 fuses for the batteries, be mindful they each have a voltage drop so that second battery that has two fuses in series is going to have a little lower voltage.

I imagine they are the same brand as the 125a.

 

[TrekkerPlanet]

Do the 200a MRBF of the battery get hot?

Also I see you have a 3 fuses for the batteries, be mindful they each have a voltage drop so that second battery that has two fuses in series is going to have a little lower voltage.

I imagine they are the same brand as the 125a.

The 80a between batteries was cold, the 200a outbound was also cold.

I touched all the cables to try to isolate the issue. All the cables to and from the bus bar were cold, it was 60 degrees here. The only one cable that was warm and mainly at the junction of where the MRBF 125a meets the cable to the inverter. I'm going to go check all the connections and swap out the 125 and retest.

 

[42OhmsPA]

At the bottom, fuse, wire lug, washer, lock washer, nut. Isn't that the order it should go in?

That's correct.

Come to think of it, the fuse itself was emitting heat.

Is the fuse base also in direct contact with the buss bar with the washers and nut on top?