Dc mini breaker confusion

12VoltInstalls said:

Depends on the brand.

I personally proved the cheapies leak water and corrode inside with multiple replacements.

One cheapie brand that worked for me (over a year later and no failures) was Bouge RV. I bought a gazillion pairs and changed every one. Because I also proved mixing ‘brands’ also leak and the cheap brands have even been ferrous (magnet proves it).

Use a proper ‘B’ crimper and you’ll be fine.

That really surprised me!

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I’m using bougerv lol that’s funny

Hedges said:

Maybe dielectric grease between boot and insulation, and mating surface of boots, is the thing to do.

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I figured out the water ingress problem I had was the rubber compression sleeves do not necessarily pass their claimed IP67
I resorted to squirting lexel into the cable-end of the MC4s and than screwing down the collet/nut which produced squeeze out. No problems with the Bouge after sealing them; their o-ring side works fine.

Hedges said:

But certainly don't want ferrous contacts, and drop in production must mean severe heating of connectors (or else some strings completely open).

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Ya, Bouge was less money than the plated steel MC4s but they neither leak nor attract pesky magnets

Today i learned: Lexel.

Never heard of it. Ordered a 5oz tube to play with.

Vigo said:

Today i learned: Lexel.

Never heard of it. Ordered a 5oz tube to play with.

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Better than silicone which is corrosive but not as long-lasting as polyurethane caulking in UV exposure

Corrosive is optional.


I thought issue was MC connector, which could have grease or silicone between boot and wire to seal (no UV exposure), but "collet/nut" sounded like junction box. Oh, MC4 connectors have a nut? The MC3 I installed were just slip-on.

Hedges said:

Corrosive is optional

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That’s probably not at the local hardware store LOL

I’m wondering- since it is also labeled, “adhesive”- if it stays stuck nicely. I may buy some for fun.

The typical hardware store and builder’s ‘silicone’ is incredibly undependable in my experience. Caulking that survives 20 years of Vermont weather or works well below the waterline on boats is sorta my criteria.

Hardware store silicone has failed to perform for me too often; I don’t think I’ve bought any in 20 years or more other than as bedding for glass or hard plastic (not for waterproofing anything). Lexel is a quick-fix that works well, sticks to wet surfaces, and sticks really well. Polyurethane caulking might as well be considered ‘permanent.’

12VoltInstalls said:

That’s probably not at the local hardware store LOL

I’m wondering- since it is also labeled, “adhesive”- if it stays stuck nicely. I may buy some for fun.

The typical hardware store and builder’s ‘silicone’ is incredibly undependable in my experience. Caulking that survives 20 years of Vermont weather or works well below the waterline on boats is sorta my criteria.

Hardware store silicone has failed to perform for me too often; I don’t think I’ve bought any in 20 years or more other than as bedding for glass or hard plastic (not for waterproofing anything). Lexel is a quick-fix that works well, sticks to wet surfaces, and sticks really well. Polyurethane caulking might as well be considered ‘permanent.’

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I use lexel for glueing down retaining wall blocks. That stuff is great.

Mannfamilywoodworks said:

I use lexel for glueing down retaining wall blocks. That stuff is great.

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US product. It looks like a silane , I use Tec7

Caulking that survives 20 years of Vermont weather or works well below the waterline on boats is sorta my criteria.

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I tried some 3M 5200 adhesive sealant one time (never worked on boats or been to Vermont) and it was tenacious and impressive. Also so sticky and messy it was a real double-edged sword to use.

But.. get this. I drilled a hole into a carburetor body to get to an internal check ball that was stuck and i couldn't get the pressed in plug over it out non-destructively, so i drilled into the housing from the other direction, got the ball free, and plugged that hole with the 5200. That hole sees fuel 100% of the time.. and it's been holding up for years.

Vigo said:

I tried some 3M 5200 adhesive sealant one time (never worked on boats or been to Vermont) and it was tenacious and impressive. Also so sticky and messy it was a real double-edged sword to use.

But.. get this. I drilled a hole into a carburetor body to get to an internal check ball that was stuck and i couldn't get the pressed in plug over it out non-destructively, so i drilled into the housing from the other direction, got the ball free, and plugged that hole with the 5200. That hole sees fuel 100% of the time.. and it's been holding up for years.

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Woah lol that is impressive. I know 3m makes decent products but this blew my mind.

.

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775 said:

Can you use that stuff instead of mortar when making concrete block walls?

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Yeah just spit on it first to make it extra sticky

.

775 said:

More like extra stinky

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Hahahahahaha

Hedges said:

I did install some MC3 on ends of PV panel wires that had been cut. It would help to have correct size contact for the wire gauge, and correct size boot for the insulation. I used wire lube but it was still tough. Someone told me soften them in hot water, will try that next time.

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If you can still find a MC-3 crimper kit, there is a special expander for inserting the contact into the boot. Chances are, if you do find one it'll be too expensive to be worth it. Simply cut off any MC-3 connectors and crimp on MC-4's instead.

I was installing the panels to replace bad ones in an existing array. Sure, could make a transition and continue in MC4. But I've got over 100 panels (of two brands) with MC3 in a number of arrays. MC4 for another brand.
I like MC3 better, seems higher quality than rolled sheetmetal contacts.

I haven't found the boot stretcher for sale, but found a forum talking about it and a link to one in use:



I find many strip & crimp kits but no boot expanders. Didn't know they existed. Thanks for the tip!

Another BougeRV pigtails user - buy a PV extension cable and cut it in half. My cheapo solar panels came with regular hookup wire and SAE connectors, which got replaced with proper MC4 connectors.
Their stuff is pretty good for china imports, they appear to do a lot of product testing to ensure reliability. I got one of their 12V coolers and it's just fantastic - keeps the beer at 35* and sips power.

On 5200 - I bought a boat some years back that had a kicker motor bracket mounted from the factory, and didn't want it cuz I don't utilize a kicker motor, I don't troll my sport fisher. The dealer agreed to remove it and take the $650 cost of the bracket off the price of the boat before delivery. Since it was an 800 mile trip to deliver it, and I was to meet them halfway, they brought it with the bracket still mounted - they couldn't get it off. It was thru-bolted through the transom and sealed on with 5200. I said no problem, I'll remove it and send it back to them. They said no, no need, we'll just take the price off the final invoice.

Once I got the boat home since I really didn't want that thing on there, and I've been working on boats my entire life, I tackled the removal in my shop. Oh dear, the only way to get 5200 to let go is to cut it. I tried everything in my arsenal of tools to get it off and finally did. But it took a sheet of gelcoat with it. On a brand new boat. I was mortified! So there I was with quite a substantial defect on the transom of a brand new outboard boat.

I ordered gelcoat patch compound from Spectrum - they match colors perfectly - and sprayable gelcoat, and properly repaired it. You can't tell, and the blind nuts are still there so conceivably the next owner that DOES want a kicker bracket could dig out the mounting holes and bolt another one on there. But oh my, that was a lesson in the tenacity of 3M adhesive-sealant. And that stuff takes days to cure - once it does it's not going anywhere.

Hedges said:

I was installing the panels to replace bad ones in an existing array. Sure, could make a transition and continue in MC4. But I've got over 100 panels (of two brands) with MC3 in a number of arrays. MC4 for another brand.
I like MC3 better, seems higher quality than rolled sheetmetal contacts.

I haven't found the boot stretcher for sale, but found a forum talking about it and a link to one in use:

https://forums.whirlpool.net.au/archive/1968400

I find many strip & crimp kits but no boot expanders. Didn't know they existed. Thanks for the tip!

Solar Panel MC3 & MC4 Crimping Tool Kits

Discontinued - Superseded by SPK-100 The Jonard Tools SPK-90 Solar Panel Crimping Tool Kit is designed to facilitate the installation and maintenance of solar panels. It includes a variety tools to make installing and maintaining solar panels quick and easy. This crimping tool kit includes the...

jonard.com

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Here it is

Would these Amphenol connectors work for you? The contacts are solid and superior to MC-4 types. Of course you need the correct die for crimping.

Amphenol H4

Browneye said:

that was a lesson in the tenacity of 3M adhesive-sealant.

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That’s a great product for sure. Cyanuratic and superior to regular urethane caulking.

But I use construction-grade polyurethane caulking 98% of the time because I can use it liberally and still afford it. ?

I find many strip & crimp kits but no boot expanders. Didn't know they existed. Thanks for the tip!

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I've never seen or done an Mc3 but i frequently have to 'temporarily stretch' things for install in my little projects. One thing i bought recently is a 'tubing swager' as seen below:

Although the reason i actually bought one was as a way to 'stretch' or oval out chain links in my shop press whenever i want to stick a pin or bolt through a chain and it doesn't fit, i push this thing into the chain link to oval it out so i can run the bolt through. But it might work for your use.

Hedges said:

"Reverse polarity protection"

If you hook 200V reverse polarity to inverter, it drives electrolytic capacitors backwards and they blow up. Maybe other things too.
A blocking diode could have held off the voltage, but would have voltage drop in normal operation, causing power loss.
A backwards diode across +/- shorts them out to about 1V or so under reverse polarity. That prevents damage.
This is one reason why there is a maximum Isc spec on MPPT inputs.

In the past, some brands of inverters didn't have the diode, and suffered near 50% failure during install.

This works well for PV, limited current. Not good for battery or AC powered DC supplies. Those may used back-to-back FETs. More expensive and limited voltage range. Typically also used to implement inrush limiting.

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So, when are blocking diodes called for in a solar build?

I'm not sure blocking diodes are ever needed.
Only if there would be excessive backfeed, which multiple parallel PV strings usually would not do.
In the case of a short circuit, fuse/breaker is supposed to protect (but polarized breakers might fail to do so). Diode, if it didn't fail, would prevent backfeed. I wouldn't consider a diode reliable enough for fire protection.

You can get "ideal diode" which is a MOSFET with drive circuit to avoid the 1 ~ 2V drop through a power diode.