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Circuit breaker fail.

H

hugemoth

Solar Enthusiast
Joined
Nov 8, 2023
Messages
132
Location
Bend, Oregon
I shut off this breaker to do some work to the system and it wouldn't complete the circuit when turned back on. The breaker was on the positive cable for a 1000 Watt inverter. No smoke or heat detected and the breaker has never clicked off on its own. I put a fuse in its place for the time being.
Screenshot_20240413-005839.jpg
 
If you absolutely have to have something 12v and cheap. Used these on lead acid battery banks, although, I'm not sure I'd trust them with a large LiFePo4.


1713006176014.png
 
I drilled out the rivits and opened it up. It's basically a bimetallic plate and contact points like an old car. The contacts are not pitted and there is no sign of overheating. My best guess is the little plastic lever inside that opens the contact points was twisted out of place and partially broken which wouldn't allow it to move enough to release the contacts, although I may have damaged it during disassembly.
 
Kornbread said:
If you absolutely have to have something 12v and cheap. Used these on lead acid battery banks, although, I'm not sure I'd trust them with a large LiFePo4.


View attachment 209100
Click to expand...
Someone here did a test of them while connected to a bunch of Victron LFP batteries, it did end up ejecting a bunch of sparks and molten metal from the fuse so definitely not good for a gas boat. But still better than a cheap piece of crap that doesn't do anything or catches on fire just sitting there working.
 
Oh yeah!

Exactly the type of breaker the rest of the internet says DO NOT USE

They work well as isolators though, I have a bunch of them. Just don't use them as breakers per se :)
 
hugemoth said:
I drilled out the rivits and opened it up. It's basically a bimetallic plate and contact points like an old car. The contacts are not pitted and there is no sign of overheating. My best guess is the little plastic lever inside that opens the contact points was twisted out of place and partially broken which wouldn't allow it to move enough to release the contacts, although I may have damaged it during disassembly.
Click to expand...
So it opened when you pressed the button, but wouldn't close again, and probably a purely mechanical problem? I guess that's a better failure mode than not tripping on overcurrent or not opening when you press the button.
 
Yes the failure would not have prevented the circuit breaker from opening in an over current situation, it just prevented it from closing the circuit once I manually opened it.
 
Brucey said:
Someone here did a test of them while connected to a bunch of Victron LFP batteries, it did end up ejecting a bunch of sparks and molten metal from the fuse so definitely not good for a gas boat. But still better than a cheap piece of crap that doesn't do anything or catches on fire just sitting there working.
Click to expand...
Dang. That's not good. So far nothing like that has occurred with pop's system, and we've popped a few of those mrbf fuses. Looking at the fuses, it was hard to even tell they were done.
 
Before pooping on the MRBF read the thread. The current used was a massive hit far in excess of what you would expect in a normal install. And it did interupt the current and extinguish the arc. There was a large flash and the plastic shattered from it. Interesting thread.

If a spark is a concern use a class T.
 
Brucey said:
It's very unlikely your pops system had anywhere near the amps involved in that test.
Click to expand...
Yeah, that's what I'm thinking. Ok, for a cheap alternative better than many other options for a small 12v lead-acid system, but IMO, it's a hard no with a larg'ish LiFePo4 bank. FWIW, all the fuses in the home system are class-T. For the first time ever, I'll be adding a dc mccb to the 48v inputs of the new nhx inverters. The breakers are more for on/off convenience than anything as those circuits are also covered by class-T fuses.
 
hugemoth said:
I shut off this breaker to do some work to the system and it wouldn't complete the circuit when turned back on. The breaker was on the positive cable for a 1000 Watt inverter. No smoke or heat detected and the breaker has never clicked off on its own. I put a fuse in its place for the time being.
View attachment 209095
Click to expand...
Knock off..knock off…knock off.. get the real deal …
 
Kornbread said:
Yeah, that's what I'm thinking. Ok, for a cheap alternative better than many other options for a small 12v lead-acid system, but IMO, it's a hard no with a larg'ish LiFePo4 bank. FWIW, all the fuses in the home system are class-T. For the first time ever, I'll be adding a dc mccb to the 48v inputs of the new nhx inverters. The breakers are more for on/off convenience than anything as those circuits are also covered by class-T fuses.
Click to expand...
Not sure what sizing you are going for but the 250A midnite breakers are on sale at altE store for $47+shipping, if you get two or more shipping isn't too bad:

diysolarforum.com

Midnite 250A 125V DC panel mount breakers for $47 at altE

I hesitate to share this one as I'm sure all 43 remaining units will be snapped up fairly quickly. Normally retail for around $90-100, altE was already the cheapest prior to this mega drop. I ordered what I could afford wish I could get them all lol. Rated for 50,000 AIC at 125V. Seems cheaper...
diysolarforum.com diysolarforum.com
 
Brucey said:
Not sure what sizing you are going for but the 250A midnite breakers are on sale at altE store for $47+shipping, if you get two or more shipping isn't too bad:

diysolarforum.com

Midnite 250A 125V DC panel mount breakers for $47 at altE

I hesitate to share this one as I'm sure all 43 remaining units will be snapped up fairly quickly. Normally retail for around $90-100, altE was already the cheapest prior to this mega drop. I ordered what I could afford wish I could get them all lol. Rated for 50,000 AIC at 125V. Seems cheaper...
diysolarforum.com diysolarforum.com
Click to expand...
Now you tell me, :fp2 and I already have some enclosures that would work to front mount those breakers.
 
Kornbread said:
Now you tell me, :fp2 and I already have some enclosures that would work to front mount those breakers.
Click to expand...
What enclosures are those? Ideally I could buy midnite DC disconnect boxes without the breakers for cheap but very rare to find them like that.
 
hugemoth said:
That one looks identical to the one that failed. It would be interesting to have a look inside to see if there is any difference in construction. A steel pivot for the plastic lever (rather than plastic) would likely prevent a similar failure.
Click to expand...
The Chinese can clone the external appearance of something perfectly. Internals and actual functionality can differ wildly.
 
hugemoth said:
That one looks identical to the one that failed. It would be interesting to have a look inside to see if there is any difference in construction. A steel pivot for the plastic lever (rather than plastic) would likely prevent a similar
Click to expand...

hugemoth said:
That one looks identical to the one that failed. It would be interesting to have a look inside to see if there is any difference in construction. A steel pivot for the plastic lever (rather than plastic) would likely prevent a similar failure.
Click to expand...
The one i posted is not a chinese knock off. They can also supply this one. I have no affiliation with any supplier. This breaker is designed to be used as a switch as well as a breaker. https://powerwerx.com/eaton-187f-waterproof-circuit-breaker-surface-mount
 
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