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Battery DC circuit breaker

Pi Curio

Pi Curio

Sunlicious
Joined
Aug 10, 2022
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Just got this little gem in the mail.
1710776356699.jpg

The idea is to use it for the battery, and as far I understand it takes a non-polarized MCB for that.

I want to test it to see if it's indeed a non-polarized MCB.

Figured maybe I could use two 100W panels in parallel with a combined Isc of 12A and then attach both cables to the MCB, and use a piece of cable to short the other side before switching the MCB on. Then test if it catches fire in either direction.

Would this suffice for the test to verify it's non-polarized? Is 10A enough for the test?

Thanks
 
Are you saying you don't trust it? Why would you buy any piece of safety gear you don't trust to be whay the manufacturer says it is?
 
Q-Dog said:
Are you saying you don't trust it? Why would you buy any piece of safety gear you don't trust to be whay the manufacturer says it is?
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It's not that I do not trust the manufacturer, but since I'm now working on a 48V system and there's not much to be found about this DC MCB, I just want to make sure it's a good fit as the battery main switch.
 
The thing is, I'm building a small 48V 1kWh battery with 105C 10AWG PV cable, so I can't just use what has been tested and verified for the 48V 100Ah server rack batteries and the cable size that goes with it. The same goes for the main battery fuse.

That's why I need to empirically test and verify that everything will work as intended.

It would be much easier if the road was already paved on this scale, but I'm not exactly building the same thing as most people who have built a 48V system did.
 
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Speaking of Circuit Breakers, I find myself looking for a good reliable one also. Installed for 11 months with no issues on a EG4 3000. Used supplied breaker and wire. Wife running a couple of things in the kitchen and it overloaded reset and kept working. Came home to find the breaker welded on. #4 wire torqued down as hard as you can. I have greater respect for the 3K but none for the breaker. Starting to wonder if crimp lug and bolt is the only way to go. Thinking of going mega fuse holder. You need some big metal to dissipate some heat. Thin metal and plastic is a no-go for me.
 

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BarracudaBob said:
Speaking of Circuit Breakers, I find myself looking for a good reliable one also. Installed for 11 months with no issues on a EG4 3000. Used supplied breaker and wire. Wife running a couple of things in the kitchen and it overloaded reset and kept working. Came home to find the breaker welded on. #4 wire torqued down as hard as you can. I have greater respect for the 3K but none for the breaker. Starting to wonder if crimp lug and bolt is the only way to go. Thinking of going mega fuse holder. You need some big metal to dissipate some heat. Thin metal and plastic is a no-go for me.
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That looks scary! How much load draw are we're talking here?

Curious, did you use ferrules and inspect the terminals for loose connections within those 11 months? 4AWG is a lot of copper, fine strands?

In my build, the draw on a single battery will probably be around 30A max in the worst-case scenario. Though it's DC and 30A is not insignificant if there's a loose cable anywhere.

As far as the MCB goes, I sorta made a mistake with the one in the first post. Its intended operational range is between 100V-250Vdc. Ah well. Guess, I'll save it for a larger build down the road.

Had some talks on the topic with their support, and they've recommended their well known DZ47-63 series with a working range between 12-120Vdc. Also, just to leave no stone unturned I ordered one of their 2-pole 500V DZ47Z-125K series with a working range between 36-500Vdc.

I'll check both and see which one does better.

BarracudaBob said:
Was thinking of something like this for the battery to inverter breaker:
MNEPV 80A Din Rail Mount Breaker To 150VDC

Some #4 & #2 Ferules too
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That piece of copper on the terminals in the photo looks very interesting. I think I've seen it somewhere being used to bridge the MCB terminals in various installations. Just not sure how reliable is the connection long term.
 
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I just bought this one:
125A, 240V AC, 60V DC, 1 Pole, DIN Rail Mount Miniature Circuit Breaker, Trip Curve: C, UL1077 https://a.co/d/6fRHHJG

I have not received it yet so I can't speak to the quality.
EDIT: I just realized, thanks to some other posts here, this this one is not bidirectional. Another clue I should have noted, it that it has Line and Load labels.
 
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Pi Curio said:
That looks scary! How much load draw are we're talking here?

Curious, did you use ferrules and inspect the terminals for loose connections within those 11 months? 4AWG is a lot of copper, fine strands?

That piece of copper on the terminals in the photo looks very interesting. I think I've seen it somewhere being used to bridge the MCB terminals in various installations. Just not sure how reliable is the connection long term.
Click to expand...
The cable was 4-AWG thin strand tin plated. It was torqued down as much as you could without breaking the plastic. It was still tight when I removed it. The wire was oxidized and the insulation slightly melted near the breaker terminals. I cut the breaker open and besides for the heat at the in/out terminals everything looked good. My only conclusion is that it was resistive enough under full load it got hot. Kept working but with increased resistance (voltage drop). I've work on DC Plant battery systems and every connection on the commercial stuff is crimp on bolt on. There is always some copper mass to the terminals. Having thin terminals inside plastic will create heat and no way to dissipate it. The Solar Assistant was on a wall wart on the output... I know.. I changed that immediately and also added a power fault sensor to sound the alarm.

I use SA with a Victron SmartShunt and only showed a peek of 72A into the battery but this was with 5KW of PV input. The wife's story was she turn on a few appliances but looking at the SA data it was caused by CHARGING the battery off the PV! That would mean that the breaker would have been REVERSE POLARITY as the "+" was towards the batteries.

So how about a non-polarized (bidirectional) DC breaker? Under load & charging will reverse direction. In a separate Charge Controller / Inverter system you can use two breakers in the correct configurations. Using a single hybrid unit at one point it will be reverse polarity on a polarized breaker.

​

The plot thickens🤬
 

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BarracudaBob said:
Speaking of Circuit Breakers, I find myself looking for a good reliable one also. Installed for 11 months with no issues on a EG4 3000. Used supplied breaker and wire. Wife running a couple of things in the kitchen and it overloaded reset and kept working. Came home to find the breaker welded on. #4 wire torqued down as hard as you can. I have greater respect for the 3K but none for the breaker. Starting to wonder if crimp lug and bolt is the only way to go. Thinking of going mega fuse holder. You need some big metal to dissipate some heat. Thin metal and plastic is a no-go for me.
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Just use stellavolta (their site or amazon) and get a midnite breaker
not sure what your amp is, I see a "125"
midnight is like one of the best.. USA designed brands.. and heavily tested by USA engineers brand
www.stellavolta.com

MidNite Solar MNEPV125-80-1PNP Circuit Breaker 125A 80VDC

Shop now for MidNite Solar MNEPV125-80-1PNP Circuit Breaker 125A 80VDC.
www.stellavolta.com www.stellavolta.com
 
Ampster said:
I just bought this one:
125A, 240V AC, 60V DC, 1 Pole, DIN Rail Mount Miniature Circuit Breaker, Trip Curve: C, UL1077 https://a.co/d/6fRHHJG

I have not received it yet so I can't speak to the quality.
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Let me know how that turns out. Now I want to build a load bank and torture test everything! The fact that it will do AC and DC is interesting. I still see +/- for the DC on the breaker.
 
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I have several from stellavolta, generally I wouldn't buy midnite (cuz too expensive and me poor) but for breakers it makes sense and somehow stellavolta is like way cheaper than other vendors so it is really a no brainer at that point.
 
+1 on Midnite

If I were in the US, midnite dc breakers would be a no brainer. Wouldn't even bother looking for alternatives.

Shipping costs to Europe are crazy expensive, why its necessary to look for alternative products here.
 
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Pi Curio said:
+1 on Midnite

If I were in the US, midnite dc breakers would be a no brainer. Wouldn't even bother looking for alternatives.

Shipping costs to Europe are crazy expensive, why its necessary to look for alternative products here.
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That's sad they don't have any there.
I have some NanQue breakers, the ones I have weren't polarized at least but they aren't the same color as yours so totally different lol
few other forum members have them as well.. so far haven't seen anyone catch anything on fire with them at least, but no idea how "good" they are
 
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