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Brown spots on battery breaker


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I just noticed Brown spots on my one battery breakers front and under on the one pole. Any ideas what is this? Should i still use it? replace? It have never switched yet

 

 

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Yeah, hot connection.

 

Pull the wire and cut off the damaged end, re-connect.

 

Hopefully it's not damaged the breaker itself.

 

Check your other connections are tight!

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Thanks for the reply. I use 2 connector in same hole. one from inverter and 1 for parallel. Here is a photo from underside where the 2 connectors connected.

 

 

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That's definitely gotten rather warm!! Clean-up and reconnect, keep an eye on it.

 

You may want to reconsider using two wires in one hole on a high-current connection.

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Posted (edited)
3 minutes ago, Crossy said:

That's definitely gotten rather warm!! Clean-up and reconnect, keep an eye on it.

 

You may want to reconsider using two wires in one hole on a high-current connection.

Yes look so. Maybe i should dessable the wires for parallel for now. And then look for other way to parallel?

 

 

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Edited by Pink7
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Currently my parallel connection is after on/off breaker and before inverter. Is there any problem to parallel the batteries before breaker on battery side?

 

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Looks like you are using some kind of lug on the wires, maybe DZ47/C45 lugs like this:

image.jpeg.0a74138fba7029534dae291b32d12944.jpeg

 

the switch however is intended for bare wire which you can see from its rounded bottom.

I use DIN-rail enclosures for all my other switches but the battery DC switch I used is this one:

 

 

 

 

image.jpeg.808ca43b43637baacf60b2d34c18f01b.jpeg

 

it has proper M8 hex bolts and not weak Philips type screws..

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18 minutes ago, lom said:

Looks like you are using some kind of lug on the wires, maybe DZ47/C45 lugs like this:

image.jpeg.0a74138fba7029534dae291b32d12944.jpeg

 

the switch however is intended for bare wire which you can see from its rounded bottom.

I use DIN-rail enclosures for all my other switches but the battery DC switch I used is this one:

 

 

 

 

image.jpeg.808ca43b43637baacf60b2d34c18f01b.jpeg

 

it has proper M8 hex bolts and not weak Philips type screws..

Looks good. I use a heavy duty type lug for high current. see photo

bbb4.jpg

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I can confirm the coloring is just outside and im able to sand off a good part of it.

 

I have just removed my parallel connection between the breakers and will find another way for doing this. I guess i can still use the the setup temporary without parallel batteries?

 

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5 minutes ago, Pink7 said:

Looks good. I use a heavy duty type lug for high current. see photo

bbb4.jpg

 

I don't think I would have done it like that!!

 

What size is your wire? It's friend?

 

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8 minutes ago, Crossy said:

 

I don't think I would have done it like that!!

 

What size is your wire? It's friend?

 

Lug and wire look as when it was new. Wire is 35mm2 but expand when remove the protection around and not easy to handle at all.

 

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2 minutes ago, Crossy said:

For high-current parallel connections I'd use a bus-bar with one lug per bolt.

 

Something like this.

https://www.lazada.co.th/products/i4750566069-s19589324451.html

 

image.png.9bcfa734d241dd3a5f0548b858821007.png

Yes that could be the route to go now. Connected between breaker and inverter. Do you see any problem to run the setup some days without parallel connection between the batteries?

 

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4 minutes ago, Pink7 said:

Do you see any problem to run the setup some days without parallel connection between the batteries?

 

Your only issue could be when you re-connect the parallel if the packs are different states of charge, significant currents could flow as one pack charges the other.

 

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IMPORTANT NOTE: - Please don't lose sight of the fact that there is a LOT of energy tied up in your battery packs.

 

These packs are quite capable of pushing several thousand amps if shorted, that 1/2" drive ratchet stands no chance.

 

A litre of petrol/gasoline contains about 33MJ or about 10kWh => 200Ah @ 48V.

 

It may be "only" 48V but please treat your pack with the respect it deserves.

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59 minutes ago, Crossy said:

IMPORTANT NOTE: - Please don't lose sight of the fact that there is a LOT of energy tied up in your battery packs.

 

These packs are quite capable of pushing several thousand amps if shorted, that 1/2" drive ratchet stands no chance.

 

A litre of petrol/gasoline contains about 33MJ or about 10kWh => 200Ah @ 48V.

 

It may be "only" 48V but please treat your pack with the respect it deserves.

Thanks for the reminder. My system is up and running again now without the parallel connectors who i will find another solution for. I will fully charge my batteries before parallel them again.

 

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28 minutes ago, Pink7 said:

Thanks for the reminder.

 

You're welcome.

 

Do note that it has absolutely nothing whatever to do with this afternoon's magical transformation of a 0.5mm2 BMS sense wire into a poof of acrid smoke and a slight black stain on the top of the battery pack I'm building! **

 

I didn't even say "Abracadabra"! :whistling:

 

** The un-stripped end of the wire contacted the B- terminal, 4 x 560Ah (2P - 280Ah) cells in series can generate an amp or two!

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7 minutes ago, Crossy said:

 

You're welcome.

 

Do note that it has absolutely nothing whatever to do with this afternoon's magical transformation of a 0.5mm2 BMS sense wire into a poof of acrid smoke and a slight black stain on the top of the battery pack I'm building! **

 

I didn't even say "Abracadabra"! :whistling:

 

** The un-stripped end of the wire contacted the B- terminal, 4 x 560Ah (2P - 280Ah) cells in series can generate an amp or two!

I had a "almost" issue today.. I closed down the 2 bms with the pushbuttons for the bms but when i checked with voltmeter i noticed it was still power...then i see the connector to the bms for the power button had slided out so it had not power off as I expected.

 

There is 70-80 cm between the battery cables i want to parallel, and they are short ( inverter to breaker), so i guess i must use cable between them not just the copper bus bar. With quality thick copper battery connectors i might could connect 3 of the them on a bolt with nut? ( 1 to inverter, 1 to breaker, 1 to parallel then same in the other end of parallel cable)

 

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9 hours ago, degrub said:

Please post a photo of the setup with the wires identified..

 

Yeah, I'm a little concerned about the positioning of the breakers/fuses in relation to the packs and inverter.

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17 hours ago, Pink7 said:

Looks good. I use a heavy duty type lug for high current. see photo

bbb4.jpg

 

That is flat lug and it should only be used in a switch that has a flat bottom, not a round bottom like your switch has.

Its connection to the switch is only on the side edges when you use it as you do

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17 hours ago, Crossy said:

IMPORTANT NOTE: - Please don't lose sight of the fact that there is a LOT of energy tied up in your battery packs.

 

These packs are quite capable of pushing several thousand amps if shorted, that 1/2" drive ratchet stands no chance

My way of doing it in the battery room under the house.

50sqmm feed, switch, 35sqmmx2 to the250A fuse and the  busbars.

Two battery stacks of each 4x5KWh (=40KWh) connected to the busbars.

 

20240421_102111.jpg

Edited by lom
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Posted (edited)
29 minutes ago, Crossy said:

Is that how the manual says to do it?

I just thought that would be the best option to parallel without connect with breakers. Please suggest options for parallel connection.

 

Edit: I also have option to parallel between breakers and BMS.

 

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Checked my battery breakers and found that the breaker i cleaned up yesterday was normal temp but the other one was very hot and so also the wire from breaker to battery. I was able to tighten the screws some and hope that will fix it.

 

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Update: Temp coming down again.. after tightening the 2 screws. Learning something everyday..i will keep my eyes on this, I even consider placing 1 of 2 temp monitors from each BMS on each battery breaker.

 

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