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Positive cable overheating on eg-4 bus bar

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Bruxollini

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I have a 5- battery system with eg-4 lifepo2 installed on signature solar rack, connected with 1awg cable to Schneider XW+ 6848. Tonight as the water heater was running and pulling 4.5kwh from the battery system, the positive cable overheated and started smoking. This is the first time this happened and we’ve run said water heater at night without any problems multiple times. Wire temp comes down after I shut off the water heater and there’s only a small load running. No alarms on the batteries or the inverter. Any points as to what is causing this and maybe how to possibly fix it? TIA
 

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I would like to know more about the busbar to include ampacity, material, thickness and how things are secured. It looks kind of thin for the wires. I am also used to studs on the busbar, and this has screws.

The wire does also look odd at the bends. At the bends the picture makes the wire look flattened out. Almost as of there's two sets of wire inside the insulation.

I tried looking up a reference for how much to bend the wires, and I did not find much. I found one reference that said the radius should be no less than three widths of the wire. I'm sure the number of strands in the wire makes a difference in how much it can be bent.

For reference I was measuring my 24 volt busbars today as they had over 60 amps flowing through them for an hour, and I had no temp change compared to other metal throughout the compartment as measured by an IR gun. I use 1/4" X 3/4" copper and designed for up to 200 amps. My guess is your busbar is 1/8" X 1/2", but I'm sure I'm off.
 
As others have mentioned, replace the cable.
Also, are your main positive and negative to the invertor both coming off the top of the buss bar?
 
Bruxollini said:
It is brass.
Click to expand...
I would change the brass bus bar to somethign that is rated for the max amperage of your system, that is copper, made by a reputable dealer, or do calculations to figure the correct thickness and make it yourself. 3/4" X 1/4" is good for around 200 amps and your 4.5 kw at 48 volts (I have no idea your voltage) pulls around 100 amps. It can't just be for the water heater but all the loads you can expect to have on at a time.

This chart tells me the thickness of the wire based off ampacity. Manufacturer spec sheet is more accurate.:

1667179037561.png
Is it possible there was another high amperage item turned on? My guests and family are not much on limits. Including letting me sleep while low voltage alarms are going off.
 
Bruxollini said:
I have a 5- battery system with eg-4 lifepo2 installed on signature solar rack, connected with 1awg cable to Schneider XW+ 6848. Tonight as the water heater was running and pulling 4.5kwh from the battery system, the positive cable overheated and started smoking. This is the first time this happened and we’ve run said water heater at night without any problems multiple times. Wire temp comes down after I shut off the water heater and there’s only a small load running. No alarms on the batteries or the inverter. Any points as to what is causing this and maybe how to possibly fix it? TIA
Click to expand...
Just noticed in your pics the batteries seem to be in parallel, but are connected similar to this making draw a bit higher on the closest batteries. is it possible this top one was the one that overheated?

From my signature block "paralleling batteries" here is the pic and draws of the way your batteries look set up:

1667179362841.png
1667179384762.png
 
timselectric said:
That's the problem.
You need tin or nickel plated copper.
Click to expand...
Do you think the batteries are paralleled incorrectly? Does the wire look deformed at the bends?

I look at this system and I see a bunch of things that raise my eyebrows.
 
Bruxollini said:
Yea they are.
Click to expand...
Iirc I've seen posts here saying you want one of the cables to be on bottom of the bus bar the other on the top, I could be wrong.
Is each battery pack at the same voltage / capacity or do you see the top behave differently than the rest?
 
I would also say bad connection, crimping...
The Negative wire from the bussbar to the loads caries the same amount of current the Positive wire from busbar to the load so one should not get hotter than the other to the point of smoking.
 
chrisski said:
Do you think the batteries are paralleled incorrectly? Does the wire look deformed at the bends?

I look at this system and I see a bunch of things that raise my eyebrows.
Click to expand...
The bend itself isn't a problem. Unless it's causing stress on the connections. That is a rack designed for those batteries. Bus bars included. The only issue I see is the brass lug.
Could connect one of the main wires to the opposite end to balance the load across the batteries. If this is important to you.
 
The Schneider documentation recommends/requires 0000 copper cable for the battery connections on the XW 6848.

I'd say your 1 awg is extremely undersized.
The brass wasn't helping the situation. Get copper this time areound.


*I can never remember if 0000 is written 4/0 or 0/4. 0000 means the same thing, but for whatever reason is a less common way to write it, but I can't get the number order backwards...
 
400bird said:
The Schneider documentation recommends/requires 0000 copper cable for the battery connections on the XW 6848.

I'd say your 1 awg is extremely undersized.
The brass wasn't helping the situation. Get copper this time areound.


*I can never remember if 0000 is written 4/0 or 0/4. 0000 means the same thing, but for whatever reason is a less common way to write it, but I can't get the number order backwards...
Click to expand...
It's 4/0
 
400bird said:
The Schneider documentation recommends/requires 0000 copper cable for the battery connections on the XW 6848.

I'd say your 1 awg is extremely undersized.
The brass wasn't helping the situation. Get copper this time areound.


*I can never remember if 0000 is written 4/0 or 0/4. 0000 means the same thing, but for whatever reason is a less common way to write it, but I can't get the number order backwards...
Click to expand...
Depending on the insulation rating and length, 1 awg may tachnically be sufficient. Larger is definitely better though
 
Insulation just lets the conductor get hot, properly over sized conductors won’t have the heat to begin with.

Heat is losses and voltage drop, something everyone should be trying to minimize.

I also don’t like that bend radius, and extra 4-8” of properly sized conductor won’t hurt the system if it avoids straining the crimped connectors

What tool are you using for your crimped connections?
 
Seems like a 1 AWG wire and brass does not seem ideal. That said, for another take, could you wire some solar panels directly to your water heater, bypassing the rest of the system?

Would be good to look at it with a thermal camera, too.
 
iwasforcedtopickausername said:
Seems like a 1 AWG wire and brass does not seem ideal. That said, for another take, could you wire some solar panels directly to your water heater, bypassing the rest of the system?

Would be good to look at it with a thermal camera, too.
Click to expand...
Water heater is most likely ac and panels produce dc…how would you bypass the device that switches dc to ac?
 
Mannfamilywoodworks said:
Water heater is most likely ac and panels produce dc…how would you bypass the device that switches dc to ac?
Click to expand...

It’s just a resistor. Doesn’t care about AC or DC.

The thermostat may be a problem. Also Need to compensate for voltage but that’s a simple math thang.

First google thing I found :

120 AC?DC water heater element

I have tried several DC hot water elements and so far none work as well as my test bench 120AC heater.
forum.solar-electric.com forum.solar-electric.com
 
42OhmsPA said:
Iirc I've seen posts here saying you want one of the cables to be on bottom of the bus bar the other on the top, I could be wrong.
Is each battery pack at the same voltage / capacity or do you see the top behave differently than the rest?
Click to expand...
Yes, I’m working on rearranging all the cables and connections and making them a little neater, and then flipping the negative bus bar over so that the positive connection is in top, and negative at the bottom, thus hopefully eliminating any current sharing problem. Right now the priority is to replace the cables with 4/0 wag ones.
 
chrisski said:
I would change the brass bus bar to somethign that is rated for the max amperage of your system, that is copper, made by a reputable dealer, or do calculations to figure the correct thickness and make it yourself. 3/4" X 1/4" is good for around 200 amps and your 4.5 kw at 48 volts (I have no idea your voltage) pulls around 100 amps. It can't just be for the water heater but all the loads you can expect to have on at a time.

This chart tells me the thickness of the wire based off ampacity. Manufacturer spec sheet is more accurate.:

View attachment 118500
Is it possible there was another high amperage item turned on? My guests and family are not much on limits. Including letting me sleep while low voltage alarms are going off.
Click to expand...
Turns out the water pump was running along with the water heater.
, probably pulling around 200 amps altogether, and my 5 battery bank is capable of 175, 35amps per battery. There in lies the problem.
 
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