Battery cable

[Djbodya]

Hey, here is the question, I want to run a 2nd battery or 2 battery set up. Here is the photo of how I want to do it
I'm running 2awg cable from the inverter to the battery directly, can I use 6awg wire to the busbars and 2awg from busbar to Inverter? Or can I just parallel the 2 battery packs directly with 2awg all the way. Can you guys provide me with some knowledge on this...

 

[jasonhc73]

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diysolarforum.com

 

[time2roll]

I would tend to fuse each battery separately before the bus. If the sum of the fuses is less than the #2 ampacity the breaker shown can be eliminated. Otherwise if one battery has an issue.... the #6 could become the fuse.

 

[Djbodya]

I would tend to fuse each battery separately before the bus. If the sum of the fuses is less than the #2 ampacity the breaker shown can be eliminated. Otherwise if one battery has an issue.... the #6 could become the fuse.

What do you mean by fusing each battery? Are you saying that using 6awg will work but if it spikes without a fuse the wire will melt? I'm using the Nader DC Circuit Breaker | 60V 200Amp......... from main battery's to Inverter. Is this not sufficient?

 

[timselectric]

When batteries are placed in parallel. Each battery should have its own OCP. If one battery has a short, the other/s will dump all of their power into the shorted one.
Also, if one batteries BMS shuts off. The other battery will try to feed the inverter on its own. Then you will have a 200a breaker protecting a #6 wire. The wire now becomes the weak point.

 

[JoeHam]

In addition, make sure that the round trip wire length from each battery to the busbar is equal to help avoid unequal current sharing between your batteries.

As drawn the lower battery has a much longer round trip wire length.

 

[Steve_S]

 

[time2roll]

Better to have 100 amp breaker on each battery and skip the 200 amp. Very possible to have an issue with one battery and 150 amps will be drawn from the working battery. 150 amps is a bit much for #6 wire.

By the diagram it is hard to know the maximum expected working amps.

 

[Djbodya]

Better to have 100 amp breaker on each battery and skip the 200 amp. Very possible to have an issue with one battery and 150 amps will be drawn from the working battery. 150 amps is a bit much for #6 wire.

By the diagram it is hard to know the maximum expected working amps.

so is using a 2 gage wire better will it eliminate the need for fuse? or is it worth it. signature solar has its server rack connecting each battery to a buss with 6awg and it seams fine. that what I wanted to run, is that not ok?

 

[Djbodya]

In addition, make sure that the round trip wire length from each battery to the busbar is equal to help avoid unequal current sharing between your batteries.

As drawn the lower battery has a much longer round trip wire length.

the wire is going to be the same length from battery to buss bar just like the signature solar server rack design

 

[timselectric]

Those server rack batteries have built-in OCP.

 

[time2roll]

Those server rack batteries have built-in OCP.

So with adequate wire ampacity no fuses are needed?

 

[timselectric]

So with adequate wire ampacity no fuses are needed?

Correct
If those are the batteries you are using.
They have a breaker on the front panel.

 

[Djbodya]

Correct
If those are the batteries you are using.
They have a breaker on the front panel.

so running a 6awg from battery to buss bar and a 2awg from buss bar to inverter is enough for a max 6500w output?

 

[John Frum]

so running a 6awg from battery to buss bar and a 2awg from buss bar to inverter is enough for a max 6500w output?

6 awg pure copper wire with 90C insulation is rated for 105 amps in free air.
Since the breaker on the AIO is rated for 125 amps you should use 4 awg wire.

https://www.uglys.net/docs/default-source/uglys-documents/errata/UglysResidentialWiring2017_Errata_Page2.pdf

For the inverter circuit 2 awg is the minimum.
I suggest 1/0 awg with a 200 amp fuse.

The battery leads that Signature Solar uses have high temperature silicone insulation and a weird size.

EG4 6500 EX48 (just a single unit)

Hey all, Noob here (kind of)! I've seen several others ask this but didn't seem to see a solid answer. I pretty much want to do the exact setup in this video except downsized to 1 EG4 6500 EX48 and smaller battery bank. Looking at the plans and watching the video it seems pretty straight...

diysolarforum.com

 

[timselectric]

Agreed
I would go 4 and 2.

 

[timselectric]

If you are using their rack and batteries. You can use what they come with.

 

[Skypower]

You can NOT use undersized cable on the DC side. Do not use a residential wiring ampacity chart/Calculator for this. What the cables are rated at is irrelevant because of the DC voltage drop in this application is more important to the inverter’s performance than you can imagine. A one volt drop under load is a lot and could make the inverter shut down early and you could even see that with the right stuff. Remember your working range is normally only between 55 and 50 volts. Look at the plaque on the side of the inverter. It says 2/0 and that’s per inverter. If you run two inverters, than up to the distribution buss from the server buss/batteries, you’d be running 4/0 and so on. Yes you can run small cable but why buy the big inverter if you struggle with a 2000 watt load. Use quality breakers AND T class fast blow fuses and not something cheap that gets hot and drops voltage. Going cheap now just means you’ll be replacing it later. Use quality Ancor or Selterm lugs and get at least an impact crimper. Hydraulic crimpers are either expensive or and the cheap ones need the dies modded to crimp correctly.

 

[JoeHam]

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[JoeHam]

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