Battery arrangement/wiring question.

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sjsamuel
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Battery arrangement/wiring question.

Post by sjsamuel » Wed Jul 29, 2020 10:14 am

Hello all, I’m currently in the process of designing and installing a system in my home for grid backup function as its primary objective, and have run into a question that I’m seeking advice for.
My system will consist of 2 Outback Radian 8048s fed by a lithium battery bank. This battery bank is a custom solution that a friend of mine got me hooked up with, and this is where I’m polling for help/opinions.
Each Lithium ion battery I have is already configured for 48v(14s), and I plan to expect alien 150ah per pack bench tested to keep cells cycling from 3.3v-4.05v to be conservative and hopefully promote longevity. I have 6 of these packs I plan to connect in Parallel to the Radians.

My question is how much should I worry about my parallel wiring cable lengths and design so that I’m not creating uneven discharge/charge rates between the parallel packs. I’m including a picture of the same batteries at at another application so you can see what I’m talking about. The terminals for the batteries are on one side of each battery (can see in pic if you zoom in). I too like in the pic will have to mount the batteries similarly in a line along the wall, but the inverters will central to the line of batteries on the other side of an interior wall. I’m just trying to see how someone with experience would recommend making the parallel connections, and what should I pay attention to. It seems that ideally, same length wires from each battery posts all meet at one central connection and then from there one wire to the inverters. This way all batteries get treated exactly the same. I'm just not sure how critical this is. Also, I plan to use 2/0 welding wire, for all my DC connections both the parallel runs and the main run to the Radians, does this sound correct?
Thanks for the help!

Sangeeth Samuel

https://drive.google.com/file/d/1UZ8R_A ... sp=sharing

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Re: Battery arrangement/wiring question.

Post by sodamo » Wed Jul 29, 2020 10:38 am

My 12 SimpliPhi batteries have all equal length conductors to a combiner box, then fed to inverters. Don’t know how critical, but equal length was manufacturer recommended and works well. The nest of wires hides behind the batteries.
David
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sjsamuel
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Re: Battery arrangement/wiring question.

Post by sjsamuel » Wed Jul 29, 2020 11:29 am

The more I look into this, I think this is the best way to do this as well. I need to figure out a combiner box type setup as well. That would sure make it cleaner. Any suggestions on wire size for a setup like this, if 2/0 needs to be used from all batteries to the parallel connection and then to the inverter as well?

raysun
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Re: Battery arrangement/wiring question.

Post by raysun » Wed Jul 29, 2020 12:53 pm

sjsamuel wrote:
Wed Jul 29, 2020 11:29 am
The more I look into this, I think this is the best way to do this as well. I need to figure out a combiner box type setup as well. That would sure make it cleaner. Any suggestions on wire size for a setup like this, if 2/0 needs to be used from all batteries to the parallel connection and then to the inverter as well?
I'd have suggested bus bars to connect the bat+/- leads.l and the Inverter feeds, but it doesn't look like the battery stacks have any sort if disconnect so the combiner box with disconnects would be the safest approach.

75°C 2/0 copper will handle 175A. Is that sufficient for each pack? If so, the disconnects should be rated the same.

The Radians have two pairs of bat +/- leads, so a bus bar to land all four sets will be in order. Again, the disconnects at the combiner output will need to be rated for the ampacity of the feed cable used.

Absolutely keep the relative wire leads identical in impedance. All 5 sets from the battery packs to combiner should be equal impedance. All 4 sets from the combiner/bus bar to the Radians should be equal impedance.

Finally, do yourself two favors:
#1 use actual battery cable and not welding cable
#2 have the cables professionally fabricated so the lugs are installed properly.

In 90% of the system failures I see that involve battery issues, home-built cables are the primary culprit.

pss
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Re: Battery arrangement/wiring question.

Post by pss » Wed Jul 29, 2020 4:01 pm

Welding wire is not allowed under latest NEC regulations. So no welding wire.
Now, how to make connections. "Professional" connections ARE NOT NEEDED. At my local American Battery, a large company of many thousand square feet with thousands of batteries, the "professionals" use a hand crimp tool to make your connections.
There are two ways for you to make connections:
1. Solder the connections. I do not recommend this because without the right torch you will get uneven flow of the solder around the many small wires that make up the cable and this will create uneven current flow and increase resistance.
2. Crimp the connections. I DO RECOMMEND THIS. proper crimping technique essentially results in a "cold solder" or fusion of the individual wires to the lug terminal. And even current flow.

To crimp a terminal connection, cut your wire to length (use a cable cutter made for the job like a Greenlee). Obtain tin plated copper lugs for the right gauge wire. Electrical supply, online or the bay will have these. Obtain a 12-16 ton hydraulic crimping tool set (essentially all come from the far east and are equivalent, and most ship out of California). Again, online or the bay or or electrical supplier. These sets come with the dies for pretty much all gauges of wires. Obtain the proper size heat shrink tubing. Cut your cable to length allowing for the exposed wire to fit into each lug end and any bends you will encounter. Place the cut heat shrink tubing over the cable for each end. Crimp the lug terminal using the hydraulic press and this will cold solder the wire and lug. Repeat as many times as necessary to make all your cables. Make sure when attaching you use the proper torque spec from cable to battery terminals. And, optionally, I use a product on my battery terminals called Kopr-Kote. It prevents any corrosion. If you are not certain of the crimp, begin my measuring the resistance with a volt meter. It should be zero. When current is flowing through, the wire should be room temperature at the highest current flows and the temperature at the battery lugs the same, no elevations. Measure with a hand held laser thermometer.

You will save a lot of money, have more control over your finished product, gain experience and satisfaction and avoid the "battery professional" and their over priced PhD.

provo
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Re: Battery arrangement/wiring question.

Post by provo » Wed Jul 29, 2020 5:21 pm

pss wrote:
Wed Jul 29, 2020 4:01 pm
"Professional" connections ARE NOT NEEDED. At my local American Battery, a large company of many thousand square feet with thousands of batteries, the "professionals" use a hand crimp tool to make your connections.

You will save a lot of money, have more control over your finished product, gain experience and satisfaction and avoid the "battery professional" and their over priced PhD.
Agreed -- one thing I like about making my own cables is I can cut the cable a little long, crimp a lug on one end, and then bend the cable into the curve I want, recut the stranding to get it square again, and crimp the second end with the curve "built in."

It's particularly helpful for the short "U" or "S" shaped cables between batteries in a string. If you buy a 12" jumper pre-made and straight, it wants to STAY straight.

raysun
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Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
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Re: Battery arrangement/wiring question.

Post by raysun » Wed Jul 29, 2020 7:43 pm

To each his own certainly.

I buy professionally made-to-my-specifications cables and have never had problems with fit or performance.

Yes, its simple enough to make ones own, and mostly one will get it right. Especially so with experience, like after the first cable-making session using the cheap Chinese hydraulic hand crimper that has the dies that almost but don't quite have the proper profile for the particular lugs and wire gauges, so make cables that look like they'll work, but fail in service. If rolling your own, get quality tools, preferably matched to lugs that are qualified to give proper clamping.

In "hot soldering" a cold soldier joint is one that is electrically and mechanically defective. In cold soldering a bad joint is guaranteed to get hot.

Notice I said it was a favor to yourself. Especially so around expensive battery blocks.

pss
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Re: Battery arrangement/wiring question.

Post by pss » Wed Jul 29, 2020 7:53 pm

Raysun, it's not to each his own. I think you are wrong. While I can honestly say I am intelligent, I had no experience making cables with hydraulic crimper. I messed up 3 crimps out of about 88. And the Chinese crimpers are what's available and used by your professionals too. I had no prior experience and have no bad or hot crimps. Because you don't have the desire or maybe have a lack of confidence or too much anxiety is no reason to dissuade others from aquiring a skill and saving money too.
The same goes for "pool professionals" of which there are none with a degree in pool.
You can say buy them from a pro, but telling people if they make their own may apply to you and not necessarily others.

raysun
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My RE system: Flexpower Two: (2) FXR3048A, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: Battery arrangement/wiring question.

Post by raysun » Wed Jul 29, 2020 8:12 pm

pss wrote:
Wed Jul 29, 2020 7:53 pm
Raysun, it's not to each his own. I think you are wrong. While I can honestly say I am intelligent, I had no experience making cables with hydraulic crimper. I messed up 3 crimps out of about 88. And the Chinese crimpers are what's available and used by your professionals too. I had no prior experience and have no bad or hot crimps. Because you don't have the desire or maybe have a lack of confidence or too much anxiety is no reason to dissuade others from aquiring a skill and saving money too.
The same goes for "pool professionals" of which there are none with a degree in pool.
You can say buy them from a pro, but telling people if they make their own may apply to you and not necessarily others.
I have neither lack of confidence nor lack of skills. I have lack of interest in troubleshooting problems and where it's practical to preemptively mitigate them, I choose to do so.

Your opinion is as valid as mine, and that's what it is, your opinion informed by your experience.

Outside of that, the only suggestion I may have is switch to decaf.

Mike Curran
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My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Battery arrangement/wiring question.

Post by Mike Curran » Thu Jul 30, 2020 7:28 am

Outside of that, the only suggestion I may have is switch to decaf.
LOL

The only thing that's prevented me from making my own crimp connections on battery cable was hesitation over the expense of buying a tool I'll seldom use. The tradeoff between cost of pre-fabbed cables and the tooling for DIY didn't seem worth it.

PS Wrote this after 2 cups of espresso, home-made :grin:
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

provo
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Posts: 531
Joined: Thu Jul 27, 2006 4:34 pm
My RE system: Sixteen Evergreen EC-120
(4 strings, total 1920W)
Eight Rolls S-550 (2 strings, total ~800Ah @ 24V)
One FM80
One VFXR3524A
Hub 10
Mate3s
FNDC and Trimetric
Location: Sierra foothills

Re: Battery arrangement/wiring question.

Post by provo » Thu Jul 30, 2020 8:03 am

Mike Curran wrote:
Thu Jul 30, 2020 7:28 am

The only thing that's prevented me from making my own crimp connections on battery cable was hesitation over the expense of buying a tool I'll seldom use. The tradeoff between cost of pre-fabbed cables and the tooling for DIY didn't seem worth it.
I might do the same if I ever cut my pack in half and want all new 2/0 instead of homemade 4/0 cables. Anyone have experience with these?

Battery Cables USA.jpg

Mike Curran
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Posts: 1803
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Battery arrangement/wiring question.

Post by Mike Curran » Thu Jul 30, 2020 8:18 am

Not that particular supplier but I bought these last year to connect my new Simpliphi 3.8's and seem fine so far:
Screenshot_20200730-111900_Samsung Internet.jpg
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

provo
Forum Czar
Posts: 531
Joined: Thu Jul 27, 2006 4:34 pm
My RE system: Sixteen Evergreen EC-120
(4 strings, total 1920W)
Eight Rolls S-550 (2 strings, total ~800Ah @ 24V)
One FM80
One VFXR3524A
Hub 10
Mate3s
FNDC and Trimetric
Location: Sierra foothills

Re: Battery arrangement/wiring question.

Post by provo » Thu Jul 30, 2020 8:27 am

Mike Curran wrote:
Thu Jul 30, 2020 8:18 am
Not that particular supplier but I bought these last year to connect my new Simpliphi 3.8's and seem fine so far (jpg).
Thanks for that! I bought some lugs a few months ago from Windy Nation, just to play with :smile: . I didn't know they made whole cables...

pss
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Re: Battery arrangement/wiring question.

Post by pss » Thu Jul 30, 2020 8:41 am

Whoa. I guess I need to go into the battery cable business. I've got all the tools and the same expertise as the other slappys out there.
Check this out (note the stuff on the terminals is Kopr-Kote).
My cables if using black insulation have a black shrink wrap end for negative terminal and a red shrink wrap end for the positive terminal. And when building your own cables, you can effectively measure the exact length from point A to B taking into account the lug fastening to the terminal and any cable twists. You can actually crimp the twist fit into the cable when making them. A nice advantage especially with 4/0 cables. Notice in 1 photo the presence of a DC terminal fuse at the last positive pole of the battery string. Pardon my battery dust in photos. All of these cables are 4/0 size. Oh yes, it wasn't the decaf, it was Cox cable who didn't show up as promised yesterday.
Attachments
battery cables 1.jpg
battery cables 3.jpg
battery cables 2.jpg

Mike Curran
Forum Emperor
Posts: 1803
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Battery arrangement/wiring question.

Post by Mike Curran » Thu Jul 30, 2020 8:49 am

With all those cables I can see why you do it yourself. When I bought my Rolls batteries back in 2007 they came with 4/0 interconnecting cables, not sure if that was Rolls supplying them or the vendor I bought from, but they were shrink-wrapped with the batteries so I assumed came from Rolls.
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

pss
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My RE system: 8330 watts in three strings, Flexmax 60 x 3, Radian 8048A, GSLC load center, Mate 3S, Hub 10.3, FN-DC and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Battery arrangement/wiring question.

Post by pss » Thu Jul 30, 2020 8:56 am

Yep, 32 batteries is a lot of cables, then into the switches for manual turn on/off of each string and then into the copper buss bar. out from the bar into the inverter. That's lots of cables, lots of different lengths and lots of crimps. Trying to make accurate measurements, then ordering the cables and then hoping you got it right would be like the gutter company measuring your house and ordering gutters to length instead of fabricating on sight. The advantages to custom making your cables should be obvious. There are only 3 mistakes you can make: ordering too little length of cable, ordering too few crimp lugs and screwing up your crimp. And if you start on the longest cable, screw up a crimp, chop off an inch and try again. Also, practice on a 1 foot piece of cable 2-4 times till you are comfortable with the tool and then you are off and running.

pss
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Posts: 634
Joined: Mon Jul 24, 2017 8:40 am
My RE system: 8330 watts in three strings, Flexmax 60 x 3, Radian 8048A, GSLC load center, Mate 3S, Hub 10.3, FN-DC and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Battery arrangement/wiring question.

Post by pss » Mon Aug 03, 2020 10:00 am

battery cables-1.jpg
battery layout-1.jpg
Being the dumbell that I am, I carefully laid out my batteries on the floor to help me figure out the wiring pattern I would use. Doing this helped me to know how many feet of battery 4/0 cable I would need to purchase as well as crimp lugs.

Then, I made my home made amateur battery cables, avoiding the professional, costly cables. Red end to positive terminal, black to negative terminal. A handy reminder.

Mike Curran
Forum Emperor
Posts: 1803
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Battery arrangement/wiring question.

Post by Mike Curran » Mon Aug 03, 2020 12:16 pm

Being the dumbell that I am, I carefully laid out my batteries on the floor to help me figure out the wiring pattern I would use.
Whatever works, man!
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

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Re: Battery arrangement/wiring question.

Post by sjsamuel » Fri Aug 21, 2020 12:24 am

Hey guys, bringing this thread back up as I have been mulling over everything you guys said and planning on how to accomplish my goals correctly.
First of all, thanks for all the suggestions and information. My setup is quite custom in both layout and location that I have decided to take the plunge and make my own cables. I have practiced on a few shorter cables and used those while I bench tested one set of batteries with one 8048 inverter on a fake wall I built in my shop, and everything seemed to work good. I'm getting more confident that I can eventually get all this working, but seems like I keep running into more and more questions, that I have to answer.
I guess this shows my ignorance when I asked in my original post about the wire type and size, but I did buy proper "battery cable" and 2/0 with lugs and a 12ton press. I see now also that I will definitely need a combiner box where the batteries can make all the parallel connections and from there a run to the inverters. I totally didn't realize the ampacity charts and requirements of the 8048s were actually TWO 2/0 sets to each inverter. I didn't plan on this with my wire length purchase. So now I'm thinking about the advantages/disadvantages of two pairs of 2/0 per inverter VS. one 4/0 pair per inverter. It seems like this would be a lot cleaner bundle to control than multiple 2/0, but also I realize that the amp rating is not quite as good as two 2/0 pairs.
Secondly, I'm wondering about a battery disconnect at the combiner box. I obviously have the 2 sets of 175amp breakers at the GSLCs but is there a DC switch that is easily installed at the combiner box to open the battery circuit prior to the inverters. Is this necessary or a good idea?

Thanks again for all the help!

raysun
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Posts: 2991
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A, (2) FM80, MATE3s, FlexNetDC
SimpliPhi 48-3.8 (6 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 strings of 2 in series)
Hyundai 355 watt panels (6 - 3 strings of 2 in series)
Honda EU7000is gas fuel generator

Re: Battery arrangement/wiring question.

Post by raysun » Fri Aug 21, 2020 4:22 am

Radian owners can speak to the advisibility of following Outback's cabling scheme to feed the inverters. By default, I'd assume the two sets of cables is purpose-designed and follow it unless I knew a valid reason for an exception. One operational advantage to the separate feed cables is the ability to take one module out of service without the necessity of shutting down the entire inverter.

Most all the "commercially packaged" lithium batteries I've looked at have disconnects on the units themselves. (Check out SimpliPhi 48V 3.8 battery blocks for example.)

I have a lead acid battery comprised of two parallel banks of four 12V monoblocks, and the monoblocks are not equipped with disconnects. However, each bank has a 175A disconnect at the POS terminal prior to feeding the battery bus bar. I have found this quite convenient for isolating a bank for service without having to take the entire battery off line.

A primary purpose of circuit breakers is to protect wiring. Its appropriate to place one in circuit wherever there would be a risk of wiring damage (and fire) in the event of circuit overload.

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Re: Battery arrangement/wiring question.

Post by EA6LE-ONE » Fri Aug 21, 2020 4:47 am

On radians if the cables are not very long from the breakers to the modules, gouge 1 is sufficient. The breakers should be 125ADC.

pss
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My RE system: 8330 watts in three strings, Flexmax 60 x 3, Radian 8048A, GSLC load center, Mate 3S, Hub 10.3, FN-DC and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Battery arrangement/wiring question.

Post by pss » Fri Aug 21, 2020 5:01 am

If you look at my photos in the thread, the combiner box is the large 1/8 copper buss bar. It will combine like 8 strings to single or multiple outputs.
I use a 125 amp terminal fuse on each string and an ON/OFF switch on each string. Total flexibility and among the lowest cost of ownership.

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Re: Battery arrangement/wiring question.

Post by sjsamuel » Fri Aug 21, 2020 9:15 am

pss wrote:
Fri Aug 21, 2020 5:01 am
If you look at my photos in the thread, the combiner box is the large 1/8 copper buss bar. It will combine like 8 strings to single or multiple outputs.
I use a 125 amp terminal fuse on each string and an ON/OFF switch on each string. Total flexibility and among the lowest cost of ownership.
I did see you post and that was a great, thanks. I’m gonna build something similar. Infact ordered some silver coated copper from McMaster in 1/4X3 and it should be more than enough(maybe overkill).
I have will have 3 sets of batteries that will feed the combiner box and will have about a 5ft run from terminal to combiner. I plan to use 2/0 for this. From the combiner to the inverters is where I’m torn as what to do. It will be less than 5ft for this run, but I’m torn between two pairs of 2/0 to each inverter vs one pair of 4/0. I think one pair of 4/0 would make for a lot cleaner install giving I am a bit space limited and have to make a couple of tight turns. Also, considering that I’m planning for a 3rd inverter later this year, I wanna make space for this. What’s you take!?

Also, would you do a disconnect for each set of batteries before the combiner box with something like this?

Fansport Battery Switch 275A DC 48V Battery Disconnect Switch with AFD for Boat https://www.amazon.com/dp/B07KXJMPRR/re ... pFbYRX62JZ
Or is there a better product that I’m unaware of. Would be awesome if I could disconnect ALL at the combiner box somehow.

Thanks again!

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EA6LE-ONE
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Re: Battery arrangement/wiring question.

Post by EA6LE-ONE » Fri Aug 21, 2020 9:39 am

sjsamuel wrote:
Fri Aug 21, 2020 9:15 am

From the combiner to the inverters is where I’m torn as what to do. It will be less than 5ft for this run, but I’m torn between two pairs of 2/0 to each inverter vs one pair of 4/0. I think one pair of 4/0 would make for a lot cleaner install giving I am a bit space limited and have to make a couple of tight turns. Also, considering that I’m planning for a 3rd inverter later this year, I wanna make space for this. What’s you take!?
You could use a 4/0 cable for negative only, for each radian you need 2 breakers of 125ADC one on each module with a cable gauge 1 at least.

pss
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My RE system: 8330 watts in three strings, Flexmax 60 x 3, Radian 8048A, GSLC load center, Mate 3S, Hub 10.3, FN-DC and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Battery arrangement/wiring question.

Post by pss » Fri Aug 21, 2020 9:43 am

Okay, here goes. An 8048 can output sustained 8000 watts. At input of 50 volts, that's 160 amps. And from my research, 2/0 wire capacity is 190 amps.

I dug this up (https://www.ecmag.com/section/codes-sta ... electrical): "this section permits aluminum, copper-clad aluminum and copper conductors that are at least 1/0 AWG or larger to be connected in parallel if these parallel conductors are electrically joined at both ends to form a single conductor". then the amperage capacity will be doubled.

In my case, I used all 4/0 connectors from my batteries to the inverter and between batteries. You can use a single run of 2/0 to each inverter and be within specs. Or you can run a single 3/0 or 4/0. I think if you plan on expanding battery capacity in the future, the connections to the buss bar are more important than the connection gauges to the inverter as the inverter will only draw 160 amps at 50 volts, with momentary short period being higher for surges and startups. That is more of a breaker/fuse consideration than wire gauge.

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