Copper vs. 4 Gauge

[TrackerJack]

I have noticed what seems to be more flatten copper tubing used to conect battery banks. I am connecting 24 Lifeline GPL-L16-2V Deep Cycle AGM Battery to make up a 48 volt system. I was thinking to go with 4 Gauge cable and tinned lugs. The kind with solder and flux built in. Would copper tubing work just as well and if so, what size pipe would be equal to 4G?... Thanks

[MagicValleyHPV]

I'm not qualified to specifically address your question, but as one who is also mid-stream fabricating batt-to-batt links, I favor stranded, insulated cables. My install is in a motorhome, so having the terminals rigidly tied together probably isn't such a good idea in my case. And insulated because no matter how careful I think I am, I have, on rare occasions, shorted terminals with tools. It's also why I insist on wing nuts instead of hex (which my newly purchased batteries came with).     

[rossw]

I have noticed what seems to be more flatten copper tubing used to conect battery banks. I am connecting 24 Lifeline GPL-L16-2V Deep Cycle AGM Battery to make up a 48 volt system. I was thinking to go with 4 Gauge cable and tinned lugs. The kind with solder and flux built in. Would copper tubing work just as well and if so, what size pipe would be equal to 4G?... Thanks

You'll probably get as many different views on this as you get replies

My original batteries, I used aluminium bar. NEVER AGAIN. It's nothing but trouble. Cheap, sure, but take a word of advice, and just plain don't!

In my case (originally 48 cells to connect), I didn't have time or patience to make seperate short cables, and the cost of lugs was terrible, and I can't admit to being a huge fan of crimp-lugs, generally.

4 AWG is near enough 21 sq mm of cable CSA. I went to the local switchboard manufacturer and purchased a bunch of their offcut busbar, by the kilo. Cost me I think $20 for enough bar to do all the interconnects, and have some left. I couldn't have got the lugs for that, much less made the cables. In those ones, I used 1" x 1/4", which is near enough 150 sq mm of copper - or around 25% more than 4/0 cable!

My current bank is done with (I think) 32mm x 6mm - 192sq mm or 7/0 cable equivalent. They're nice and flat, I just set up a jig to drill them all at the same point, placed the cells (carefully) and bolted them in.

Flattened Cu pipe sounds like a lot of hard work to me

Pic of a handfull of blanks after I cut them, before drilling, deburring and cleaning:



On the batteries:

[jvnn]

Looking good Ross!

@magic, I do appreciate your insistence on insulation.

[thirteen]

Rossw What is the yellow battery for? Just wondering why you have the batteries stacked on top of each other?  They look nice and do not take up unneeded room on the floor and should be easy to work on when needed. I am going to build a power shed this summer and I like ithe idea of things off the floor.  As an idea I would try and find a small plastic cover for each bus bar connection. I would be foolish enough to reach over them and use the terminels to rest something on and short everything. But that is me. Looks nice. Thirteen

[TrackerJack]

Rossw... My mistake, should of looked closer. Much more copper than you could get by flattening pipe. Man that's alot of copper for $20. Can you get me this deal. I would be glad to pay for shipping and your trouble.
Shrink would work nice to insulate. Yea, what about that yellow battery.

[hayfarmer]

  " . Yea, what about that yellow battery."
 
Ross shared this pic with me ,hope he doesn't  mind me sharing.when I grow up I want to get a system like his,    (he has it going on)

  Ross, I was waiting to ask in the picture above the multimeter the block with an x on it looked like a replacement block,  Is there a rest of the story?

 also what year was the battery bank installed/lifespan,and how are they doing?

hayfarmer

[rossw]

Ross shared this pic with me ,hope he doesn't  mind me sharing.when I grow up I want to get a system like his,    (he has it going on)

Thats cool.

Ross, I was waiting to ask in the picture above the multimeter the block with an x on it looked like a replacement block,  Is there a rest of the story?

Haha. There's a story alright - this place is built out of 14,000 odd blocks. The brickies used to bill me weekly for how much they'd done. They put 'X' on blocks to mark them so they they knew where they were up to each week.

also what year was the battery bank installed/lifespan,and how are they doing?

Well, they were second-hand batteries. The yellow bank (shown on the floor) were the first ones, I got them in August 2006.


I added the other two banks of grey cells in conjunction with upgrading the PV. The cells are doing great. Their specs say 500AH down to 1.8V/cell
.

I'm usually still at 48.3 volts in the morning before the sun comes up, after pulling 150 to 200 amphours from them overnight.

[ghurd]

"Well, they were second-hand batteries"
Gosh Ross!  Why not just build a real system, with good parts?

That pile of batteries never ceases to amaze me.
Well done.
G-

[rossw]

Rossw What is the yellow battery for?

Answered already...  The yellow and grey ones are identical specifications, just different cases. Not even sure why.

Just wondering why you have the batteries stacked on top of each other?

In one of the other pics I posted, shows the batteries stood on end, 2 banks deep (front/back) with terminals at the top.
Stacking them the "new" way makes them not protrude into the room quite so far, and prevents anything put on top of them (or falling onto them) from landing across terminals. Even uninsulated, I feel they're safer and more compact this way.

They look nice and do not take up unneeded room on the floor and should be easy to work on when needed.

Yes, I also like that it's much easier to just run along with a multimeter from time to time and measure the voltages.

I am going to build a power shed this summer and I like ithe idea of things off the floor.

Thats why I built that plinth. It's solid, and it brings the cells up to a nice, convenient work height. No bending to get cells in or out, or to check them etc.

As an idea I would try and find a small plastic cover for each bus bar connection.

I have covers. I hate them. They fall off when you want them to stay put. They stay on when you want them off. It makes running along a bank to check voltages a long, protracted, 3-pass exercise (remove, measure, replace).

I would be foolish enough to reach over them and use the terminels to rest something on and short everything. But that is me. Looks nice. Thirteen

With them mounted as they are, I tend not to come into contact with batteries at all. It's a low-traffic area, the only other two people that have access to the area know not to take anything metal in their - and that if they DO, contact with the batteries will KILL them.... and if the batteries don't, *I* will.

[RP]

With them mounted as they are, I tend not to come into contact with batteries at all.

-- except for "the incedent" with my belt buckle!   

[rossw]

-- except for "the incedent" with my belt buckle!   

ok, I have to ask: why have you got the dogs dinner dish tied to your stomach?      

[TrackerJack]

rossw,  sorry to bother you with that. i actually like building my on cables. never was much on exposed connections, but found these and will use shrink on 2nd bank of Lifeline GPL-L16T Deep Cycle AGM.
http://www.amazon.com/gp/product/B000FN1ACO

[DanG]

Think Industrial. When they are in a DEDICATED battery room with a LOCKABLE door...  exposed connections are fine.

It's not a break room, there's no work bench, no tool storage, no visitors, no loitering.

When we grow up maybe we can do the same.

[TrackerJack]

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