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Copper pipe for cross connections

  • Thread starter 'Captain' Kirk DeHaan
  • Start date
C

'Captain' Kirk DeHaan

Jan 1, 1970
0
I'm planning on using copper pipe, flatten of course, to interconnect
the 6 volt cells in my 12 volt battery bank. The flexible cables get
in the way of the caps. I will still use flexible cables to
interconnect the pairs in parallel. These are L16's. What pipe
diameter is sufficient?



Kirk

"Moe, Larry, the cheese!", Curly

www.sandpoint.net/captkirk
www.stormyacres.com
 
B

Bob Peterson

Jan 1, 1970
0
depends entirely on the current it is required to carry.
 
E

Ecnerwal

Jan 1, 1970
0
Bob Peterson said:
depends entirely on the current it is required to carry.

And the wall-thickness of the pipe - they are not all the same.
 
W

William P.N. Smith

Jan 1, 1970
0
'Captain' Kirk DeHaan said:
I'm planning on using copper pipe, flatten of course, to interconnect
the 6 volt cells in my 12 volt battery bank.

My brain wants to say there's something about rigid interbattery
connections that's tough on battery posts, but I can't really
remember. Maybe something about inherent stresses or small battery
movements being clamped down?
 
C

'Captain' Kirk DeHaan

Jan 1, 1970
0
If it were me, Cap'n, I'd consider going to the scrap yard and asking
for some bus bar for that purpose; it's heavier, less loss.

Sounds like a plan to me. I'll see if the local steel recycling
outfit has any. The handle all metals.

However, if you do decide to go the pipe route, two things:
One, drill a few holes in the pipe to make sure there's no air
pockets trapped inside, so the pipe can cool if the draw heats it up
Two, make sure you clean off the waxy-shellac that they coat copper
pipe with where it contacts the cell posts.

As for your connectors, I'd use pipe that would leave a good quarter
inch on either side of the post after it was flattened.

I haven't considered doing this myself, but would be interested in
hearing, too, if anyone has, and if there are any other issues with it
I haven't thought of...

To support it's use, in many residential builds, the copper water
pipe is used as the main electrical ground for the AC box, so it does
conduct well, obviously, and there's, imperically, more copper in,
say, a 3/4" pipe flattened than in many of the connector cables some
use...

DJ


Kirk

"Moe, Larry, the cheese!", Curly

www.sandpoint.net/captkirk
www.stormyacres.com
 
C

'Captain' Kirk DeHaan

Jan 1, 1970
0
If you use copper buss bar 1/4" by 1" it will handle 200 to 250 amperes on a
continuous basis.

Jack

More than adequate considering I'm using 8 L16's in series-parallel.
The inverter is 2500w and I rarely get to 1500w and that's when using
a skill saw, etc.

My calc's say that would be about 31 amps on each pair. Well below
what you stated.



Kirk

"Moe, Larry, the cheese!", Curly

www.sandpoint.net/captkirk
www.stormyacres.com
 
C

'Captain' Kirk DeHaan

Jan 1, 1970
0
My brain wants to say there's something about rigid interbattery
connections that's tough on battery posts, but I can't really
remember. Maybe something about inherent stresses or small battery
movements being clamped down?


Perhaps a slightly oversized hole that would allow some expansion or
movement. But then if it's capable of moving you probably have a
reduction in conductivity. I can't believe though it would be that
much stress as the connection is angled and the span is only about 6
inches.



Kirk

"Moe, Larry, the cheese!", Curly

www.sandpoint.net/captkirk
www.stormyacres.com
 
B

Bob Adkins

Jan 1, 1970
0
I'm planning on using copper pipe, flatten of course, to interconnect
the 6 volt cells in my 12 volt battery bank. The flexible cables get
in the way of the caps. I will still use flexible cables to
interconnect the pairs in parallel. These are L16's. What pipe
diameter is sufficient?

A good educated guess would be 3/8 for up to 200A, and 1/2 for up to 500A.
Of course you need to make sure the pipe is not getting hot. If so, just go
up a size.

Why not just get copper flat stock? some 1/8 x 1" would carry a hell of a
lot of current, and you wouldn't have to do all that flattening.

Don't forget to get some nice 1/4 or 5/16 copper or brass bolts, nuts, and
washers while you're at it.

Bob

Remove "kins" from address to reply.
 
C

'Captain' Kirk DeHaan

Jan 1, 1970
0
A good educated guess would be 3/8 for up to 200A, and 1/2 for up to 500A.
Of course you need to make sure the pipe is not getting hot. If so, just go
up a size.

Why not just get copper flat stock? some 1/8 x 1" would carry a hell of a
lot of current, and you wouldn't have to do all that flattening.

Don't forget to get some nice 1/4 or 5/16 copper or brass bolts, nuts, and
washers while you're at it.

Bob

Remove "kins" from address to reply.


Found some 1/2" x 1/4" stock for .38 a foot. Should be sufficient for
my needs. Currently using #2 cable for interconnect.



Kirk

"Moe, Larry, the cheese!", Curly

www.sandpoint.net/captkirk
www.stormyacres.com
 
W

William P.N. Smith

Jan 1, 1970
0
When flattening be careful that you don't crack the sides
thereby creating a possible discontinuity.

Yabut the cracks would be parallel to the current flow, so would not
effect it. Not that you'd want cracks, but it's not going to effect
your ampacity. You probably will have more concern about your
home-made battery terminals than the copper between them...
 
B

Bob Adkins

Jan 1, 1970
0
Found some 1/2" x 1/4" stock for .38 a foot. Should be sufficient for
my needs. Currently using #2 cable for interconnect.

Oh yea! That'll carry some serious current! Good price, too!

Bob

Remove "kins" from address to reply.
 
C

clare @ snyder.on .ca

Jan 1, 1970
0
I'm planning on using copper pipe, flatten of course, to interconnect
the 6 volt cells in my 12 volt battery bank. The flexible cables get
in the way of the caps. I will still use flexible cables to
interconnect the pairs in parallel. These are L16's. What pipe
diameter is sufficient?



Kirk

"Moe, Larry, the cheese!", Curly

www.sandpoint.net/captkirk
www.stormyacres.com
I would reconsider the pipe - it is RIGID and any
expansion/contraction cam break the posts out of the batteries. Rather
use a few copper ribbons cut from copper flashing and bent to allow
some movement. Broken links inside batteries can cause battery
explsions. Don't ask how I know - suffice it to say I used sheet
copper ribbons to connect the batteries in my electrified Fiat.
 
C

'Captain' Kirk DeHaan

Jan 1, 1970
0
I would reconsider the pipe - it is RIGID and any
expansion/contraction cam break the posts out of the batteries. Rather
use a few copper ribbons cut from copper flashing and bent to allow
some movement. Broken links inside batteries can cause battery
explsions. Don't ask how I know - suffice it to say I used sheet
copper ribbons to connect the batteries in my electrified Fiat.


But my batteries will not be moving. Expansion will be at a minimum as
the ambient temp is within 5 degrees year round in the room.



Kirk

"Moe, Larry, the cheese!", Curly

www.sandpoint.net/captkirk
www.stormyacres.com
 
B

Bruce in Alaska

Jan 1, 1970
0
I would reconsider the pipe - it is RIGID and any
expansion/contraction cam break the posts out of the batteries. Rather
use a few copper ribbons cut from copper flashing and bent to allow
some movement. Broken links inside batteries can cause battery
explsions. Don't ask how I know - suffice it to say I used sheet
copper ribbons to connect the batteries in my electrified Fiat.

I have a bank of Absolyte II AGM's that I have built my own links
out of 1/2" copper tubing flattened on the ends and drilled with
1/4 inch holes. These links replaced the original links that were
solderplatted copper 1/2"X 1/8"X 6". This bank runs my ISP Servers,
Routers, WiFi Access Points, and Networking Systems, for 99850.net
here in the bush of Alaska. I have a Trace U2624 that provides the
Inverter/Charger for this bank and is AC powered from a 20Kw Diesel
Genset, that runs 10 hours a day. (7am to noon, and 5 Pm to 10 Pm)
Just enough to keep the freezers cold and the inverter batteries topped
off.

Copper tubing works very well for these battery links, on this
800Amp/hour bank.

Bruce in alaska
 
C

clare @ snyder.on .ca

Jan 1, 1970
0
But my batteries will not be moving. Expansion will be at a minimum as
the ambient temp is within 5 degrees year round in the room.



Kirk

"Moe, Larry, the cheese!", Curly

www.sandpoint.net/captkirk
www.stormyacres.com
It's up to you - but generally "forwarned is forarmed". Just the
cyclic heating and cooling of the batteries with charge and discharge
CAN cause problems. I would NEVER advise it.
 
G

Graig Pearen

Jan 1, 1970
0
ALL the telcos have been using busbars between cells "forever" - well over 50 years at least. It
never causes a problem in a heated building and these strings are usually 12 cells in a row. The big
cells are at least 18 inches square so that is a lot of copper lined up end to end. Even in poorly
heated and non-airconditioned huts, I've never seen a problem in my 40 years in the business.

Graig
 
C

'Captain' Kirk DeHaan

Jan 1, 1970
0
Assuming the distance between the holes in the bars is 6" and the bars
are installed at 20°C and the maximum operating temperature is 105°C,
then the free expansion will be 0.0086".


The expansion I would see appears extremely insignificant.



Kirk

"Moe, Larry, the cheese!", Curly

www.sandpoint.net/captkirk
www.stormyacres.com
 
D

daestrom

Jan 1, 1970
0
I would reconsider the pipe - it is RIGID and any
expansion/contraction cam break the posts out of the batteries. Rather
use a few copper ribbons cut from copper flashing and bent to allow
some movement. Broken links inside batteries can cause battery
explsions. Don't ask how I know - suffice it to say I used sheet
copper ribbons to connect the batteries in my electrified Fiat.

The vibration and movement in an 'electrified Fiat' is probably more than
what we're going to experience in any permanent setup.

But for the record, even very large batteries like the ones we used on
submarines can be bolted with 'rigid' connections. The cells are wedged
tightly together with wooden wedges, then the connections made up. We never
had more than about 7 cells connected in a single row, but that was for
magnetic field suppression. The 7 cells would be connected with eight
pieces of lead-covered copper bus bar about 1 foot long. Each cell measured
about 18" square with the negative posts on one side of one cell connected
to the positive posts of the adjacent cell. After about six of seven cells
in one row, the bus-bars would jump sideways to cell in the next row for
about six cells. This formed adjacent loops that would cancel their
magnetic fields (to foil magnetic mines).

Despite all the 'angles and dangles' the boat would take on, we didn't have
a problem with inter-cell connections working loose very much (did test them
while doing test-discharges every month).

daestrom
P.S. For safety, we only used shortened, non-sparking (phosphor-bronze)
tools in the battery well. Including a specially made torque wrench for
making up bus-bar connections.
 
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