Battery Cables!

[WStayton]

Hi All!

  I have started gettng the pieces/parts in one pile for the solar install - so as not to be up on the roof in the middle of December!!! <grin>

  I got to the part in the Xantrex Manul where they talk about Battery Cables and they say that, for what I am doing, they have to be 0000 (4/0) and fine wire with swaged and soldered terminals.

  I was thinking to use eyelet cales and hook them to wing-nut terminal lead battery connectors . . .

  And then I went and looked at the price of what I WANTED and found that the cables/terminals are going to cost about half as much as the batteries they are connecting!!!

  So then I did a cursory investigation of fabricating the cables myself and found that if I made them with my own two hands, I would save about 50% of the cost, if I didn't ruin too many of them in the fabrication - I need 32 short cables and six longer cables, ultimately!

  A few questions:

1)  Having never soldered something of the size of a 40/0000 terminal, what do I need to do it?  Is a propane torch sufficient to do the job?

2)  Simple strike-with-a-hammer swager's are cheap (my middle name!) and readily available, but I see that results are highly variable.  Is such a swager sufficient/adequate for my needs, or do I need a "squeeze" type to do the job?

3)  If a squeeze type is required, I see modified bolt cutters sold for about twice the price of a hammer-type ($25 +/-), will they work or do I need a $100 hydraulic machine.

4)  Do you solder then swage, or swage then solder?

5)  And finally, fine wire 40/0000 is about twice the price per foot that regular old coarse wire, service entrance cable is.  Xantrex says that the reason to use fine wire is so that no undue stresses are placed on the terminal connections due to the coarse wire being much less flexible than the fine wire.  Can I get away with coarse wire and just be very careful about pre-bending the wire to fit before installation - since after insatillation it will be clamped down and won't be moving - I hope?!?!?

  All ye who have an opinion and/or have done this job, please speak!

  All responses are hereby solicited!

Regardz,

Wayne Stayton

[WGB]

I've been reseaching doing on the cheap too!
Swage then solder is what I  intend to do.
I've soldered for over forty years, done a ton of wire ends, propane will work fine. Then a nice clean heat shrink cover.
Fine strand wire will carry more amps also.

[LowGear]

Sorry, but I have to ask the traditional question.

If they're properly soldered (slight interchange of molecular matter) why do they need swaggering?  Besides the manual saying so.

Casey

[DanG]

Hard soldering is melting temps above 800~ °F... Silver soldering and brazing fall under that label.

Soft soldering (electronics) has melting temps from 340 to 800~ °F... Mixed alloy like 60/40 Tin/lead melts at 370 °F.

If you have an electrical problem, like having a bad connection making its own heat, 370 °F is easily reached and then it becomes its own little Chernobyl.

Having it hydraulically clamped, to the point the copper goes plastic, makes it 99.5% bonded like soldered. Not talking about homeowner equipment, telling about the terminal and cable flowing to the crimp mold like putty. Heavy tin plated terminals actually do solder at the contact areas under those pressures. A good hydraulic crimper new starts around $800.

Terminals designed for the bolt-cutter type crimps have a 2 to 4x deeper barrel and are marked to crimp 3 or 4 times to ensure the internal strands get jammed hard enough the crimp won't unravel. Also, flipping the crimper die between crimps is sometimes called for especially if it exerts any curve to the lug barrel.

It may be the one-in-ten thousand connection that burns the house down but it still happens.

I have an ancient hand hydraulic crimper w/ dies I got off ebay for $200 - it leaked pressure, I took it apart and rebuilt it; I found and arc-ring inside the barrel of it where somewhen it had conducted some huge amperage... hoping its not a killer tool but someone sure was having a helluva bad day that day.

[Thob]

Call around to local welding shops and see if they have any remnants of wire in the size you need.  They buy welding cable in large rolls and sell it by the foot, then save the last 10-15 feet from the roll for people who want to make good jumper cables, battery cables, and such.

You may find it easier to get two cables of half the size you need for each connection, they can be easier to work with than one large cable.

[Lloyd]

I could write a small white paper on the subject. In an average year I build about 50k worth of cables and that's the whole sale price of parts.

1st rule, any DC connections should be crimped not soldered, dc as a rule is high amperage low voltage for the voltage drop wire size(below 50 volts).

2nd rule is  DC amperage will start fires and not electrocute you. AC amperage is low compared to voltage, and will electrocute you to death, and may cause fires if a high resistance connection develops.

3rd rule solder high voltage low amp only, small wire(anything smaller than 20 gauge awg), use only enough heat to make the connection. It's way faster, easier, and safer to use a crimp connection, until you get to 22 awg and smaller.

A solder only connection will melt, if high heat develops from a high resistance connection lacking a good crimp connection, the joint will fall apart as a result of solder melt....add vibration and a fire is sure to result. Go ahead and ask me how I know!!!!

A 65 foot 1956 Chris Craft right across the dock from my slip had new batteries and cables installed in May of this year, the owner came down in June for the first time after the work was done. The old diesel were hard starting, so he just cranked on the the starter to get em running(like always,finical old 671's, that's another story) finally they started with in 3 minutes he was screaming down the dock FIRE. After I ran aboard and pulled his engine room halon, and opened the hatch and squirted two fire extinguishers.

We let the smoke clear. Point source of the fire was the negative bat cable for the starboard engine, it had completely melted the cable and plunged deep into the battery. Someone (not me, he didn't want to pay my rate) made a bad cable connection on the neg cable, on top of that, the they didn't cross connect the starters between the negatives on the start bats.


Solder was used in the old days before tinned wire and heat shrink tube was available. Where cables were subject to high corrosion due to nasty environments..think seaside, and commercially corrosive installations, using copper wire. Crimps with solder were in those situations the norm and used since the 40's until the 60's when heat shrink first came on scene. Anybody doing anything else was only doing it because they were ill informed. Tinned copper wire was used as far back as the mid 40's for marine use, when the yard and the naval architect, were well informed, crimp, then solder.

Solder causes 1 big problem, it hardens the wire. Any installation that is subject to any vibration should only use crimped with no solder. It does this due to the fact that the solder creeps back up the insulation, and now instead of stranded wire you have a solid wire. That brings up another issue in re low voltage and high amp wire installations.

Low voltage high amperage and or high HZ, has a tendency to skin effects, which means the wire can carry less amperage for it's nominal size. So a solid wire of the same nominal size can't carry as much amperage as a stranded wire of equal awg. Now we have an additional issue in stranded wire. We have Type 1, Type 2 and Type 3, each have a different capacity of amperage in the same nominal size. The difference is the number of strands in each size. An increase in type can increase amperisity for the same nominal wire size. Next you have to consider insulation class.

Wire runs made through a building could easily be made with a solid or a type one awg wire as long as it's sized for the amp load, and as long as it's not subject vibration. The building runs should be made to a firmly mounted junction block, and then either type two of type three cable to the equipment, dependent on vibration and amperisity....all should be crimped and heat shrinked not soldered ...in my opinion.

A good quality crimper for 10 awg through 20 awg wire can be had for less than $100.00 new. A good quality  crimper  for 8 awg through 4/0 awg wire can be had new for less than $300.00. A smart shopper can find em on e-pay for considerably less. The hammer type crimper can due in a pinch for a low number of connections on the heaver guage wire...it's just not very effecient....but if you have all the time in the world, and time isn't money, then the $25.00 hammer type crimper and a vise will do an excellent job, after a little practice. A hair dryer will sufice to heat shrink with, and they even sell a little butane tourche, but a commercial heat gun for less than $75.00 dollars will more than pay for it's self.

Lloyd


Any Q's?

[Randybee1]

I could write a small white paper on the subject.

I think you just did!
Thanks!
Randy B

[Mad_Labs]

I have a 1200aH, 12V battery bank. I used copper tubing to connect the batteries together and the 4/0 to the inverter. I flatten the last inch of the tube and drill a lug hole in it. Works great and is really cheap. I put heat shrink on the tubes for some insulation. They never get warm, even after running my welder. It certainly isn't up to code but it saved me a pantload.

Jonathan

[Lloyd]

I have a 1200aH, 12V battery bank. I used copper tubing to connect the batteries together and the 4/0 to the inverter. I flatten the last inch of the tube and drill a lug hole in it. Works great and is really cheap. I put heat shrink on the tubes for some insulation. They never get warm, even after running my welder. It certainly isn't up to code but it saved me a pantload.

Jonathan

Madlabs,

How old is the bank?, and have you ever dismantled the series/parallel connections and let the bats rest for 24hrs to do a proper SPG on each cell and voltage test on each bat?

My concern with using the copper pipe is that it's already hard to maintain cell balance. And what if a fire develops in the battery room, and burns down your house, the fire investigator determines that the fire started due to the bats and connections. Being out of code, the insurance co denies the claim do to negligence? In my mind cable is cheap insurance so the your expensive policy works as it supposed to.

In this day and age Insurance companies aren't in the insurance business anymore, they are in business to collect the premiums and the claim denying business, it's a much higher profit business model.

And I forgot to add to my mini white paper don't use wing nuts always use hex nuts and torque them evenly to spec between the bats. Improper/uneven torque will cause the cell to go out of balance.

Lloyd

[Mad_Labs]

The bank will be three years old next June. No, I have never dismantled and let rest. I would have no power for 24 hours if I did that, as I am off the grid. I do equalize regularly. After an equalizing I have tested the SG's and they were all very close. Why would copper pipe cause imbalance?

My batteries, solar panels are all installed on and in a shipping container, not in my domestic space. I don't have any fire insurance anyway, so I don't need to worry about that.

Jonathan

[LowGear]

If they're properly soldered (slight interchange of molecular matter) why do they need swaggering?  Besides the manual saying so.

Casey

OK!  Nice short answers; just what I like.  Next Question:
     So I'm running maybe 50 Amps through my three 12 volt batteries (series to 36 Volts) on a converted Polaris ATV so there will be bumps and vibration.  Do I have to throw my brass wing nuts out and go back to brass hex nuts and a torque wrench?  How close to perfect do my connectors need to be to perfect as per the above standards document.

Please don't let my cavalier writing style offend you or the other folks on this blog.  I do appreciate your excellent product and process knowledge.  Thank you for taking the time to share with us all and especially this barbarian.

Casey

[WStayton]

Hi All!

 Thanx for all the input - I'll try to address each in order!

 But first, a note - since I'm going to be hooking to NYSEG's grid, I have to do it in a way that NYSEG will approve - if they say "Why did you do XYZ?"  I've got to be able to show them where XYZ came from, otherwise they can, and will, and have, said "Nope, we don't like that - do it our way or the highway!"  And since doing it their way means a payment from them of somewhere between Four and Five thousand dollars, AND they will hook it to the network, I'm knida stuck doing it there way, unless I can show them that there is some reason to do it some other way, such as the manual for the equipment proscribed something other than their way.  So,  I think that kinda rules out using tubing for interbattery connections, etc., etc.  I'm not even sure that I can get away with using regular service entrance 4/0 cable instead of the fine wire stuff that the manual calls for - but I was thinking of asking them, since the manual says that fine wire is specified because it reduces the strain on the connections.

Thob:

 I hadn't though of local welding shops - wse are not exactly in the industrial heartland, but there are SOME welding shops around and they are worth at least a call to see if they have anything available.

 Is welding cable also known as fine wire?  If I produce the label for the NYSEG guys to read will they be happy?  I'd hate to go to the trouble and then have NYSEG say "Nope!".  <grin>

Lloyd:

 You say that DC connections should be crimped and not soldered, but the manual that NYSEG is going to look at says that they MUST be crimped AND soldered, so I am stuck!  Or, I can kiss four to five thousand bucks and a connection to the network goodbye!

 Do you agree that if I have to do both that they should be swaged first and then soldered?

 I don't think that corrosion or vibration are going to be an issue with this installation, since it will be in a ventilated building, resting firmly on terra-firma - though we did have a 5.xx trembler a month ago!  <grin>

 My intention is to completely spray the connections, after they are made, with the red battery terminal sealer and then slip the shrink tubing on over that, so everything is completely covered, again spraying the terminals after they are mounted to the lead battery lugs, and then spraying the battery lugs/terminals.

 About using nuts, instead of wing-nuts:  I envision using 3'8 stud battery terminals, what torques setting do you reccommend for 3/8 nuts on those terminals?  I'm sure it must be less than for a simple bolt, since the lead would tear out at something less than the steel would stand!

 I also planned on using tinned copper terminals, figuring that these would give me the best chance to have a physical bond with the cable when it is crimped/soldered and tinned terminals are only slightly more expensive than bare copper ones.  I suppose I could buy bare copper ones and then tin them myself, before inserting the wire, but I'm not sure I can do it cheaper than I can buy them and I'm sure the purchased-tinned terminals would be superior to my hand tinned ones.

 I have seen, at Harbor Freight, a hydraulic swager that has a die for size 0 (single 0) cable.  I have found, on the internet where several guys have either purchased a die to do 4/0 cable (available in England for this unit) or have machined out the size single 0 die to the 4/0 size, and the Harbor Freight unit is the princly sum of $50.00!  

 Machining out the die is, apparently a real job, since the dies are hardened, but it is something that can be done by any machine shop for not a lot of money, so I was considering going in this direction.  What do you think. Okay, or No???

 Heat shrinking is something I THINK I can handle, in as much as I have a heat gun and it has seemed to work adequately for any smaller heat shrink that I have used it on - I don't THINK that size 4/0 heat shrink is really much different from the stuff that I have shrunk onto #10 or #12 electrical wires, just will take a little longer.

 You say that there is always the one-in-a-million connection that isn't adequately crimped/soldered, etc. and that is the one that burns your house down!  Inasmuch as I don't want my house to burn down, is there any way that I can test the swaged/soldered connections to try and identify any that might be suspect??  Like a megger, or some other test that will show a faulty/deficient connection???

Mad_Labs:

 Using flattened copper tubing seems like a reasonable idea to me, but I am stuck doing it the way that the manual says if I want the $$$, so I don't think that will work for me.


LowGear:

  A man after my own heart!  I am all for making the job simpler if there is a way to do so that doesn't compromise safety or my check from NYSEG!  <grin>  

 Unfortunately, I think I am stuck doing both for the reasons that others have given and to get my check! <smile>

 Oh, and about the "526 project objectives" . . . I think that it stands at about 530 at the moment - a couple of new ones snuck in while I wasn't looking - like I had to stop and install the living room woodstove so that I can have heat UNTIL I get the whole mess up and running.  It IS nice to see something sitting on the granite slabs that were my near undoing earlier in the summer!


DanG:

 You said:  "Having it hydraulically clamped, to the point the copper goes plastic, makes it 99.5% bonded like soldered. Not talking about homeowner equipment, telling about the terminal and cable flowing to the crimp mold like putty."

 That is one of the reasons that I have thought about the hydraulic crimper from Harbor Freight.  That, and the fact that it makes every joint the same, there is no variation caused by the different strangth of an operator's hammer stroke, or no variation in how much you turned the cable to clamp it with the modified bolt cutters - every crimp is, supposedly, exactly the same!

 The Harbor Freight unit is, of course, homeowner equipment, but I would think that it is a step up from a hammer die or a bolt cutter, if not quite in the class of a thousand dollar tool!


WGB:

 I'm not sure that I need more amp carrying capacity, since service entrance cable is adequate for 100 amps per cable and the Inverter only makes a maximum (transitory) of 60 amps per phase for about 60 seconds before it tails off to 30 amps.  In that case, I would need about 2.4 time as many amps at 48 volts DC to get the 60 amps 120V AC, which puts me at  113 amps through the cable for a very short time.  I sorta figured that 113 was close enough to 100, especially since it is a short transitory, to be okay.

 If you look at the ampacity of 4/0 cable, it can be as high as 300 amps, depending on how it is housed and what temperature it is kept to.  I suspect that it won't heat enough in 60 seconds to severly compromise its current carrying capacity, expecially since it will be in free air, not in a conduit - am I wrong???

 Thanx everybody for the input!  Keep 'em coming!

Regardz,

Wayne Stayton

[Lloyd]

Well in my mind it makes no sense to invest tens of thousands of dollars in a system and go cheap on the proper cable ends.

As an example the picture below is of a ten year old cable from a very well known yacht builder, the subject boat is a 44 footer that costs in excess of 300 k when it was purchased new. It cost the owner almost 50 k for me to come in and rewire the boat after ten years.

Pic 1 is the starboard alternator charge cable, the manufacture is a member of the ABYC yet they still used improper wire and cable ends in this boat. All of the  #6 through #1 cables were installed with type 1 stranded instead of type 3 as required by the ABYC. Then they proceeded to use all automotive style cable lugs, with heatshrink. The picture shows why you should only use type 3 stranded, and how the heatshrink was a waste of time on the open ended auto style lugs. Heatshrink can't seal off the open ended lug. Type 1 cable work hardens and breaks with any amount of vibration.



Pic 2 shows a new auto style lug, it's even tinned. These lugs were never intended for large bat banks, and associated inverters, high charge and amp draws, for sustained periods of time. They were designed to spend 20 seconds spinning a starter motor.



Pic 3 shows the corrosion that wicked up the cable even with heatshrink.



Pic 4 shows the lug end wher the corrosion starts up the cable.



Pic 5  shows another cable, with the heatshrink removed, and another fault of the lug, the braised seem.



Pic 6 shows a proper sealed end lug.



Pic 7 shows a proper crimped and heatshink sealed cable end. No corrosion can enter the cable because the end of the lug is sealed, and the heatshrink, seals the insulation to the lug.



I myself will not use welding cable, even though it type 3 stranded, first it does meet the insulation class requirements, and 2 they wrap the stranded wire with a paper product prior to extruding the insulation on an this paper wicks moisture into the cable and corrodes the wire. I have personally cut many welding cables out of boats that actually drained water out of the cable after being cut.

Battery hex nuts should always be set to the torque specified by the battery manufacture. Every manufacture publish these specs for each battery they produce.

Feel free to do as you like, but I won't use wingnuts, welding cable, or automotive style lugs.

Hope this helps you find the path.

Lloyd


Here's a link to buy a tool new for $197.35 plus shipping.
http://www.go2marine.com/product.do?no=16213F#list-of-products

[DanG]

. ..since I'm going to be hooking to NYSEG's grid.. .

Do not slime the connectors until its inspected & probably safe to say do not heat-shrink the heat-shrink until its inspected.

Harbor Freight, a hydraulic swager.. . . ..4/0 cable available in England for this unit.. .

http://www.bulkwire.com/wiregauge.asp <---  see AWG vs. BWG vs. SWG; 0.46" vs. 0.45" vs. 0.40"; make sure the units are the same.

The HF unit may be great for 1/0 and lighter wire... really.

But - 3/8" (.375) travel on the HF crimper... 4/0 cable is 0.46~ diameter; the lug will be 0.51~ ID and 0.71~ OD...

IF it opens enough to accept the blank lug will it still travel far enough to crimp?

Looks like they 'cheat' with a bar across the 1/0 AWG dies to yield the correct pressure across a smaller section of the lug barrel as insurance. The 8-ton promise may be just that. There is a big difference between 0.325 and 0.46 when it comes time to scqoosh it into putty...

Also - I believe the best cable (marine) to be wrapped with Mylar and tinned.

I think you should look into bulk purchase of copper buss bar and fabricate the battery interconnects...

http://www.stormcopper.com/design/Buss-Bar-Ampacities.htm

[LowGear]

I've gotta ask:

What kind of solder and flux do you recommend?  What do you recommend using to clean up the solder joints before I heat shrink them?

Be gentle.

Casey

Oh!  Great photos!  Thanks.