| Author | Message | ||
| Randy Davidson Rating: N/A |
Folks, I'm wiring my eight 8D 12v batteries into a star pattern to feed two 12v Trace inverters that will be series stacked. Each inverter will have a 400 amp class-T fuse fed by 4/O cables on the positive side. I could wire the batteries in parallel and feed the inverters from each of the opposite + terminals, but the wire size between each battery would have to be >4/O to handle perhaps 800 amps! So, I'm thinking I can use much smaller cable (say 2/O or O) to bolt to some magical copper bar and the two 4/O's could come from the magical bar to each inverter thru it's fuse. Anyone ever done/seen this before? Anyone have any idea where to get a magical bar of copper that I could bolt battery cables to? BTW, I'd like another magical bar for the negative side. I'm planning for the two 4/O negatives to bolt to one side of a 1000amp-100mV shunt. The other side of the shunt would bolt to "Mr. Magic" and the batteries would each bolt to that. Can you visualize it? I have a drill press and taps -- I suppose I could drill my own part from bar stock if I knew where to get such stuff. | ||
| John MC9 Rating: N/A |
Doesn't copper corrode too quick? Wouldn't brass be better? Both Home Depot and Lowes have (well, they had) brass flat stock. | ||
| kevin schooler (Sylverstone_pd4501864)
Rating: N/A |
in the high end car audio universe we used to do this all the time. off the top, the larger the wire, the smaller the numbers. i.e. 4 ga is way smaller than 2 or 0 ga. that said, the copper setup you're talking about is called a buss bar, and some batteries just have bolts on the top for them, instead of battery clamps. i personally use 0 ga welding cables for alternator to battery, battery to ground, and alternator to ground connections, on everythng i own, old habit  if you want to use copper buss bars to tie your batts together, get the kind of clamps that take a bolt, put them where you want them, put the clamps on, drill the holes in the bars to bolt them to the clamps, and then use heat shrink tubing, (or clear vinyl tubing if you want to see all the copper) on all the "non clamping" parts of the positive bar. the car audio world has gold plates ones if you really want some bling bling.. the insulation may seem like overkill, but you *really* don't want to see what happens when you drop a wrench across a pair of buss bars  -dd | ||
| Andre Ducote Rating: N/A |
There is an example in the pictures on this link: http://www.prevost-stuff.com/shellelectrical.htm | ||
| dick egler (Dickegler)
Rating: N/A |
I used 1/4x1" copper bar and the screw top batteries in my eagle. Material available from McMaster-Carr.(www.mcmaster.com). They have a great selection of sizes if you prefer something different. Just search for copper bar. My part # was 8964K84. Less than 40 bucks for a 6 foot stick. As Kevin stated above, insulation between the posts is a must for safety.. I paralleled three group 31 batteries this way and seems to work well. dick | ||
| Marc Bourget Rating: N/A |
One concern I have with Buss Bar set ups is the lack of guidance given towards selecting the proper "size" (cross-sectional area) of the buss bar. Another concern is equalizing the length of the conductor between the batteries to match load and promote equal "sharing" by each battery. Much easier task with cables. The term "circular currents" also pops into my thougths, but I'd have to refer to notes before I commit to offering more. Maybe someone else can weigh in here on these points. To clarify a point above, after "O" (or "aught") size wire are the larger guages of 2-0 and 4-0, after which you go to MCM for example 600 MCM. | ||
| John MC9 Rating: N/A |
Randy - I didn't think a battery mounted buss bar was what you had in mind, but if so.... Keep in mind that to remove one battery, or to disconnect one battery for testing, or for charging one battery alone, you'll have to disconnect the bar from all the batteries.. It's a PIA. Running the connection of each individual battery to a buss bar, seems easy enough, but it'll be more connections to worry about, than the easier way of just cabling from one to the next. I'm sure one of the lectickal gurus will step in here soon to either reinforce, or knock hell out this...... But flat stock should carry as much current as square stock, and you'll find flat stock much easier to locate for this project. Oh.... one other thing to consider? 8D's don't take to deep cycling too well, for too long. You might want to design the devices used for the 8D bank to be easily changed to accommodate a different type of battery/size. | ||
| C Fred Rating: N/A |
Wire that has a lot of strands will carry more electric than solid conductors. as voltage runs on the out side of each wire strand. That is the reason that wielding cable will carry more amprage than solid wire of the same size. Also wire is flexabe and will exorbe vibration between batteries. My vote is for 4/0 wielding cable. C Fred | ||
| Jerry Liebler (Jerry_liebler)
Rating: N/A |
Randy, If you are in or near a major city, there is probably a metal supply company that will have sheet copper. I picked up a piece of 3/8" thick 4" x 30" in Portland Or. I have about 2 feet left. The 3/8" thickness allows one to tap into it for a 3/8" or 5/16" bolt and bolt on a terminal lug. I'd use SS bolts and a SS star washer. The next trick is mounting the buss bars. For this I found some 3/8" thick fiber glass flat stock. It would be a very good idea to make an insulating cover over the hot buss bar. Ideally you want the same total(+ added to -) length of the same guage between your junctions and each battery. I wouldn't worry about trying to make the buss bars symetrical, just make the arrangement of holes & lugs compact. I'd use 2 AWG between batterys and bus bars and 5/16" bolts on these wires, then 3/8" bolts and 4/0 wires from buss bars to inverters. All the lugs should be crimped and soldered and then shrink wrapped. BTW you can make a fine terminal lug for the 2 AWG from 3/8" copper tubing, you'll need lots of them. A small 'solder pot' (I use a steel 'ladle' over a propane torch) makes soldering the terminals very easy and solder plates them as well. You can get solder in bars from most plumbing wholesalers. If you need some of my leftover material email me off board. Regards Jerry 4107 1120 | ||
| Art Gill (Sandcastle)
Rating: N/A |
The ground bars we use at radio tower sites would work good. They even come with insulators for mounting. Search for Tessco as a source. As for battery cable, terminals, plugs of solder for making the connectors, search for Dell City Wire. They have a good selection and everything I have purchased from them has been quality. Copper will be much better than brass. On towers we use stainless steel hardware, flat washers and lock washers. You need to make sure that everything stays tight with heating and cooling both external and electical. I hope this helps. Art Eagle NJT model 20 | ||
| Ed Jewett (Kristinsgrandpa)
Rating: N/A |
For ampacities of copper buss bar try: www.stormcopper.com/design/buss-bar-ampacities.htm Also keep in mind that welding cable is not approved for battery cable use, therefore is illegal. There used to be a website with info about the situation, but it no longer exists. I think the guy finally gave up the fight with the gov't. Ed | ||
| username Rating: N/A |
Wow, I didn't know that my eyes could roll so far upwards into their sockets! There is some seriously bad stuff in this thread. All the loose conjecture as to what sizes of wire and bus bars ought be used is quite simply dangerous handwaving, completely unsupported by references to code. Even given access to the code, the poster did not supply adequate information (e.g. wire run lengths) for the making of any recommendations. The electrical system is by far the most hazardous aspect of a conversion, in part due to the intrinsic shock and fire hazards, and in part due to the, forgive me, simply immense ignorance and lack of qualifications of those who attempt to design and install systems for handling a basically insensible force. I very seriously recommend that you get a licensed electrical engineer who is familiar with battery powered inverters to do your system design, and a licensed electrician to do the install. Now, what exactly is a "star pattern"? This is not by any means standard nomenclature. What is subsequently described sounds simply like a massively parallel array. Paralleling 8 batteries is a definite invitation to trouble, due to differences between individual batteries; you are much better off running as few parallel strings as possible, by using larger (higher AH capacity) cells/batteries. And, yes, you can get much larger cells than those of an 8D, and at a better TCO (Total Cost of Ownership), as the array will last longer. In a parallel (or series parallel) array, you need to have an overcurrent protection device (fuse or breaker) on each parallel string (of 1 or more series connected batteries). You also will want a disconnect (switch or breaker) on each string as well, for maintenance and troubleshooting. Given the generally limited space requirements, breakers are to be preferred as they can perform both functions. Overcurrent protection devices have several ratings that are significant. One is the maximum system voltage (e.g. a 12V system can easily see over 16V) and voltage type (DC vs. AC). Another is the trip amperage. A third is the AIC, or Amps Interrupting Capacity: this is the maximum amount of current that the device is able to interrupt. If one has a short circuit situation where the power source and upstream wiring are such that current flow exceeds this value, the device will attempt to act, but will be unable to extinguish the arc that then develops across its internal disconnect. So, for a current limited source such as a solar panel or a genset, the required AIC rating of a device is quite low. For sources such as the power grid or a battery, fault currents can run into the several thousands of amps..... Given the use of the above devices, the practical means of joining the parallel strings is with single point means at both positive and negative terminals. There are widgets called combiner blocks that are ideal for this purpose; they are a chunk of metal with several holes for the various cables, with each hole having a setscrew. Any electrical supply house that handles commercial work will be knowledgeable of these; don't even bother trying to make your own. However, they may not be the best thing for very finely stranded cables; for such cables you should have a solid sleeve, or a terminal with a stud end, crimped & soldered onto the cable ends, so that the setscrews have something solid to bite into. Note that it is important that the total resistance of all the interconnects (cables, terminals, combiners, etc.) in each parallel string be as close to identical as possible; otherwise the individual strings will not see the same charge / discharge profiles as each other, inducing differences in how each string ages, which will then lead to Marc's "circulating currents", between the strings, and the life of the overall array will suffer. Actually, differential aging will happen anyhow, as the batteries themselves are not identical; uneven interconnect resistance just exacerbates the problem. If one chooses to forgo the above safety devices on each string, and instead go with a "daisy chain" approach to joining parallel strings, the points at which this array is connected to external sources/loads should be "diagonally opposed", e.g. the positive attachment should be at string #1, and the negative attachment should be at string #N. If not done this way, the aforementioned phenomenon of differential aging will occur. The proposed peak ampacity of >800A is a strong contraindication of daisy chaining, and the proposed degree of parallelism is a strong indication for use of protection devices on each parallel string. Also, the proposed array capacity of ~20KWH is is a strong indication for use of a higher system voltage. Finally, C Fred's assertion that current runs only on the surface of wires is entirely false, at least at the frequencies which are applicable here. If it is indeed the case that welding cable has a higher ampacity rating than other wire types of like gauge, it is due to other factors. | ||
| Richard Bowyer (Drivingmisslazy)
Rating: N/A |
Skin effect, or the flow of electrons on the skin of a conductor, is only applicable in the higher frequencies. I do not know exactly where the problem starts, but I used to do a lot of work on 400 hertz equipment for the aircraft industry and the mainframe computer industry and we had some very special techniques we utilized to minimize the effect. In working at even higher frequencies, Such as Radar, waveguide is often used and this is just a rectangular box of aluminum. Size of the box varies with the frequency. I also read on one of the boards within the last couple of days that the NEC states that battery terminals are to be crimped only. They are not to be soldered. Richard | ||
| kevin schooler (Sylverstone_pd4501864)
Rating: N/A |
i'm not the end all to be all of this sort of thing, but i've done systems that draw in excess of 1200 amps when they are run to the rails. that said, my commentary consists of: andre ducote: thanks for the link! (the link he provided is a better way to do it than full bank buss bars). Marc Bourget: re: sizing of buss bars. the lack of guideance is pretty common, since welding cable is a better way, albeit more expensive, way to do it. that said, "biggest you can use" is what we went with when we did the banks with buss bars. John MC9: hi john yeah, battery mounted buss bars are a pain in the butt, and i personally, wouldn't use them unless i had a battery drawer that rolls out, and even then, i don't think i'll do that on my bus. the panel mounted ones that all the battery connectors connect to have their uses (i.e. like the prevost) but i'm not sure that having the extra connections is worth the effort. you're right on flat stock vs square stock. C Fred: "Wire that has a lot of strands will carry more electric than solid conductors. as voltage runs on the out side of each wire strand. That is the reason that wielding cable will carry more amprage than solid wire of the same size. Also wire is flexabe and will exorbe vibration between batteries. My vote is for 4/0 wielding cable." a little bit of overkill but only a little, and i appreciate that. (you really cannot get too big with the cabling, the bigger it is, the less voltage loss and heat generation you have, all of which turns into better efficiency. cables of this size are custom cut and crimped, and will last about the same time, if not longer, than your coach. and he's absolutely correct on the "voltage travels on the outside of the wire" situation. high voltage systems are a totally different animal than low voltage ones. ed jewett: "Also keep in mind that welding cable is not approved for battery cable use, therefore is illegal. " i've heard nothing about this whatsoever. it's used allmost everywhere in solar and battery backup systems. if there's a problem with it, it may be due to how it handles external heat and chemicals, but i've never even heard of a problem with it. username: "Note that it is important that the total resistance of all the interconnects (cables, terminals, combiners, etc.) in each parallel string be as close to identical as possible;" true. we hadn't gotten that far yet. this is also why you want as few connections in the system as possible. as far as sizing goes, any sane run in a bus can be done with 0 guage welding cable (hell, my scenic has smaller wire than that at the moment, to my dismay) but, like i said, we hadn't gotten that far yet. and his bus won't haul enough batteries to need anything bigger than 4/0 which is what we, for the most part, suggested. he asked about buss bars, we told him about buss bars. i'm quite sure that once he goes and works all his wire routing out (shorter is better, less connections is better) then we can tell him what sizing he can get away with. then when he's all done he loads it down as far as it'll go and looks at it with a thermal scanner to make sure all the connections are perfect, and he's done -dd | ||
| username Rating: N/A |
Ken, you're dead wrong on at least 2 points: 1) "and he's absolutely correct on the "voltage travels on the outside of the wire" situation." Voltage doesn't travel anywhere; current does, though. And, no, it travels in the body of the wire, not on the surface. This is a just plain stupid assertion, and anyone making it has zero credibility in my eyes as a source of information on electrical matters. Get equal length pieces of wire and coaxial cable, each having the same diameter (at the wire or shield, not at the insulation jacket); I'm speaking of a true shield, i.e. one made of wire, and not simply foil. Now, the coax's shield will have about twice the surface area of the wire, because it has an inner surface and an outer surface, whereas the wire has only its outer surface. By your assertion, the resistance of the shield should be half that of the wire, and should exhibit far less heating than the wire when substantial currents are passed through it. You go and test this out, and then I'll get you a hat to eat. 2) "any sane run in a bus can be done with 0 guage welding cable" Utter bullshit; again, you lose all credibility in my view. Case in point: starter motors that draw >1000A. Another case in point: a 12V, 2.5KVA inverter can easily draw in the neighborhood of 400A, which is well beyond what should be passed through 1/0 wire. There are several other errors in your various assertions, btw. | ||
| username Rating: N/A |
Oops, that post should be Kevin Schooler, not Ken | ||
| kevin schooler (Sylverstone_pd4501864)
Rating: N/A |
"because i said so" isn't proof anywhere, sorry. (and i could care less about my credibility in your eyes) 1) "surface effect" it has been *my experience* that a large number of strands in a cable carries much more current at much less resistance, than a solid copper bar of the same density. i've tested both to critical failure, and i'm sticking with the "large amount of small strands" wire. *your* mileage may vary, and i don't give a rip how you wire your bus. i would expect that there is a reason that high amperage welders use the cabling that they do, i'll leave it as an excersize for the reader to figure that out. 2) 400 amp draw @ 12 volts, through a 5 ft run of 0 ga cable is .5 volts, or 4.2% 400 amp draw @ 12 volts, through a 4 ft run of 0 ga cable is .4 volts, or 3.3% 400 amp draw @ 12 volts, through a 3 ft run of 0 ga cable is .3 volts, or 2.5% 400 amp draw @ 12 volts, through a 2 ft run of 0 ga cable is .2 volts, or 1.7% 400 amp draw @ 12 volts, through a 1 ft run of 0 ga cable is .1 volts, or 0.8% because it takes much more effort to move 12 volts than it does to move 110, it's smarter to put your inverter next to your battery bank than elsewhere. if this was my inverter, i would up the wire size, as i have said elsewhere, but 0 ga will work fine on it. so where is yours that you can't run 400 amps through a 0 ga cable to drive it? (i said sane runs, a 5 ft cable run to a power inverter isn't sane) 3) if your starter motor is drawing >1000 amps, i highly suggest you quit starting it in gear. 4) anyone that takes what someone says on an internet bbs over "factory recommendations" really shouldn't be behind the wheel of anything, *especially* a bus. if those numbers are unavailable, 0 gauge welding cable will work fine. *i* recommend higher, and am using higher in my bus. you don't even have a username, so i assume we can draw the conclusion that you're a 14 year old kid who lives in a school bus that cut and pasted off a website somewhere. .. and watch your mouth, this is a family establishment. -dd | ||
| kevin schooler (Sylverstone_pd4501864)
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and for the rest of you, you might check out http://www.picwire.com/technical/paper9.html for a bit of explanation on "skin effect" -dd | ||
| username Rating: N/A |
Umm, if stranding has such a signifcant impact upon ampacity, why doesn't one see wire gauge tables that take this into account? Gee! Welders use welding cable because it's flexible. Duh! Googling "wire gauge table", right at the top is www.powerstream.com/Wire_Size.htm; referring to their table, 1/0 wire has a power transmission ampacity figure of 150A, which is rather distant from 400A. Gosh! Setting that aside, let's look at the 0.0000983 ohms/ft. figure: for a 5' distant load, and thus a 10' overall run, that's 0.000983 ohms, for a voltage drop at 400A of .3932V, which is also somewhat different from your numbers. Golly! Your inaccuracies aside, it isn't a matter of what's "fine" or "sane", whatever those words mean. It's about engineering, standards, and objectively defined levels of safety. Zounds! If statements given on a bbs are not to be given value, then why do you bother to make them? Hmm? 14 year old? ROFLMAO!!! As if! Struck a nerve, have we? Hmmph! Myself, I worry a lot less about the 'family suitability' of words like "bullshit" (and, btw, it's emanating from my fingers, not my mouth, no speech to text software in use at this end), and instead worry a lot more about those who 'mouth' various inanities such as "fine" and "sane", along with unsafe recommendations that some poor schmuck might just end up getting himself and/or others killed via. | ||
| username Rating: N/A |
The picwire site does not explain the skin effect at all, but rather simply asserts that the frequency at which it skin conductivity exceeds body conductivity is about 1 GHz - which is so very far beyond the range of frequencies that are of issue here as to be unworthy of mention. Kevin should make a circle and divest himself of the evil spirits that cloud his mind and move him to cast stones. | ||
| kevin schooler (Sylverstone_pd4501864)
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then why don't you post suggestions and recommendations instead of just running your mouth bashing on everyone else? or is "constructive" not in your vocabulary? -dd | ||
| Phil Smith
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Wow, that was fun ! | ||
| H3-40 Rating: N/A |
Yea and I wasn't even in it... for a change! I MUST be getting better at this! Ace | ||
| Richard Bowyer (Drivingmisslazy)
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Ace, I'm proud of you. For any of you who have not worked with higher frequencies, skin effect starts showing up at the 400 hertz range. I know. I have worked with this type of power for the past 50 years. Also, another problem at this frequency and higher is the actual inductance/impedance of the cable. Cables must be run in non ferrous conduit such as aluminum and a three phase, four wire cable consists of a total of seven conductors, spiral wrapped in a certain sequence to reduce losses. If you have never installed a large IBM 370 series mainframe computer then please do not bother to argue with me. Richard | ||
| Gary Stadler (Boogiethecat)
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EEK. We finally get rid of some bad dogs, and now Username comes 'round to replace him!! AArggh, it never ends. But I guess there's gotta be one. Well, at least username, whoever he is, apparently has some engineering experience... same mouth as the dogs though...Oh well, I hope he finds a real name someday... | ||
| Stan Rating: N/A |
"then why don't you post suggestions and recommendations instead of just running your mouth bashing on everyone else?" Kevin: This is a reasonable suggestion but there is no 'Good Samaritan Law" for engineers. That is why they charge for their designs and take responsibility for them. Any advice he gives out can get him in a world of trouble if it is misused. On bulletin boards you get all kinds of bable from anyone who wants to post. On this board we have one member who said he didn't know how to check the oil when he bought his bus A couple of years ago and now he is an authority on every subject. If you follow this board long enough, you will find that the really knowledgeable people stop posting because they get flamed or they spend all their time correcting bad advice. BTW I am not username but have been around this board for many years. | ||
| Tim Strommen (Tim_strommen)
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Okay I'll chime in... and I'm siding with "username" for most points (the others I think are moot). Here's one of the BEST informative sites as to the "rhyme or reason" why wire has to be a certain size for a certain length, current, voltage, etc. This page refers to the characteristics of a conductive material under circumstances. It provides in-depth explanations (unlike the http://www.picwire.com/technical/paper9.html link which just suggests "magic"). This site is created and run by Perry Babin and is a very knowledgeable and respected individual in the field of car audio (hopefully since you've stated that you do car audio you can say that you know this guy Kevin...) Welding cable: Typically a rubberized, non-environmentally sealed cable - designed to run high current low voltage electricity for short duty cycles (less than 50%). For a 2400 Watt inverter or higher don't use this stuff. Especially if you're running it through bulkheads, floors or under a vehicle - it's designed to be thrown out after the first sign of damage. Use a cable correctly sized and rated for the length of your run, current draw plus 20-30% (typical engineering safety margin), and make sure the cable is rated for the temperature and environment you're using it in). They use more, smaller strands to ensure that the cable is flexible while welding, and that over flexing (which results in broken strands) only slowly reduces its current capacity. Welders are still supposed to replace their leads on a regular basis to prevent a short or electrical fire. Safety devices should be located as closely to the power source as is possible - with a limit of 18" MAXIMUM. Also, any time the wire size is reduced on the way to the load, there must be a fuse there as well. THIS IS IMPORTANT!!! Skimp on this part and you may just kill your family while you burn down your bus. As any insurance person or fire-fighter says: “Safety First!” Fuses and Breakers: There can be arguments for fuses and arguments for breakers. I prefer fuses as circuit breakers can become dirty if not used to a high enough current when switching, and sometimes fail. When a high current fuse blows - it's due to a high surge or very bad overload. The arc that is created during the initial break will burn the fuse material off until the space between the two parts is far enough to discontinue transfer of current. This is why you will see a flash when a fuse breaks under a severe fault. Besides... if you have a 400 amp fuse blow - how quickly do you think you'll be able to find and repair the problem? Will you be ready to reset a breaker in two minuets? Also a fuse reduces the likelihood that a "McGyver user" will jamb a breaker in the "on" position to prevent it from tripping when there is a fault. If you need to save space and still be able to disconnect the battery for service purposes, there are high-current battery-disconnect plugs available. The final safety of the electrical system you install is your responsibility. Do your homework, and if you don’t under stand even one part of it – accept the fact that you are probably not the correct person for that job. It’s great to learn new things, but electricity doesn’t usually allow second chances at these current levels – so there’s less room for error. Find an electrician that has worked on DC powered forklifts to give you more information (those can go up to 90+ Volts DC at several KAmps), and you may still want to hire an electrician to at least check your work and/or be present when you power it up for the first time. Be safe. Cheers! -Tim | ||
| Kyle Brandt (Kyle4501)
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It is threads like this that teach so much. Just a thought, but a few things will decrease your credibility on the bbs; - personal attacks with ulgy name calling. - anonymous posting. - saying anything derogatory about Scenicruisers. - disagreeing with me :^) Lighten up ya'll, Santa is watching.....& you can't burn coal in a DD. kyle4501 | ||
| kevin schooler (Sylverstone_pd4501864)
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tim: yeah, i know of him. fuses: i agree on the fuses (both the installation method and the location) the only thing a fuse is there to protect is the wire (and therefore the vehicle) so it should be as close to the source as possible. welding cable: the welding cable i use is not the type you're talking about. i use premium welding cable that is highly resistant to oil, grease, cutting fluids and abrasion. i have to ask though, where are you guys putting your inverters that you would be running the cables under carpeting? (it's starting to become clear that my "sane" assumption needs a little work) -dd | ||
| Tim Hoskinson (Tdh37514151)
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Hey Randy did you really want some info or did you want to start a war! Safety is important guys but so is making everyone feel welcome and a part of the board. I have worked in electronics for 29 years I see some good info. here and some thats a little off the mark. Certainly nothing here to get worked up over. The best thing about this site is all the different opinions given here will get the info. seeker thinking strongly about what he is working on. This will lead to him or her finding more info. on the net. Or possibly deciding to have someone else do the work if it looks to be to much after all. Tim | ||
| John MC9 Rating: N/A |
I had to replace over 50' of welding cable used in a commercially made motorhome. The insulation had cracked and deteriorated to the point of serious hazard. The cable was shorting on the chassis in multiple areas, from front to rear. I had been informed at that time, that the welding cable insulation is made with a formula that releases chemicals each time it is flexed, that keep the insulation soft and pliable. Tires are made the same way. For that reason, a tire that is rarely used, will crack and it's life greatly shortened, while one rolling frequently, will last many, many years. Using welding cable for a permanently fixed feed, may not be in your best interest. Especially so, if it will be exposed to nature's forces. | ||
| Jerry Liebler (Jerry_liebler)
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John, And I had to replace the 4/0 cables to the starter in my bus because the insullation on the automotive cables GM used in 1968 failed. I put in neoprene jacketed welding cables and they will last nearly forever. Regards Jerry 4107 1120 | ||
| John MC9 Rating: N/A |
I hope so, Jerry! | ||
| username Rating: N/A |
Folks, y'all gotta get into the Google thing a bit; using "battery wire" got me here: http://www.tiewraps.com/marinebatterycable.html, which looks like some nice juicy stuff; also, there's www.waytekwire.com, which is an old standby. Of course, you need to look up in the code as to what is approved for the application and let that guide your search, but there is decidedly better stuff than welding cable out there... Richard, not to pick an argument with you, particularly as I've not myself done any 400Hz supply work, but it seems odd to me that this would be a big deal, e.g. what about mere speaker cable, which handles frequencies 50x higher at considerable power levels, or the fact that there is all kinds of electronics out there, e.g. computers, where there are relatively immense data rates, e.g. the 1.5 gigabits/sec of SATA (Serial ATA) disk drive interfaces; granted, these are for signal (vs. power) transmission, but, still, I don't see folks using particularly fancy methods in their cable construction. Tim S., I am having trouble parsing your statement about that breaker failure mode; any chance of more detail? As for the breaker handle, everything I've ever seen doesn't care if it's been locked into the on position, the breaker will trip regardless. Gary, Tim H., et al: Sorry if I'm coming across as an asshole, but I'm gonna stay pretty adamant about this. As I've said earlier, electrical systems have the potential (pardon the pun) of being extraordinarily dangerous. It's a testament to decades of industry self-regulation, as e.g. manifested in the code, that so few accidents do occur. Sadly, that tends to lead to complacency; the generous safety margins implicit in the code also can contribute to a false sense of security in those who just whip up a little bailing wire special that hasn't gotten around to biting them yet. I will continue to speak up when I encounter those who blithely spout their bailing wire aphorisms and attempt to hold forth from a position that is not founded in first principles. And if they subsequently want to get ad hominum with me and/or continue with their looseness, I have no qualms about putting them in their place. And, as for those who hope that those neophytes who witness a mere plethora of opinion will axiomatically get religion, well, I've seen way too much stubbornness and self delusion to hew to that particular faith, and so I do speak out strongly, rather than defer to the "can't we all get along?" crowd. Not by any means to pick on Richard Bowyer, but just look: a man who spent his entire career, 50 years or so, in power electronics; his coach was destroyed by mere goddamn dust bunnies in his heaters. Don't anyone ever dare think that it cannot happen to them, or that there is truly any room for casualness in these matters. | ||
| Pat Bartlett (Muddog16)
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Ropes are tied a little to close for comfort! But the information was excellant. Thanks! | ||
| bruce knee (Bruceknee)
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I was planning on using welding cable. I will have to reconsider based on all of the information in this thread. Thanks again guys. | ||
| Richard Bowyer (Drivingmisslazy)
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UN, power audio is relatively low power in the power world. The 400 hertz machines I manufactured were typically 75,000 watts each and it was not unusual to have at least three units running in parallel on each of the IBM mainframes. On the Cray super computers they were typically 156,000 watts each. It was not uncommon to have over 1,000,000 watts of 400 hertz power in addition to the massive amounts of 60 hertz power required. All conduit runs and fittings had to be aluminum and all conductors over sized significantly to reduce the effects of skin loss which is the effect of electrons, at higher frequencies, to travel on the skin of the conductor instead of completely thru the conductor. The power cable consisted of seven conductors, two each for phase A, two for phase B, two for phase C and one for neutral. The phase conductors were alternated and spirally wound around the neutral conductor. There is NO skin loss at DC up to 60 hertz. I really do not know where it starts affecting conductor size and composition, but it is somewhere above 60 hertz. Someone else mentioned coaxial cable and the shield on it. Coax was designed for lower frequency radio frequency transmission and not for power transmission. A whole different world. The same holds for waveguide which is another means to transmit power in the even higher frequencies utilized in radar systems. Probably more than most of you wanted to know but once I get started, it is sometimes hard to stop. LOL Richard | ||
| Buswarrior (Buswarrior)
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Hello. Just for fun, let's add another variable: How about "shipboard cable"? The fine strands are tinned the entire length of the cable during manufacture. Designed for use aboard ship: salty, wet, vibrates. Sounds like a bus conversion? Resists the creeping green corrosion, both at the ends as well as nicks in the cable. Flexible enough for easy busnut use. Big Transit here in Toronto uses it to re-wire the streetcars. Anixter Wire and Cable is where I got mine. You won't find it in the local Home Depot, and it will cost a bit more, but relative to rest of it, what's the big deal for a few bucks? happy coaching! buswarrior | ||
| John MC9 Rating: N/A |
Anixter Wire and Cable | ||
| Richard Bowyer (Drivingmisslazy)
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Not only boat cable has tinned copper conductors. Just about all cable, except for the Pep Boys automotive variety, is this construction. I never used boat cable because for the most part it is not UL listed but I never bought any cable or conductor that was not multi-strand, tinned copper, and met UL requirements for the specific application. Richard | ||
| username Rating: N/A |
I'm just becoming a certified Google addict! Searching for "skin effect" yields http://www.mos.org/sln/toe/skineffect.html, which gives a good definition of the basic cause of the effect. Also, there is some good stuff, including formulas, at: http://www.audioholics.com/techtips/audioprinciples/interconnects/SkinEffect_Cables.htm A followup article: http://www.audioholics.com/techtips/audioprinciples/interconnects/howardjohnsonskineffect. php To extract some interesting points: - The frequency at which skin effect becomes significant depends on wire diameter; the smaller the diameter, the higher the frequency. - For stranded wires, to the extent that there is good electrical conductivity between the strands along the length of the wire, it's going to behave pretty much like a solid wire. However, if the strands are insulated from each other, then things get more interesting, with the physical topology of the wire's stranding becoming significant; see the discussions in the areas of "Litz wire". This helps me to understand the rationale behind the cabling that Richard has described; it's basically a form of Litz wire. But, his application was of a much higher power level, which in turn required larger gauge wiring, which lowers the threshold frequency of skin effect, etc. Basically, though, for the application at hand here, unless one is willing to go to the considerable cost and difficulty of making/using Litz wire, the skin effect should not influence the stranded vs. solid aspect of wire selection. I would further argue that the magnitude of the skin effect is so low in this application as to not be worth worrying about. Perhaps someone would like to generate some scenarios and play around with the math, in order to either validate or challenge this assertion. Good night and good luck. | ||
| John MC9 Rating: N/A |
Hmmm... "I'm just becoming a certified Google addict! Searching for "skin effect" yields ......." And yet..... when I do it...... all I get are the porno sites. | ||
| username Rating: N/A |
LOL! Maybe Google is adapting to your browsing habits.... | ||
| C Fred
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For those that are down on wielding cable. If you read my statment my suggestion was to use it as a bus between battiers. It is more flexable than battery cable and makes connections a lot easyer. As for it insulation it sure bet sold uninsulated bus bars if you cross somthing across out. this is the exact reason that I rarly answer on any board. C Fred | ||
| John MC9 Rating: N/A |
And no-one was arguing against using it for short sections between batteries in a bank of batteries, Fred. It's when long lengths of it are used to replace the existing DC wiring (or extend the DC wiring) from the front battery compartment to the engine (rear) of the Bus/RV, that it can be a problem. Likewise, using it for a starter hookup where the cable will be coming into contact with the chassis or engine block, may not be such a great idea. The welding wire run in our RV went from the house battery set and engine battery (all in the front, with the engine), to the rear of the RV, to the genset. Since replacing it, I had found quite a few others that ran into the same situation, where the insulation on the welding cable had deteriorated under the vehicle, and shorted against the chassis. It just wasn't designed for that usage. | ||
| Ian Giffin (Admin)
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Username, Identify yourself or you will no longer have the pleasure of seeing your insulting words on this bulletin board system. Ian Giffin www.busnut.com | ||
| Tim Strommen (Tim_strommen)
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Username, I gotta side with Ian on this... I prefer to kow who I'm dealing with when I discuss this stuff. It doesn't matter to me if you're a 15 year old kid or a 70 year old kid... Fift years of electrical experience or 5 days. I chose to treat people with the same respect one age or another. As it happens I'm 25 years old - and have only been doing this (DC electrical systems) for 10 years. The first four years were spent doing competition automotive sound systems (some exceeded 10KW). I've had two years experience with DC forklifts, so I've handled DC at 96 Volts with over 300 amps continuous. That said, I'm dissapointed at the low blows both you and Kevin Schooler chose to use. I like to think of this board as a respectful friendly place to share information. If I really wanted to hear people poke at eachother and make childish comments about eachothers intelligence, I'd go visit my mother's kindergarden class... As Username has "called me out" ove the Breakers vs. Fuses issue - consider the following: Breakers require moving parts. Breakers are also designed with contacts. The movement of the contacts requires a continuous current pulse of a high enough amplitude to physiscally actuate the contacts and the associated spring. This "continuous pulse" can be up to a millisecond - way longer than what it takes to burn up a voltage regulator or a senative component. When there is a high-current potential available accoss the two contacts - arcing can/will happen. When you cause a high enough arcing current you can pit your contacts. With an enclosed contact, you can't inspect them for pitting - so you're more inclined to use the breaker past the point at which it should have been replaced. Also the contacts on a breaker (since it would be used as a switch) have the full potential across the contacts - you can weld the contacts closed when you first turn on the circuit if there is still a fault. With a fuse, it would just blow. Several agencies have done independant testing between fuses and breakers. Breakers have their place in electrical protection but just about everyone who has done real-world testing has concluded that a high-current DC "first line of defense" is not a good place for a breaker (ie. between batteries in a pack). Since Username has admitted to a Google adiction, I'm using his tool to answer his own question. Below are two sources that came up on the first four results by entering "Breakers vs Fuses" in Google. I think the first link below provides the best presentation of the information via a "real world" test - where they destroyed seveal fuses and breakers while connected to a few 6-Volt batteries. http://www.homepower.com/files/hp27-26.pdf http://www.bfs-ind.com/disc/disc202.htm Make your own determinations ("your way") for which type of circuits protector you want to use. As for wire - there's a reason they call it "welding cable". Wire is available for numerous uses and environments. Pick one designed for yours... Cheers! -Tim | ||
| Richard Bowyer (Drivingmisslazy)
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F. Fred, Please do not get your feelings hurt. Like you, I sometimes get shot down over something that I was sure I knew everything about, but there always seems to be someone that knows more than I do. LOL I personally really appreciate your comments and hope you will continue. I may not always agree with you, but I have to believe that you are right on for the majority of the time. As a personal preference, I do not like to use welding cable for anything other than connecting a stinger to a welder as I have found multi-strand flexible cable available to carry the large currents sometimes required. I used to build large DC supplies for UPS and the bus voltage was a nominal 600 volts DC. This required 50 twelve volt batteries in series and sometimes three or four strings of these in parallel. Typically group 31 batteries or larger. Talk about a lot of current and you definitely only used fuses on a system like this. Never a Circuit Breaker. Enough rambling for now. Please keep posting and sharing your wealth of knowledge with us less knowledgeable folks. Richard | ||
| Richard Bowyer (Drivingmisslazy)
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Above post should have been to C. Fred instead of F. Fred. Sorry. Richard |