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Californio Samba Member
Joined: May 17, 2007 Posts: 1306
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Posted: Tue Feb 09, 2010 9:48 pm Post subject: Builders' wire |
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Hey folks,
I just installed a piece of 8AWG stranded builder's wire from the alternator to the + battery terminal to cure a low charging-voltage problem. Easy to do--just get 12 feet of the wire, put it in a piece of 3/8" polyvinyl tubing for extra protection, solder some good-quality copper eye connectors on (I had to use a torch as the soldering iron wouldn't heat wire that big), and connect at both ends.
Result: before 12.5 volts, now 14.5 volts at the battery.
Question I have, though, is this: is it ok to use builder's wire in an automotive situation? What's the difference? If it's not as heat resistant for engine compartment use, why not put an additional piece of tubing around it, as in fuel line?
Sure is cheap and it definitely carries the current.
?? |
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syncrodoka Samba Member
Joined: December 27, 2005 Posts: 12006 Location: Santa Cruz, CA
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Posted: Tue Feb 09, 2010 9:53 pm Post subject: |
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I dunno what builder's wire is?
I do know that automotive wire is more pliable to resist breakage from the vibrations transmitted while driving. |
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buildyourown Samba Member
Joined: March 01, 2009 Posts: 1668 Location: Seattle
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Posted: Tue Feb 09, 2010 11:02 pm Post subject: |
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I'm afraid he might be talking about Romex?
If so, that is a horrible ghetto repair. Step up and spend the $10 on a real wire. |
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TroySmith80 Samba Member
Joined: October 09, 2008 Posts: 272 Location: Bend, OR
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Posted: Tue Feb 09, 2010 11:08 pm Post subject: |
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Maybe he means single-strand wire? If so, yeah, vibration will likely get it eventually. You want something very soft and flexy for automotive applications. _________________ 1984 Westfalia Wolfsburg - 2.5L Subaru - Sold - Preparing to move to the dark side (4x4 Ford van) |
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PDXWesty Samba Member
Joined: April 11, 2006 Posts: 6246 Location: Portland OR
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Posted: Wed Feb 10, 2010 12:57 am Post subject: |
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Stranded copper wire used for building (THHN) doesn't stand up well to the heat and vibration in an automotive application. The copper strands are too big and rigid and are prone to crack. Auto or marine wire has many more strands and is more flexible. That's why they don't use building wire. Also, the wire insualtion holds up better to solvents and higher temperature and are less flammable on marine and automotive wire. _________________ 89 Westy 2.1 Auto |
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greenbus pilot Samba Member
Joined: March 14, 2008 Posts: 1285 Location: Wisconsin: Rustbelt, USA baby!!
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Posted: Wed Feb 10, 2010 2:17 am Post subject: |
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I have a #6 welding cable from my alternator to the battery. Many fine strands in welding cable, and I got it free from work(after crimping on the appropriate lugs). Welding cable is THE way to wire a car. _________________ Sent from a white van down the street. |
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simd0ggie Samba Member
Joined: April 24, 2008 Posts: 418 Location: Chincoteague, VA
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Posted: Wed Feb 10, 2010 4:33 am Post subject: |
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In addition to stranded wire being more flexible, it also helps reduce electrical noise. Welding cable is fine, especially for areas with more vibration, but any stranded wire will do. Solid wire and romex are a no-no. MTW has a more flexible insulation and finer stranding, and it generally the type you'll find at Autozone and Radio Shack. THHN is stiffer & thicker stranded, but much more abrasion resistant, and is what you'll find at home depot.
Adding shrink tube will not make it any more heat resistant, it will only help with abrasion. _________________ -Matt
'85 Westfalia w/EJ25, '14 Tiguan R-Line 4 Motion
"There are two possible outcomes: if the result confirms the hypothesis, then you've made a measurement. If the result is contrary to the hypothesis, then you've made a discovery.” |
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Californio Samba Member
Joined: May 17, 2007 Posts: 1306
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Posted: Wed Feb 10, 2010 9:56 am Post subject: |
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What I used was stranded 8AWG from the hardware store. Cheap, but it sounds like there's a reason.
I've never seen 8AWG in the local auto parts places--why I used the builders' wire. To my mind the 10 and 12AWG automotive wires just don't carry enough current for a 12 foot run. Looks like time to search marine supply places online...anybody have a good source?
True, Romex would have that ghetto look...especially if you run it outside... |
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simd0ggie Samba Member
Joined: April 24, 2008 Posts: 418 Location: Chincoteague, VA
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Posted: Wed Feb 10, 2010 1:27 pm Post subject: |
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Just go to the local electrical distributor and ask for 8AWG MTW wire. _________________ -Matt
'85 Westfalia w/EJ25, '14 Tiguan R-Line 4 Motion
"There are two possible outcomes: if the result confirms the hypothesis, then you've made a measurement. If the result is contrary to the hypothesis, then you've made a discovery.” |
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PDXWesty Samba Member
Joined: April 11, 2006 Posts: 6246 Location: Portland OR
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Posted: Wed Feb 10, 2010 1:59 pm Post subject: |
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I got mine here. Super fast shipping and pretty low prices for marine grade wire. He'll even make a custom cable and put ends on it if you like or provide them with the wire. Check out the site.
http://gregsmarinewiresupply.com/
You can get 6 ga marine battery cable for $0.99/ft
8 ga for $0.67/ft _________________ 89 Westy 2.1 Auto |
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Californio Samba Member
Joined: May 17, 2007 Posts: 1306
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Posted: Wed Feb 10, 2010 2:04 pm Post subject: |
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That's the kind of place I was looking for. All I could find online was 100' rolls of automotive wire, costing $100 or so. Thanks for the link. |
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W1K1 Samba Member
Joined: March 04, 2004 Posts: 4921 Location: Southern AB
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Posted: Wed Feb 10, 2010 4:55 pm Post subject: |
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Go to your local auto battery store, ours makes cables any length/gauge with the ends crimped. And it was cheaper than the stiff cheap cables from Canadian Tire. _________________ http://www.thesamba.com/vw/archives/manuals/jim_martin_engine_build.php
1973 super
1965 squareback 1500E
1971 bay window westy- subi swap |
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syncrodoka Samba Member
Joined: December 27, 2005 Posts: 12006 Location: Santa Cruz, CA
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Posted: Wed Feb 10, 2010 5:00 pm Post subject: |
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West Marine stores carry some heavy guage wire in bulk that is sold by the foot. |
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PDXWesty Samba Member
Joined: April 11, 2006 Posts: 6246 Location: Portland OR
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Posted: Wed Feb 10, 2010 5:08 pm Post subject: |
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syncrodoka wrote: |
West Marine stores carry some heavy guage wire in bulk that is sold by the foot. |
They do carry wire by the foot, but it is 5 times more expensive than I found it on line. $2.99/ft compared to $0.67/ft for 8 ga; $4.99/ft compared to $0.99/ft for 6 ga. _________________ 89 Westy 2.1 Auto |
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thummmper Samba Member
Joined: November 25, 2009 Posts: 2015 Location: Meadow Valley, California Republic
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Posted: Wed Feb 10, 2010 9:34 pm Post subject: |
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walters whlsl electrical supply or whatever supply stocks multistrand for auto/machinery.
the reason you don't want single strand wire is because electricity travels over the surface of metal, not through it. the jacketing is specialized for the intended use as well. like these guys said, the heat and vibration play into it.
Next time you drive past a power substation, look at the ridgid jumpers they use on the jungle gyms---hollow thickwall copper tubing for all those amps. |
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syncrodoka Samba Member
Joined: December 27, 2005 Posts: 12006 Location: Santa Cruz, CA
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Posted: Wed Feb 10, 2010 10:17 pm Post subject: |
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Quote: |
They do carry wire by the foot, but it is 5 times more expensive than I found it on line. $2.99/ft compared to $0.67/ft for 8 ga; $4.99/ft compared to $0.99/ft for 6 ga. |
Yup. I never said that they were the cheapest though.
Paying for postage and waiting for the package to arrive is not worth the cost savings if someone wants to get something done now. If I wanted a small amount I would pay the premium. |
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fatboypaul Samba Member
Joined: August 24, 2004 Posts: 432 Location: Emeryville, Ca, SF Bay.
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Posted: Thu Feb 11, 2010 12:01 am Post subject: |
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When I rewired my boat I came across a wire supply company that was excellent, this is their address.
http://genuinedealz.com/
Way cheaper than West Marine, fast free shipping, and they never messed up an order.
I'm also losing voltage between the alternator (14.4v) and the battery(13.6v). I'm a little confused as to why. |
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Californio Samba Member
Joined: May 17, 2007 Posts: 1306
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Posted: Thu Feb 11, 2010 8:42 am Post subject: |
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13.6 V isn't bad. That's about normal voltage drop for 12' of 10AWG wire. Mine was less than 12.5. Adding the 8AWG wire brings it up to past 14. |
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PDXWesty Samba Member
Joined: April 11, 2006 Posts: 6246 Location: Portland OR
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Posted: Thu Feb 11, 2010 9:23 am Post subject: |
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fatboypaul wrote: |
I'm also losing voltage between the alternator (14.4v) and the battery(13.6v). I'm a little confused as to why. |
The current travels first from the alternator to the starter, then to the battery. There is no direct wire from the alternator to the battery. Measure the voltage at the alternator, starter terminals, and battery to find out which leg your drop is in. I added a second #8 or #10 wire from my alternator to the starter to minimize the voltage drop. The cable from the battery to the starter is big enough to carry charging current with minimal loss, unless you have a bad cable. Recheck and clean your ground connections too. There shouldn't be more than 0.1-0.2 voltage drop in the system without any load. _________________ 89 Westy 2.1 Auto |
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Perales Samba Member
Joined: May 07, 2007 Posts: 2046 Location: Nova Scotia
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