Big $$$ and weight saving tip

3523 Views 22 Replies 5 Participants Last post by cyclops2, Feb 21, 2011

ElectriCar

Discussion Starter · Feb 19, 2011 (Edited)

I recently learned something and thought I'd pass it along for you guys. I had a salesman visit last week and point out the differences in pricing of Copper and Aluminum wiring. I hadn't really noticed as copper is the wire of choice in building construction because it's readily available and has a little less resistance for a given size. Lately though copper costs have gone sky high and the raw cost of copper is about 5X the price of aluminum! And aluminum weighs about a third what copper weighs. Just don't expect to save that large of a difference for aluminum but it is still much cheaper.

I'm about to rework my ride with new Calb batteries. I'm also going to replace the copper from the pack to the controller and save a few pounds. 2/0 copper weighs .4lbs/foot. Aluminum weighs .12, about 30% the weight of copper.

I have about a 43' loop in my lead batteries so with that as an example if I were to use 2/0 wire the copper would weigh 17.2lbs. Aluminum would weigh 5.25 so I'd shave about 12 lbs. However for the aluminum to approximate the current ability of the copper you would need to increase the size by 1 and the weight savings would be a little less.

Reducing weight is like adding free mileage and there are a number of other things you can do.
Aluminum wire substitution is just something I've not read about here. Using my numbers I estimated the savings per pound at about .12 watts/pound. Below are links for weights for your own calculations and a link for amperage capacity comparison.

Ampacity table

Aluminum wire properties

Copper wire properties

1 - 20 of 23 Posts

major

· #2 · Feb 19, 2011

We've been through the Cu vs Al many times here. Bottom line: More trouble than it's worth

ElectriCar

Discussion Starter · #3 · Feb 19, 2011

Must have missed it. I've been a member about 3 years. What sort of problems since you brought it up?

Cimpso

· #4 · Feb 19, 2011

*Wall 'O Text Alert*

The reason copper is "more trade standard" then aluminum are the connection and brittleness of the conductors. With smaller conductors, repeated flexing and vibration can cause stress cracks to open up in the conductors, increasing resistance, thus increasing heat and causing a cascading effect on the wire.
This cracking can be caused from even relatively small sources, such as motor vibrations; but much more likely in circumstances where a unsupported bend or length of wire is allowed movement and is then subjected to standard road conditions. The other weak point is the connections, where aluminum oxide can build up on the terminal connections etc... This can be alleviated by products such as no-alox, which is a anti-corrosion grease and aerobic sealant which helps protect connections, but is still not a perfect system.
In the Canadian electrical code, no aluminum wire smaller then 1/0 can be used and it cannot be used in any environment subject to movement or vibrations that would damage or otherwise compromise the conductor or connections.

Hope this helps enlighten Alu's weakness in these circumstances

See less See more

G

· #5 · Feb 19, 2011

Use the copper. Don't bother with a few lbs in a street vehicle. There are other things that can be done to strip a few lbs over going with aluminum. Unless your trying to gain that extra 1/100th of a second to your 1/4 mile time then it really does not matter.

I think you have heard that one before. A few tiny lbs on a street machine is no real big deal. At the drags it could be the difference between a win or loose.

cyclops2

· #6 · Feb 19, 2011

There are very few standards in Aluminum, the way there is in USA electrical & plumbing copper.
There is a higher CONSISTANT QA in our building codes that require the 99.9 % purity of both trades.
Could be not so good anymore with world wide suppliers pushing out a USA only market. India, China & Africa come to mind. What else is new.

major

· #7 · Feb 19, 2011

ElectriCar said:
Must have missed it. I've been a member about 3 years. What sort of problems since you brought it up?

http://www.diyelectriccar.com/forums/showthread.php?t=48720&highlight=aluminum+cable

Just a few months ago. And wasn't the only one. Took about 27 seconds using the search in forum tool bar.

ElectriCar

Discussion Starter · #8 · Feb 20, 2011

To address a couple of points.
1. Connections: The terminals do need to be rated for aluminum or they may not hold up. And an anti oxidation compound is required for dissimilar metals to prevent corrosion.

2. The salesman addressed the historically brittle aspect of aluminum wire. His vendor is using a new alloy in the new wire to give it more flexibility making it much harder to break.

I'll find out what brand wire he's selling. I know from experience that the old aluminum wire was very brittle.

I'm going to install it in mine for the application I mentioned above, battery to the controller area. I'm not so sure I'd want it where the wire was flexing a lot but that's not happening where I'm planning to use it.

ElectriCar

Discussion Starter · #9 · Feb 20, 2011

gottdi said:
Use the copper. Don't bother with a few lbs in a street vehicle. There are other things that can be done to strip a few lbs over going with aluminum. Unless your trying to gain that extra 1/100th of a second to your 1/4 mile time then it really does not matter.

I think you have heard that one before. A few tiny lbs on a street machine is no real big deal. At the drags it could be the difference between a win or loose.

So far I've quickly removed 43 lbs which I estimated should save about 5 watts/mile. When I rebuild the racks for the new batteries I'm making them much lighter as well. You can very quickly add a lot of weight overbuilding if you don't know the material strength and what it can support as was my case.

cyclops2

· #10 · Feb 20, 2011

Electricar

Do you leave airspace between the cells in the center, to allow cooling during hot days & heavy loads on the batteries ?

ElectriCar

Discussion Starter · #11 · Feb 20, 2011

cyclops2 said:
There are very few standards in Aluminum, the way there is in USA electrical & plumbing copper.
There is a higher CONSISTANT QA in our building codes that require the 99.9 % purity of both trades.
Could be not so good anymore with world wide suppliers pushing out a USA only market. India, China & Africa come to mind. What else is new.

Cyclops, we use aluminum in building wiring in the USA all the time, usually in building the services and underground feeders. With the huge difference in copper and aluminum prices now it's going to be in more use unless copper prices decline. It can be used for interior wiring in the US BUT there are requirements just as there are with copper that must be adhered to for it to provide good service.

There is a FEAR of aluminum wiring but the issues with aluminum are erroneous installations, not the wire itself or it wouldn't be allowed. Just like a wooden joist has codes that must be followed for it to be successful. Wood also is brittle, it breaks easily if you stress it too much but is fine and economical if used properly.

ElectriCar

Discussion Starter · #12 · Feb 20, 2011

cyclops2 said:
Electricar

Do you leave airspace between the cells in the center, to allow cooling during hot days & heavy loads on the batteries ?

Haven't received them yet but I don't plan to do that. I may install some type ventilation at some point and use it to heat and cool. The Calb batteries have ribs on all sides and the bottom to allow air flow. If air is forced up from beneath it will spread and flow upward through the channels the ribs create.

cyclops2

· #13 · Feb 20, 2011

Way back in Aluminum wiring of houses. The last reason I heard was the problem of " thermal racheting " The constant heating up & cooling of the wire under the screwhead was actually allowing the screw pressure to reduce over time. Back then EVERYBODY was trying to blame someone else to prevent paying out tons of money for the fires.

I do know that Aluminum dual intake manifolds & carburator bases for my 1952 Ford V8 became so soft from " metal fatigue " that I was forced to resurface them every 6 months. About 12 years of daily use & cruising at night.

ElectriCar

Discussion Starter · #14 · Feb 20, 2011

I think it will be fine and I'm willing to try it but I will ensure a proper install. U don't want to cut corners for sure.

rwaudio

· #15 · Feb 20, 2011

I've used CCA (copper clad aluminum) wire in car audio for years with no problems. On the other hand I've never used PURE aluminum wire so I can't say how it would behave. I think in the years to come as demand increases and copper prices hit the roof there will be development in aluminum alloys that will replace copper all over the place with equal performance (given that you have to upsize slightly for the same current capacity) but long term vibration reliability will probably be matched.

I think a broad statement saying aluminum wire can never work in cars is exactly the same as saying electric cars will never replace gas. Sure it's not a direct replacement but if you work out the bugs it could be a great solution.

cyclops2

· #16 · Feb 20, 2011

Good logic rwaudio.

We just need to use more INSULATING supports than Copper needed. Nothing fancy.
Blocks of wood are fine that have been drilled with hole saws the same size as the cables & then cut thru the cable hole. 2 more holes for a Ty Rap. 2 more holes to mount the block of wood. It works just fine.

ElectriCar

Discussion Starter · #17 · Feb 20, 2011

My supplier stated the new wire he's selling is a new allow made to eliminate the brittle aspects. In older wire, you could take a strand, bend it double and it would break when you tried to straighten it out. He said the new wire he took a strand and kept bending it until it finally broke.

Cyclops, I'm going to install a twisted pair cable (to minimize magnetic radiation) in plastic liquid tight conduit strapped to the frame rails like I have the copper installed now.

I have to find some crimp lugs rated for Al to connect the ends and I think I'm installing 2/0 as I'll hardly ever draw over 200A and only for a hill climb etc.

cyclops2

· #18 · Feb 21, 2011

ElectriCar

I would carry some $ 20 - 10 - 5 bills with me. Cruise around to a Power & Light repair station. Tell them how much Aluminum wire & size you need for the car. Tell them your friend works at the nearest coffee & doughnut shop. You can do the rest
You should be getting the best covered wire in the USA. Those guys USUALLY love projects like this.

Do not let both of us down.

Rich

ElectriCar

Discussion Starter · #19 · Feb 21, 2011 (Edited)

For the skeptics, this article should allay concerns mentioned so far in this thread with aluminum wiring.

Demystifying Aluminum Wire

cyclops2

· #20 · Feb 21, 2011

ElictriCar

Thanks for the article.

It is reassuring to know the old brain is still ticking. Most of the time.

If a power & light repair station can not help you. Call several COMMERCIAL electrical + H D & Lowes for pricing.of wire & combination lugs that can be used on Aluminum & Copper equally well.

Rich

1 - 20 of 23 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.