Tinned Copper cables or not

[LakeNut]

I suspect that tinned vs bare is targeting the same total cross section area of metal. The substitution of tin for some of the copper may increase resistance to the point where you should upsize the cable. It may just not make sense to pay for both tinned and upsized cable.

[Muddog]

In marine applications we used the same size specs as bare copper. Wire gauge was the same.

[LakeNut]

I'm saying skin effect doesn't push the current out to the tinning layer in DC or near DC applications. If you look at my second post, I suggest that the substitution of some copper for tin may require an upsize to compensate.

[Seaquell]

I just replaced my wiring with 2ga pure copper, at that size I feel like its oversized so much that tin or not wouldn't have an effect.
Even with 4ga it might not matter much,connections are probably the biggest loss and corrosion problem.

[Roxyflash]

I have scrapped alot of copper cable i did this for a guy that did ups battery back up systems.One cable we stripped was locomotive cable these cables run the trucks that power the train.They were rated for a 1000 amps they run the motors that run a million miles tinned copper.I never seen much corrosion on tinned cable but pure copper differant story.Im sure the tinned cable if good grade probably costs more.Now most lugs i use at work are tinned so that being said theres a reason to help from corroreding.Half of the wire we stripped was tinned and there hooked up to huge battery packs makes the golf cart batteries look like flashlight batteries.So im sure there a reason most of the tinned wire was like new probably for the high end jobs for data backup.New batteries new cables.

[teecro]

With tinned cable and ends the seal between the lug and cable is not quite as important whereas if copper wire is used the seal is absolutely IMPERATIVE as corrosion from the acid vapors will creep right up and into the wire. Add moisture and a salty environment and it gets worse...

[Sergio]

I personally use tinned cable and lugs on my cart, just another layer of protection.

I also prefer the adhesive lined heat-shrink tube to seal the cable/lug end.

[JohnnieB]

Originally Posted by crash test dummy

sent him a P M
HOPE HE GETS IT

I got the PM.

The operating frequency of the PWM output of the DC controllers is in the 18kHz range and a skin effect does exist in that frequency range. The conductive depth is only about 21 mils of the conductor's circumference at 18kHz, but the output waveshape is very complex with a large DC component since there is flyback action when the magnetic fields generated by the motor's Armature and Field coils collapse and there are filter capacitors across the MOSFETs in the controller. The net effect is that the bulk of the current is more or less DC and more or less flows throughout the cross section of the conductor. See attached drawing.

It is true that the "Tinning" is less conductive than copper (unless Silver is used,which is more conductive than Copper), but the thickness is only from about 1 to 50 microns and takes little away from the 533 micron conductive depth at 18kHz if a pure sinewave was being transmitted.

Other than being more expensive initially, I can't think of a reason not to use tinned copper cables for a cart's high current cables. Of course, they should have a high strand count for mechanical flexibility and a jacket suitable for the acid laden atmosphere in the battery proximity.

The cable lugs should be crimped and soldered and sealed airtight.

4Ga is typically adequate for use with 400A controllers and below, while 2Ga is typically adequate for 500A controllers up to about 750A controllers.


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The drawing below shows an approximation of the waveshape between controller and motor with the PWM at about 75% duty cycle. At 100%, it would be very close to pure DC and a lower duty cycle, the ripple would be greater.

[dundeebarnbuggy]

Good info! Thanks.

[Sergio]

Here is a better composite graph as to why "skin effect" is not an issue with our carts.

Given the high frequency of the PWM and the high inductance of the motor reacting against current change, the current does not vary/fluctuates much at just about any duty cycle.

The graph also shows why that would not be the case if the load was purely resistive.

You can also see ripple or spikes JohnnieB mentioned.

I though other members may find it interesting.