openinverter forum

What should I use for high voltage cables on my tesla project. Keep buying really expensive cables from teslas on ebay because they definitely worked in the application at one point. Still some of my componants are from a model x and a model s so cables arent exactly compatible. I have really nice tinned copper selterm 2/O ring terminals but I am kinda afraid to cut up my tesla cables because I dont want to mess up the shielding engineering. Is the shielding grounded to the case at the ends? If a cable end shielding does not connect to the case is the shielding totally not going to work?

Also john Volk talks about the 300 dollar welding cables from amazon in his videos, wich looks like a super steal. His bmw shreds and works awesome. However the stuff looks like it has 0 shielding going on at all. My dad is getting really good at welding and collecting welders at the boatyard and stringly suggest to stay away from that cheap high voltage welding cable. I really want to be like I dont care but this project is kinda draining me of my lifes savings and I dont have anything working yet. Sooo I kinda dont want to mess up and start blowing things up just yet but its probably inevitable knowing myself. Lol just trying to do the best I can.

Also can I just use any type of solder to connect my ring terminals? The stuff I used with my 120 volt car worked great. Is there a massive difference running 350-400 volts?

Relying on solder for mechanichal connection is a super bad idea, you understand what happens when your solder melts away and your cables detach from those terminals?

Nope but sounds kinda like an arching scenario that welds everything together and creates a fire that leads to a battery explosion. Thanks for the input. Glad I asked!

What method should I use then? I have big heavy duty crimpers. We used solder and then filled the ring terminals and then crimped them on my last build. Is ther like a wiki or YouTube that talks about this stuff been searching for a while now and it seems like 101 stuff that I just have no idea why I am so totally not able to get educated on.

Crimping is preferable for high power because it doesn't melt (unless you really mess up).
Also it provides an extremely strong mechanical connection that cannot be pulled apart without cutting the wires. Solder wicks up the wire and causes stress points at bends, which then leads to broken wires.

I'm really not sure if shielding is needed; I've shielded some of my high power wires because I'm having encoder issues, but I really don't know whether it's necessary. Damien doesn't seem to shield things at all and he's still on his way to Lanzarote with all his BMWs working fine.

-Isaac

I've shielded my AC cables (which do not exist in integrated drive units) but never the DC cables. While NOT shielding AC cables completely threw off encoder readings and made the mousepad of my laptop jumpy in proximity of the car, the unshielded DC cables had no adverse effects and the car even passed EMC inspection with them.

I used so called "solar" cable with double insulation.

OEMs ALWAYS connect shielding on both ends despite some rumours that tell you to connect only one end.

I would consider any double insulated cable with the appropriate temperature rating to be good. The cable I used in my conversion was marketed as double insulated welding cable.

You can get hydraulic crimpers from China for like 40€. Definitely worth it.

Also, you can get ring terminals with varying material thicknesses. Some EV conversion shops sell really thick ones that I personally prefer.

leman2112 wrote: ↑Fri Oct 30, 2020 1:39 pm What should I use for high voltage cables on my tesla project. Keep buying really expensive cables from teslas on ebay because they definitely worked in the application at one point. Still some of my componants are from a model x and a model s so cables arent exactly compatible. I have really nice tinned copper selterm 2/O ring terminals but I am kinda afraid to cut up my tesla cables because I dont want to mess up the shielding engineering. Is the shielding grounded to the case at the ends? If a cable end shielding does not connect to the case is the shielding totally not going to work?

As many others have suggested, the answer for AC is likely different than DC.

Welding cable is typically 600v DC continuous-duty rated and adequate for the high current DC power with appropriate sizing. I was shocked to read the actual current limits are as much as 5x higher over short distances (typical ratings are published for a 50ft length!).

In my case, I plan to use Toyota HV cabling between the inverter and motor. One reason I can get away with this is the modest 50kW power, the other is that there are very short distances involved - under 1m is planned

I am planning to use metal "electrically bonding" cable glands so I can install wire shielding on the AC cables and bond them to the motor and inverter, for EMI suppression. It may also be possible for me to route the shielding over nonmetallic glands and still bond them adequately, but certainly the metal glands would provide a cleaner installation.

celeron55 wrote: ↑Fri Oct 30, 2020 4:56 pm

Also, you can get ring terminals with varying material thicknesses. Some EV conversion shops sell really thick ones that I personally prefer.

If you know someone working with HV installations in industrial or power utility you might get some very cheap or free high quality ring terminals. Likely the same stuff that EV conversion shops sell.

johu wrote: ↑Fri Oct 30, 2020 3:47 pm OEMs ALWAYS connect shielding on both ends despite some rumours that tell you to connect only one end.

Well it depends on the type of application and if provisions are made at either side.

The biggest drawback of shielding at both ends is that a ground loop may occur at some point.
Because when both end touch metal a new wire / connection has been made. In a car application i won't recommend that.
Simply because you don't wanna end up sending power through your braided part of the wire.

Now what you see sometimes is that at motor side its metal nut/grommet etc. aka the EMC connection
and on drive side there is a special place for the shield to go. That doesn't necessarily mean that both sides are plain grounded.

So in general: one side for electrical field interference, two sides for magnetic field interference.

EMC:
http://www.hottconsultants.com/pdf_files/APEC-2002.pdf