Since I have never used cables that come with ZWO products, I have also never measured them. With all the complaints about connectivity with the ASIAIR, I decided to pull a (pristine and never used) 1m power cable from the 4th generation ASIAIR (the newest ASIAIR that I have). Called "plus," but there are at least now 3 different ASIAIR plus models.

First, a table of what a good copper wired cable should be:

When converted to metric units, an 18 AWG copper cable should have 20.9 milliohms per meter, a 19 AWG should have 26.4 mΩ/meter, 20 AWG 33.3 mΩ/m , 21 AGC 42 mΩ/m, etc.

However, when I measured the resistance of the 1m cable, I see this:

Just in case it is the (Switchcraft) connector that I used at the two ends, I measured the connector itself, and it shows this:

So, the two connectors together should contribute just 0.5 mΩ. Leaving a whopping 43 mΩ for just a 1 meter long cable.

The milliohmmeter is actually a 4-wire milliohm meter (two wires to supply current through the load, and two wires to measure, with almost no current, and thus no voltage drop). It further has a manual knob to zero out any residual resistance.

40 mΩ is not good news. A 3A load would experience a 0.12V drop, for example. For just a 1 meter long cable.

They are either using a cable that does not use decent sized copper (it is equivalent to a 21 AWG copper wire), or the connectors are of poor quality (even the Switchcraft connectors that I used in the test jig are not even close to being expensive -- but bought from a real source, Mouser Electronics).

Many "18 AWG" cables that are sold at Amazon are also measured by other people to be equivalent to be only equivalent to just 21 AWG. I have only come across one source at Amazon with a true gauge, and luckily, it also has silicone insulation that does not become stiff when the temperature is cold.

Caveat Emptor.

Chen

ckoos Which cable on Amazon is it?

https://www.amazon.com/gp/product/B0785FJNBJ

The 18 AWG runs about half a dollar a foot.

I use a 14 AWG run to get from indoors to my ABS box at the base of my tri-pier. Then from there, it becomes 18 AWG (all distribution cables are less than 1.5m to 2m long). Until the final distribution, the connectors are PowerPoles (easy to handle 14 AWG and even 12 AWG cables). The final connectors are mostly 5.5mm/2.5mm or 5.5mm/2.1mm axial connectors, since that is what the hobby devices like to use.

I have been using PowerPoles for years now, so much so that I have the crimp tools for them.

I get my axial connectors from Mouser and DigiKey. Avoid Amazon too.

Chen

AstroDude42 I know PegasusAstro sells some quite thick (and pricey) cables but i still can’t really tell if they work any better than the original ones.

Don't ever buy cables from astronomy outlets, Olli. Like dew straps from these places, they are way overpriced (not just "Apple-tax" type price premiums, but borderline Mafia type criminal). Worst of all, they publish no specifications. I suspect a lot of them don't even have real electical engineers in the outfits, otherwise you would see specs. Engineers live on specs :-).

Make everything yourself. Get yourself these, and you are set for life:

https://powerwerx.com/tricrimp-powerpole-connector-crimping-tool
https://www.amazon.com/gp/product/B00CXKOEQ6

Once you use the auto-wire strippers, you will never go back, and for just 20 bucks; from Klein, no less.

Ditto the crimp tools for the PowerPole -- crimping is actually much more reliable than soldering. Good soldering requires skills (HP in the 1960s require their incoming engineers to take a soldering class :-), but anyone can produce a good crimp.

Looking at how many of the contacts that I have bought over time, I must have made more than 100 pairs of wires between my two hobbies :-). I have essentially memorized the orientation of the keyed connectors (once assembled correctly, you cannot reverse the black and red connectors, and you can keep daisy chaining them to extend length).

You can then make connectors at your heart's content with the Anderson PowerPole connectors:

https://powerwerx.com/anderson-power-powerpole-sb-connectors

I doubt you will ever need a to pass 30A, but the real reason is that you need them is for wire gauges that are thicker than 15 AWG (i.e., for long 12 AWG or 14 AWG wire runs). For 18 AWG, just use the "15A" connectors. I do have some 45A ones for my other hobby, but I doubt you will ever need them for this hobby.

The PowerWerx outfit above sells good wires, too. With 18 AWG running about 20 cents a foot if you buy larger spools. I have a bunch of their spools for indoors use. But with PVC sleeve, they do get hard in cold weather, so I have been using the silicone insulated wires from my last post (albeit more expensive) for outdoors use (my wires and ABS box are outdoors all the time, even when I am not brave enough to go out on the cold nights).

Aloha, Olli.

Chen

AstroDude42 how do i know which USB cables are the good ones and should be bought?

Most USB cables that are shorter than 1 meter work fine. Have you ever have one fail when you connect a hard drive to a computer?

The reason you read of so many failures in this forum is that ZWO's USB interface hardware appears to be flawed, especially after USB 3.1. I don't think they considered the fact that USB 3 data spectrum reaches up to 5 GHz, and PC board layout of the USB 3 data lines need to be treated as RF when they are over 1/4 wavelength long.

Chen

AstroDude42 I even never had a problem with the stock USB cables that come with the ZWO products.

I always throw those cables away when I open up a ZWO box. I have one that I keep for charging my wireless mouse :-).

Chen