Power connector - XLR vs XT60
August 08, 2011 04:41PM
Hi, I am working on my second 3D printer (a prusa mendel) and had a recommendation. The "official" power connector is said to be a XLR connector[1] which makes very little sense to me and is actually possibly dangerous to recommend.

XLR connectors can generally take only 2A, though some can get up to 10A. You can't really tell from looking at one what type it is. The things were not meant for high current use. They look huge, but the amps is a function of how much contact the connectors make and how likely heat is to warp the connector at best, or ignite it as worst. XLR connectors were designed for some voltage, almost no current, and low RF noise, the opposite of low voltage high amperage power. Modern designs can pull 15Amps which I can easily see causing an electrical fire with some of the XLR connectors out there.

But a better reason to switch is that there already is a cheap, unpatented, plausibly printable at some point, and already de facto 12V connector out there, the XT60[2]. They can take 65A, have molded + and - indicators on them, are polarized, are very difficult to accidently short, are small, have no exposed contacts, and are already the standard 12-24V connector in the RC hobby world. Plus they are very easy to find locally at any RC store and online at palolu and sparkfun.

It also means you can run your reprap off a standard RC rechargable battery pack unmodified, combined with an SD card reader it would be great for quick demos.

Now, it looks like XLR connectors have not really caught on in the wild despite them being declared the "standard" connector so probably others realized their disadvantages, but I think we should stop recommending them anyway and start recommending the XT60 if anything. (of course, people are free not to use it, but I'd at least like to recommend something decent as a starting point). I made a little cable that connects to the screw terminals of the RAMPS on one end and the XT60 on the other which is clamped down to a pole with a makeshift holder, it works quite well and is aethetically pleasing to boot. Not to mention it just feels good to use a standard I know works in the wild.


[1] [reprap.org]
[2] [www.pololu.com]
Re: Power connector - XLR vs XT60
August 08, 2011 10:45PM
It seems like the folks at Pololu are thinking along the same lines.

Re: Power connector - XLR vs XT60
August 09, 2011 02:28AM
The Wiki page zou're refering to is about Gen3 electronics, which is old. Most electronics use either screw terminals or the connectors available on PC power supplies. The "4 pin molex" on the later are rated for something like 15 amps (depending on the connected wire), so they're fine for RepRap usages.

As an example, see Generation 7 Electronic's power source options.

Generation 7 Electronics Teacup Firmware RepRap DIY
Re: Power connector - XLR vs XT60
August 09, 2011 02:42AM
@Traumflug: Your Gen7 wiki documentation is looking pretty good. You do still need to add some text to a lot of your step-by-step construction pictures but otherwise you've done a great job of documenting the board! thumbs up

Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
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