Quick connectors for Extruder wires

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satoer
Posts: 436
Joined: Mon Oct 01, 2012 8:00 pm
Location: Netherlands

Re: Quick connectors for Extruder wires

Post by satoer »

Trnquill wrote:
Kjetilei wrote:I believe the cartridge heaters are 40 watt. 12V*3A=36W. Maybe it is possible to use the JST connectors?
They will be fine!
Probably, but if you’re planning leaving the printer unattended (like overnight) I wouldn’t use these connector outside its rated max current. A overheating connector can cause fire (especially in a plastic extruder design). And it’s not guaranteed that if the connector stays cool the first couple of prints, it always stays cool. If there’s some corrosion after some time, the resistance can go up.
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dognotdog
Posts: 181
Joined: Tue Sep 04, 2012 9:22 pm

Post by dognotdog »

After some experimentation, I can now confirm that EC3 style plugs are worlds better than the small JST plugs for the extruders. The JSTs tend to corrode somewhat over time, and are generally not suited for the high current, in a sense that the connector's resistance is quite high. Heating with the EC3 plugs is more than 50% faster than JST in the case I tested.

However, the JSTs seem to be just fine with the sensor connectors.

Kjetilei
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Location: Stavanger, Norway

Post by Kjetilei »

dognotdog: thanks for the feedback!

kimmoli
Posts: 62
Joined: Fri Mar 08, 2013 1:15 pm
Location: Finland

Post by kimmoli »

And i wouldn't use those JST connectors for the thermistor either.
Those are tin plated and NOT good for signal currents below 10mA ,specially in environment where movement is present. The corrosion dotnotdog speaks is afaik "fretting corrosion" (see wikipedia).

Use gold plated contacts.

And i propose that the V2 (V2.1) controller should use spring loaded wire terminals rather than those screw-tightened.

dognotdog
Posts: 181
Joined: Tue Sep 04, 2012 9:22 pm

Post by dognotdog »

I haven't actually found movement to have much to do with it. In my setup, the connections are quite snug and there's no tension on them. However, I believe it's the slightly different metals in the hole/plug parts of the connectors that electrically corrode with the higher currents, especially with acid from fingerprints etc being mixed in ever-so-slightly. And yea, they're cheap-ass connectors. Anything gold plated will be better, but maybe not by enough to justify the price or inconvenience. The thermistor readout is not very demanding, and even several ohms of resistance on the connector don't matter on a 100k thermistor, while it does eat up a lot of power with a high current application.

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