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I have to add some resistors to an aluminium plate on a 3D printer, because it only goes to 67'C without foam insulation. The heated bed currently reads 1.6 ohms (90W at 12V)

I wish to add about 96W of resistors to the aluminium plate, to run on 12V, to reach 110 degrees in 10 minutes. There is a 3cm margin of free aluminium at both ends for attaching resistors.

Are $4 Chinese power resistors like this reliable at 110 degrees? I can't find their temp rating and mean time before failure.

enter image description here

If use 2s2p of 1.5 ohm 50W resistor, same as 2x 100W 3 ohm resistors, it'll draw 96W, with 104W of safety in case i insulate the resistors?

I am going to:

  • buff the aluminium contact surfaces
  • glue them with arctic silver adhesive/bolt them
  • insulate the underside so that the heat goes into the aluminium
  • put them on a different power supply with an on/off switch

Am i missing some pitfalls?

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  • \$\begingroup\$ Please import a picture of the resistor you want to use. These questions remain accessible to other users long after your eBay link expires. \$\endgroup\$ Mar 19 '15 at 12:04
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    \$\begingroup\$ eBay is a terrible source of electronic components. \$\endgroup\$
    – Matt Young
    Mar 19 '15 at 12:31
  • \$\begingroup\$ On a positive note, there's no need to insulate them. That style has the housing already insulated. 2 bolt holes and a dab of silicone thermal compound or a silpad will do you. \$\endgroup\$ Mar 19 '15 at 13:01
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    \$\begingroup\$ Those are not a whole lot cheaper than equivalent components from a reputable supplier. \$\endgroup\$ Mar 19 '15 at 13:10
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You ask: "Are cheap Chinese power resistors like this reliable at 110 degrees?" Usually, yes. Dale was the first company whom I saw make that style of resistor and their data sheet says that their parts are good for a maximum of 250C. Hopefully, your Chinese supplier uses similar construction to the Dale parts.

As always, the data sheet holds the answer. Since you don't have a data sheet, the best you can do is take your chances.

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