15A Fuse burning out
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Hello
I have Tronxy X5S and configure Duet Wifi from this video. https://www.youtube.com/watch?v=6nqddfxHla0
Every thing working good but 15 A fuse (bedheater) all the time burn out, when i want to heat up my table from 30 to 40 (burn out), when 30 to 100 (burn out).
My Power Supply is 12V 30A.Someone knows something?
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What's the resistance of your bed heater? 0.8Ohm or below and that's your issue. Too higher power heater for the fuse.
Also check that there are no shorts between the heater +/- and the surface of the bed heater, or the bolts securing it.
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Resistance is 0,8/0,9 Ohm
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Then What?
I don't know if i can buy bigger fuse, like 20 A for start.
Maybe board wont withstand such current. (or Mosfet) -
As a temporary fix you can reduce the duty cycle of the bed heater, but it'll take longer to get up to temperature.
ref P parameter in M303
https://duet3d.dozuki.com/Wiki/Gcode#Section_M303_Run_heater_tuning -
yes i would suggest you get a mosfet for the bed.
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Modulating the heatbed to avoid the high current would be my first choice, second redesigning the heatbed with a more powerful heater at 24V.
Another simple option is an external mosfet like the ones used for RAMPs boards.
On the following page the limit is stated at 18A for the duet 2:
https://duet3d.dozuki.com/Wiki/Choosing_a_bed_heater
I think it is just 18A fuses aren't available for automotive style fuses. You can get 18A fuses. If you desperately want to run at full wack on your current setup at 12V and if your 0.8/0.9 ohm reading is accurate you will be able to to put an 18A fuse between a spare posative output from your PSU and ground the heater through the normal negative heater connection on the board. Keep the fuse as close as practical to the PSU with the length of wire between the board and inline fuse well protected.
All that said at 0.8ohm you have a 180w heatbed heating a 300 x 300mm bed. Excusing the dress makers units the recommendation on the previous link was 0.4W per square cm, and 360W for your build size. I think your heatbed is going to seem very slow and going much past 50C maybe a challenge. Your efforts may be better spent upgrading to a more powerful heatbed.
Edit: @Veti responded whule I was writing.
Edit2: Always make sure you understand and are happy with the recommendations before doing something.
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@beginning-freak said in 15A Fuse burning out:
Resistance is 0,8/0,9 Ohm
Did you subtract the reading you get when you short the two meter leads together? That is often a significant fraction of 1 ohm.
A 15A fuse will take quite a lot more than 15A for a few minutes before it burns out. Therefore, if the fuse is burning out quickly, the bed heater is likely to be drawing more than the 18A limit of the Duet. So you should use an external SSR or mosfet switch for the bed heater. Best is the Auberin DC-DC SSR that I link to he the wiki page about bed heaters.
