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Watt/Ampere for heatbed
Posted: Thu Nov 24, 2016 3:43 pm
by robvoi
Hi,
how many Watt/Ampere can I draw for my heated bed when running the GT2560 with 12V?
Thanks
Robert
Re: Watt/Ampere for heatbed
Posted: Fri Nov 25, 2016 9:26 pm
by russellz
The heatbed measures 3.7 ohm so at 12 V it will draw 12/3.7 = 3.24 A (less a bit for the voltage dropped by the mosfet). So about 3.2 x 12 = 38 W.
Russell.
Re: Watt/Ampere for heatbed
Posted: Fri Nov 25, 2016 9:34 pm
by robvoi
Hi Rüssel,
thank you for your reply. I would like to know what the max is which I am allowed to draw from this board/port.
Robert
Re: Watt/Ampere for heatbed
Posted: Sat Nov 26, 2016 4:18 am
by russellz
Have a look at the user manual here
https://www.geeetech.com/Documents/User ... GT2560.pdf. It seems to suggest 12 A is the maximum.
However I wouldn't want to go any higher than the current draw of the standard heatbed without extra heatsinking. The heatsink on the output mosfet gets pretty hot as it is. Higher current will make it run hotter and increase the likelihood of failure. I would also be unsure of the rating of the connectors on the board but then I'm cautious.
Russell.
Re: Watt/Ampere for heatbed
Posted: Sat Nov 26, 2016 4:48 am
by robvoi
Thank you for the advise.
Re: Watt/Ampere for heatbed
Posted: Wed Nov 30, 2016 5:28 pm
by russellz
Apologies, 3.7 ohm is for the extruder. The heatbed is 1.2 ohms so 10 A and 120 W. I have placed insulation under the bed and I put an insulated blanket on top while pre-heating to speed things up.
Russell.