I bought a Helios heated bed as an upgrade to my MendelMax 1.5. No clue how to hook it up. I’m using a RAMPS board with Marlin firmware. I know I need a thermistor, but I don’t know which type or where to buy it. I’m also wondering if I need to run the power through a relay or can I connect it directly to the ramps board? I’ve got a 30amp power supply… Any help would be GREATLY appreciated. http://www.panucatt.com/product_p/hbp200.htm
Thank you Colin! So I can wire the bed directly to the ramps board? I don’t need an intermediate relay to run power more direct from the power supply?
You can run it directly from the Ramps board as long as your power supply has enough juice which is sound like it does.
Make sure to measure the resistance of your bed. Using ohms law, you can calculate the current that will actually go across the bed. For example if you had a 2 ohm bed and 12vdc supply, the current would be v/r, or 6 amps. The power would be v^2/r or 72 watts if my math is right. No matter how much current or power your silly is rated for, it will never exceed this. To increase current and power given a constant resistance, you need to increase voltage. Good luck
@Eric_Moy most multimeters have a hard time measuring resistances that low. Panucatt states 12A on their website, which is right in line with a standard Prusa PBC.
The Ramps uses polyfuses (the tall yellow things next to the power connectors) by default, which can cause some really weird behavior. If your printer unpredictably “dies” in the middle of prints or fails to move properly at times, try shorting each fuse and see if that helps, @Matt_Donley .
@Thomas_Sanladerer , 12 amps at what voltage? If the resistance is so low that a dmm won’t measure it, the the power output would be incredibly low. I have a 2 ohm heater on a 12 volt power supply and I can’t get my bed above 80c. Given, my bed is enormous, but just from a power standpoint, sub ohm haters aren’t going to provide too much heat.
Thanks @Eric_Moy @Thomas_Sanladerer for the help. It sounds like my 30amp power supply can handle it but I’ll do some more homework before I hook it all up.
@Eric_Moy all at 12V, so the resistance is somewhere around 1Ohm. As you mentioned, P=U²/R, so for 1Ohm and 12V that’s 144W. These heated beds get up to 125C after a while, possibly a bit higher if you have fat wiring and a low-RDSon mosfet.
@Thomas_Sanladerer , gotcha. I’m STILL slowly redesigning my printer and collecting my BOM so I’m always looking for options. I still think I’m going to buy a 120VAC silicone pad to use with my already purchased SSR though