Re: 24V with Ramps 1.4 questions February 10, 2014 04:15PM |
Registered: 14 years ago Posts: 1,092 |
Re: 24V with Ramps 1.4 questions February 14, 2014 03:58AM |
Registered: 11 years ago Posts: 18 |
Re: 24V with Ramps 1.4 questions February 14, 2014 07:05AM |
Registered: 14 years ago Posts: 1,092 |
Re: 24V with Ramps 1.4 questions March 24, 2014 03:31PM |
Registered: 10 years ago Posts: 8 |
Re: 24V with Ramps 1.4 questions March 24, 2014 05:48PM |
Registered: 11 years ago Posts: 14 |
Re: 24V with Ramps 1.4 questions March 24, 2014 08:18PM |
Registered: 14 years ago Posts: 1,092 |
Re: 24V with Ramps 1.4 questions March 25, 2014 12:11PM |
Registered: 11 years ago Posts: 14 |
I had the SSR mounted to a heatsink. I got a replacement shipped to me and I'll be adding a cooling fan to the heatsink to hopefully prevent the SSR from overheating.Quote
Cefiar
mkelly: if the heater is 1.1 ohm, at 24V that's closer to 22A, and possibly more at startup/cold. Note also that SSR's need to be mounted on a heatsink to handle their full current capacity. Also make sure you're using BANG-BANG control in your firmware, as the high switching speed of PID control on a heated bed will just make an SSR heat up faster.
Re: 24V with Ramps 1.4 questions April 02, 2014 07:44AM |
Registered: 11 years ago Posts: 32 |
Re: 24V with Ramps 1.4 questions October 16, 2014 03:06PM |
Registered: 11 years ago Posts: 66 |
Re: 24V with Ramps 1.4 questions October 18, 2014 02:59AM |
Registered: 10 years ago Posts: 590 |
Re: 24V with Ramps 1.4 questions October 18, 2014 09:27PM |
Registered: 14 years ago Posts: 1,092 |
Re: 24V with Ramps 1.4 questions January 16, 2015 12:50PM |
Registered: 10 years ago Posts: 752 |
Re: 24V with Ramps 1.4 questions January 20, 2015 01:28AM |
Registered: 10 years ago Posts: 6 |
Re: 24V with Ramps 1.4 questions January 20, 2015 04:32AM |
Registered: 11 years ago Posts: 14,685 |
Re: 24V with Ramps 1.4 questions May 18, 2015 02:46AM |
Registered: 12 years ago Posts: 25 |
Quote
imqqmi
Just wanted to share my experience on 12V heated beds on 24V.
I've got the following setup:
- Prusa i3 printer
- 12V 5A PSU for RAMPS 1.4 and arduino
- 24V 15A for heated bed cheap chinese PSU
- RAMPS board is a clone that supports 24V (fuse2 rated at 30V, 9A, markings: 30 FU900)
- MOSFETS on the board are IRF3205, Vds = 55V, Rdson = 8mOhm, Id = 110A. This MOSFET is a lot better than the original specced board. Vds is higher and the Rdson about a third of the original, which means that it will get far less hot. There are many MOSFETS that are suitable. Just lookup the datasheet of the MOSFET on your board and look for these values. IRLB8743 is also a good alternative.
- MK2b heated bed, 12V. Resistance = 1.26 Ohm. This means I = U/R 12/1.26 = 9.5A@12V, 24/1.26 = 19A@24V
I use two separate power supplies as the heatbed draws a lot of power and will give a dip in the voltage. This might have an effect on the stepper motors and fans. Whenever the heated bed is heating, the fan cooling the hotend heatbreak slows down, a sure sign that the voltage drops.
Hope this helps someone!
Re: 24V with Ramps 1.4 questions May 19, 2015 01:43AM |
Registered: 10 years ago Posts: 752 |
Re: 24V with Ramps 1.4 questions May 19, 2015 01:50AM |
Registered: 12 years ago Posts: 25 |
Re: 24V with Ramps 1.4 questions May 19, 2015 02:56AM |
Registered: 10 years ago Posts: 752 |
Re: 24V with Ramps 1.4 questions May 19, 2015 03:07AM |
Registered: 10 years ago Posts: 1,159 |
Quote
imqqmi
Yes, replace the step up converter by your dedicated 24V psu, that should do the trick. To avoid confusion, you say straight to the heated bed, which would mean without wiring it to the ramps board, that's not correct. You just need to wire the 24V to the 11A connector and the heated bed to it's own connector as is described in the wiki, to connector D8.
Re: 24V with Ramps 1.4 questions May 19, 2015 03:16AM |
Registered: 12 years ago Posts: 25 |
Re: 24V with Ramps 1.4 questions August 21, 2015 03:20PM |
Registered: 12 years ago Posts: 72 |
Re: 24V with Ramps 1.4 questions August 21, 2015 04:28PM |
Registered: 10 years ago Posts: 752 |
Re: 24V with Ramps 1.4 questions August 22, 2015 12:47AM |
Registered: 14 years ago Posts: 1,092 |
Re: 24V with Ramps 1.4 questions September 12, 2015 03:42AM |
Registered: 9 years ago Posts: 245 |
Re: 24V with Ramps 1.4 questions April 02, 2016 09:58AM |
Registered: 9 years ago Posts: 21 |
Re: 24V with Ramps 1.4 questions April 02, 2016 03:17PM |
Registered: 10 years ago Posts: 752 |
Re: 24V with Ramps 1.4 questions May 25, 2016 09:01AM |
Registered: 9 years ago Posts: 18 |
I do have 2 power supplies and I'm thinking of using the 24V one for the heatedbed. As far as I can understand I should connect the 24V PS to the 11A input of the ramps and the 12V PS to the 5A. What I don't understand is how to tie them together on the RAMPS board on the ground pin.Quote
Cefiar
You can run the 11A input on 24V and the 5A on 12V if you have either two power supplies or one that produces both voltages. If you are using two power supplies, they will be tied together via the RAMPS board on the ground pin. In 99.9% of cases this should be fine, as long as the PSU have independent grounds (some cheap knock-offs do not). You can also do the reverse if you remove the diode D1, assuming other components are rated appropriately.
Re: 24V with Ramps 1.4 questions May 25, 2016 01:05PM |
Registered: 10 years ago Posts: 752 |
If you connect both power supplies, effectively you tie both the 12V psu ground to 24V psu ground through the PCB tracks on the RAMPS. Some cheap and badly designed psu units may not have a properly decoupled ground and will cause a short circuit. It may be prudent to use a resistor between the two grounds without connecting it to anything else and see if it heats up. If one is not decoupled, it poses a danger to yourself too, so take proper precautions of not touching the wires.Quote
Khaled
I do have 2 power supplies and I'm thinking of using the 24V one for the heatedbed. As far as I can understand I should connect the 24V PS to the 11A input of the ramps and the 12V PS to the 5A. What I don't understand is how to tie them together on the RAMPS board on the ground pin.
Re: 24V with Ramps 1.4 questions May 26, 2016 02:29AM |
Registered: 9 years ago Posts: 245 |
I just Draw a line directly from DC GND out on one PSU and DC GND out on the other PSU. Always worked on every cheap chinese PSU I've ever used.Quote
Khaled
Hi,
I know I'm 3 years late with this question but I'd be grateful if you could elaborate a bit on this part of your answer
I do have 2 power supplies and I'm thinking of using the 24V one for the heatedbed. As far as I can understand I should connect the 24V PS to the 11A input of the ramps and the 12V PS to the 5A. What I don't understand is how to tie them together on the RAMPS board on the ground pin.Quote
Cefiar
You can run the 11A input on 24V and the 5A on 12V if you have either two power supplies or one that produces both voltages. If you are using two power supplies, they will be tied together via the RAMPS board on the ground pin. In 99.9% of cases this should be fine, as long as the PSU have independent grounds (some cheap knock-offs do not). You can also do the reverse if you remove the diode D1, assuming other components are rated appropriately.
Re: 24V with Ramps 1.4 questions July 16, 2017 07:56AM |
Registered: 10 years ago Posts: 6 |