12V to 24V



  • I am doing some upgrades to my already heavily modified Rostock V3. This time it's PSU upgrade time 🙂 . My current setup consists out of a Duet WiFi with a 12V PSU, with an external 5V PSU arriving soon (see here). The 12V PSU supplies power to the motors and hotend heater. The bed is fed from 240V mains, with an SSR to control it. With the Duet having continuous power from the 5V PSU soon, it is time to tie in remote control of the main PSU. Coincidently I want to upgrade to 24V for the motors and hotend heater.

    I'm looking for tips on the upgrade process. I understand I only need to change the (E3D-V6) heater cartridge to a 24V suitable one and the thermistor/motors/SSR/Due 5'' can remain the same.

    Recommendations on a PSU are very much welcome as well 🙂 . I am looking at some Mean Well's that support a remote control signal to turn the PSU on or off. I'm thinking something around the 300W range. Both the HRPG-300-24 and the MSP-300-24 seem to offer what I need (As I understand the latter is just medical rated).


  • administrators

    Even a 150W PSU would be enough for that setup, assuming a standard single extrusion hot end.

    Don't forget that unless your fans are 5V already, you will need to either replace them by 24V or 5V fans or supply 12V to them.



  • For info, I have a 24v 200W fanless PSU running all but the bed heater on my printer. It's CoreXYUV. The mass of the XYUV is around 4.2kg and I'm currently sitting here watching it print at 240mm/sec continuously running 3 extruders. It's been throwing that mass around at these sorts of speeds for 13 hours.

    M122 reports this:

    Supply voltage: min 24.1, current 24.3, max 24.7, under voltage events: 0, over voltage events: 0

    So my recommendation would be a fan less 150 to 200W PSU because it's more than adequate and it's silent.



  • @dc42 Most of my fans are 12V Noctua's any tips on keeping these powered, buck converter maybe?

    @dc42 @deckingman I'd love to go with a fanless PSU for obvious reasons but I'm kind of held back by the fact that the PSU sits in the bottom compartment of my delta. While there is a 60mm Noctua mounted in the side, I wouldn't say there is much of an airflow. On top of that, there is the high powered bed heater that I imagine radiates quite a bit of heat to the compartment as well. Those things combined I assume the PSU will have a hard time keeping itself cool. For this same reason I was looking at an overrated (300W) PSU.
    Do you guys follow this logic or am I overthinking this?


  • administrators

    Do you have thermal insulation under the bed heater? I use a thick sheet of cork. Triple skin corrugated cardboard also works quite well.



  • @nxt-1 the PSU may have a spec sheet that will tell you the preferred orientation for installation as well as max ambient temp. Sometimes they need to be mounted vertically to allow for convective forces to cool the components.



  • @nxt-1 Well a fan less PSU does need free air around it so if it has to be enclosed, then maybe not such a good idea. Of course, having a fan blowing air into, or out of, the enclosure will help but that kind of defeats the object of having a fan less PSU.☺ 200 W will still be plenty though.

    As David has said, insulation under the bed is good idea for so many reasons (faster warm up, less fluctuations etc) as well as shielding other components from radiated heat. As well as David's suggestions, you could also consider what I use, which is the semi rigid glass fibre backed board as used with under floor heating.



  • @dc42 said in 12V to 24V:

    Do you have thermal insulation under the bed heater? I use a thick sheet of cork. Triple skin corrugated cardboard also works quite well.

    I have a 150x200mm sheet of aerogel insulator under the bed (see the attached picture) but that doesn't cover the entire 310mm dia bed.
    EDIT: please to excuse the crudity of the tape, this is only temporary 😉

    0_1539119625115_2018-10-09 22.59.12.jpg



  • @deckingman

    @deckingman said in 12V to 24V:

    @nxt-1 Well a fan less PSU does need free air around it so if it has to be enclosed, then maybe not such a good idea. Of course, having a fan blowing air into, or out of, the enclosure will help but that kind of defeats the object of having a fan less PSU.☺ 200 W will still be plenty though.

    As David has said, insulation under the bed is good idea for so many reasons (faster warm up, less fluctuations etc) as well as shielding other components from radiated heat. As well as David's suggestions, you could also consider what I use, which is the semi rigid glass fibre backed board as used with under floor heating.

    The Noctua is very quiet though so that's not an issue. Bellow a picture of the current state of affairs.0_1539119824550_2018-10-09 22.59.21.jpg



  • I have a 24V on a large-ish delta (600MM diameter bed, 24 inches), running everything but the heat bed (bed is on mains, via SSR). It has a fan that cycles sometimes when printing. Depends a little bit on room temp, and maybe a few other things. When it does cycle, it probably only runs 20% of the time.

    This PS: https://www.amazon.com/gp/product/B00KTJE3L4



  • Maybe @dc42 can answer this. Following the recommendations in this thread shifted my look from the HRPG-300-24 to the HRPG-200-24, which in fact is fanless. Would the Duet's PS_ON be compatible with the PSU's remote ON/OFF function? If I understand correct all the PSU needs is an open circuit between two pins to turn on and a short to turn off.



  • All of my PSUs that are that style have venting along the base, which in your picture seems to be all blocked. |This makes the fan pretty much useless to move air through much of the area that needs cooling.

    Most of these PSUs will tolerate a fair amount of heat, and if you're not really straining the PSU, it's probably not a big deal.

    Given the venting fan that you have though, I'd say that with some nice ducting, and a little modification to how things are mounted, you should be able to use a fanless supply, or use a supply that has a fan, and get rid of the extra. You want to direct air so that it must pass through the PSU, or at least over the mainboard plane. This could be done by way of a cover over the area between the fan and the PSU, assuming that air is drawn from below the printer.

    My Makerbot clone printer uses a fanless 12V supply and a fanless 24V supply. (The 24V supply is 200W, not enough to power the heated bed, and I had a 12V heated bed and 250W 12V supply, so I'm running those via an extra MOSFET.) These are cooled by a single 80mm 12V fan, which I have set up to pull air through both PSUs via some ducting, with the air drawn from the back, and exhausted out the front. (For now. I plan to change that at some point, but it works for now, and I can tell how hot the PSUs are by feeling the exhausted air.


 

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