I recently cooked a skr 1.4 so I bought an MKS Gen L 2.1 with 2209 and some external mosfets for the heat bed and extruder. I am powering this board with a 500w atx power supply and want to step up the board’s power to 24v as the 2209s will perform even better. I was thinking of using the 150W DC-DC Boost Converter 10-32V to 12-35V 6A (Step-up only) SKU: 018-DCDC-BOOST-150W to step up the power and need to throw fuses in the system some were for the everything. Am I on the right path with what I’m thinking. Any suggestion will be appreciated.
Certainly, on the right track!
A couple of considerations when using converters is the amount of power used by the sub-system on the output and that the input can supply that amount of power (you also have to take into consideration the efficiency of the converter and the heat generated by the stepping-up).
Fuses are definitely a must when using the converter and even double and triple-checking the polarity before plugging it into the mainboard (learning the hard way isn’t the greatest experience)
A quick aside, were you making a RepRap printer? We love seeing makers getting there hands dirty and getting new things up and running!
Thats good I’m heading in the right direction because I ordered the parts the other day. I was finding it hard to find info on what amp draw different parts of a printer used. The printer came with a 12v 20 amp PSU, so my rule of thumb is that no part can draw more than 10 amps at any time and to increase safty I will use 8 or 9 amp inline fuses on the 12v side with active cooling.
While I can’t recommend unenclosed power supplies from MeanWell, as they require wiring to mains voltage, they do have some enclosed supplies that would simplify your installation quite a bit if everything can run on 24V:
Just something to think about, I’m not against your original idea at all!
Hi Thor and Liam
There are a couple of things to think about re these little beasties.
They DO NOT protect any equipment on the load side. Even as mostly they are mounted in said equipment. They protect the supply and wiring TO the equipment.
It is often said that the fuse protects the equipment it is fitted into. Not so. The reason a fuse fails is usually because something has gone amiss with this equipment and it has gone U/S anyway. The failure of the fuse has prevented any further damage to the supply and wiring.
If a failure is caused by over voltage and semiconductors fail open circuit they usually protect the fuse very nicely. If they fail short circuit the fuse will fail but this takes a finite time which is usually enough to cause every affected semi on the board to fail also. Most up market stuff will have over voltage protection in the form of a “crowbar” circuit which , in the event of a higher than safe voltage, bangs a short circuit across the supply purposely blowing the fuse.
I had occasion to measure this time once. At 100% over current a “normal” fuse took 7 to 10 msec to fail. Plenty of time for most semis to turn up their toes.
Just something to think about.
Unfortunately I ran into that issue quite recently with my printers LCD screen popping, now I’ve got a headless printer
I’m not sure that boost and buck DC-DC converters are the way to go here. They’re quite efficient and for fixed voltages they tend to also be quite reliable depending on the brand, although they do tend to get quite warm and depending on the ratio of voltage due to Kirchoff’s laws you will also need to consider the amount of current running through each side of the circuit (in the case of a spike for an extended period this could quite easily damage your printer’s hardware, it’s unlikely as your power supply will likely be quite stable on the output, but certainly something to consider as a disadvantage when using boost/buck converters in this setting).
As an alternative, if you do need to run both 12V and 24V in the same printer (which does seem a little strange, but not entirely unheard of when modding), I’d pick up a second supply if your ATX doesn’t provide both 12V and 24V out, and use some appropriately rated opto-isolated relays or MOSFETs set up to keep the two circuits isolated from each other, as this will provide much fewer headaches down the line if any components fail and be much simpler to rig up and maintain, nor do you have to worry about accidentally drawing too much current off your original supply when using the converters.
All the best with your project! Let us know how you go with it.
Ah that’ll do it! Was that one of the Creality printers? If so, it may be a good opportunity to give this a go if you replace it. I haven’t done so myself as I usually use OctoPrint and rarely use the actual controls on mine, other than for bed levelling or filament swapping. But it may be something interesting to look into for a quick weekend project, I suspect it will be the same or very similar with the Pro or v2:
I wouldn’t assume that. The controller board is able to manage the two high-current components separately, and it is quite possible that it will not turn both on at full power at the same time. If so, then the bed might draw more than 10A at initial heat, then get turned back to say 5A while the extruder draws perhaps 12A to get to its temperature. If you monitor temperatures as the printer prepares to start printing your will likely see that the bed and the hotend do not heat up simultaneously, and this might be the reason.
A bit of non invasive measuring would not go astray here, like a clamp meter or similar would it not.
It’d certainly make testing a fair bit easier and give us a better idea of what’s going on, but if as Jeff said the main board provides higher power output to the heat bed for example to cause it to head up more quickly and that hasn’t been previously measured it’s a good way to fry some relatively expensive parts very quickly, and be a potential fire risk
I’m not a printer expert, but your wiring diagram puzzles me.
You want the heat bed to run from 24Volt. If you use a 12 to 24 convertor to power it and then switch it off/on it with a MOSFET, there’s no need to have 24V on the MKS. If you supply the MKS with 24V then just use it to handle the heat bed directly, no need for a MOSFET.
Also, a ‘heater’ is almost purely resistive, so doubling the voltage will double the current. Rather than trying to measure current, you could try to measure the resistance with a multimeter, but I expect that it will be too low (something less than 2 ohms) for an accurate reading.
All in all, if the MKS can handle 24V, just get a big enough convertor, or run a 24V power supply.
I think you have replies mixed up here
I have not drawn any wiring diagrams.
I have not commented re mosfets use to switch a heater.
I did have some comments regarding fuses and their use.
I did suggest some non invasive current measurements maybe using a clamp meter or similar. A cold resistance measurement would mean nothing as the resistance of a heater (or incandescent lamp etc) will increase significantly when hot.
Once again I think you have me mixed up with someone else.
comments were intended for OP.
Thank you everyone for the info, theres nothing easy about this and this info helps
I’m keen to see where you go with this project! Let us know if you have any other questions!!
I ended up getting two of the 12v - 24v step ups, one for the control board and one for the bed as these can take 24v and so far the house hasn’t burnt down. I have a 10 amp fast blow fuse on both step ups and everything seems to be working nicely and I’ve done a couple of prints without any issues.