Help ! Converting RAMPS 1.4 to 24 V

I came across following statement on reddit while searching on how to use 24 V for RAMPs 1.4

Quote "Other than that, you need to set your PID_MAX to 64 in your firmware if your hotend is designed for 12v. This limits the on time of the hotend to 1/4 to make a 12v hotend work on the 24v system." Unquote

I am not questioning the authority of this statement. However, will the RAMPS 1.4 eventually work if I remove D1, use dedicated supply for arduino and just power up 24 V on RAMPS board ?

IMO it is most unwise to run a 12V hotend on 24V with reduced PWM. If the firmware or hardware goes wrong and applies 100% PWM, it may melt the heater block and/or start a fire.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Your still applying 24v to a device that was designed for 12v, even if briefly. That will stress the device out and eventually kill it

DC42 and Dust are way more knowledgeable than I on these things, but I have a fair bit of electronics background and I would NEVER run a resistive element on double the designed voltage and trust that a switching device would flip it on and off at a high rate of speed to compensate!

DONT DO IT!!!

get a 24v heat cartridge....

[www.aliexpress.com]

Ouch !

I don't know how to thank you all people. But you saved me - literally.

But than in actual sense, is it really a good idea to convert to 24 V because if it is so, why the RAMPS is basically 12 V design ?

Best Regards

Viren

Edited 1 time(s). Last edit at 12/05/2017 08:39AM by viren.

Arduino/RAMPS + stepsticks is budget electronics - probable the lowest-cost electronics you can get, which is why it is so popular. If you are on a tight budget and you have some reason why you need to use 24V power, then go ahead and upgrade it to 24V. But if you are spending a serious amount of money building a large or fast printer, then I suggest you buy better electronics that is already 24V-capable and may offer additional advantages (e.g. reconfiguring the firmware without having to rebuild and upload it, web interface, 32-bit processing power, etc.).

The benefits of 24V power are:

1. It halves the current you need for the heated bed compared to using 12V power. This is an advantage if you have a large or powerful bed heater. An alternative is to use an AC mains voltage bed heater.

2. It allows the stepper drivers to move the stepper motors faster, especially if they are 0.9deg motors. This is especially significant on delta printers (but you also need a 32-bit controller to get high speeds on a delta).

For the typical budget Cartesian printer with 200mm square bed, 24V power doesn't offer any significant advantages.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
viren
Ouch !

I don't know how to thank you all people. But you saved me - literally.

But than in actual sense, is it really a good idea to convert to 24 V because if it is so, why the RAMPS is basically 12 V design ?

Best Regards

Viren

IMO its really NOT a good idea to convert a Ramps to 24v. If your really on a budget spend the extra $5 or $8 and get the MKS Gen 1.4 as its 24v ready and make sure you have 24v parts to go with it.

If you can fit it in the budget get the Duet WiFi. I did a lot of looking around and I honestly think that the Duet is the best designed controller out there at this time.

The way that DC42 keeps up on assisting users made the decision for me. If you want good help, read the duet section here and see how he keeps everyone working well...

Edited 1 time(s). Last edit at 12/05/2017 12:02PM by JustSumGuy.

Quote
dc42
.....
The benefits of 24V power are:

1. It halves the current you need for the heated bed compared to using 12V power. This is an advantage if you have a large or powerful bed heater. An alternative is to use an AC mains voltage bed heater.
.......

Half the current or Double the current ?....Let me verify my understanding and clarify my basic - I may be grossly wrong here.

Hypothesis #1
What I understand is say I have a heated bed which is having a fixed resistance due to its physical configuration/setup etc. Now Current = Voltage / Resistance. Now, resistance of my bed is fixed and I am increasing voltage from 12 V to 24 V i.e. Will the current requirement not get doubled ?.

Hypothesis #2
On the contrary, Watt = Voltage x Current and since the power requirement of bed is same and I am doubling the voltage, current will get halved for keeping the multiplication same

Which of the above is true and why ?

Quote
viren

Quote
dc42
.....
The benefits of 24V power are:

1. It halves the current you need for the heated bed compared to using 12V power. This is an advantage if you have a large or powerful bed heater. An alternative is to use an AC mains voltage bed heater.
.......

Half the current or Double the current ?....Let me verify my understanding and clarify my basic - I may be grossly wrong here.

Hypothesis #1
What I understand is say I have a heated bed which is having a fixed resistance due to its physical configuration/setup etc. Now Current = Voltage / Resistance. Now, resistance of my bed is fixed and I am increasing voltage from 12 V to 24 V i.e. Will the current requirement not get doubled ?.

Hypothesis #2
On the contrary, Watt = Voltage x Current and since the power requirement of bed is same and I am doubling the voltage, current will get halved for keeping the multiplication same

Which of the above is true and why ?

Both are essentially true, in #1 your taking a 12v heat bed and running it on 24v so your amp would be doubled and your heat bed would burn out....
for #2 your heat bed is designed for 24v and has a higher resistance. The result is your amp draw is cut in half and your total wattage remains the same.

Many hotbeds have two 12v heating elements, run in parallel you have a 12v hotbed of say 200 watts. To run 24v you change to serial configuration in order to double your resistance and you still have a 200 watt hotbed btw....

Edited 2 time(s). Last edit at 12/06/2017 11:26AM by JustSumGuy.

Thanks everyone. Everything is answered.