RAMPS with higher than 15A power supply

I have an over 20Amps 12volt power supply and looking to use it for the heated bed. My RAMPS is 1.3 version. My MOSFETS are the same as listed in the main parts list for 1.2 and 1.3.
I found a reference on the RAMPS 1.2 page:

Quote
RAMPS 1.2
powering the heated bed directly form the main PSU, grounding on the RAMPS
connect + from the PSU to the power plug of the RAMPS; connect the bed directly to the main power +, connect the other side of the bed (ground) to - on the RAMPS (D8) cause the mosfet is just switching the bed on and off it is barely getting hot and can handle the power pretty well.

Is anyone currently doing this? I do not want to toast anything on my board.
I am trying to do this without installing a relay. I have 6.0 and 6.8 resistors for the heated bed and would prefer to use the 6.0 to try an get some more heat.

Suggestions, comments

Yes. This is how I do it. You can never have too many amps. Think of it like money. Each piece of the electronics will require a little bit of your amp money, and as long as you don't go broke, everything should work. Now. If you are drawing 2 amps on each stepper (assume 5), that's 10 amps, and you got 5 left. Not enough for hot end AND heated bed.

I use a PC power supply rated 12VDC @ 29 amps. It was not easy to find, but it works much better than the 23amp PSU that I had been using before I got the heated bed. Hope this helps.

... it's not the amperage of the PSU what's burning the tracks, but the consumption of the specific device - you can attach a PSU with >100Amps, but only the current will flow, that your heated bed, extruder or motors draws.

So check what's the power consumption per connector if you want to stay safe with the copper track width or Ampere ratings of the MOSFETS.

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Viktor
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mc_n_g Wrote:
-------------------------------------------------------
> I have an over 20Amps 12volt power supply and
> looking to use it for the heated bed. My RAMPS is
> 1.3 version. My MOSFETS are the same as listed in
> the main parts list for 1.2 and 1.3.
> I found a reference on the RAMPS 1.2 page:
>
> powering the heated bed directly form the main
> PSU, grounding on the RAMPS
> connect + from the PSU to the power plug of the
> RAMPS; connect the bed directly to the main power
> +, connect the other side of the bed (ground) to -
> on the RAMPS (D8) cause the mosfet is just
> switching the bed on and off it is barely getting
> hot and can handle the power pretty well.
>
>
> Is anyone currently doing this? I do not want to
> toast anything on my board.
> I am trying to do this without installing a relay.
> I have 6.0 and 6.8 resistors for the heated bed
> and would prefer to use the 6.0 to try an get some
> more heat.
>
> Suggestions, comments

The effective resistance of your heated bed should be around 1 ohm if you want to get enough power with a 12V power supply (I=V/R = 12 A, P=V^2/R = 144 watts) to heat it for use with ABS which needs 110C or above. You can do this by combining your resistors in series and parallel. Six 6 ohm resistors in parallel would give 1 ohm while six 6.8 ohm resistors would give 1.13, slightly less power but probably still enough. You can also do it with 4x 4 ohm resistors or 4x 1 ohm resistors in parallel/serial.

I appreciate the replies. That helps to know someone else is doing similar hookups.
I will have to experiment with the resisitors and power supply and see how it works.
Just a little bit more and then onto testing phase.

Thanks,
Jon