24V powersupply vs. 12V

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24V powersupply vs. 12V

Post by Tadpole1 » Wed Jan 15, 2014 4:15 pm

Excuse me if this was covered already. I looked but didn't find anything.
I recieved a 24v powersupply with my order for the European full kit. I see a lot of references to a 12V power supply. The GBRL v5 says it can take up to 30V. What are the Advantages/disadvantages to the different power supplies, and is there a reference online that would go into more Detail about the Steppers and how they function? Thanks in advance.

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Re: 24V powersupply vs. 12V

Post by potatotron » Wed Jan 15, 2014 5:07 pm

Taken from http://www.schmalzhaus.com/EasyDriver/#Q14
Lower voltages produce a lot less heat (on the ED and the motor) but produce lower maximum speed and torque. Higher voltages (up to 30V) get you more torque at higher speeds, but your ED will get much hotter. You make the decision.

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Re: 24V powersupply vs. 12V

Post by cvoinescu » Fri Jan 17, 2014 9:12 pm

I can't find the link, but Alden from Syntehtos (the makers of TinyG and grblShield aka gShield) said that driver chips actually run cooler at higher voltages. Synthetos use Texas Instruments DRV8811, 8818 and 8825 chips in their products, but the observation applies to the Allegro A4988 too. This makes sense, because most heat in a modern driver is due to the non-zero R_DS(on) of the MOSFETs; with an inductive load, the current stays the same and a shorter on time translates directly into smaller losses. With older, slower choppers, a significant part of the loss is due to the finite turn on and off times, and increases with the supply voltage; this type of loss is small in the drivers we use these days.
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