questions: linear vs switching power supply

[haddow]

Why is a linear supply "better" for charging batteries? what is a switching power supply and why is it more efficient?

It take it efficient means easier on mother nature, not more efficient  at getting a battery charged?

haddow

[Tom]

A switching power supply works using the same principles as an ESC, while a linear power supply works using similar principles as a MSC.

A switching power supply will produce a square-wave output, which is smoothed with capacitors.  However, these capacitors won't even out the power completely; there will always be some ripples.  This is fairly efficient, since the "on" resistance of the transistors is quite low, and they don't spend a whole heck of a lot of time switching, which is when the drop across the transistor produces heat.

However, a linear power supply will use its transistors as a form of variable resistor, which converts all the excess electricity into heat.  However, since they're not switching, the output power is steady and "clean."  The power will be truely DC, while the output from a switching supply is AC, with a DC offset.

One further difference between the two styles is RF radiation.  Switching power supplies tend to put out a great deal more radio interferance than linear power supplies, and this is somewhat significant around the R/C track.  I've been to more than one R/C car race where people tend to glitch around one pit area due to noise generated by the switching power supply.

A linear power supply will tend to use more electricity out of a wall plug to do the same thing than a switching power supply, but other than that, they will both get the job done.  I wouldn't be surprised if people would get more false-peaks out of a switching supply than a linear supply, depending on exactly how clean the output is.

[Tom]

Basically, linear is better than switching, but switching is more efficient (difference between power in and power out) than linear.

[haddow]

thanx thomas that answers the question and stimulates a few more

[Grinder]

A linear supply is big and heavy because of the required large transformers.  Its also good for mono block amplifiers that require very clean power.  They are also good for heating small rooms and holding heavy doors open or large stacks of paper down.

Most of the new chargers are switching power supplys inside anyhow!  Any charger that will charge higher than its input voltage is a switching supply.  I've use quite a few chargers on a switching power supply and I've never seen any false peak on a switcher that wouldn't false peak on a battery (cleaner than a linear supply).  False peaking has more to do with the "brains" of the charger than its supply.  The only time I've seen a charger false peak from a supply is when the voltage varries by a volt or more (like when you are driving your car and charging from the lighter plug).

A linear supply is typically easier to fix if its require (as long as the transformer doesn't go - expensive!).  Go with a switcher though.  Its lighter, uses less power and typically much cheaper and won't cause false peaking.

Oh and batteries like to be pulse charged anyhow....  but thats a function of the charger not the supply....