Smart power supplies for turntable

Battery power supplies are great for turntables, phono stages, and all kinds of low power components. They all run on DC anyway. The trick is to get the right voltage to the right place, something they don't tend to make very easy. But it is worth doing even if you do have pretty good AC. Simply because the battery supply is disconnected from and eliminates all the RFI and noise riding on the AC.

Sbooster and Farad both make very high quality power supplies. Sbooster is AC, essentially just a higher grade power supply. Farad is virtually a big super cap battery supply. Going with batteries you could just buy litium ion batteries in the right voltage and figure out how to hook em up. Use a charger with a relay designed to stop charging so the unit is disconnected from AC when playing music.

I had a battery supply just like this for my Teres turntable motor. It was a nice improvement over AC, and consisted of little more than a motorcycle battery and a charger on a circuit board. 

The trick isn't really the power supply. Those are easy. The trick is getting the power supply connected. Not that hard, it can be done, but usually not plug and play. 

If your local AC is truly "dirty" and unstable as to line voltage, then you might consider a power regenerator, like any of several made by PS Audio.  These devices are like amplifiers; they run off your line AC, convert it to DC, and then put out a pure sine wave at 60Hz.  The PS Audio P3, which makes 300W of pure AC, is probably sufficient for your TT.  DC supplies made from batteries are fine also, if your TT uses a DC motor. You fail to specify what kind of motor is in your TT and what DC voltage it requires, if in fact it is a DC motor.  Meantime, your Nagra conditioner ought to be at least helping the situation, although conditioners and filters cannot control the magnitude of the AC voltage; they can only clean it up.

Forgot to mention the key fact that AC power regenerators deliver a rock stable clean 120V, as well as pure 60Hz. 

@millercarbon ​​​​@lewm Thanks to you both for your responses, which confirm I am on the right track. 
 

To clarify, I have a Clearaudio turntable with a 12v DC motor. Clearaudio indicates  that their DC power supply is voltage stabilized, yet they sell a separate 12v battery power supply. This suggests the stock power supply has some limitations. 
 

My APC S-20 power conditioner and UPS which I use for computer and video gear has a voltage display that clearly indicates variations from 120 to as low as 113 volts, with changes at seemingly random times. I suspect this may have an effect on the turntable speed, but haven’t checked with a strobe or other device. If I can confirm that is the case, then the question is whether to get a battery power supply like the Clearaudio or a regenerator or similar device that can power multiple devices. The Farad LPS suggested by @millercarbon is for a single device, but is a lower cost alternative to the battery supply. Will it work as well?

As to EMI/RFI, I am confident the Niagara 1000 is doing a good job there, as my wife and I both can discern a very noticeable improvement in resolution and detail with the digital sources, pre-amp and amp plugged into that unit. 

Any further thoughts you may have are sincerely appreciated.