Possibly Dumb Question re:Battery as a power supply

@lubachl 
I actually have an Amazon Model One - it's a superb motor unit - I think that is a great buy because the Amazon motor is actually not your usual DC motor - I think the UK importer at the time advised me it was from a nautical clock. It is exceptionally smooth and quiet.
@kingharold - why more people don't rug up a car battery is beyond me - they can easily be tucked away. Lithium Ion is particularly good as the voltage drop is very consistent. Be careful though not to discharge them too much as they become unstable and in fact volatile. I know all of this from Radio Control car racing. Not all lithium ions are created equally and I am more than happy to recommend those used in RC racing that are of a good quality. 

@terry9-

ELECTRICAL CHARACTERISTICS (Vin = 19 V, IO = 500 mA, TJ = Tlow to 125°C (Note 17), unless otherwise noted)

That is the standard disclaimer at the top of the chart of parameters. It is the operating point used in all of the measurements below it. One of those parameters is DROP OUT VOLTAGE which was listed as 2.0VDC (assuming 500mA load) on the datasheet I found on-line. The disclaimer does not mean the device has to be operated at those parameters, only that the published specifications were measured at that operating point.

Agree with your point about noise not being an issue. I don’t know that I’ve ever seen a measurement for this on a battery, but the internal resistance of a fully charged battery is extremely low so the equivalent noise resistance should be microscopic.

I would think a Sealed Lead Acid battery would be better (and cheaper) than a NiCad. SLAs tend to last longer and don’t suffer from memory effect if they are not fully cycled between charge and discharge as NiCads do. YMMV.

Phoenix, agree with what you say, but let me add that 19VDC is the voltage at which the part is known to meet spec. With obvious consequences - which, to an engineer such as yourself, pose no issues.

Battery noise was measured by someone in Germany some years back. I think they were looking at powering phono stages. He found that all technologies made a fair bit of noise, except NiCd, which measured at the noise floor of his HP instrumentation.

Anyway, I'm in the process of designing a new phono power supply based on NiCd's for listening and a linear PS for warming, and the unexpected issue is charging. Seems that no-one does it right - i.e. warning at 1.1VDC per cell to avoid memory effect and separate current source for each cell.

Expect to start building in a couple of weeks, will let you know if it makes a perceptible improvement over alkaline with LC filter.

Previous experience with improving power has shown a worthwhile improvement in sound. This manifests as smoother with no shrill overtones or sibilance (dare I say 'more musical') as well as quieter. 

1. Isolation transformers
2. Brute force DC rails for amps: 200kg inductors and a Farad of capacitance
3. Alkaline battery with LC filter for phono/pre
4. Quadrature AC adjusted to AC motor

My experience. YMMV

@phoenixengr, glad to see you join in this discussion, your expertise is greatly appreciated!
BTW, I’ve been using the Teres battery power supply on my turntable for more than 15 years without any problem and only replaced the SLA battery about 5 years ago. The SLA battery will charge up to 13.8V if not in use.

I found an internal image on the Hifitest.de review of Clearaudio smart power 12V.

https://www.hifitest.de/images/testbilder/big/clearaudio-smart-power-12v-hifi-sonstiges-57224.jpg

I can clearly see a LM317T regulator chip in the circuit, I could be wrong, but I think the LM317T is to regulate the output voltage while the 19V wall wart charging the NiMh battery and at the same time supply power to the turntable. In pure battery mode, I not sure if the regulator chip is in circuit or not. Without a schematic, just take a wild guess.
The user manual also warn that if connect the 19V wall wart directly to the turntable instead of the OEM 12V wall wart can seriously damage the turntable!
Since we don’t know what is the highest voltage the turntable can safely take, and OP also concerned if 14V will be too high for his turntable, that’s why I came out the " overthinking " dumb idea of install a simple voltage regulator between the battery and turntable.