Possibly Dumb Question re:Battery as a power supply


I have bought a new Clearaudio Performance DC Wood turntable.  I plan to drive to the dealer in Atlanta and pick it up next Wednesday.  I have seen the wall wart power supply which comes with the TT, and it is not a pretty sight.  Clearaudio sells an upgraded 12V battery and charger supply for "only" $1,200.00.  I don't wish to present myself as a parsimonious individual,  but $1,200.00 seems a bit steep to me.  I am wondering what problems would ensue if I bought a moderately sized (say 25 or 30 lbs.) , sealed, lead acid, 12V rechargeable battery; attached the proper wires to connect to the TT, and used it as a power supply.  When the battery runs down I could just take it to my workshop and use my electronic, automatic battery charger I use to recharge car, truck and tractor batteries to bring it back to full power.  As little current as the TT uses this shouldn't be too frequent a chore.  It is just a possibility, but if it is feasible I might try it.  I would really appreciate any and all comments, criticism or warnings.
kingharold

Showing 6 responses by lewm

Like a wealthy friend of mine often says, it's easiest to write the check.
Drop out due to VR is usually dependent upon many factors including current draw most importantly. I built a PS for my Klyne 6LX which has regulators on board the audio chassis. The PS needed to put out not more than 4-6V above the needed regulated V. I am sure an 18V battery or a 24V one at most would work for the clearaudio. We don’t have enough info even to guess.
Terry, you make some very good points, which make me wonder what is the voltage rating of the battery in the Clearaudio kit. You can’t add regulation, which is needed to hold V constant, to an unregulated 12V output and still have 12V downstream from the regulator, assuming the motor requires all of 12V. All regulators consume some V. So either they use a battery that puts out >12V or the motor runs on less than 12V.
Dear Mijostyn and anyone else, Did you not read my response to Noromance’s warning about noxious gases? Optima batteries are sealed, have no vents, and do not emit anything, let alone noxious gases. From the website:


"Sealed absorbent glass mat (AGM) batteries like OPTIMA® Batteries do not spill, sulfate or degrade like flooded batteries do. AGM design holds the electrolyte in suspension while keeping it in constant contact with the active lead material on the plates. This results in higher efficiency when both discharging and recharging.


AGM design offers lower internal resistance and greater plate area, which provides superior starting power, the ability to recharge much faster and higher voltage characteristics during discharge."


The blurb goes on to mention the Optima digital trickle charger, which I also own and which I recommended to the OP. I have used Optima batteries in all my collector cars since the early 90s with zero problems. I have also run 12V tube filaments with a huge Optima battery sitting in my living room, for several years, with no problem. Shame on you for not having one in your Porsche. After a conventional 6V battery, chosen because it was an accurate reproduction of the OEM Porsche 6V battery in my 550RS Spyder, puked acid into the forward area of the car, I replaced it with an Optima 6V battery, which you can even mount lying on its side, as I did to make it fit into the Spyder. (Early Spyders were 6V.)


Clearthinker, The question asked by the OP was not "whether" he should use a battery to run his turntable.  The question was whether he should spend $1200 on the Clearaudio battery and charger vs using some other battery. I don't disagree that maybe the OP would be best off with an outboard linear regulated 12VDC power supply, but I certainly do think the Clearaudio battery and charger are overpriced and could be replaced by excellent much less expensive equivalents.  (Actually, now I think of it, there may be a voltage regulator built into the turntable, which is why it can be run by a simple external battery.  So maybe the outboard linear supply need not be regulated.)


First, my condolences to you, Kingharold. So sorry to learn of your recent bereavement.  Sounds like your wife was a wonderful person.

Second, having been the first to recommend substitution of an Optima auto battery for the $1200 Clearaudio battery supply, I would point out that Optima batteries are sealed and do not vent any noxious gases, ever. Noromance makes a valid point that an unloaded car battery will make up to 14V when fully charged.  Whether that would damage the DC motor or not is definitely worth worrying about, but I don't think the danger would be much ameliorated by an in-line fuse.  A fuse senses current, not over-voltage. One would have to determine whether the load presented by the motor will pull down the voltage to an acceptable range around 12V, and if not, and if one were really determined to go this route, one could calculate the current draw necessary to bring down the voltage to the desired range and insert an appropriate resistor in series.  (I really doubt it would be necessary but worth evaluating.) Optima make a sophisticated trickle charger specifically designed for use with their batteries.  I recommend that too.  I have been using Optima batteries for 20-25 years on one or another classic car in my closed garage, with nary a problem.  I am sure some of the smaller size batteries discussed here would also work, but there you would have to worry about its maintaining output voltage over the course of a long listening session, because in my experience battery-powered audio gear does not sound good with charger in operation.  Smaller batteries tend to have less capacity to store current. And finally, I did find that capacitance in parallel with the battery output did audibly improve sonics, for whatever reason, in my one long term experience with battery power.  I used a couple thousand microfarads in the form of 16V electrolytics wired in parallel.

But third, I also like what Bill said about using a regulated linear power supply.  I am sure you can buy a good one off the shelf for less than half of $1200.
I don’t see a problem. The clearaudio price is beyond ridiculous. Get a 12V Optima car battery and the Optima “smart” trickle charger, for maybe $200 or so, and be happy. Best to shut down the charger when you’re running the TT, and for an extra tweak, bypass the battery with a couple of thousand uF of capacitance. This reduces the output impedance.