A Battery Power Supply for the SL1200???

[Mike_New]

Hi Folks;

Regarding high energy power supplies; an economical, simple and relatively easy to make PS can be put together using Lithium batteries.
Using 3.75V @ 6800mAh These cost $143.00; and having 6 of them will cost $850.00 (about 500 pounds)
This will give a voltage of 22.5V, which in my judgment will not in any way upset the control system as the basic 21V input voltage is mainly used to power the driver chip and motor coils.

The running current is approx 220mA as measured on my Fluke meter. and using my Copper Bonded Alluminium Platter and Bearing.
The starting current is a max of 600mA for about 2 secs.
The braking current is about the same.

So assuming a worst case of 250mA then the set of batteries will last
6800/250 = 27hrs of running time.
And can be recharged over night at any time as they do no exhibit memory problems.
No enormous transformer to produce ‘noise’ and no electronics to be made up.

If you are concerned about the 22.5V; then alternative Lithium/Ion batteries can be obtained at 3.5V giving of course 21V. these however do not come in the high AmpHour ranges. These batteries are less costly so the set of 6 will probably cost only about $600.00 and give about 18Hrs running time.
I am not an expert on these batteries, however I understand that they can be left on permanent charge, as long as you use the correct type of charger.
Incidentally these batteries can release very heavy currents on demand.

So a high power PS with no transistors or transformers or diodes or smingle wiggets.

[UV101]

Interesting idea :)

I doubt the additional 1.5v will make much difference but it would be worth checking any maximum voltage for anything directly connected to this rail.

I think charging would be a royal PITA!

All the batteries would be in series and I'm guessing that they'd need to be separated for charging or at best in parallel? or are there charges set for this type of cell that can be adjusted to output the correct charging voltage.
If we assume you can charge the in series, you'd need to disconnect the batterys from the techie whilst charging.

[Mike_New]

The 21V rail is regulated down to 9V and also to 5v via a resistor network to supply the 5V to the quad NandGate IC not a problem IMO.
My ideas as posted, represent a possible solution, I would be happy to persue the topic with anyone who is interested. Charging would be a problem to investigate.
But these days everyone is using Lithium/Ion for obvious reasons, except perhaps Boeing!!!

[NRG]

There's lithium and there's lithium. I'd advise caution.

LiFePO4 cells have a nominal 3v3 cell voltage and on full charge 3v6, 6 cells will give 21.6v on full charge but drop to an average 19.8v for the majority of their discharge.

The more commonly found LiCoO2 and compound cathode types have a nominal voltage of 3.6/3.7v with a max charge of 4.2v....6 cells will give you 25.2v on full charge...are the electronics going to be OK at that voltage?

The voltage will be approx. 22v for the majority of the discharge which should be OK I would guess.

Charging is an issue with Lithium cells, ask any RC hobbyist and monitoring the discharge important so as you don't discharge the cells too low and damage them...

Capacity wise you probably wont realize the full cell capacity as for long life its best to stop short the discharge not only for protection but to increase the cycle life of the cell.

To me is sounds a hassle and if you really wanted to use batteries maybe a pair of SLA's would be better.

[NRG]

Forgot to add there's another lithium type, LiMn2O4, with nominal 3.6v cells. Same charge/discharge as above but this type of cell self degrades over time loosing anywhere from 10 to 20% (and sometimes more if poor production) of its capacity per year....best avoided IMHO.


.... I understand that they can be left on permanent charge, as long as you use the correct type of charger.
Incidentally these batteries can release very heavy currents on demand.



Most definitely do not leave them on permanent charge! And yes they can discharge huge amounts of current so be very very careful with them.

[Concerto Audio]

Red Wine Audio can make battery power supply according to your specaiications.I have bought Black Lightning 26 Vdc pure battery power supply and use it on my YBA cd plyer powering the anolog circuit with great effect. Battery charge lasts around 60 hrs.

[Mark Grant]

Incidentally these batteries can release very heavy currents on demand.


If they are accidentally shorted out the results can be spectacular :eek:, remember to fit a fuse as near to or attached to a battery terminal.

A fuse in the turntable wont do as the wire from battery to turntable could be shorted accidentally. The fuse needs to be at the batteries.

These things really can be a fire hazard if things go wrong.

[Wakefield Turntables]

Sounds like a good idea in principle but most 1210 freaks have some form of power regulation / regeneration / cleaning for getting the best current into there 1210's.