My 24vdc Battery Project

These are actual measured voltages and not nameplate ratings which can differ on load if not regulated.

Also, it is very important NOT to try and power the Elevator EXP by the same supply that our other products are using (in this case the Era Gold V).

This is because the zero volt terminal (the negative terminal of the battery in this case) is actually -9V DC in the Elevator EXP. And in the case of the other products (Era Gold V included) zero means 0V.

By powering both from the same source they won't instantly destruct UNTIL you connect them together with an interconnect, when the RCA jack 0V of the Elevator EXP, which is actually 9 volts above the power supply zero terminal, is shorted by the 0V connection via the interconnect to the RCA jack 0V of the Era Gold V, which IS the zero terminal of the supply.

You instantly lose 9 volts via the interconnect and that's a short circuit, and if using a PSU1 the fuse would blow. With a battery things are not entirely the same - a series fuse may not prevent it.

So DON'T DO IT!

OK, now the info you wanted...

Firstly the currents: EXP = 50mA approx.; Era Gold V = 15mA approx.

To prevent the EXP's internal regulator overheating it is wise to stick as close as possible to its regular 24 V DC (27 volts is OK). The regulator will not be damaged because it is thermally protected, but it could shut down.

The Era Gold V draws substantially less current and can take up to 35V DC measured. Any more and the input filter electrolytic capacitor's life would be shortened. A considerable proportion more and it would blow.

The minimum voltage is not the regulator input voltage but the series protection diode voltage drop has to be factored in. With a zero ripple supply (which a battery is) 21 volts is the minimum. However, with an AC derived supply there will always be some ripple, and although minimal, it is best to allow half a volt more (21.5V DC, actual measured voltage again).

If you do use lead-acid remember that a discharged battery needs to be charged straight away, otherwise it will sulfate and be ruined.

I'm running the Elevator EXP off a pair of 12vdc SLA batteries now.  The PSU1 linear supply must be outstanding because my quick unscientific test proved no difference between the battery pack and PSU1. ;-)

As posted on Audio Asylum including photos:
http://www.audioasylum.com/audio/vinyl/messages/86/868379.html