Batteries as power-supply filters?

[Dartagnan]

Hi folks,

I was just thinking about battery power supplies, and how many people say they are the ultimate. Of course, the whole charging circuit and duty cycle can be a bit of a pain, so I got wondering about just feeding rectified ac to series batteries in a PS. (See attachment)

Wouldn't this give you all the benefits of a pure battery supply with fewer headaches? Am I wrong in thinking that the batteries would filter out all but the lowest-frequency ripple and give the PS huge reserve?

Is there any reason this wouldn't work?

Dart

[Paul Rose]

A bit confused by your series arrangement.

You end up with +24 0 -24, half your voltage coming from the batteries?

What keeps them charged?

With paralell arrangement would basically end up with a car type system. Your rectified current from your alternator in parallel with the battery. How well does that work? (of course not apples to apples b/c the alternator is likely noiser than your AC line to begin with)

[Steve Eddy]

Originally posted by Dartagnan
Hi folks,

I was just thinking about battery power supplies, and how many people say they are the ultimate. Of course, the whole charging circuit and duty cycle can be a bit of a pain, so I got wondering about just feeding rectified ac to series batteries in a PS. (See attachment)

Wouldn't this give you all the benefits of a pure battery supply with fewer headaches? Am I wrong in thinking that the batteries would filter out all but the lowest-frequency ripple and give the PS huge reserve?

Is there any reason this wouldn't work?

The batteries need to be wired across your AC supply, not in series with it. In other words, the batteries should be in parallel with the caps you have in your drawing.

This technique can work and was in fact used by Jean Hiraga for his Le Monstre power amplifier.

The batteries work to keep the supply voltage constant as opposed to a plain Jane capacitor-based supply where the voltage across the caps drops as current is drawn from them between refresh cycles.

This tehcnique however still leaves you with the problem of chassis leakage currents and interchassis currents due to the AC portion of the supply which can create noise problems.

se

[Dartagnan]

Oops.

I see the error in my thinking. I was forgetting how battery recharging works. How embarrassing.

Thanks for steering me right, guys.