Batteries in Power Supply

In view of the recent interest in power supplies has anyone thought
about using batteries in place of capacitors in some of the larger
power supplies?

If you used 5 12Volt batteries and 1 6Volt that would give a nominal
66 volt, with a fully charged cell rising to 2.4 volt that would give
an additional 13.2Volt (33 cells @ .2V) for a total of 79.2 volt.

In a recent post Les Watts reports routinely seeing 60 amp peaks on
rapid starts, stops and sharp curves, I would think batteries could
cope with these conditions better than conventional caps.

I'm not sure if there would be any significant price difference
between caps and batteries, a 100Volt 15,000uF cap is almost $30 and
for a reasonably stiff supply you probably need at least 3 in
parallel. Without doing the math, I suspect you need more than 3 caps
to cope with 60 Amp peaks. 12V 4.5 A/Hour batteries are about $17 and
6V 4.2 A/H $9 for a total of $94. (12V 12 AH cost $$35)

I'm not sure how effectively batteries kill spikes, I would have
thought much better than caps, they should absorb overvoltage from
motors quite effectively.

I can see difficulties in disconnecting the batteries from the drives
at power off, but this should be offset by being able to use smaller
transformers.

Just a thought.

Bernard