ICE amps need cooling?

Batteries are potentially messy and some can emit either fumes or hydrogen gas. Enough battery power for a pair of BelCanto 1kw monoblocs would take up a bunch of space, too.
Than you gotta deal with the charger and battery maintenance.
You would ALWAYS run the batteries down at the WRONG time. that is one of the RULES.
But, on the other hand, I just received an IR amplifier module, stereo class 'd' which I intend to power with batteries. Amp takes +-50v which is good for 4x12 on each rail. I'll deal with the charging and other issues later. The attraction of zero ripple and huge, near-instant current is very seductive.
Battery chemistries other than lead-acid / gel cell is available in Lithium/Lithium polymer and varios Nickel Metal Hydride cells along with the old standby, NiCad. I don't know the half cell voltage of these, but some require smart chargers (the charger, not YOU) and certain other usage restrictions.
For DIY where there are few restrictions, it's worth an experiment, but in the commercial market, batteries may be too much.
Also, a note on the numbers:: IF you run at what works out to be high power levels, say 4 amp total average draw, on each 'rail', you may need considerable battery capacity. A set of batteries in series will have the amp hour capacity of 1 battery.....1 12v battery of 50amp/hours will still have 50amp hours when 4 are in series....but have 4X the WATT hours.(P=IE) But, measuring in amp hours, my made-up 4amp draw, per rail, will use up each rails batteries in 10 hours of listening, with a small reserve.
Clearly, in this instance you couldn't run a Class 'A' system, but rather the numbers prefer Class 'D'.....

Magfan, the old JRDG model 9 mono amp used sealed Lead acid batteries. It as a class A/B design. Conversely, the JRDG Criterion linestage uses industrial-grade NiMH and has a built in smart charger.

maab you are more then correct far far away from high end sound we crave.

Muralman1...Nice that Mr Ho's preamp is "Class A". By the way, how do you make a preamp that is anything else? Can you name one?

How much power in the JRDG#9? How much battery capacity? That'll give me some idea how long between charges.

I was just giving some 'considerations'. If you go with lead/acid or Nicad, you've got shipping weight to factor in, too. No Fair giving the UPS guy a hernia luggin 80lb of class 'a' chassis and another 200lb of batteries!
I work for International Rectifier, which has several class'd' entries, of which I own one. I am attracted to the battery PS simply because I don't have the skillset to design a good, clean PS, though I suspect I could build it if given a kit of parts..........

I can close to guarantee that the above amp had some problems. Perhaps battery storage with the fumes? That stuff is Really corrosive. I suspect that using some Optima sealed gel cells for automotive use may help. I further suspect the WAF is near zero. How you hide a dozen car batteries 'discreetly' is beyond me!

Thanks for the Info, which I'll look up. I have also seen, here on the 'gon, an amp called 'Emitter'.....something, which is a massive battery operated power amp. And, Massively Expensive, to boot. It is in the 25,000$ range, new.

My 'rule' is that there is NO bad topology of whatever ilk. Almost anything can be made, and made good / good sounding...some stuff just takes more development, parts count and is inherently more expensive. Arguing about what sounds better a SET or Triode or whatever tube philosophy is not the correct approach, IMO. How's it sound? Some arguements about this stuff is starting to sound religious.