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In the Forum: Audio Discussions
In the Thread: It’s mad, mad, mad... electricity.
Post Subject: Uncompromising SolutionsPosted by Paul S on: 5/25/2010
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It's kinda fun every now and then to try to figure out a BEP solution on my own. The following will illustrate why I don't do this very often...
One problem that is very hard to deal with is efficiency, in the broadest sense. Without "hi-tech" compromises that PS, APS and other home-use companies employ, things get pretty large, heavy, inefficient and expensive, pretty fast. Well, never mind that for now...
Alrighty- then: Since - according to users - PP2000 seems to work better off battery alone, I thought I'd start with the pure idea and then do an imaginary power supply from there. A basic 3000 W "pure sine wave" inverter (turns battery power to 120 VAC) is about 30 lbs and runs about $1k (USD). Batteries required to run a 1,500 W system would vary according to whether one wanted to run the thing off batteries alone or if it was OK to charge the battery while the hi-fi was playing. If batteries alone, then figure 1,200 Ah, plus charger (about 650 lbs. and $1.5k). Otherwise, figure about 200 Ah battery (110 lbs, $675) and 200 A alternator (ZENA, $675), which needs an 11 hp motor to drive it (Arrow continuous duty gas engine, ~$7.5k, refurbished, 450 lbs.)
I was taught to figure ~2 hp per kW to be generated, so the power required to run the alternator to keep up with the battery drain would be roughly equivalent to a motor required to run a 5.5 kW generator; but that wouldn't have the coveted "battery buffer".
If to use an 11 hp electric motor to drive the alternator that charges/keeps up with the battery/buffer, it would require on the order of 27 amps for each leg of a 230 V motor. (This would be very heavy and very expensive.)
Engineers are welcome to tell how PS and APS get their units so small "without compromises".
Paul SRerurn to Romy the Cat's Site