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<blockquote data-quote="akillj" data-source="post: 8305363" data-attributes="member: 644272"><p>There is some misinformation here..</p><p></p><p>100 watts to 10 amps is only useful if you're charging at 10 volts. 100w / 10a = 10v</p><p></p><p>Realistically, if you want to calculate how many amps of alt you need, calculate it like this:</p><p></p><p>EXAMPLE:</p><p></p><p>5000w amp @ 1 ohm</p><p></p><p>70% efficient at 1 ohm</p><p></p><p>(5000 / .7) / 14.4 = ~500 amps</p><p></p><p>In this case, you would need 500 amps of alternator amperage to sustain that amp. Now, keep in mind, this would apply to a constant-tone scenerio. Music is not a constant tone. So you could get away with less than this.</p><p></p><p>Now, you said you have 410 AH worth of battery, and 320 max amps from your alt. Saying your max draw capable is 730 amps is only correct if you plan to run a tone for 1 hour (With the car revved up to optimal alt RPM)</p><p></p><p>410 AH = your battery's can supply 410 amps, for 1 hour. Or 820 amps, for half an hour. Or 205 amps, for 2 hours. So really you can supply way more than 730, that's not your 'absolute max draw capable.' Also keep in mind, the more current you draw (amperage) the hotter your batteries will run, thus lowering their efficiency and lowering their AH rating temporarily.</p><p></p><p>EDIT: Just realized that your 100 to 10 system would actually still apply to my example. You're not wrong, just that it would likely only work in monoblock amp situations, where their efficiency is relatively high. Anyone running their amp lower than 1 ohm where most monoblocks these days are rated, that system goes right out the window. To anyone else reading: running your amp at .5 does not instantly double power for free, as some people seem to think. The amp would become terribly in-efficient, run way hotter at that load, and tax your electrical even harder. If your electrical can't keep up with this added load, then it will be up to chance whether your alt or amp blows first.</p><p></p><p>I'm not hating on you, just clearing it up for anyone else reading //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif</p></blockquote><p></p>
[QUOTE="akillj, post: 8305363, member: 644272"] There is some misinformation here.. 100 watts to 10 amps is only useful if you're charging at 10 volts. 100w / 10a = 10v Realistically, if you want to calculate how many amps of alt you need, calculate it like this: EXAMPLE: 5000w amp @ 1 ohm 70% efficient at 1 ohm (5000 / .7) / 14.4 = ~500 amps In this case, you would need 500 amps of alternator amperage to sustain that amp. Now, keep in mind, this would apply to a constant-tone scenerio. Music is not a constant tone. So you could get away with less than this. Now, you said you have 410 AH worth of battery, and 320 max amps from your alt. Saying your max draw capable is 730 amps is only correct if you plan to run a tone for 1 hour (With the car revved up to optimal alt RPM) 410 AH = your battery's can supply 410 amps, for 1 hour. Or 820 amps, for half an hour. Or 205 amps, for 2 hours. So really you can supply way more than 730, that's not your 'absolute max draw capable.' Also keep in mind, the more current you draw (amperage) the hotter your batteries will run, thus lowering their efficiency and lowering their AH rating temporarily. EDIT: Just realized that your 100 to 10 system would actually still apply to my example. You're not wrong, just that it would likely only work in monoblock amp situations, where their efficiency is relatively high. Anyone running their amp lower than 1 ohm where most monoblocks these days are rated, that system goes right out the window. To anyone else reading: running your amp at .5 does not instantly double power for free, as some people seem to think. The amp would become terribly in-efficient, run way hotter at that load, and tax your electrical even harder. If your electrical can't keep up with this added load, then it will be up to chance whether your alt or amp blows first. I'm not hating on you, just clearing it up for anyone else reading [IMG]//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif[/IMG] [/QUOTE]
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