quote:

Originally posted by G`Dave I am but a poor little first year, probably seems pathetic that I would complain about how hard it is, I assume your in ECSE, which I've heard is that hardest (and my first prefence, why do I keep doing this to myself ), but I'm gonna do it anyways. I've got one tomorrow (Mechanical) not too worried about that one. And Monday is Materials, that'll be a walk in the park. But today I had Systems.. *shudder* I really hate that subject, should be a pass however. 1902 was a bit of a prick, but that should be fine too.

yeah i do electrical/commerce double degree. compared to engineering commerce subjects are a walk in the park. i got 50 for systems . I'd love to offer you any help/past assignments but i dont think i would be much use :P

The year's pretty much done now, only two easy exams left.
But next yeat (assuming I get into ECSE, dunno how hard that's gonna be) I might take you up on that.

I don't know anyone in electrical.

Engineering ehh..
Here's some engineering from me! Both technical and cost effective! Sometimes too much theory can be misleading practice makes it much better!

A 4 piece battery bank rated at 500A each will be efficient enough to supply Astroboys party needs
One of the biggest mistakes made by those just starting out is not understanding the relationship between amps and amp-hour requirements of 240 volt AC items versus the effects on their DC low voltage batteries. For example, say you have a 24 volt nominal system powering a load of 3 amps, 240VAC, which has a duty cycle of 4 hours per day. You would have a 12 amp hour load (3A X 4 hrs=12 ah). However, in order to determine the true drain on your batteries you have to divide your nominal battery voltage (24v) into the voltage of the load (240v), which is 10, and then multiply this times your amp hours (12 ah). So in this case the calculation would be 120 amp/hours drained from your batteries.


The easiest way to quickly determine the total battery amp hours required is to first determine total watt-hours required by all loads, and then divide by the nominal DC system voltage. This resulting number will indicate the amount of amp hours needed to operate all loads for a given period. However, additional amp hour capacity would typically be added for more "reserve" capacity or to prevent complete discharge. Using the above example, 3 amps x 240 VAC x 4 hours = 2880 watt-hours divided by 24 VDC battery environment equals 120 amp-hours; the same answer as before, but another way to get it.

As it can be seen you will get hours and hours battery life combined with the running idle car alternator...
Trust me it'll be much cheaper than the genarators and of course reliable too.
But with the right amount of money a generator is much better. i don't have the slightest idea how much a decent one would cost and can only assume would be running around $10000+ mark
my 2 cents

also dont forget voltage drop. Could cause damage to your inverters as the night wears on

quote:

Originally posted by Tranceilvania Engineering ehh.. Here's some engineering from me! Both technical and cost effective! Sometimes too much theory can be misleading practice makes it much better! A 4 piece battery bank rated at 500A each will be efficient enough to supply Astroboys party needs One of the biggest mistakes made by those just starting out is not understanding the relationship between amps and amp-hour requirements of 240 volt AC items versus the effects on their DC low voltage batteries. For example, say you have a 24 volt nominal system powering a load of 3 amps, 240VAC, which has a duty cycle of 4 hours per day. You would have a 12 amp hour load (3A X 4 hrs=12 ah). However, in order to determine the true drain on your batteries you have to divide your nominal battery voltage (24v) into the voltage of the load (240v), which is 10, and then multiply this times your amp hours (12 ah). So in this case the calculation would be 120 amp/hours drained from your batteries. The easiest way to quickly determine the total battery amp hours required is to first determine total watt-hours required by all loads, and then divide by the nominal DC system voltage. This resulting number will indicate the amount of amp hours needed to operate all loads for a given period. However, additional amp hour capacity would typically be added for more "reserve" capacity or to prevent complete discharge. Using the above example, 3 amps x 240 VAC x 4 hours = 2880 watt-hours divided by 24 VDC battery environment equals 120 amp-hours; the same answer as before, but another way to get it. As it can be seen you will get hours and hours battery life combined with the running idle car alternator... Trust me it'll be much cheaper than the genarators and of course reliable too. But with the right amount of money a generator is much better. i don't have the slightest idea how much a decent one would cost and can only assume would be running around $10000+ mark my 2 cents

these calculations may be correct, but i have no idea why you are using 24v for the car battery, 3 amps at 240V, and 4 hours. In this instance 4 or so car batteries would work because a normal car battery holds 30-50AH....

But... car batteries are 12v, he is probably looking at drawing 7 Amps on the 240v side (1680 watts 2*800 for speakers + mixer + turntables) and i am guessing running the system for a lot more than 4 hours. this results in 140A on the 12v side which is a lot of current an consequently uses 560AH for 4 hours, even if the alternator was giving 40A you would still need 400AH of battery storage for just 4 hours.

If you decided to rig up lots and lots of batteries it may be a feasible solution but when you add up the cost of the batteries and the invertor and all the things that could go wrong i really dont think its worth the hastle.

2in series x 2 banks parellel =24V 2000AH

Last edited by Tranceilvania on Nov-04-2004 at 08:12

quote:

Originally posted by Tranceilvania 2in series x 2 banks parellel =24V 2000AH

where can u get 1000AH batteries? i want some!!

From one of this babies!!


All jokes aside; you're forgettin parallel and serial battery combinations!!!

How so?

4 12V 1000AH (if there is such a thing, i know there are 200AH ones for large UPS systems) batteries setup with 2 sets of 2 in series in parallel gives 24v and 2000AH, if they were all in series it would be 48v and 1000AH, all in parallel and it would be 12v and 4000AH

don't mean to interrupt the whole car battery debate, however i saw recenly that hardware stores [bunnings, etc] had cheap [~200$] generators at 800watts, whether or not they'd be powerful enuff for outdoor event useage or not remains to be seen....

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Some companies, such as Honda, make generators that produce DC power and then run it through an inverter module to give a constant AC output voltage, making them electronic circuit friendly.


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