I need to figure out how to rebuild my own alternater - diyAudio
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Old 2nd November 2004, 10:20 PM   #1
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Default I need to figure out how to rebuild my own alternater

Alright guys, here's what's up. I'm using stock alternater which runs at 105A peak. I just installed a very very powerful Rockford Fosgate Rf X7. At 1 ohm it's pumping out about 3000w. I'm using 3 infinity kappa subs and I'm hitting around 153 db ( I could probably make it hit abit harder though) .

Now for the problem: My alternater fries in about 2 days time. I've upgraded the battery to a red top Optima dry cell battery, and have a 3 farad cap on the way. But I don't think the alternater will still hold up. I need to find out how to rebuild a alternater (I've got 3 extra's sitting around that I keep... and it sucks changing them out). Now this system hits so hard that it hurts to breathe in my car when it's turned up... I love it ... scare the crap outta old ladies next to me . Would anyone be able to shoot me any advice ? I just had to replace another alternater today, it still puts out 14v , but is only cranking out about 30A after 2 days usage, most of the time with the amp turned 2/3 of the way down. Also ... if anyone wants ... would you mind sending any advice to KevinS69@sprintpcs.com ? Would be extremely appriciated.

Thanks,
-Kevin
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Old 3rd November 2004, 12:12 AM   #2
dangus is offline dangus  Canada
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So, what part of the alternator fails first?
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Old 3rd November 2004, 12:25 AM   #3
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You should be more concerned about your hearing than your alternators.
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Old 3rd November 2004, 12:28 AM   #4
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1st off, car alternators arent rated to supply there advertised current rating full time. a 105 amp alternator has a specific duty cylce that will allow it to run at max output for a short period of time only.

2ndly the optima batteries are very cool, but what you want is a battery with a long reserve time. and the optimas dont ahve a very long reserve time. they work very well for short burst tests but if you want sustained power, you need a BIG Battery. Interstate has the longest reserve time of any car battery on the market with a 165 minute reserve, but the Sears Die Hard Gold is easier to get/replace and comes very close at 160 minutes reserve.

I did a lot of research on car batteries for my Bronco 4X4 for winter use and with a die hard gold, you could crank a dead engine at -30 below for days and it still wouldnt be dead! (i tested this therory last winter in fact!)

If your alternator is failing, there is normally only 3 things that go bad. 1-the diode pack, 2- the regulator 3- the brushes. But the bearings can fail and you can overheat an alternator and burn up the windings, but thats not likley.

So, you alternators that failed, i would bet the diode packs are blown, so your only getting one or 2 coils working not all 3

If you talk to a alternator shop, they can rewind the coils for more output. but be careful sometimes this also means more voltage and you can fry computers etc.

An alternator isnt designed to run like a generator where you can draw full power at sustained rates. instead its only designed to recharge your battery.

Best thing to do is add more batteries!!! and then add a seperate high amperage alternator to do nothing but recharge those batteries.

I have even seen some cool setups using hydrolic pumps and motors with the alternators chromed and running in the trunk!!!

There was a cool S-10 blazer i saw at a show that had a hydrolic pump on the engine and a Hydrolic motor mounted that ran 2 chromed out high amp alternators in the back, very cool setup, mondo power!!!


Bets of luck


Zero
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Old 3rd November 2004, 01:43 AM   #5
FrankWW is offline FrankWW  Canada
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He should be concerned about more than his hearing.

http://thorax.bmjjournals.com/cgi/co...tract/59/8/722

Thorax 2004;59:722-724
© 2004 BMJ Publishing Group Ltd & British Thoracic Society
CASE REPORT
Music: a new cause of primary spontaneous pneumothorax
M Noppen1, S Verbanck1, J Harvey2, R Van Herreweghe1, M Meysman1, W Vincken1 and M Paiva3

1 Interventional Endoscopy Clinic and Respiratory Division, Academic Hospital AZ VUB, Brussels, Belgium
2 Respiratory Division, Department of Respiratory Medicine, Southmead Hospital, Bristol, UK
3 Laboratoire de Physique Biomédicale, ULB, Brussels, Belgium

Correspondence to:
Dr M Noppen
Head, Interventional Endoscopy Clinic, Academic Hospital AZ VUB, 101 Laarbeeklaan, B-1090 Brussels, Belgium; marc.noppen@az.vub.ac.be

Most cases of primary spontaneous pneumothorax are thought to be caused by air leaks at so-called "emphysema-like changes" or in areas of pleural porosity at the surface of the lung. Environmental pressure swings may cause air leaks as a result of transpulmonary pressure changes across areas of trapped gas in the distal lung. This is the first report of music as a specific form of air pressure change causing pneumothorax (five episodes in four patients). While rupture of the interface between the alveolar space and pleural cavity in these patients may be linked to the mechanical effects of acute transpulmonary pressure differences caused by exposure to sound energy in association with some form of distal air trapping, we speculate that repetitive pressure changes in the high energy-low frequency range of the sound exposures is more likely to be responsible. Exposure to loud music should be included as a precipitating factor in the history of patients with spontaneous pneumothorax.
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Old 4th November 2004, 01:34 PM   #6
klm1 is offline klm1  United States
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yes, zero cool is right; auto alternator is designed to supply one third to two-thirds rated wattage for short times(20 min.-one hour).
If you need more than this, you need more batteries-or more alternators.
you can also get alternators with heavy duty stators/diodes;see
water powered generator companies.
you are only putting out 1260 watts @ full output; and that
will only happen @ highway speeds.
you will need to install ALL THREE alternators to meet your amp's supply demand.
I hope this helps.
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Old 4th November 2004, 01:57 PM   #7
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Please understand that POWER is whats its all about, or more so in this case POWER CONVERSION!

Your amplifier has to take 12Vdc and turn it into a whole lote more! a 200 watt @ 8 ohm home amp usually has + & - 70VDC power supply rails internally at 5 amps per channel. that equates to 400 watts @ 4 ohms and 10 amps!! and to get that from a single 12V supply means that the current draw at 12V will be substantially higher. 12V 10 amps in means about 120V 1 amp out.

thats a pretty big jump and if your running super big car amps, then that jump is even higher. the current draw at 12V can be enormous! a cars electrical system, even a super heavy duty electrical system just isnt meant to have that kind of constant current draw!

Think about it. how long would your battery last if you had to constantly crank your engine over with the starter? thats about the same electric draw if not LESS!

Take a serious look at any of the competion car stereo vehicles. the most commonly over looked item is the electrical system. everyone is so worried about what SPL they can "Hit" or how many amps, or what ohm load or how many 15's that can stuff into a MINI that they never stop to seriously consider how much power they can DRAW from the electrical system!

A friend of mine in Dallas was into that car stereo competition crap. i helped him out with the technical stuff. this guy was genious at design. some very nice interiors and layouts etc. but he was trying to run all these big amps and stuff from those optima batteries and was getting very bad performance. we went over to a local truck stop, bought a pair of huge semi truck batteries and he went on to win 6 different competitions that year!

The trick was, a stiff, well regulated electrical system. those big truck batteries wouldnt even flinch at a 100 amp draw! forget all that crap about capacitors etc. fix the foundation first. then play witht he toys!


Zero
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Old 8th November 2004, 12:34 PM   #8
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Maybe you could try ducting cold air into the back of the alternator instead of letting hot underhood air get in. A 60-70 deg C drop in temperature would be extremely salubrious.
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