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Discussion Starter #1 (Edited)
Well Mr. Aukland suggested that I put a couple of my FAQs up here and since the title to this thread question seems to come up a lot I figured it a good start.
Q: What size Alternator do I need?

A: This is a question that seems to be arising more and more these days with the addition of larger (more powerful) amplifiers.

1)First you will need to look at the amplifier(s) themselves and their fuse values (total).
2)Next you will be required to know the amperage rating of your stock alternator

Most typical stock alternators use a value of 70-80%, meaning that the vehicles maximum load is 70-80% used under vehicle usage.
Now we take the alternators amperage rating and multiply an average of 75% (you may use 80% if you wish to allow yourself an added protection of power). Now take that number and add the total fuse values of the amplifier(s) and the final figure will be how much power you will require from an alternator.

Side Note #1: The addition of added aftermarket items that will require power will increase your amperage load and you should judge accordingly. Items such as Video Monitors, On Board Gaming Systems, DVD Players, Lighting, ETC. may not require a huge amount of power alone, but added with together or with an aftermarket audio system may have a larger load than expected. If you are planning (or even thinking about) the additional items afore mentioned then you may wish to just add the total calculated fuse value(s) to the stock 100% value of the alternator.

Side Note #2: If you are currently only adding a single amp for subwoofer(s) and are planning (or even thinking about) the additional amplifier(s) for highs, midrange, components, etc. then please estimate the amount of power required and add to the total fuse value(s) to save yourself the headache, time, and money of having to upgrade your alternator again in the future.

Examples:
Example #1
Adding a single amplifier with (2) 40 amp fuses
Stock alternator rated at 90amps
Fuse values total = 80 amps
90 x 75% = 67.5 (always round up) = 68
68 + 80 = 148
So therefore you will require an alternator with a minimum rating of 150 amps

Example #2
Adding a single amplifier with (2) 40 amp fuses
Stock alternator rated at 105 amps
Fuse values total = 80 amps
105 x nothing as we will (or do) add for additional items (let’s just say Monitor, DVD, HID lighting, & a couple neons)
80 + 105 = 185
So therefore you will require an alternator with a minimum rating of 185 amps

Example #3
Adding multiple amplifiers with (2) 40 amp fuses (amp #1) and (2) 25 amp fuses (amp #2)
Stock alternator rated at 120 amps
Fuse values total = 130 amps
120 x 75% = 90
130 + 90 = 220
So therefore you will require an alternator with a minimum rating of 220 amps

Side Note #3: While other electrical components of your vehicle may help such as the Big 3, Upgraded or Additional Batteries, (Capacitors not suggested) these are not a direct replacement for creating power and are only to assist in transferring and storing power and are Not and should Not be used as a substitute.

Thanks and above all when dealing with electricity of any sort, think smart and safe for yourself and your equipment :thumbsup:
 

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Discussion Starter #3
What would this be....
(4) 250 amp fuses, (1) 150 amp fuse with a stock alt of 150 amps??:thx
I think you're trying to add up the wrong fuses... you need to add up all the fuses in your amplifiers themselves and not the fuses leading to the amps... In some cases you may have to use an external fuse rating as some amplifiers do not have internal fuses and give you a recommendation of external fuse size and in that case you would you that as your figure added in with any other internal fuses you may have for other amplifiers (if they are present).
 

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I think you're trying to add up the wrong fuses... you need to add up all the fuses in your amplifiers themselves and not the fuses leading to the amps... In some cases you may have to use an external fuse rating as some amplifiers do not have internal fuses and give you a recommendation of external fuse size and in that case you would you that as your figure added in with any other internal fuses you may have for other amplifiers (if they are present).
Nope. Its the internal fuses of the amps...:eek: (4) T20001's = (4) 250 amp fuses, and (1) T8004 = (1) 150 amp fuse. I also have a 275 amp HO alt if that makes a difference....
He might be talking about the T2k's he has, I don't remember the fuse ratings on them though:undecided.
Bingo!:thumbsup:
 

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Discussion Starter #8
Okay then... with the 4) T2Ks by calculations you would need over 1250 amps, but I also know that the T2Ks only require about half of their fuse ratings for true power thus for optimum performance about 600 amps would be premium and would probably get you beyond that 150 mark as long as you had the power reserves to hold it (batteries for those of you that didn't understand that last part) ;)

To give a more accurate calculation for most as a reference:
Trailblazer/ Envoy stock alt ='s 150amp 75% is 112.5 amp (so we'll round to 115 amp for safety)
Standard amp of 2000watts rms 2 x 40 (some very but this is a close estimate) ='s 80 amps
So we take those figures and add them together 115 + 80 ='s 195 thus you would need a 200 amp alternator
In addition remember that even with a h/o alt you need to have the reserve to hold the power... battery(s) and proper wiring to handle the current or all is for not.
Hope this helps everyone out a lil bit :)
 

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Okay then... with the 4) T2Ks by calculations you would need over 1250 amps, but I also know that the T2Ks only require about half of their fuse ratings for true power thus for optimum performance about 600 amps would be premium and would probably get you beyond that 150 mark as long as you had the power reserves to hold it (batteries for those of you that didn't understand that last part) ;)

To give a more accurate calculation for most as a reference:
Trailblazer/ Envoy stock alt ='s 150amp 75% is 112.5 amp (so we'll round to 115 amp for safety)
Standard amp of 2000watts rms 2 x 40 (some very but this is a close estimate) ='s 80 amps
So we take those figures and add them together 115 + 80 ='s 195 thus you would need a 200 amp alternator
In addition remember that even with a h/o alt you need to have the reserve to hold the power... battery(s) and proper wiring to handle the current or all is for not.
Hope this helps everyone out a lil bit :)
Thanks, but why is this different than what you explained above? First you're saying that 1250 amps is what that fuse rating calls for, but then you're saying that it only needs 600 amps of power?? Thats a huge difference.. Can you explain a little more for those that are going WTF??? :thx
And if by 150 mark, you mean 150DB.:duh: LMAO. I'll be over that with my 2nd T2K and 2nd Kinetik HC2400:thumbsup:
 

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Discussion Starter #10
As I said about the 1250/ 600 amp difference... The T2Ks are more efficient than there fuse ratings and for daily 600 would be plenty to power them, but if you were looking to compete in dB Drag on a burp 1250 would be the amount to get to full charge quickly ;)
And yes I did mean 150 dBs and a second T2K may not guarantee a 150+ score as the estimate of +3 dBs for doubling power is only that an estimate.
The 150 mark (dB) is a tough one to break... I speak from experience as we built a Buick with a wall of 4) 15" that ranked #12 in the country with a 153 and we were doing a 149 with Autoteks and 3000w and 3) 2150 batts, 150 with it when it had 4) Elevation Executions with 6000 watts and 4) 2150 batts, when we made some mods to the rear and port, then swapped out for 4 specialty built FSQs and 8000 watts and 5) 2150 batts to finally get to the 153 dB mark. If 150+ dB was easy everyone would be doing it ;)
 

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As I said about the 1250/ 600 amp difference... The T2Ks are more efficient than there fuse ratings and for daily 600 would be plenty to power them, but if you were looking to compete in dB Drag on a burp 1250 would be the amount to get to full charge quickly ;)
And yes I did mean 150 dBs and a second T2K may not guarantee a 150+ score as the estimate of +3 dBs for doubling power is only that an estimate.
The 150 mark (dB) is a tough one to break... I speak from experience as we built a Buick with a wall of 4) 15" that ranked #12 in the country with a 153 and we were doing a 149 with Autoteks and 3000w and 3) 2150 batts, 150 with it when it had 4) Elevation Executions with 6000 watts and 4) 2150 batts, when we made some mods to the rear and port, then swapped out for 4 specialty built FSQs and 8000 watts and 5) 2150 batts to finally get to the 153 dB mark. If 150+ dB was easy everyone would be doing it ;)
I'm already doing a 48.7 with just 1 T2K at the "C" pillar. That in itself is a pretty badass task @ 45hz.:yes: I have no doubts that I'll break the 50 mark this year when I add the second one. Adam (my friend that helps me) placed 6th last year at world finals. If all else fails, I'll have to resort to plan c, which is taking the rear seats out and putting 4 of those 15's (memphis Mojos) and 4 T4K's with a couple HO alts and several Hc2400's. I don't want to do that, but everyone else may force my hand. I want to be and remain the loudest TB.:duh::weird:
 

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Discussion Starter #12
I'm already doing a 48.7 with just 1 T2K at the "C" pillar. That in itself is a pretty badass task @ 45hz.:yes: I have no doubts that I'll break the 50 mark this year when I add the second one. Adam (my friend that helps me) placed 6th last year at world finals. If all else fails, I'll have to resort to plan c, which is taking the rear seats out and putting 4 of those 15's (memphis Mojos) and 4 T4K's with a couple HO alts and several Hc2400's. I don't want to do that, but everyone else may force my hand. I want to be and remain the loudest TB.:duh::weird:
Well I wish you luck as I believe the sport of SPL may be on the rebound this year (as long as the gas prices don't effect it) and you may have a new rival in Aukland for the loudest TB if he comes up with the funds to do what we have planed for his... And he may only be running 2 subs :D ... And he's got me with decades of experience on my side... Hell here at the shop a few years ago me and my righthand installer put ourselves in a spot to make the loudest thing we could with what we had available to us in 1 hour the day before a local comp... It ended up being 4) 12" diamonds 1) SPL 1600watt amp 1) Honda civic coupe 2) vented enclosures (backseat removed) and did a 143 with no matt... Not bad for 2 people and 1 hour :D
 

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At 45hz thats pretty high tuning and you only did 148.7. Its easier to hit higher numbers with higher tuning. I did 146.7 @ 35hz with less than 2k of a modded mtx81000D with only one 18. My new setup is gonna break 150s without a sweat and at low tuning. I predict mid 150s. Doing two 18s in 11cu.ft. encloser and over 4000watts rms. 280amp H/O alt from Mean Green and two g31's in rear.
 

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Discussion Starter #14
For SPL higher tuning (above 40hz) is where it's at for a comp vehicle... We had the Buick tuned lower at first, but decided to up it when there was a threat of losing the windshield... The middle of it was flexing out over 1/2 inch :D
 

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At 45hz thats pretty high tuning and you only did 148.7. Its easier to hit higher numbers with higher tuning. I did 146.7 @ 35hz with less than 2k of a modded mtx81000D with only one 18. My new setup is gonna break 150s without a sweat and at low tuning. I predict mid 150s. Doing two 18s in 11cu.ft. encloser and over 4000watts rms. 280amp H/O alt from Mean Green and two g31's in rear.
So right now we have 4 TB's estimated to break the 150's. This is gonna be a fun summer:thumbsup:.

Does our 4th contestant wanna chime in with his plans?:D
 

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At 45hz thats pretty high tuning and you only did 148.7. Its easier to hit higher numbers with higher tuning. I did 146.7 @ 35hz with less than 2k of a modded mtx81000D with only one 18. My new setup is gonna break 150s without a sweat and at low tuning. I predict mid 150s. Doing two 18s in 11cu.ft. encloser and over 4000watts rms. 280amp H/O alt from Mean Green and two g31's in rear.
Only:duh: Thats on the dash, doors closed, all sealed up, all legal like. Good luck with your quest, keep us posted and show us lots of pics.:yes:
So right now we have 4 TB's estimated to break the 150's. This is gonna be a fun summer:thumbsup:.

Does our 4th contestant wanna chime in with his plans?:D
Who are the other 2?? Me and Sleepy, who are the other 2? I know you're not in that catergory:raspberry
 

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Who are the other 2?? Me and Sleepy, who are the other 2? I know you're not in that catergory:raspberry
I hope you are jokin' with this remark, if not, that's fine, when I am done we can take it to the lanes.:cool::laugh:

@Andrew

The batteries (depeng how big and/or many) will carry for a little while, eventually they will drain and system will need to be turned down to recharge.

Take mead's for example, taking the basic addition of the fuse ratings, with all his power would need say about 2k amps to maintain that much power runing full tilt for an extended duration, iirc he added a third alt bringing him to 900 amps of charging power. The 4 or 5 batts in the back will help maintain it while needed but he also knows when i is time to turn it down.
 

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Discussion Starter #20
Im still not sure about this.....if the demand of the amps exceed the supply of the alt, do the extra batts handle the load like during burps?
^Exactly... For competitions you will see many that have amps that will far outweigh the alts capabilties and that's why you need to have all of the extra reserve from the batteries... These systems are not for daily purpose and many competitors also use larger wheeled type battery chargers to help recharge the batteries quicker.
Example: The Buick I have mentioned (although fully drivable) was not set up as a daily driver and the 300 amp externally regulated amp would not be able to feed the amps for general purpose... The 5) 2150s in the back though would hold the current in the lanes and the Deka under the hood would allow the car to start up again every time so that the alt could recharge them (15V) while waiting for the next run.
The FAQ formula is for using when applied to daily driving to meet the demands required for a fully operational electrical system with no light dimming ;)
 
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