How Many Amps?

[78 Chevyrado]

How many Amps does my truck need?  Not including the stereo.  It used to have a 63A alternator, but the headlights would dim at idle so I upgraded to a 78A and that fixed it all up.   Now since the rebuild I've added Keyless entry and a stereo and amplifier. 

I know the 78A can't be enough.  The Stereo has a 10A fuse and the Amplifier has a 40A fuse (which is what both called for).  So call that 50A.  Bascally I'm thinking 78A + 50A = 128A

What do you think?  Is my train of thought correct?   I found a good looking 140A alternator (powermaster)  but it says only 80A at idle.  I think this would do good.  If the 140A alternator only puts out 80A at idle, God knows what the poor little 78A one puts out at idle.

What do you think, does the 140A sound good?

[78 Chevyrado]

Here's the best deal
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=360221743597&ssPageName=STRK:MEWAX:IT


I was thinking about this, a 160A "kit"

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=390088386651&viewitem=&sspagename=STRK%3AMEWAX%3AIT

Or maybe this one complete  140A

It's the D1-7273-140...140 Amp 12-SI type Internal Regulator Alternator
http://www.alternatorparts.com/alternators_gm.htm

or this
http://www.classicchevy.com/product.asp?pf_id=207-103&dept_id=1196&cm_mmc=Froogle-_-Engine+%26+Related+-+Alternators+%26+Generators+-+Alternators-_-207-103-_-X

[VileZambonie]

If you aren't having any issues with it don't worry about it. The odds that you are drawing that high amperage is slim to none. All you have to do is turn on all your accessories and see how many amps you are drawing. Use an inductive amp clamp to measure it. Keep in mind to your battery is there as a voltage stabilizer as well as your source of back up in the event you overdraw the system.

[78 Chevyrado]

What's making me wonder is that I can't keep batteries or alternators in that thing.  I had to get a new battery a couple of months ago and in the last year and a half, I've had to get 3 new alternators because they quit charging.  I never had a problem until I put in all the stereo stuff.  And I like to ride around with it pretty loud, so i do push the amp and stuff, that and running headlights  (day or night) and the A/C.

[Irish_Alley]

are you buying good parts? not the cheap ones? when i worked at autozone back in 04 i think or 03 but this guy turned in a red top battery knowing how much we sell them for he just wanted us to scrap it as a core well i had a cheap bat under the counter i swapped them out the guy never knew so i put the red top on trickle charger and its still in my 94 today. this guy told me he had it for a while and it quit on him he tried charging it and nothing.

[Lt.Del]

i've got a 1,000 sony amp under my middle seat in my sub.  I think i have a 50 amp fuse --one of those bigger 2 inch wide fuses.   I don't know what amperage my alt is, but, I never replaced it and it does fine.  i have 12 inch subwoofers on the 3rd seat (when that seat is in, or behind the middle seats).  She sound great and I have no visible amperage problems and when my son is not in the sub with me, I turn that puppy up quite a bit when listening to Slim Shady or some good Montgomery Gentry...I know, my taste for a 40+ yr old is quite eclectic.  Bill Monroe's Uncle Penn sounds good too on that.

[78 Chevyrado]

Sounds like I'll be fine with my 78 Amp setup sgtdel.  I only have a 500watt amp and no sub so I guess I'll get another 78 amp one.  I don't want autozone, advance or oreillys brands.   maybe I'm getting crappy parts.  I know I had real bad luck with autozone and oreilly's (had to return 2 to each store within a week)  so now I have one from advance.  I never had a problem with their stuff, but maybe alternators are gonna be my unlucky spot on this truck...

what do yall think of napa parts.  is delco worth paying the extra for?

any other brands that are good?

Thanks fellas!

Here's a new one from napa.  It's pricey, but if that's the best one, I'll buy it.
http://www.napaonline.com/Search/Detail.aspx?A=NNE1N4350_0198910448&An=599001+101983+50014+2014028+3014032+3999999#

[malibu795]

i got a napa 63a on both my 468 and 383... both are getting replace wiht 100a

[78 Chevyrado]

I think I'm going to go with this one.  105A new alternator.  Shipping and all it's still $5-10 cheaper than most of the new alternators and I get 27 extra amps.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=360217102434&ssPageName=STRK:MEWAX:IT

[dirtmod0]

that ebay unit what kind of connector does it have cant see on page?  is it the regular truck style?

[78 Chevyrado]

It's supposed to be a 3-wire hookup.  Yeah that's just the stock GM hookup, the big charging wire and the pigtail with two wires.

[k5blazerfan]

good rule of thumb..... 100 watts to 10 amps keep that in mind

[VileZambonie]

Volts X Amps = watts

[k5blazerfan]

yeah vile but if you run 500 watts on a 20 amp fuse your gonna starve the thing your trying to run so thats why i say 10amps to 100 watts at least thats the rule you go by running cb equipment

[choptop]

A fuse does not restrict or starve the electrical device in any way. Smaller wire over a long distance will, but the fuse will not unless it burns up the fuse do to overload. Most fuses are sized according to what the device or curcuit they are protecting is, not what they use. You have to take into consideration also that juat because the amp says 500 amp doesnt mean it consumes 500 amp at all times. An amp clamp is the best way to determine exactly what you are using. Normally what I see is that the consumption is usually half of what the fuse is rated for, with it spiking at only 2/3 of the fuse rating.