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dimming after new alt and finished big 3 but not before

Old 09-14-2006, 11:04 AM
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dimming after new alt and finished big 3 but not before

ok, heres the deal, about two weeks ago my battery died, got a new one, died in two days, so the problem was the altenator. i went to the place where i got my battery (insterstate) and they said theyd build me a 160a alt for $150 cdn, they did and i installed it. i also finished my big 3 upgrade and added a 2.4 farad cap to the system. now the strange part, before i never noticed any dimming period.. never.. now when im idleing at a light (around 700rpm on the cavi) i get severe dimming in dome lights and headlights. as soon as i bring it up to 1000rpm the dimming goes away, unless have it cranked then i notice it again. the thing that confuses me is that with my old battery and alternator (105a stock) i never had any dimming problems but now i do... im lost as to why this is happening....thanks for any help
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Old 09-14-2006, 11:17 AM
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Well as you know to get most out of your alt your engine needs to be at 2000 rpm.

Unless you have one hell of a system i can't see that straneg your electrical system.

can i ask is this 160 max if so find out what they set the regualter at and see if you have any loose conections,that could cause problems as well.

is this a 2.2 or 2.4
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Old 09-14-2006, 11:39 AM
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I have seen that happened many many times...... alot of the alternator shop don't realize that we need the alternator to charge at low RPM (700-900rpm)vs 1000 & up.

unless you could change the pulley to make up for the rpm difference, you will have to get a different alternator.
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Old 09-14-2006, 11:44 AM
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the car is a 2.2.. and i see what you mean, its just that the problem is that everytime i stop i have to turn down the stereo or my fronts even start to clip from low voltage
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Old 09-14-2006, 12:18 PM
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u mention that your battery died just 2 days after right ! so try charging your battery to full , might help your dimming issues
hope that works
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Old 09-14-2006, 12:34 PM
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i did that the day it died.. plugged into trickle charger that night got new alt in the morning
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Old 09-14-2006, 01:07 PM
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The first thing that comes to mind, CApacitor, only because you never noticed it dimming BEFORE you added it and a Altenator, and battery...Try taking that out...I noticed with mine that I didn't dim as much and I gained a db and a
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Old 09-14-2006, 01:21 PM
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your car dosen't have the torque to turn that alt at idle... that is the main drawback of a HO alt; especially on a 4banger.....

you can try adding a different pully, but expect to loose HP.... you could also increase your idle rpm...

aside from that..... we all know the saying..... ' if it aint broke, don't fix it'
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Old 09-14-2006, 01:25 PM
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would putting a smaller pulley on overload the alternator at the higher rpms though?
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Old 09-14-2006, 02:13 PM
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^ potentially. You need an increase of 43% for your 700rpm motor to turn the alternator at 1000rpm. Once you get to 5500rpm though, the alternator will be spinning around 7865rpm. Sure you don't drive at 5500rpm, but then you don't usually sit at 700rpm either.

As suggested, I would either live with it or get your idle speed bumped to 1000rpm.
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