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100A not enough?

 

Bronze Member
Username: Phx

Post Number: 16
Registered: Dec-04
sup yall, i had an old RF amp that puts out ~950Wrms (tested) in my 96 volvo 850 with a 100A alternator. the headlights dim quite a bit, as to be expected, and i took the amp out. now i recently bought a 98 volvo s70 t5 with the same alternator, and i've installed a memphis mc3004 (300Wrms@4ohm) and a hifonics bx500d (250Wrms@2ohm) and the headlights dim like crazy sometimes, even more than in the 850 with that bigass rf amp pounding. sometimes i notice it even at low volumes. i know, i know, amps are less effecient at lower volumes, but wtf? is there anything i can do to remedy this, short of spending $699 on a 180 amp alternator? why did the 850 (virtually identical car) perform better with a more powerful amp?? might the link from alternator to battery+, or battery- to ground be too shitty to properly transfer energy? i think the amps are grounded well, there is very little resistance from the grounding point in the trunk to the battery. the amps are fed by a single ~16ft 4ga lead and individually grounded with 4ga as well. thanks for any help, and merry Christmas everyone!
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 6888
Registered: Dec-03
the RF amp would draw up to about 100A at full output, but chances are you never got it near it's peak output, so it was probably drawing considerably less than that. The differences between the two cars may not be the alternators themselves, but the load placed on them by the car and how much actual reserve the alternator in each car had to spare for amplifiers. Remember most factory alternators are pretty closely matched to the cars, not allowing a LOT of room for added current drain.

the new setup you have should draw up to 60A at full output, but again, normally much less at listening levels.

try upgrading the motor to chassis ground cable, alternator to battery, and battery to ground, all using the same gauge you ran to the amplifiers, which should probably be 4ga.

failing that, a larger alternator is pretty much the solution.
you can try using a capacitor but all that really does is mask the symptoms at best. It doesn't solve the core of the problem.
 

Bronze Member
Username: Phx

Post Number: 18
Registered: Dec-04
thanks, i'll try upgrading those cables. I'm not wasting my money on a capacitor, from my experience they don't mask anything, generally making problems worse. maybe if i want a really big voltage meter :-)
 

Unregistered guest
just thinking?? Which is better? the extra battery for the accesories or upgrading the alternator?
 

Bronze Member
Username: Rzarector

Coquitlam, Bc Canada

Post Number: 66
Registered: Dec-04
you still need a bigger alternator if your charging system cant handle the load placed on it
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 7066
Registered: Dec-03
http://www.wickedcases.com/caraudio/charging.html

 

New member
Username: Killerbuffalo

Post Number: 9
Registered: Dec-04
Say the alt can't handle all that can you just unhook the amp until you get a new alt so it isn't using all that power?
 

Anonymous
 
an RF gell cell battery under the hood and a matching one in the trunk should do the trick...
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 7094
Registered: Dec-03
may not even need to disconnect the amp.
just keep the volume down so the lights don't dim etc..
every time you audibly double the volume of the system, you're drawing ten times the current, so lowering teh volume shoud stop the problems.

the batteries would only help when the car isn't running.
otherwise the alternator puts out a higher voltage than the batteries do, so the batteries are in a charging state.
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