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Lately my lights have been dimming A LOT at night. To the point where the bass has to go down. I also find myself cleaning battery acid goo stuff off the pos. terminal once or twice a month. When bass hits, lights dim pretty bad. Also, when starting the car, it starts kinda harsh when its been sitting. Does this sound like my battery? Or alternator..?

Thanks for any input.
 

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alternator. i am assuming the car is running when this happens. when your system asks for more power than your alternator + battery can deliver, stuff like that happens. a battery might work, but remember, the purpose of the alternator is to run the cars electrical when the engine runs AND to charge the battery. So in theory, with a bigger battery the alternator would have to spend more time charging it. You would be better off getting your current alternator rewound OR putting on a new one that can deliver more current.

Jeff
 
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It'll do it also when the car is off, but acc. is on.
 

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YA. Then you are just on battery power. If you wanted to run your system with the car off alot too , i would reccommend a new battery.

Jeff
 

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My car does this alot too. Its only really bad when i'm idling, I can see the battery gauge bounce around and the lights dim. It used to be much worse but I installed a 1 farad capacator which seemed to help. I also replaced the battery a month or so ago and its still doing it, so I have a feeling that the Probe's alternator just cannot dish out enough power for a large system. After talking with some Audiophiles we came to the conclusion that the best choice would be to get an Optima Gel batter and a stronger alternator. Also I would NOT reccomend an underdrive pully. Good luck!
 

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The reason your dimming is more noticeable at idle:

Your alternator can put out a different amount of theoretical (and actual) current based on how fast your engine is spinning. At highway speed the engine spins faster (forgive me for not being mechanically correct with that) , so the alternator spins faster, and thus can deliver more current. At idle speed your alternator is more limited.

You can either have your alternator rewound or buy a new one. Just keep in mind that you can't ever get something for nothing. If I understand right, you can get your alt rewound to make more current, but most of the time this extra current is only available at high rpm's. Same thing when you buy a new alt. It might say it can deliver 150 amps, but you should find out how fast its spinning to do that. It might only produce 50 amps when your engine is at idle.


The alternator on a stock gt can put out 90 amps max. I have found that this is actually pretty good. Most imports have ~40 amp alternators. The base models have an alternator that puts out up to 60 amps i think.

A cap can help alot. I'm surprised i forgot to suggest it. Some people consider them bandaids rather than solutions to these problems. Anyway, your amps almost never draw their peak current, and when they do its only for a split second. This is why caps are useful. sometimes your amp asks for current faster than your alternator or even your battery can physically deliver it. Because of their design, caps can deliver power much quicker than batteries and alternators.

Jeff
 

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Crown Victoria P71 Member
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No offense but who ever says a cap is a bandaid for a charging problem is full of crap. A cap is a device that stores energy, it's other advantage is it can take a small amount of energy and double the out put. Hence the coil on an ignition, you don't get that kind of voltage from 12 volts only. If you don't want to fork out the money for a new high power alt, then run either multiple batteries or multiple caps. Most people will run amps off of multiple batteries ran in series causing them to run 24vdc. If you look at amps spec sheets most are tested at 24vdc to get a higher output rating and more stability across the circuits. And you guys are correct that all import altinators suck. As for running optima batteries the main advantage is that they are not suppose to corode. But be weary of gold plated terminals on them. The plating tends to eat off after awhile just like acide cells batts. In my mini running two RF 200ix's and one RF 100ix I have no problems when using two optimas, but when I run one the alt can't keep up. However this is a pickup with room under the hood for that sort of thing. Go with a cap it will help out alot.
 

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Crown Victoria P71 Member
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Your problem is with the charging system. One of the easiest things to do is to start the car with out the system on. Using a multimeter check the voltage of the charge. It should be above 14.vdc while running. Turn on the head lights and recheck the voltage. It should stay at 13 to 14 if it drops below that then the altinator has a problem. While running large amounts of currents most batteries and altinators are not designed for this type of use. One thing to remember is that the more load you induce into the charging system the quicker your alt will fry. The stiffening cap is great for helping this problem. Plus they are alot cheaper than a huge alt.
 

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as someone who is in "the game" of car stereo's yes a cap is a bandaid if you have a powerfull system and play it all the time ... for shorts bursts it might help out, however if your banging all day it wont help you it will hurt you cause the cap becomes a load on the system. i personally have a 15 farrad cap and it does help alot for very short bursts but for the long run dont help at all. now extra batterys that too is a bandaid with gause cause it will put out more current for a longer period of time but in the long run you lights will begin to dim again. unless your like me and have a battery charger to charge up those extra batterys every couple of days. the cheaper route at times.... then you have the upgraded alternater the best solution and better with multiple batterys. very costly ohio generater is a very good brand alot of pro's in the circuit use them.
 
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