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200 amp alternator not what i had expected...

Discussion in 'Explorer Audio & Navigation' started by Fish Man, December 19, 2004.

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    1. Fish Man

      Fish Man Elite Explorer

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      Hey everyone. this weekend i plopped a 200 amp alternator into my car. really quick and easy job, i was happy with how well the install went and didnt run into any problems doing it. i cranked up the car in the garage, put on all the lights (2 sets of 55w fogs, one set of 100w fogs, the high beams and some interior neons) and all was well. even at idle there was no voltage drop. so i cranked up the system (350w amp pushing a 10 inch sub plus the pioneer head unit putting out whatever it puts out) and the batter gauge dropped a tiny bit on bass hits but with all that other stuff running i was really impressed at how little it dropped, especially since it was at idle. there was no dimming. so today im out driving around and when i pull into my driveway tonight i notice that as i pull into my spot to park the guage dropped about 1/4-1/2" and the headlights noticibly dimmed as it hit idle speed. i turned of the stereo and all aux lighting and put the revs up a little and the guage shot back up and the lights were normal brightness again. as soon as i let off the gas pedal and it went to idle the lights dimmed and the battery guage dropped...even the guage lighting dimmed noticably as if i had a civic with a 35 amp alternator. this was with nothing but the stock low beams on. no fog lights, no stero, no nothing. my old 95 amp alternator, even though it was about ready to crap out on me didnt even do this. it would dim when i had all the lights on and the stereo going but even the stock half dead one wouldnt do this. why would this be happening? i installed it correctly...is there anything else i needed to upgrade when i installed it? please let me know whats up with this silly alternator before i pull it out and send it back.
       
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    3. B94Sport

      B94Sport Well-Known Member

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      Does it have a stock-sized pulley or a smaller pulley?
       
    4. Fish Man

      Fish Man Elite Explorer

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      stock sized...i was talking to my boss (at the aquarium store...he used to compete in spl) and he said i could downsize the pulley but not to bother.
       
    5. X~FACTOR

      X~FACTOR Name is Ray

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      Loose connection? Battery still good? Was it a rebuilt one? Maybe it was it's time to go.
       
    6. superedge88

      superedge88 Active Member

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      Sounds to me like the battery may have been going bad from the last alternator going down hill. I would look into an exide orbital battery (like optima, but a better version of "spira cell" technology) This may help with the idle problems. You could also look at getting a different pulley thrown on the alt.
       
    7. Fish Man

      Fish Man Elite Explorer

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      the connections are good. the alt is rebuilt as far as i know and has never been used since the rebuild. guess ill have to get my battery checked out. how can i know if it is messed up? i can get it checked at autozone or something right? dont think the current one is too old but i was thinking about a dual battery set up anyway. with such a mild system i wouldnt think i would need a dual battery set up but this sucks.
       
    8. taxx

      taxx Make em say Ugh

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      battery checked out or not thats a lot of drain on a typical battery, even if you turn it all off and rev the engine it takes a little more than that for the battery to recover. At idle the alt isn't putting out much like it is when driving down the road. If your concerned about that get a better battery like a blue or yellow top optima or get two or as mentioned downsize the pully so the alt is running at a higher RPM.
       
    9. Nate1

      Nate1 All 4 wheels locked

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      Upgrade the big 3... pos wire from alt to battery, neg wire to body of truck, neg wire to engine block. If you search the internet you'll find lots of info about it, but it will prob make the biggest difference at this point.
       
    10. Fish Man

      Fish Man Elite Explorer

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      taxxman...i know the alt isnt putting out much at idle but this new alt is putting out less than my p.o.s. stock alt...and thats not right. would a battery make that much difference? i will have to try upgrading the big 3, i have heard them mentioned, ill do a search
       
    11. taxx

      taxx Make em say Ugh

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      Yes a battery makes a huge difference, more so than an alt. It may put out less than the stock alt at idle, it depends how it is built. Thing is there is something called recovery time. If you wear your battery down no matter what the alt is putting out its gonna take some time to bring the battery back up. Thats why when you rev it, it gets juice from the alt and runs fine, when you are at idle the alt doesn't put out as much as everything is demanding and the battery is hurting to keep up.

      Although those wires need upgrading for larger draw, your not going to see a differnce at idle from changing those wires. All that does is lower the resistance in the system and allow the current to flow easier. Its not going to make you have more power. When the alt is putting out 200 amps then yes they will help a lot but at idle its not putting out much at all so there is no gain from larger wires.

      There is no magical answer. The power system does not rely on one component. I know people with better batteries, bigger alts and a cap and they still get headlight dimming. If you want the best run two alts and a ton of batteries, but if it was me I would just live with it and not run all that crap at idle for a long duration.

      But a dual purpose (start and deep cycle) battery such as an optima blue top or yellow top (I preffer the blue for its wing nut posts) would help quite a bit.

      I ran stock alt, optima blue top, and I could run my winch, 4 100 watt lights, 2 55 watt lights and some other crap at idle speeds and not even phase the system.
       
    12. Fish Man

      Fish Man Elite Explorer

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      taxxman-thanks for the info. maybe i should upgrade my battery? i really dont care about running all my crap at idle...but i would think that i should be able to stop at a stop light without my headlight dimming. thats just rediculous. so this recovery time thing...if i run it for awhile technically that would bring the battery up to normal right? i drove it for 5 or 10 miles today, stop and go...how much does it take to get it back up? since its so cold ive had the heat way up and even the friggen heater fan slows way down when i stop at a light. and now its been doing this rediculous shudder thing at lights too. kinda pissed about this...wish you could give me a magic answer! ;)
       
    13. taxx

      taxx Make em say Ugh

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      I am not saying it will be solved. I am just saying a decent battery makes a world of difference. I have no idea what you have in there now. If you are running a sub chances are good you'll still have some dimming when it hits, I always did even with just one 10". A cap helps that some. I have one 10 in my 250 and it doesn't do squat but I have 2 batteries and a nice alternator from the factory ;).

      I wish I could give you a better answer, all I am trying to say is just because you upgraded the alt, there isn't any reason for it to act better. In my 73 I have a decent alt and a great battery but with no radio at idle my lights dim, I have crappy wiring so when I upgrade that I am hoping it will help, but there is more to it than just that.

      Theoretically you should be ok at idle with the system going. But with it all going your going to get hidelight dimming, thats part of the game unless you want to dump a ton into your power problem, but its not gonna kill the truck. If it was me, I would put a decent battery in (even if its a generic that I know is good) upgrade those wires (needs to be done someday and its cheap) and see what happens. if it still dims live with it, cause thats life. But know your in good shape.

      As far as recovery time (prolly not the right words to use) you should be fine driving it normal. battery should charge pretty fast. Just look at your gage. Now if your getting lights dimming and shuddering on the fan without much anything on to draw power you have issues. Double check your wiring, and if that is all new (the problems) since the new alt, I'd have the alt and battery checked. IMO your not going to get much out of an alt at idle, but without the radio running that shouldn't happen and I would be getting it all checked out.

      If the battery checks out fine (sometimes bad ones still will) and without the radio you get dimming contact where ever you got the alt from and see what they say.

      I am far from an expert on this just trying to give some insight on the electrical system and such from experience. There may be others with some better advice, I would definetely do some testing and playing around before I spent any more money. I may be wrong on the wires but I don't think so. From an electrical standpoint they shouldn't make a difference at idle. But it very well could due to components putting a draw on it. As cheap as it is to do the wires you might do it and see what happens. Hell maybe I'll be wrong and you'll be ahead of the game money wise.
       
      Last edited: December 21, 2004
    14. Nate1

      Nate1 All 4 wheels locked

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      FWIW the BMW 540i's dash dims at idle with the HIDs on. On such a nice german car, you can be sure that if something like a small voltage drop at idle was a problem, they would not allow it. Then again, you have to consider, the BMW is a V8 idling around 350 rpms without the compressor on... so :D

      But still, point in case... you are ALWAYS going to get voltage drop on all but the utter creme de la creme of electrical systems at idle. If you are charging everything back up as soon as you get some RPMs, don't worry about it.
       
    15. terdrocket

      terdrocket Traitor SS

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      Did you check the specs on the alt closely?
      Some aftermarket alts boast the big amps they put out rated at high rpms, while they will actually make less than stock at idle rpms.
       
    16. Billy177

      Billy177 Well-Known Member

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      maby the belt took a crap and started slipping
       
    17. Jason94sport

      Jason94sport Well-Known Member

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      I'd replace the wire from the alternator to the battery with a 1 or 2 gauge wire. Anything over 160 amp you really should replaced the wire with a thinker one to handle the increased loads. It's also a fire risk running such a high amp alt on a thin wire. After that I'd replace the battery with an deep cycle yellow top from Optima.
       
    18. davesexplorer

      davesexplorer Well-Known Member

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      how does the battery make a difference since batt = 12v and alt = 13.5-14v

      you are not getting any power from the battery unless you are overdrawing the alternator... a new battery will not solve your alternator problem...

      def do some heavier guage wiring than stock...
      And terdrocket is soooo right, a bunch of the "high-amp" alternators out there that label them as 200 or 240--that is peak amperage out of it, say cruising on the highway with o/d off lol, more rpms will net you more power, and sometimes the "idle" power put out by one of these alts is actually less than the stock...
       
    19. superedge88

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      I agree, you have to pay some crazy cash ($300-$500) to get a higher output alt that actually does well at idle. I would upgrade some of the wires, it won't help a lot, but is a good idea anyway. I wouldn't go with a cap or second battery, that will just introduce more loads on the electrical system...less efficiency...more parasitic loads, the list goes on, expecially since your new alt doesn't do well at idle. Get a hybrid battery that is a starting battery/deep cycle, these batteries are very good, like I said before, I like the exide orbital line of batteries. Keep in mind though, you may do all these things and see very little in return.
       
    20. Fish Man

      Fish Man Elite Explorer

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      i really dont want to live with the dimming...i mean i know that yes with all the stuff running i should get some dimming and thats fine. what bothers me is that with nothing running i get alot of dimming. thats not cool at all. the battery gauge dances around more than it ever did with that crappy old 95 amp. i think ill get the battery checked out and see what that alt is putting out at idle. dunno the specs on the alternator. dunno if the belt is slipping...i would think id hear that though? would be something to look at. so dave are you saying that a new battery wont help? i'll have to try some bigger wire...
       
    21. superedge88

      superedge88 Active Member

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    22. davesexplorer

      davesexplorer Well-Known Member

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    23. davesexplorer

      davesexplorer Well-Known Member

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      yea definitely check the alternator, could be something wrong with it too?

      The battery will only help when your voltage drops to its voltage range, the battery cannot supply above its charged voltage state, if its 12.9v resting, It cannot supply your components @ 14v. Bigger batt will help if your voltage is dropping below the batts resting voltage though..
       
    24. Fish Man

      Fish Man Elite Explorer

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      ill get the alt checked out...dunno if something could be wrong with it but i woudl think it should be doing better than it is now. i just dont see how this thing would not be able to power my stock head lights. thats pretty rediculous to me...
       
    25. davesexplorer

      davesexplorer Well-Known Member

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      I agree with you, if it cant power the stock headlights.. tsk tsk...
       
    26. 97BlackX5.0

      97BlackX5.0 Active Member

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      okay... im having the same problem with my stock alternator at idle running my headlights (silverstars) my heater and the rear heater full blast with the fogs on and having a 200watt amp hooked up but not pounding.... in my opinion its almost always the battery....do this for me.... somplace that you have a vehicle to jump your car or a battery charger... turn all your crap on without the car running.... leave it run for maybe say 10 minutes at the max.... then turn it off.... and immediately try to start your truck... if it wont or its really really slow then its your battery.... it has lost the resiliency that it once had.... it will still hold a charge and start your truck but the power out put is way down and isnt much good other than just starting the truck.... this happens alot to older batterys.... no matter how big they are this can still happen to.... im also assuming that you have a maintenance free battery.... if you can open the indivdiual cells you might want to get a cell tester..... try it again but instead of starting the truck after using the battery for ten minutes ... test the cells.... ill bet you have at least one or two bad....

      i had this exact problem and i replaced the battery and bingo it was gone.... i kept the old one around to jumpstart lawntractors and stuff like that cause it still works for that... just cant put a load for any lenth of time on it or its kaput...and needs to be charged by a battery charger....
       

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