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Very weird voltage drop..........


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My Jeep does this all the time. Even when I had a new alternator, belt, and wires. The only explanation I can think is that when the fan turns on it places a sudden strain and the belt slips for a second.

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I know that alot of little things can cause voltage drop but im pretty sure nothing should cause such a drastic drop such as what I'm seeing..

How old is your batt.? Im going to guess sence your only running 500watts you never got a new one, which is fine. But sounds like its time for a new battery.

Not too sure... resting voltage is around 12.6 so im pretty sure its still good but ya never know..

Im eventually replacing the stock with an XS 5100R so i guess i just might be doin that sooner than later :pardon:

Honda's have an ELD circuit on them could be causing this problem just search about it, I have never had any trouble with it personally but something to think about.

THIS!! I looked around a bit and found a thread on a civic forum and it sounds like you have to bypass it. Kinda pissed i might have to spend an extra $100 or so on a stupid adapter. Also says I might have to replace my ECU??? <_< I am guessing that this ELD circuit is the case but here are some VIDS showing different times when it drops into the 12's

--cruising around 50 then slow down, turn, stop, floor it to show the voltage gaining then leveling off around 40mph. heres the weird part... after that i just coast and put it in nuetral, then back to drive.

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cruisin on the highway, then slowing down to about 20 then speeding back up

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sitting in traffic, put it into nuetral, then when i put it back into drive voltage stays up until i accelerate.jumps up to normal when i floor it, drops down when i start to cruise, then bumps back up as i level off :trippy:

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These vids give anybody any more ideas?

06 Jeep Grand Cherokee

2 DC Level4 12"

Soundstream TA1.3000d

4 RF Punch 6.5" Components

2 RF Punch 3.5" 2-ways

RF Prime 400.4D

XS Power XP950 +&-run of XScorpion 1/0 OFC My Civic Build

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when the car drops down like that, let it sit if it continues to go down (as in you put in drive it drops to 12.6 and after a few seconds if it goes to 12.5 then 12.4 you know your alternator is not charging and your running off the battery

what are the rpms in drive, i had a build civic once it idled about 900 rpm never had a stock one

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when the car drops down like that, let it sit if it continues to go down (as in you put in drive it drops to 12.6 and after a few seconds if it goes to 12.5 then 12.4 you know your alternator is not charging and your running off the battery

what are the rpms in drive, i had a build civic once it idled about 900 rpm never had a stock one

AHH thats what i forgot to add. the idle rpm is usually 900-1000. and someone mentioned something about the alternator not putting out voltage because the rpms are not high enough. i dont think this cant be it b/c i can drive steadily around 20-40mph with rpms sitting anywhere from 2-3k and the voltage will still sit in the 12 range from time to time

Edited by KickerKid58

06 Jeep Grand Cherokee

2 DC Level4 12"

Soundstream TA1.3000d

4 RF Punch 6.5" Components

2 RF Punch 3.5" 2-ways

RF Prime 400.4D

XS Power XP950 +&-run of XScorpion 1/0 OFC My Civic Build

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The engine rpm probably drops below the alternators "turn on" rpm. Most Alts won't put out almost anything untill they reach a cirtain rpm. If the engines rpm drops below what the car would idle at, that means the alt could just not be putting out any current.

^ this.

If it bothers you or if it is causing problems, you might look into getting an overdrive pulley to spin the alt faster.

12 - 12"s in the STAY PUFT 1989 Chevy Astro

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The engine rpm probably drops below the alternators "turn on" rpm. Most Alts won't put out almost anything untill they reach a cirtain rpm. If the engines rpm drops below what the car would idle at, that means the alt could just not be putting out any current.

Sounds good to me...I've also seen 'older' hondas have idling issues (less than desired) Causing such things to happen. Other symptoms may include hard to steer-a/c cutting on/off or not producing the difference in ambient temperature that's that great...even engine vibration. Again, this should only occur on AT models and more obviously while in gear as the transmission adds a load to the engine

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