I have an Odessy pc680 battery which is relocated to my trunk in my 2000 honda prelude. I also have aem pulleys and UR crank pulley. I also am running a 12inch sub with 250watt amp.

Problem is I start the car (after jumping it) and im looking at my vtec controller and it shows the batt voltage...its at 14.6v....then after about 10 mins drops to 12volts...then if i turn on the interior and exterior lights and about 5 mins later its at 9 volts....and eventually the battery light comes on and it will shut off... Also ill be in stop and go stop and go traffic and its about to stall...The only way i can get the volt to climb back up is revving the engine up.....

What seems to be the problem...the 680cranking power batter reloctated to trunk....or the aem alternator pulley?

 

if its your battery that you think is messing u up then maybe try to get a capacitor and hook your amp and subs to it

 

what i think is the alternator is not sensing a pulley exists...because its so light...the alternator itself is getting the proper voltage however its not charging the batter at idle...the battery voltage wont maintain unless im driving and the rpms are up... i personnally think is alt pulley has expletiveed up my whole ****...let me know experts

 

well i know nothing about the pulleys so im not gonna say anytting cuz id be lying. but i do know that on my friends mustang, he has 2 10" subs and a jbl amp and if hes in park and he is playing his music loud, his car will turn off. he just never got around to buy a capacitor to stop that yet.

 

im going to swap the battery out see what the vtec controller reads check the alt volts as well...if anyone else has any info greatly appricated

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by billabongkid13 &raquo;</TD></TR><TR><TD CLASS="quote">im going to swap the battery out see what the vtec controller reads check the alt volts as well...if anyone else has any info greatly appricated</TD></TR></TABLE>

First off, the battery is only there to start the car, after that you're running off the alternator. As long as the car starts I would not worry about the battery.

The first and easiest thing I would do if I were you is check all the connections on the alternator and then double check all your grounds (transmission, battery, valve cover, etc). Unbolt them, clean and inspect them. Especially the ground in the trunk for the battery that was surely 'custom'.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by billabongkid13 &raquo;</TD></TR><TR><TD CLASS="quote">what i think is the alternator is not sensing a pulley exists...because its so light</TD></TR></TABLE>

I'm sorry but that is incredibly silly The alternator doesn't really care how light the pulley on it is and those pulleys don't really do much of anything anyway.

You have a thing inside your alternator called a voltage regulator that is like the brains of the alternator. It controls how much power the alt puts out...and it is capable of WAY more than 14-15 volts. I would remove the alternator and take it to a local auto parts place and just have them test it.

 

it is because you are underdriving your alternator. slightly bigger pulley = slightly less voltage output

 

My room mate has this problem in his civic with AEM pulleys, yet he still runs the OEM battery..... The problem is not the fact that the pulley is lighter, but normally weight is not enough to affect the *** dyno so companies also reduce the diameter of the pulley. This will lessen the frictional force on the crack, which results in a bump in the *** dyno chart.

The problem with this is, in fact, that the alternator spins faster and the coils generate the power at a slower constant but to reach full efficienty the alternator pulley must be spun faster/engine revved. In turn this will charge your car. It's a bad price you pay for lil *** bumpage IMO.

 

ive been running AEM overdrive pulleys for almost 4 years and have not had a single problem. note i still have the OEM battery and i'm also running a 800watt amp too.

i would seriously check your alternator output and all your ground wires. don't go buying useless parts because u think thats what is wrong, go buy a good multi-meter and actually diagnose the problem, and have NAPA or some other place check ur alternator output.

good luck

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bluedlude &raquo;</TD></TR><TR><TD CLASS="quote">it is because you are underdriving your alternator. slightly bigger pulley = slightly less voltage output</TD></TR></TABLE>

True that but I never had a problem with my underdrive stuff with an Odyssey PC680...plus he said his power keeps going down until the car shuts off, a pulley shouldn't do that.

 

He also has a 250 watt amp sucking the power out of the battery faster than the under-driven alt. can recharge it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by axlline &raquo;</TD></TR><TR><TD CLASS="quote">He also has a 250 watt amp sucking the power out of the battery faster than the under-driven alt. can recharge it.</TD></TR></TABLE>

bingo

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by axlline &raquo;</TD></TR><TR><TD CLASS="quote">He also has a 250 watt amp sucking the power out of the battery faster than the under-driven alt. can recharge it.</TD></TR></TABLE>

Haha, yeah that'll do it. He didn't really mention if the amp was at full-blast or not when it died, hopefully that's what it is.

Why would you want to run a lightweight battery when you have a big stereo system? Or any kind of subs at all for that matter...switch over to an Optima or at least a normal sized car battery.

 

optima red top should be fine and same as everyone else said get the alt tested. do not buy a capacitor it more than likely wont do jack **** for your problem but waste your money.

 

i took the sub/amp completley out still does it!

 

did you go get your alternator tested? its free

 

all signs point to a weak alternator...j/w what guage wire did you run when you relocated the battery?

any shop will have a battery/alternator tester...but id check your connections first..it has to be one of the two, deff not that battery

 

It sounds like the perfect storm of every iffy thing you can do to your electrical system.

- Use tiny "race" battery
- Relocate battery to trunk
- Underdrive alternator
- Electrical bling bling

I would just start removing things off that list one by one and seeing what you can get away with. *shrug*