2001 Honda Civic Alternator Question

[Drummer65 10+ year member]

Hello, so my stock alternator blew out due to my 2400 watt rms stereo. My car has been at an alternator shop to have the alternator rebuilt to high output but they are saying that they cannot make the alternator high output. If i replace the alternator with another stock 70 amp alternator could i just run a second battery in my trunk with an isolator between the two batteries or will i just kill the alternator again? thanks

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[Skittles619 10+ year member]

Have a HO alt made i know mechman makes good ones, DC power i think too.

 

[keep_hope_alive Premium Member]

you need a higher output alt to charge both batteries and the stereo - you'll just kill the batteries without charging them properly.

the Honda Electronic Load Detector (ELD) is going to cause you issues as well:

http://forum.sounddomain.com/ubbthreads.php?ubb=showflat&Number=1804618&page=1#Post1804618

Contact Ohio Generator for one.

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Note that it will be a larger load on the engine and reduce performance and fuel mileage. I found 2000 Civic 130A alts from Eagle Auto Electric that are reman on ebay, but it doesn't list 2001.

A second battery might be a good idea once you get the alt upgraded and do the Big 3 wiring upgrade. You're looking at a $500-900 investment in the alt, wiring, battery - depending on who you go with.

A battery isolator is to allow you to play with your system off, using only the extra batteries and not draining your starting battery. when the car is on, the batteries are connected and charging. an isolator won't help you either.

 

[Drummer65 10+ year member]

Okay so the ELD is only going to cause an issue if i upgrade the alternator not if i add a second battery?

 

[keep_hope_alive Premium Member]

the ELD is causing you an issue right now, and will be an issue until you bypass or work around it. it shuts off your alt to save fuel mileage when the ignition load is low. so you drop to 12V or lower while driving. that means it won't charge your main battery or your second battery. upgrading the alt won't change that either, it's part of the powertrain control module.

this is assuming your Civic has one. Only US domestic Honda's have them.

 

[jdmferio13 10+ year member]

the ELD is causing you an issue right now, and will be an issue until you bypass or work around it. it shuts off your alt to save fuel mileage when the ignition load is low. so you drop to 12V or lower while driving. that means it won't charge your main battery or your second battery. upgrading the alt won't change that either, it's part of the powertrain control module.
this is assuming your Civic has one. Only US domestic Honda's have them.

have you made a better diy with this.

 

[keep_hope_alive Premium Member]

have you made a better diy with this.

huh? i already wrote up a DIY for bypassing the ELD, see my first post in this thread. that is how i bypassed the ELD in my Accord. it functions the same in other cars, so the work-around would be similar but unique for each vehicle and year given the location of the ELD. note that some cars don't have easily accessed wiring like my Accord. you could always make the connection at the powertrain control module, since you are only really interested in intercepting the 5V signal to the ELD.

here is a post for a Civic forum, i make no claims for the validity, it's just proof the Civic has one.

Meet your ELD - Electrical Load Detector.... - Honda Civic Forum

 

[Drummer65 10+ year member]

So it prevents voltage above 12V? when my car is running the cap shows 14.4v not 12v, does that mean i do not have one?

 

[Drummer65 10+ year member]

*Edit* actually it stays at 13.5v not 14.4v

 

[Aldundra 10+ year member]

the ELD is causing you an issue right now, and will be an issue until you bypass or work around it. it shuts off your alt to save fuel mileage when the ignition load is low. so you drop to 12V or lower while driving. that means it won't charge your main battery or your second battery. upgrading the alt won't change that either, it's part of the powertrain control module.
this is assuming your Civic has one. Only US domestic Honda's have them.

This explains a whole hell of a lot.

I recently installed a voltmeter in my 1998 honda civic lx and noticed that during the day when driving around that when I came to a stop the voltage dropped to 12.8-12.5v but at night it wouldn't do it.

I figured out after reading this that it wouldn't do it when my lights were on because the alternator was needed for the headlights.

Also, for some weird reason, it only drops voltage while in drive, if I'm in neutral or park the voltage wont drop.

it's pretty annoying, not gonna lie

 

[keep_hope_alive Premium Member]

yea, annoying and not well known. installing a volt meter helped me notice it also. i strongly believe a volt meter is a required accessory when installing an aftermarket sound system.

you are right, it won't do it in park, just in drive while crusing with low ignition load. but turning on accessories to keep the alt up defeats the purpose since you are stealing current from the alt to do it.

the bypass i designed works perfect. it is a two-stage bypass that requires both the switch be on and the HU be on. so for low listening levels i can get the fuel mileage savings, or when the HU is off. i explain the system very well in my bypass thread.

 

[keep_hope_alive Premium Member]

So it prevents voltage above 12V? when my car is running the cap shows 14.4v not 12v, does that mean i do not have one?

you can see your cap while you are driving?

 

[Drummer65 10+ year member]

Quick ELD question

Okay so i got my new alternator but i have a question about the charging voltage. When in park or neutral my voltage is 14.4v at my cap and around 14.0v on my cigarette volt meter. Now when im driving around 2000 rpm with headlights on high beam and AC on full my voltage will drop to 12.2v on my cigarette volt meter. Now every 2 minutes it will jump back to around 13.8v for about 30 seconds then go back down to 12.2-12.6v. Also when i am braking i find that volts jump back to 13.8v. Is this an alternator problem or is it the ELD just controlling the alternator. I find it weird that in neutral i get 14.4v but as soon as i put it in drive it goes down to 12.2v, this is with the lights on high beam and AC on. maybe in drive the alternator pulley is not moving as fast? Any input would be great.

 

[bigaudiofanatic 10+ year member]

I have had no problems with mine al though I am not trying to do a crazy bass setup either.

 

[keep_hope_alive Premium Member]

Quick ELD question
Okay so i got my new alternator but i have a question about the charging voltage. When in park or neutral my voltage is 14.4v at my cap and around 14.0v on my cigarette volt meter. Now when im driving around 2000 rpm with headlights on high beam and AC on full my voltage will drop to 12.2v on my cigarette volt meter. Now every 2 minutes it will jump back to around 13.8v for about 30 seconds then go back down to 12.2-12.6v. Also when i am braking i find that volts jump back to 13.8v. Is this an alternator problem or is it the ELD just controlling the alternator. I find it weird that in neutral i get 14.4v but as soon as i put it in drive it goes down to 12.2v, this is with the lights on high beam and AC on. maybe in drive the alternator pulley is not moving as fast? Any input would be great.

That is the ELD saving you gas mileage. nothing is wrong, everything is working as-is. the ELD doesn't turn off the alt unless the vehicle is in gear.

Lighting isn't through the ignition, since you can have lighting while the car is turned off. the ELD only monitors the load on the ELD that is ignition based (and fed through the ELD).

Turn your A/C on or defrost on, etc. and the voltage will increase. But this isn't a solution since it robs the alt of current for those devices.

The ELD bypass I developed works great.

http://forum.sounddomain.com/ubbthreads.php?ubb=showflat&Number=1804618&page=1#Post1804618