meanshyguy

I have a charging problem, alternator is good, battery is good, battery grounds are new, new terminals as well, there is voltage on the green connector that connects to the alternator, swapped fuse boxes, here's what happens:
While the car is idling, I used a voltmeter to test the voltage after jump starting the car, voltage drops very slowly, when I rev the car, it drops quick, then slowly goes back up but around to 9 volts. After I turn off the car it won't start anymore, then the voltage goes up just a little very slowly, so in other words, something is the my voltage when I rev the car. obviously the Amps too.

TheMuffinMan

iTrader: (1)

Mind posting what car, motor, mods, etc?

poorman212

After that, are you testing all of this from the green connector, what is the voltage from the "main cable" coming from the alt?...sorry Muffinman for jumping in, that was unclear in my mind as well.

meanshyguy

No not testing this from the green connector, just tested the connector checking for voltage to see if there was any short throughout the wiring, and it's an H23 motor, only mods is a dc header.

TheMuffinMan

iTrader: (1)

Swapped into a CD5 or 7? It looks like a Prelude in your avatar...

Generally speaking the Accord's charging system should put 14-14.5V to the battery terminals while the car is running. If you are not seeing that then something is squirrelly with your alternator. How do you know it's good? Did you get it from a different car? Is it new?

Do you have a sound system? Did you install an aftermarket radio?

You really haven't given much other than the motor....

poorman212

Still not sure of what year we have -86 to 02?

So the voltage at the main cable from the alt is at best 9v while running....and the alt is good? While running, the main battery cable to the battery-10mm bolt under black cap-single wire, what volt reading are you getting.

EDIT: Muffinman got to this while I was typing.

TheMuffinMan

iTrader: (1)

*high five*

meanshyguy

Yeah it's swapped into a prelude, its a good alternator from another car in which the voltage is over 13v at the battery while running so I know it's good, I have two more good ones as well, and no I don't have a sound system.
The power cable from the alt reads 13v or 14v I don't remember, but at the battery it's now reading 12.30 cuz I barely got it fully charged at school, but won't go pass 12v and and if I drive the car for a couple of days I'm gonna end up needing a jump just like last time I exchanged the battery for a new one, it's like something's eating extra voltage while the car is running cuz the battery doesn't reach 13v, 12.5? at the most.

TheMuffinMan

iTrader: (1)

Well you have an H23 from a Prelude swapped into a Prelude...You may have better luck posting in the Prelude forum?

If the car is running you should have 14-14.5V ON THE BATTERY, which means it is charging it. Anything less than that it is not correctly charging the battery, so as you drive you do not replenish the battery and it slowly dies.

chikin pickle

If your battery has a dead cell it can cause problems similar to this. When a cell dies in a battery (very common in hot areas like the southwest) the lead plates inside the battery will buckle, and touch each other. This shorts the battery and dumps all your current into the chassis.

Happened on my car when the battery died. The car would be jumped, and the electrical system voltage would slowly drop until the tach stopped working.

poorman212

Have you chased the cable from the alt to the fuse, to the battery to be sure there is not a loose/dirty connection/blown fuse...12.3 sounds like the volts from a somewhat good battery (12.5v is about good), I like to see alt put out 14.5v. So if you have 13~14 at the alt and 12.3 at the battery????? It's going somewhere, I hope I've given a few things to check.

meanshyguy

I'm posting here cuz I've seen ASE certified techs help others here, even if not ase certified I've seen more help here.
The battery is new, I went to autozone to exchange it, we tried my battery also and did the same thing.
We checked all fuses and grounds, wires and all good, I'm gonna test all relays tomorrow and see how it goes.

TheMuffinMan

iTrader: (1)

I am rereading your one post, the battery itself when the car is turned off will never go above ~12V.

When the car is running, use a multimeter across the battery terminals and you should see 14V. If you don't see that, either your alternator or something between the alternator and the battery is a problem.

As to posting in the wrong section - more people are going to be familiar with the chassis and common issues with the charging system than the Accord section will.

meanshyguy

Thanks man, I found the problem, happened to be the bad ac compressor pulley, it was sort of creating some kind of resistance not letting the alt spin at it's proper rpm, so I took it off and problem solved, thanks for all the help to you all.