last saturday this happened as well , i was driving and the voltage drops below the middle line and into the first spot of ///// . i unplugged the fuse to my amp but it still did it, the abs light tripped first as the voltage dropped. it turned out to be the + cable 2 the alternator. However today when i started it at 5pm the voltage was low , then i drove around for an hour and the same things happened as last saturday. i checked the + cable to the alt and it was tight , i have a brand new battery (2 weeks old) and a newer alternator 6 months old ( i didnt drive in the winter though) so its like 3 months old. has this happend to anyone? i need to be able to drive to work in the morning , which is an hour drive. what can i do to fix this? here are pics of the gauges.
thanks

http://community.webshots.com/album/128671551VxWalq

 

could it be the ground on my amp? thanks

 

checked battery, all amp wires, alt wire, i am stumped .

 

I would say your alternator is not charging. You won't get far with it like that. Your battery will drain and your engine will eventually stop.

 

thats what it did last saturday! but that was b/c my + cable , going to the alt was off of the tab. This alternator is relatively new though, the only thing i have doen to the Z is put that 800 watt amp in , but i have a 1 farad cap . what do u think i should do? I will prolly go to autozone tommarow and have them test my amp, do they test it to find out the amperage? or what? aalso a guy on here reffered me to dominick@tds.net, who specializes in high output alternators said he could get me a 200 amp alt for $340. is the alternator that i have in here right now a 140 amp ? it was the ac delco replacement. also i have a 93 with the fan blades on the outside. thanks for the help

 

i just went outside and messed with it a bit, it would turn over but then if i turned my a/c on it would drop a few notches back into thte ////// , then i turned it off , turned it on, turned the a/c off and it was still at that mark. n e help would be apprecieated thanks.

 

i have a 1500 watt amp and the stock 140 amp alternator and i dont have any problem like this so i cant c that the amp i ur problem....

where did u get ur alternator from....is it remanufactured or brand new?/ there is a posibility ur alternator is bad....if it keeps running like that ur battery will be f-ed to ...

try getting ur alternator tested

 

EDIT: even without my caps my battery doesnt drop below 12.5 volts or in that range....

i hit the wrong buttont to edit

 

you need to make sure you are using the same gauge wire for the ground wire, from the battery to the chassis, as the power wire to the amp. you may also run a larger gauge wire from the batttery to the alt.

I was having trouble with the lights on and tune up loud, the lights would dim as the sub would hit. amp is a ppi 480 with cap. So, I went to 200 amp powermaster from summit, It is a direct bolt in...

 

i thought about getting the 200 amp alternator...dont u have to upgrade to a samller guage wire (smaller is in thicker lol)

 

i ran 8 guage from battery to cap then 6 gauge from cap to amp then 6 gauge ground from amp, but i didnt have a problem before , it has been happening ever since i put the new amp in , i think the alt . was remanufactured, im not sure, it looked brand new though. i am going to have it tested at autozone tommarow, thanks for all the help guys. any other info is appreciated.

 

how much is that 200 amp alt from summit? how has it worked for ya ?

 

Yes, but I haven't yet. I haven't had any troubles though. The only thing I had to do was reclock the atl because the battery term was in the wrong location.

 

If your alternator is charging, then something is putting up too much resistance somewhere in your electrical system.

This most likely isn't your problem, but in my case my ignition switch was dropping the voltage significantly. With lights and fans on and car warmed up at night, the needle would sit right at the top of the red. Now it won't go below half no matter what I do. I'm not saying it's that, but there's gotta be something that's not pulling it's weight. My best advice is to take a multimeter out and start testing voltage at different points in the car and try to narrow it down. Your problem could be very simple, it's just finding out exactly what it is that's hard.

BTW thanks shoebox for the great tech info on your website. Although I must say getting that one cable at the back of the switch to come out and go back in was a PITA.

 

alright i got the alt. tested and it was bad , only putting out 11-12 volts, not 14 like the guy from autozone said, should i get a brand new alt? remanufactured one? or a high output one? thanks