Hello. I hope you guys will be able to help me out.

Since I've owned the car, my voltage has varied depending on whether it was humid or not, or if it was extremely hot or cold. Usually when I start the car up cold, the voltage gauge would register near 3/4. Driving down the street it would be right at half. If you have headlights on, A/C, or hit the brakes, or a combination of them, it drops as low as 10 volts.

I figured it was my alternator, and given I have a H/C and an aftermarket sound system I upgraded to a 220AMP variation w/ an overddrive pulley. After installing the new alternator, at idle, it registers a lower voltage then my factory alt, around 11. It drops to about 9 1/2 - 10 under load.

They both will come back up to mid range above 1200-1600RPM. My friend has a B4C w/ a high output alternator, and his rain-sleet-sknow registers around 3/4, and I was hoping for my new alt to be the same.

We did damage the exciter wire when we removed the old alternator. We took a same gauge wire, and soldered it back onto the metal terminal, then connected the two wires together. To the best of our knowledge it has a firm connection.

Any thoughts? Thanks so much!

 

thanks for looking!

 

hi,
regarding sound system just turn it all off while troubleshooting. Disconnect the + wires to the sound system to rule out any possibilities it is drawing power when off.

get a digital volt meter and hook it to the battery terminals.

a good battery, engine not running, at full charge is 12.6 to 12.65 volts. It will read higher if there is a surface charge on the battery, such as after you just shut the engine off and the alternator has been supplying 13 or more volts to the battery. A battery at rest having 12.45'ish and lower is a weak battery and should be charged.

engine running and alternator spinning should put out 13.2 volts at minimum, this is at idle with no accessories on- no headlights, no heater, no radio, etc. The normal voltage output is 13.8 to 14.5, depending on temperature and state of charge of the battery.

it is normal once you turn on accessories at idle for voltage to drop from 14+ down to 13, but when you rev the engine to 1500-2000 rpms the voltage should come right back up to where it was prior to turning on all the accessories. Alternator output is dependent on how fast it spins, which is dependent on the size of alternator pulley. Smaller alternator pulley = spins faster. And smaller crankshaft pulley = alternator spins slower, so take these into account for when at idle.

Try googling about aftermarket high output alternators, I thought they were typically a scam because they really can't output the extra power they're rated for without overheating because they're built with the same case as the oem alternator is; the cooling capacity just isn't there. And they only output the extra power at high rpm, at 2000 rpm and less where the engine runs at they put out the same power or less as oem.

i don't know offhand the wiring hookup of the alternator, I know there's the big output wire which is 10 or 12 ga. The other 2 or 3 wires are either the excitor wire, the sense wire, and the gauge lamp wire. You can google these too; i don't think these would cause the alternator to have a low voltage, except for maybe the exciter wire which just guarantees the alt. will charge as soon as it spins. Best guess would be the alt. is of foreign quality with a bad/poor voltage regulator, combined with too low of a rotation speed for the output that is needed. I've gone through a few duralast alternators on my truck, were remanned and advertised as high output 100 or 200 amp units which sucked.

 

Not saying this is it, but..........

You shouldn't have soldered it. You should use those crimpers that you stick the wires into each end of and squeeze it. Then use those heat shrink covers to keep the water out.

 

I know this sounds crazy but, just go to Advance Auto and get another alternator, put it in and see if solves the problem. if it doesn't fix it, just clean it off and return it.

Its a good alternator too, I have a 1,000 watt amp and it never faulters in any way, its perfect.

 

Thanks for the tips. I will try to return the 220AMP alt And go from there.

Thanks for the help!

Also for testing voltages using a DMM, what setting should it be on? The one I have has 3 Voltage sections, one w/ a wavy thing underneith another w/ a dotted line (I know these are AC and DC but I'm not sure which one is which and which one I should be using) and then they have the option for BAT voltage and it has 1.5V and 9V settings.

 

Mines been doing this also since it's been really cold here. Just when I start it up it will drop below 13 volts, down to about 11 like yours. Drive it for a few minutes and it magically jumps back to charging. Back when I 1st bought the car in August it started charging/not charging as if it had a short or something. Got to looking and it was the main battery feed wire, the largest guage one that didn't have a good connection. It wasn't even hardly crimped, it could just be pulled out. I crimped it as best I could but maybe it's acting up again. Just check all your wires to make sure there's good contact. If you do take the alternator off have it checked just to make sure it's the culprit.

 

Thanks. I think I will also upgrade the "Big 3" Ground/Hot wires, I heard this helps since the wires carry less resistance, the voltage drop should be less.