Hello all, I have a 2000 Chevy blazer 4dr 4x4 4.3L V6. My issue is when I am driving on the highway, my volts drop down to 12.8 to 13.0 volts. And my motor sounds sluggish and does not have good performance. Also, when I am city driving and have my sound system on, my volts drop below 13 volts and does fluctuate all the time when system is on. I am running 900w rms 1800w max power amplifier. And a 1000w rms 2000w max single 15 inch sub. I did the big 3 upgrade with 1/0 AWG wiring, I have an optima red top that is about 2 or 3 years old, stock alternator which I believe is a 100 or 105A alternator. Its just that I major voltage drop and lights dimming. Even when I use my rear defrogger, my voltage drops. Anything you can think of that might be wrong?? Do I need a new alternator?? My blazer has 112,000 Miles on it. I am thinking there is too much strain on stock alternator, that I need to upgrade to a HO alternator. I am pretty good with my hands and I am sure I can replace the alternator if need be. Now, with voltage drop, could it be the battery?? Or is it just an alternator issue?? Thanks and hope you could help.

 

The battery can only put out 12.6 volts fulling charged, but it losses amps the day it is filled. A 650 CCA battery will put on those amps the day it made, but a couple years down may only put out 100 to 200 CCA depending on the cilmate you live in. I would get couple of motorcycle batteries and wire them in parallel (keeps the voltage at 12.6, but ups the amperage output for your sound system). A high output alternator is must, unless you change alternators every couple of years.

So, yes your alternator is fault for causing your engine to acting sluggish and the massive voltage drop, but it is probably because it's puting out close to its max output with sound system you have setup and the alternator is connected to engine via belt.

I have guys at my school with simular sound setups and they all had the same problems, they fixed it with more batteries and high output alternators. If you do put in more batteries, wire them in parallel (red to red or positive to positive), not series (red to black or positive to negative) or could fry your engine computer.

 

If my votage would drop to 13 I would check it out (Blazer in the shop right now and the same yr and model as yours) My voltage meter runs around 14.2 when engine running, it has been dropping to 13.8 and not recoverying back to 14 or above. Your battery might only put out 12.6 but your alt puts out what ever the battery needs to stay up and then run the accys on the vech, ie, radio, gages, lights, A/C, etc. So at 13 yep I can see your lights dimming etc. Maybe you are making the alt work to hard to keep up and need that heavy duty one you mention. But there is a problem there, that I can re-issure you.
I "Think" part of my situation is a bad ground in the turn sigs for the vote meter goes back and forth and the votes drops when I hit the turn sigs..but its in the shop now for them to figure out.

1st go for the high out put alt and make sure your battery is up to suff and maybe try that 2 M.C. batteries together...

Good Luck

 

Hello, My volt meter in my blazer does not go back and forth like you mentioned it might. It stays at a constant 13.0V, but when for example I turn on the stereo, It will then drop and bounce around. But, Volt meter stays the same when I am just driving the car with no stereo on. I think my alternator is working too hard to keep up. I checked the grounds, all looks good. My big 3 upgrade looks solid. I used a brush and cloth to clean my ground connections. Using 1/0 for my big 3 upgrade is okay is it?? Too big of wire?? The alternator I am getting is from DC Power and is 185A version that they have in stock. My amp for my sub is only rated at 60A, thats what the fuse is..2x30A. The alternator installation guide says that a wire upgrade is required for the new HO alt. I have done that part and the new HO alt is going to be shipped to me on monday. So, looks as if I will be installing the new alternator in about a week or so. I have seen videos on youtube and directions on how to install a new alt such as this one. Looks pretty straight forward. Only problems I would think I would run into is the belt routing and getting the new alt in place of old one. Just gotta make sure to take my time and do a good job. I will see how the new alt does before I get into more batteries. thanks again.

 

Well, I tested my battery and alternator. With car off, battery reads 12.32V with my multimeter. And with the car on it read 13.34V with the multimeter. With the heat on full blast and headlights on it still reads 13.34V with the multimeter. When I turned on the heat and headlights it did dip in volts but recovered back to 13.34V and I was told that the desired range is 12.6 to 12.8V when car is off and 13.8 to 14.8 when car is running. Sound correct to you?? Not sure if its a battery issue or alternator issue. My optima redtop is about 3 years old, maybe 4 at most. I head these batteries can last a long time. But, the stereo I have not as long I am guessing. Let me know what you think might be at fault. thanks.

 

Those are correct ranges for the for the battery engine off (12.6-12.8 volts) and charging system (about 14 volts). I don't know where your voltage regulater is for the alternator, either in the alternator or in engine computer. Getting the voltage regulator corrected should fix your problem; I don't know exactly where the voltage regulator is though your local mechanic should know tell him what's going on and ask him where the voltage regulator is.

As for the battery, I had a class in auto electronics and we covered these types of batteries. The optima sytle batteries are great because they a nearly perefectly sealed battery and they are maintenance free, but in hotter climates they tend to suffer short life span than normal lead-acid batteries.

 

I called the place where I bought my new HO Alternator and they said the only issues I would run into when installing a new HO alternator is that the belt might slip. So, they said to make sure I have a brand new belt or a high grade one installed already. I have the most expensive belt from Napa on my blazer right now. About 1 year old or so, I am sure that is good enough. What you think? I mean the alternator has roller bearings or whatever to make the pulley spin or turn. I gotta use a wire brush to clean off the battery terminals and connections on the big 3 upgrade as well. They said they will be shipping the alternator to me on Monday the 20th of August. So, I probably will get it on Thursday or so. Install it on Saturday I guess. Just gotta make sure I do a neat and clean job on the install.

 

Would I have to remove the back bracket to install the new 185A DC power HO alternator? I heard somewhere that I might have to. Thanks.

 

Your belt should do the job, just make sure it's not cracking or rotting. As for the back bracket removal, I don't know the dimensions of the new alternator other than it will be bigger than your old one. I'm sure someone will know what to do.

 

Well, Just heard from DC Power, Should have no problems installing the new alternator, as it will not require any other new brackets or additional hardware. Plug and play alternator. Yes, bigger as far as Amps, but casting wise, the same size as OEM.