Need Help! Bad Battery or Alternator?

[toddmingnworld]

Hey guys help please,


OK this is my problem, My car I think has a weak battery and/or Alternator. The car starts, idles & runs fine....I have a Volt Booster, Viper Alarm Sytem & Sound Sytem all draining the battery for juice...When I turn the sound sytem up to a moderate level the lights on the Dash blink & fade, same with the headlights, parking lights & Etc.....Is this the sign of a weak/bad battery or Alternator? If so what kind of Battery or Alternator should I invest in for our kinds of cars? Thanks in advance for the help..


Todd

 

[RareT]

With engine running and stereo on, check voltage at terminal at the rear of the alternator. If it shows a consistant 14 volts, that's good. However, If you have an amperage sucking amplifier in the stereo system, you may have enough volts to run everything but not enough amperage. What kind of amp do ya have?

Ed

 

[zam70]

Doesn't sound like anything is bad, ust not up to the task you're expecting it to handle. Your ONLY solution is a bigger alternator.

One thing you should do is reestablish your battery to body ground. The factory ground is to small. Reground with 4 gauge and if your lucky that could solve your problem.

 

[salvageV6]

Finally make sure your alternator to battery wire is good.

I would put voltmeters on the amplifier, battery, and the ign. terminal in the fuse box and compare the results.

Scanmaster, car battery voltmeter, and a third on the amplifier are also good crossreferences to run down voltage problems.

I use 3 meters on my car with the stereo in it.

 

[2QUIK6]

If you don't have a volt meter handy, another good way to check the alt is start the car, and while running, disconnect the positive side of the battery cable, car should continue to run if the alt is good, then go turn on the tunes and see if you still have the same result or if the car almost or does die, if so, you probably need a bigger altenator.

 

[zam70]

NO NO NO NEVER disconnect the positive/negative cables on a car with an ECM while it is running. The battery works as a buffer.

This was a common practice on carbed cars but on computer controlled cars it is a really bad idea. It might not hurt it the first 10 times but your gambling by doing this.

 

[toddmingnworld]

Guys,

Thanks for the suggestions fella's....I think my entire wiring system set-up maybe all $#%@$ up if you know what I mean because my car was a stolen recovery & I think everything wiring included is all messed up....I think I'm gonna have to take my time with this one...

Zam70: What size/Brand Alternator do you recommend?

Thanks,

Todd

 

[2QUIK6]

Originally posted by zam70
NO NO NO NEVER disconnect the positive/negative cables on a car with an ECM while it is running. The battery works as a buffer.

Well sorry about that if thats the case. I'd like to know for sure as I've never heard of this, but I ain't a mechanic or an electrical guru either. The ECM wire runs directly into the positive battery cable so it should be seeing the same voltage as the altenator is outputing because of this I would think. If your alt is outputting too high of voltage it will fry alot of things in the car though, the ECM would be the first.
Anybody else have some knowledge of this as I've always done this lots of times?
How can the voltage be tested on the alt come to think of it because if the alt is bad, the voltage at the post will be what ever the battery is outputting at that point? I guess disconnect the wire to the battery and test the post voltage.

 

[Rollin]

Gone to tech...

-------->

 

[zam70]

To check the alternator just use a volt meter...a battery alone cannot read higher than 12.5 volts (give or take) if the Alt is working it'll be 13.5+(acc off)...measure voltage engine not running and running...if there is a big difference (higher when running), alt is OK.

I've always liked the Wrangler Alts...buy as big as will fit and you can afford. They are big bucks but I promise you'll NEVER have a voltage problem again.


An alternators output is actually a 3 phase output of alternating current (AC)...the reason why you don't want to disconnect the battery is it works as a voltage "buffer" for lack of a better word...helps keep voltage smooth and absorb minor spikes etc...

You can disconnect it, 24 times out 25 it'll hurt nothing. There's always that one chance though.

 

[toddmingnworld]

Hey,

Thanks for the info guys, hey are any of you fella's familiar with the Optima Battery...Quite expensive piece; however, unsure if its worth the price....Any thoughts??


Thanks,

Todd

 

[Steve Wood]

They seem to have a habit of going bad quickly....that is my experience.

And I third or fourth the comment about not unplugging your positive cable.....that is a '50s solution that was okay when running a generator.

 

[zam70]

Not a big fan of dry/gel cell batterys...alot of people are but I've had to many bad experiences my self

 

[salvageV6]

I like the Optimas. I have 3 of them one Red, one Yellow, one Blue top.

Two are in my two cars, oldest is 3 years old.

One ended up in my Dads '95 Sable P.O.S.

All have worked as good as the Sears Die Hard Golds I went through every 3-4 years.

Just my .02.