Dead Battery - Caused by Radio?

If this thread is better suited for anothe forum - please advise.

My son owns a 95 Cavalier and the battery check light kept lighting and now the battery is dead. The interior lights of the car are not lit when we open a door.
I am not very familiar with batteries or high powered stereos that are added to cars but I am wondering if this problem is caused by the equipment that he added. He had the same problem on a Corolla that he owned previously.
The battery is rated at '865 cranks, 690 cold cranks and 90 RC' (not that I understand what that means :(. The stereo is 780 watts.
All suggestions on how to remedy this problem are appreciated.
Also, he is working with a limited budget.

Thank you in advance.

I had the same problem with my car when I put in my stereo. But this was after i left my lights on a lot because i took out he factory chimes when i got my aftermarket stereo installed. Eventually becasue the battery was going dead so much and i kept having to get jumpstarted, the battery died on me.

I purchased the Optima red top battery and never have the problem anymore. Oh and i have a new alternator. I have a 900 - 1000 watt system and with the Optima battery....it never fails :)

I had the same problem with my car when I put in my stereo. But this was after i left my lights on a lot because i took out he factory chimes when i got my aftermarket stereo installed. Eventually becasue the battery was going dead so much and i kept having to get jumpstarted, the battery died on me.

I purchased the Optima red top battery and never have the problem anymore. Oh and i have a new alternator. I have a 900 - 1000 watt system and with the Optima battery....it never fails :)
What specs do we need on the alternator?

you could get a regular alternator for a cavalier with all options power windows ect the higher voltage on form the scrap yard, then you should definitly add a power capacitor in the trunk so that the stereo is not a constant drain on the battery , this is what i would do or you could add a second battery that can be charged by the alternator in the trunk that you would hook your stereo up to. positive from the original battery to the new one in the trunk and ground to the frame floor ect. with at least four gauge wire.

you could get a regular alternator for a cavalier with all options power windows ect the higher voltage on form the scrap yard, then you should definitly add a power capacitor in the trunk so that the stereo is not a constant drain on the battery , this is what i would do or you could add a second battery that can be charged by the alternator in the trunk that you would hook your stereo up to. positive from the original battery to the new one in the trunk and ground to the frame floor ect. with at least four gauge wire.
Sorry, I did not quite follow you above.
Are you saying that the regulator alternator that he has in the car should be sufficient and that he should get a power capacitor for the trunk?
He currently does not have power windows or door locks. He does have air conditioning.

ya get a capacitor or second battery get the higher powered alternator for the car they make two one for the base model and one for the higher end models but they are the same just have a higher charging capcity but you definitly need a new one but i would buy a used one incase he ruins it again, also make sure that he has not done something stupid make sure that the power cable from the amp is hooked right up to the battery and not like the alt wire ect.

ya get a capacitor or second battery get the higher powered alternator for the car they make two one for the base model and one for the higher end models but they are the same just have a higher charging capcity but you definitly need a new one but i would buy a used one incase he ruins it again, also make sure that he has not done something stupid make sure that the power cable from the amp is hooked right up to the battery and not like the alt wire ect.
Tks.
He had the installation done professionally ... but who knows what they did.
Any idea what the power capacitor would cost in terms of the product and installation?

it would cost hi, about three hundred to 350 at my shop installed plus a used alt for about 100 installed to do a favor cause they are easy to do

it would cost hi, about three hundred to 350 at my shop installed plus a used alt for about 100 installed to do a favor cause they are easy to do
Wow!
That is a ton of money!
Thank you for all of your assistance.
It is sincerely appreciated.

hmm...you shouldnt need to get a new alternator. How old is the battery first off, and second is he leaving his stereo system on when the car is turned off?

hmm...you shouldnt need to get a new alternator. How old is the battery first off, and second is he leaving his stereo system on when the car is turned off?
Well, the battery is now * new * because we could not boost/charge it. We had it changed yesterday.
No, he is not leaving the radio on when the car is turned off.

Check the alternator, connections, and belt. The charge light indicates that the alternator isn't outputting anything. With his car running around 1500 RPM, if you measure the voltage across the terminals at the battery with a meter, it should read 14-14.5V. If it measures less then 13V, your alternator has a problem. If it's between 13V and 14V, it could go either way.

His system isn't high enough powered that you would need to get an high output alternator, a 2nd battery, or a cap. It may be rated at 780 watts, but the normal draw is likely much less only hitting 780watts on the very loud, deep bass notes.

From the FAQ in the Car Audio Forum (http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=675) here (http://www.automotiveforums.com/vbulletin/showthread.php?t=16804):
Alternators - if you're system draws less than 1000 watts RMS, you probably don't need an uprade; if you are between 1000 and 1500, you may need one - depends on the draw; 1500+ you most likely need another alternator.

Batteries - the alternator supplies ALL the power for the car once the car is started, so a bigger battery may not help unless you play the stereo with the car off a lot. Multiple batteries will increase car off listening time but will be an a LOAD on the alternator once the car is started.

Capacitors - They help in some cases and do nothing in others. They are NOT a solution for an underpowered alternator. Do not use ones with voltmeters on the top, their high ESL will render them useless.

Check the alternator, connections, and belt. The charge light indicates that the alternator isn't outputting anything. With his car running around 1500 RPM, if you measure the voltage across the terminals at the battery with a meter, it should read 14-14.5V. If it measures less then 13V, your alternator has a problem. If it's between 13V and 14V, it could go either way.

His system isn't high enough powered that you would need to get an high output alternator, a 2nd battery, or a cap. It may be rated at 780 watts, but the normal draw is likely much less only hitting 780watts on the very loud, deep bass notes.

From the FAQ in the Car Audio Forum (http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=675) here (http://www.automotiveforums.com/vbulletin/showthread.php?t=16804):
Alternators - if you're system draws less than 1000 watts RMS, you probably don't need an uprade; if you are between 1000 and 1500, you may need one - depends on the draw; 1500+ you most likely need another alternator.

Batteries - the alternator supplies ALL the power for the car once the car is started, so a bigger battery may not help unless you play the stereo with the car off a lot. Multiple batteries will increase car off listening time but will be an a LOAD on the alternator once the car is started.

Capacitors - They help in some cases and do nothing in others. They are NOT a solution for an underpowered alternator. Do not use ones with voltmeters on the top, their high ESL will render them useless.
Thank you. I will pass this information onto my son.

Hi, I have the same problem in my 94 cav. Turns out it was a piece of paper in the glove box keeping the light on. It could also be the mercury sensor in the trunk. It is on the left side of the trunk. A piece of plastic mounted on the trunk bar with wires ( that connects the trunk lid to the car). If he installed a sub box it might have been moved if the box was in the way and allways on. My car would only go dead over the weekend when i did not drive it. Hope this helps. Please let me know if it does.

Hi, I have the same problem in my 94 cav. Turns out it was a piece of paper in the glove box keeping the light on. It could also be the mercury sensor in the trunk. It is on the left side of the trunk. A piece of plastic mounted on the trunk bar with wires ( that connects the trunk lid to the car). If he installed a sub box it might have been moved if the box was in the way and allways on. My car would only go dead over the weekend when i did not drive it. Hope this helps. Please let me know if it does.
Was the battery warning light on when you were driving the car?

get a good battery and a 100amp alternator