I have a 1998 Monte Carlo, LS, 3.1L. Having a little charging system issue. The battery appears to be dead (does not start engine). So, I jump the battery with a portable jumpstart device (from Costco and works perfectly everytime). But, I can run for quite a distance and as soon as I turn off the engine and immediately go to start back up.. same thing.. no juice. Now, I check the voltage on battery, not running, and it reads around 10-11 volts.. same as with my F350(and no problem in starting that vehicle). I had another charging problem about 2 years(same vehicle) that resulted in going dead on side of road and paying a shop to replace the alternator and $500 later. Havn't had any issues with the charging system since, except for corroded and loose battery terminals on occasion that kept the car from starting. So, I would say it may be the alternator, but less than 2 years seems a little too soon for it to go bad. Would anything else in the charging system allow the alternator to go bad prematurely? Any advice would be helpful. Thanks.

hi Shellie.
this link should show you a video on how to do it.
plus you will be able to read up on it just below the video.
its not saying its a Ls.but see if this is the one.

The video above shows you how to replace the battery in your 1999 Chevrolet Monte Carlo. We recommend changing the battery in Chevrolets every 4 years. Although some batteries last much longer, most batteries begin breaking down chemically after four years, so you could experience dimmer headlights and other negative effects before you have a dead battery in your Monte Carlo that you need to replace.

Replacing the battery in your Monte Carlo involves removing the terminals. When you reconnect the terminals, your radio presets are likely to be cleared out. In some Monte Carlos, you may need to re-enter a security code to get your radio to work again. Check for this code in your owners manual - it will usually be either a sticker or small card in the booklet. If you can't find it, call Chevrolet and they will give you the code for free. In many Chevrolets, the transmission "learns" how you drive over time and makes adjustments, so you may experience altered driving dynamics as your car re-learns your driving style after changing the battery.

Battery Replacement 1995 1999 Chevrolet Monte Carlo 1999 Chevrolet Monte...
or go to this link for more videos.
how to change the battery in my 1995 Monte Carlo Ls Google Search

I think it's doubtful that your starter is draining the battery. Once your starter is engaged upon start up, it is done with its job, and it is not needed until the next start up. It does sound like your starter is going bad. If all of the electrical parts seem to come on when you trying to start it, it should have plenty enough juice to start it. One possible cheap solution is it could be the starter relay. The relay takes power from your battery and routes it through to your starter. If this isn't working, your starter isn't even getting any juice. I hope this is the problem. I have seen many starters replaced that should not have been because fo a bad starter relay. You would have to Google that info on a Monte Carlo. I could not tell you where it is on any Chevy.

how old is the battery

Could be a bad battery, and or alternator, if the alternator does not charge the battery when the vehicle is running your battery will drain causing no start.

This is a dead ringer symptom of a vacuum leak

Im pretty knowledgable in the whole SECURITY light issue... I dont think this could cause the door lock to not work correctly, but anything is possible. Newer cars are wound up pretty tight. Here is a link to help understand how the security works.
http://vatspasslockpasskeysecurityhelp.yolasite.com/

I'd go ahead and do a "security relearn" on you car. It might help if that is what caused the door issue.
Turn the key forward 2 clicks till right before it would normally start, leave like that for 10 minutes. ( no less ) Turn back your key to regular position and check the door lock. May have to do this process 3x

Ground connects LAST. Look around there is a positive attachment somewhere, usually under a red plactic cover, that is the positive hook up, negative to some major metal somewhere on the engine...
No smoking during this event, explosion hazard.

Hi!!

The battery is in a compartment in the fender well, but you should have a positive and negative jump start terminals.

Follow the fat (usually RED) cable coming from the Alternator or the one coming from the Starter, they go straight to the battery (+). The ground (-) you can get it from the chassis or the block.

Dont forget to rate this post. Good Luck!!!

Well, something seems to be draining your battery. Are any accessories left on? Too unusual to get a bad new battery. Get a load test done on the battery...will tell you if the battery is holding a charge. If it is fine, then the alternator might be faulty and would not charge the battery as you drive. Hope this helps. Worst case there is a short somewhere in the electrical system that is draining your battery.

Hey first thing you want to do is make sure its getting fuel .. Try shooting a little gas into the air cleaner and crank it and see if it starts .. if it does your fuel pump might be the problem .. or use a little either instead of gas either will let you know if its a fuel problem .. sounds like to me that might be what it is. holler if you need more and thanks Jerry