Battery or Alternator issues? Help!?!

Hi Everyone, Posted on another board but submitting here to get additional thoughts! :-) Yesterday during a spirited drive, my ABS, airbag, PSM, battery lights all came on in the dash and stayed lit. I then noticed my battery voltage on the dash was down to maybe 3-4 volts, not running normally up in the 13-14 range. I quickly got the car home, thinking the battery could be potentially bad or going, put it on a battery tender overnight and went out to the car to check it. Here are the issues and more info: -The car starts fine, was also just in the dealership and they tested it and said it was fine a few weeks ago (could it go bad that quickly in the northeast weather where it is 10 degrees and I have barely drove it)? -After the full recharge with the battery tender, the car starts and the voltage goes up to 13-14...however after 10-20 secnods it drops down to 3-4 again, lights up all the dash lights I mentioned above, then after a few more seconds goes up to 13-14, the lights go off but the battery light comes on and flashes/stays on... Then after I turn off the car and start it again, the voltage only goes to 3-4 and the dash lights are all on. Is this a battery or alternator issue? The battery seems to be working fine and is charged, maybe its just not giving enough juice after the initial car start? Or is this alternator issues? Any ideas or Help would be helpful!!!! Thanks!!!

hey welcome - so you have a dealer or shop close by and sounds like you have been there before... most places will do a battery diagnosis very reasonable (if not free) and can run a check of the alternator in about the same amount of time - pretty easy with the right tools... pretty hard over the interwebs. My suggestiong is to check the battery again, and then check the charging system' Now its possible there is another issue (ignition switch, ground strap or other) but rule out the easy ones first. Cold weather can kill a battery and yes, quickly - not saying that is what you have but just confirming it can happen

Check the date on the battery install and if its near a year of replacement time just replace the thing. Could be battery, loose wire on alternator or battery, ignition switch, voltage regulator whatevers.

Just bought the car a few months ago so not sure how old the battery is. However, it is a triple AAA battery so not sure if that is anything... The connections to the battery are pretty solid... If I add a new battery, I don't have the radio code - will I need that and how do I find that out? Also, the car seems to start fine with no hesitation, that is why I don't think it is a battery issue... Any other thoughts? How much is alternator work at the dealer? THANKS!

RE radio code - depends what year and color the car is - well year anyhow battery issues "sometimes" act funny - they can have strange glitches occur due to degrading conditions... and its a AAA ? if I remember correctly these take AA just bouhgt? is it covered by any warranty? - that will help decide what steps to take for sure

Radio code might be retrieveable through its menu. I have an aftermarket radio. Still could be the battery. Bad cells do strange things. A slow charger can get the battery up to full charge over night but an alternator can have problems trying to force juice into the battery at faster rates past a bad cell. A bad cell is one of the symptoms of rapid voltage drop. Also loose wires can do that but the car always starts up so thats less likely. You have to put a multitester on the system and watch for the voltage to change the + and - symbols back and forth to figure out its bad diodes in the alternator. Sure its 12 volts coming out of the alternator but with a diode stack loosing it will throw intermitent polarity's out which kills the batterys voltage pretty quick when doing it while still looking like 12 volts is being charged. So if you are at the stage just prior to the alternator falling on its face yah its the alternator. Put a multitester that shows an LCD + or - symbol for polarity when testing 12 volts then watch the tester for intermitent changes of the symbols. A shop can waste your time only checking the voltage and not polarity coming out of the alternator. You can spot the changes with the probes on the connectors of the battery while connected. Cost of alternator repair? Let's see....hmmm....superbowl coming up.....wanna cover bets....ohhh......$550 maybe hehehe Wait WAIT make that $900-$1200.

So whats the verdict, should I throw a new battery in there and hope for the best or take it in for alternator?

[Image-only post; no author-written text. Original image references:] https://rennlist.com/forums/images/smilies/rolleyes.gif https://rennlist.com/forums/images/smilies/popcorn.gif

Quotes source post: 8217127

A battery can go from good to bad in no time. Actually, it goes from good to bad over time but the battery's margin will tend to mask this until it can no longer. Until the condition/deterioration reaches a certain point. Cold weather and lack of use (battery discharges from sitting) is real hard on a battery. Winter use is hard on a good battery. On one that is not so good... The battery can be checked. Ideally it wants to be checked twice, with the second check coming hours after the 1st one. Why? Well, my experience is when my 996 Turbo started taking a bit longer to crank and fire I took the car in to the dealer (CPO car) and the tech tested the battery and it checked ok. But he checked it again later in the day and found the battery had lost around 40% of its charge. Bad cell, at least one bad cell. I did not bother to check how old the battery was. A bad battery is a bad battery no matter its age. Oh, the CPO warranty did not cover the battery. The battery is a 'wear' item. The battery supplies the electrical power to start the engine. Once the engine is running the alternator is the electrical power source and I would think were the alternator bad it would be evident that the battery would lose power and the car would stop running. You can't run a modern car on just a battery alone for very long. So, you can try a new battery. This is easier if the battery's old(er). But a battery can fail at any time. Or take the car someplace that can properly check and verify the battery is ok and then that leaves the alternator. And if it can check the battery properly the shop should be able to check the alternator out. So, it may be a battery. Less likely but still possible it could be an alternator. Or it may be something else. Others have pointed out other possible causes of the symtpoms you are reporting. The battery cables and connections must be in good shape. While the battery connections at the battery look good -- and they should since they are protected from the elements -- what do the battery cables and connections look like at the other end? But the symptoms point to a battery first with an alternator a distant second. If you get past the battery and alternator and cabling/connections and nothing turns up, then well, let's see what the battery check out and alternator check out turn up. Sincerely, Macster.

"If I add a new battery, I don't have the radio code - will I need that and how do I find that out?" You can obtain radio code from the RennTech.org site.

Quotes source post: 8217730

some dealers will give them to you.... just give them your vin.

some cars dont need a radio code

Sometimes people write the battery code in the manual or some other place in the documents you may have. Look for a four digit code there. ABS, PSM lights can also be a symptom of a bad MAF.

Sounds like an opportune time to throw in a good radio.

I re-read this today and I'm thinking a "sticky" voltage regulator. Did they test the alternator output??

alternator is bad. battery has nothing to do once the car is running.

Just closing up the chain, it was the alternator and it needed to be replaced. Covered under warranty, only paid $100 deductible.

Well done, nice to know that issue is fixed.

Thank you for reporting back. You lucked out with warranty that's a very expensive item!!

Glad to hear it turned out well!

That's great to hear that you got the alternator fixed. I hope you got the expiration date of the battery. Knowing when its near is helpful to keep from having a bad battery that will drag your alternator down causing it to fail. A bad battery can overwork your alternator making it flake out. You have to remember alternators or generator are made to maintain the battery not charge it. An alternator having to charge a dead battery after a jump gets more than designed for stress. My feeling is if the alternator is always having to charge a failing battery that it will cause the end of the alternator from having to over work.