Power with no fire - Pain in the arse problem.

[Gcustoms]

so a few weeks back i acadently left the lights on all day. a week later i got a friend to finally give me a boost, battery died in MIDDRIVE! that pissed me off... later i borrowed a booster from the school and boosted it... it seemed fine, went out the next day nothing... alarm barely chirped when i hit the unlock. so i gave up.. went to bed and while i was lying there i thought "terminals" so next day i went out and cleaned the terminals. the negitive was barely touching from all the crap on it. so i cleaned them and their connectors the point of which i could almost see myself, and of course as soon as i touched the connector to the terminal the alarmed blared as if it was on a full charge. still wouldnt crank though? i threw it back on the charger at a 50A charge still took like 10 minuts to work up the power to fire. like wtf so i assumed it was all okay since the terminals were cleaner than a nun and the alternator was charging the battery on its own. so i left. this morning i went out and tried to fire it. it sounded like the battery was at 50%. big crank, then got smaller, and smaller, and smaller until the starter wouldnt eject. so im all confused i turn on the sound system - still pounds, i hit the alarm still f***in loud, its as if the battery is at 100% but only 50% is reaching the starter... bad ground? any help will be appreciated thanks.

[wrightme43]

you need a battery.

The battery will fail a load test. You have sulfated the plates in the battery and it needs to be replaced.

[Gcustoms]

i don't think its sulfated since the battery takes and holds a charge like new, right now i can listen to the radio for hours if i wanted to. basically the battery has 100% power but its as if onoly 50% of the required power is actually reaching the starter. dirty-as* engine bay, i was thinking it could b a contaminated ground?

[sx moneypit]

You need to check for a voltage drop to the starter.Be sure all your grounds are clean and tight.

[wrightme43]

The radio is not a real draw. I would really reccomend that you get a load test. If it passes a load test, then it would make sense to begin running down cables and checking them.

You left the lights on all day. (very very hard on a battery) That discharged the battery (causes sulfation) and then the acid tried to build the juice back up while it sat for a week (more sulfation). Then you jumpped it and used the alt to charge it (really really had on the alt. by the way) then later charged it at 50 amps (slow charge in the future, be patient fast charges destroy batteries).

Those actions are a sure fire way to kill a battery dead.