alrighty here is the situation. '87 convertible that runs fine. i've left it sitting for 3-4 months in my parents driveway. i exspected the battery to be dead. I charged it and cleaned and decided to drive it up to college. On way to school ( its a 45-60min drive from house to campus) the midway mark is conroe and i stoped to talk to a used car lot. i was there about 5-8min before i hopped back in my car. The car wouldnt start and just clicked when i turned the key. the battery was under charged like 11-12 volts. I touched the jumper cable to another battery and it started no problem, didnt need the other car on, just touched it.

This happened after a full battery charge and a 20-30min drive. Y??

Next: this week i just took the battery to autozone to check it maybe a dead cell, NO the battery is 100% fine. so i take the car up there with a charged battery, to check the alternator its 100% fine as well.

Y is the car dieing after a short period of time then??

thanx, Stephen

 

no help??

 

When you let a battery sit doing nothing, even disconnected, for 3 months, you wind up with a motorcycle battery in amp-hour capacity if the battery will even take a charge. I have posted this info about lead acid batteries many times, but let me educate another car owner. Lead acid batteries self discharge even disconnected up to 1% each day. As they discharge, lead sulphate collects on their plates. If you charge the battery back up right away, the lead sulphate converts to lead and sulfuric acid. Left sitting for long periods, the lead sulfate becomes hard and won't convert to lead and sulfuric acid. Lead sulfate is an insulator and fully sulfated batteries won't draw current when charged and partially sulfated batteries have dramatically reduced amp-hour capacity due to the lead plates being covered with hard lead sulfate. If you are going to park for long (4+ wks) periods, charge the battery every week, or buy a battery tender which only charges the battery when it detects a 10% drop in charge and then turns off. Kept charged, the battery will have a normal life. Car batteries do not like sitting long periods doing nothing.
Replace your battery and don't abuse it any longer!

 

awesome, thank you.
also if the lead sulfate is hard on the plate and has a reduced amp-hour would that effect the recharge? like at autozone if the battery was bad when tey put it on the charger, the charger would have notified them. but the charger had a green light after charge. if there was a problem with the acid wouldnt it read "bad"? just wondering b/c i have no idea lol

 

Parts stores don't have very sophisticated battery testers, and really meaningful tests can't be done in a couple of minutes. A low capacity battery will appear to take a charge normally and a short duration full load test may test barely ok, but if you load the battery and see how fast it is discharging (only sophisticated battery testers do this), you then learn what the amp-hour capacity is. Also, by charging the battery weekly, I mean use a battery charger, driving your car for 15 minutes will put very little charge in the battery. Many owners think that 15 minutes keeps their batteries up.....not true. Buy a new battery and a battery tender!

 

alrighty, thank you for your help.

the plan is to drive my c4 while my c5 is down in the garage and i just wanted to make sure my car is gonna start when i go to get it in every time lol. so this tells me i should get a new battery

 

yesterday i was having no problems strting the car after the recharge. this morning i went out to start it and it would barrely click. the battery read 8 volts.

So i'm thinking i need a new battery from this and from my chemistry lesson from last night. all agreed??

 

Does the same sulfating happen with a gel cell battery?