car wouldnt start when I got out of work (2012 Fit Sport, 35k miles) a couple weeks ago. So I had it jumped and drove home. was fine for a day then it happened again. I took the battery to advanced auto parts and they gave me a new one ( the 3 year warranty had a month left. Felt pretty lucky). Then a couple days later, the same thing happens. So I jump it again and use a multimeter to keep tabs on the battery for a day and dont detect any drain. A couple days later, driven every day, battery is dead again.

I take it to a shop. They cant find any drain. they say they test the battery to see if its good an after several tests, the last 2 say it has a bad cell. but this seems unlikely to be the source of the problem to me since the old battery was failing the same way as the new.

Wondering if anyone has any other idea of what else could be going on here? or any advice on how I should proceed.
thanks!

 

Did you check to see if the alternator was charging the battery? The charging voltage should be around 14 volts.

 

Charge it overnight then leave the headlights on for 5 minutes to get rid of surface charge. Turn everything back off wait 5 minutes and check voltage. Should be 12.4 or greater. If not your new battery probably has an issue.

If that checks out start the car and turn on your headlights, rear defroster, turn ac on high and check voltage again. Should be at least 13.8 probably higher. If it is low <13.5 the alternator may not be charging well. If it is low try turn off as many things as you can and see if it will get above 13.8 with things off.

If the alternator and battery check out test for parasitic draw.

 

Quick tip, dont turn on rear defrost if you have a tint. that's how you get bubbles.

 

Keep in mind that a multimeter isn't monitoring battery amperage, which greatly matters. Looking at it on plain terms, you could hook up nine or ten flashlight batteries to produce the proper voltage, but your car would never start.