Will 17-18v kill a 12v battery?
 

I'm having a problem with my alternator (at least I think its the alternator) that when running the car it puts out 17v-18v. I'm wondering if it will kill my new optima d34 yellow top.

The car is a nissan sentra and up until a few days ago ran fine. its a normal 12-14.4v car but recently its been running at 17v and I think it killed my shitty walmart battery. Although I think that battery was on the way out anyways (its 3-4 years old and was like $70)

I plan to keep the car parked for as long as I can but I still need to get around until I figure out whats wrong (I think I'm going to buy a new alternator)

Is this new battery doomed?

Thanks.

It wont be happy, it may not be killed yet but it will. There is actually a little vent on the top of the battery to prevent explosion if the battery were to "boil"(not sure what you would call it in a gel cell). Check if it is noticeably open or looks suspect.

it will kill the battery and any other component that's ment for 14volts.

something is wrong with your voltage regulator.

do not drive it and have it towed to a shop to have the regulator/electrical system checked...at 17-18 volts, you'll fry your car's electronics, including the computer (ecm), dash, climate control etc...a very expensive repair.

Thanks for the info guys. Its surprising but I actually drove the car around for about an hour (before I know it was running at 17v) and so far nothing bad has happened. Although my alpine amp sure did complain. It turned off every time my cars voltage went above 16v (found out later when I was trying to figure out what was going on)

Guess I have to give nissan some credit that their electronics didn't die on me. I plan to keep the car parked until my new 200A alt comes (stock is 80A). Should be a nice upgrade.

I'm surprised the yellow top can't handle the increased voltage. I've read about people running 18v for their SPL systems. I guess they're not using yellow tops. Must have been some other battery I saw.

Thanks again.

I think I remember reading the literature on the yellow tops.. the max charging voltage should be 15v... and fully charged will read 13.1

About as much credit as my old Sunfire gets. I got a H.O. alt for it and it had a faulty regulator in it. It ran up ~18v before I noticed it. The only thing that cooked was one of those little anti-rust modules that was on the car when I bought it.
As the others stated, DON'T DRIVE IT.