I posted on old thread but no response so decided to make new thread.

I just check my battery, it shows 10.55v...and when I start it only makes ticking sound. and all others (a/c, radio etc..) have power but car doesn't start. This happens often last 2 years but last weekend I washed the under hood and I guess accidentally water got in somewhere. now it starts weird.. when I start the engin, it sounds so weak. once it starts everything is fine. I already check the spark plugs, no water there.
but this morning, I can't start at all. I'm sure it'll work again later if I wait for a while..

so at this point, I'm not sure if it's my battery(1 yr old), alternator, ign coil, starter, or cable. I cleaned up the battery cable connection and make it tight. like I said before, my battery shows 10.55v before engine starts. I haven't changed my alternator/power steerin fluid but it doesn't seem it's leaking at all. (maybe water from car wash...)

how to check if the alt is bad? I read somwhere that start the engine and disconnect the battery cable?? is it safe to other devices?

I'll try jump start with other battery.
(update: with jump start, it starts no problem. while it's been idle, I checked the voltage of battery:
13.90v with no a/c, radio, or lights
13.35v with a/c full power, radio, and lights on.

I'm sure I need to check alot more but is it possible that my battery needs to be replaced?
or there's still possiblity that my alt is bad?

I'm looking forward to change the battery terminal but is it ok that it's from local store like pepboys/autozone?

any recommendation what to do now?

 

update: I just changed to new battery. so far so good.

 

10.55 is a dead cell in the battery. the new one should work.