Red Top Battery Question

[rocksteady_racer]

I have an Optima Red Top about 2 years old. It wasn't starting my 90 240 so I pulled it out and put in my brand new miata sized battery prepping for the turbo install. So now its running fine. So since I wanted to get my 91 240 running (all it needs is a battery and some seats so I can limp it down to my garage and replace the trans), I decided to charge it up to see if it was ok. I checked the voltage on it after sitting for about a month = 12.4V. So I started charging it. why wouldn't the 90 240 start with a 12.4v charge? The battery just needed a little bump maybe?

[ixfxi]

voltage doesnt indicate battery condition. what you need to crank a motor is amperage + voltage. get the battery properly tested and most likely, if its not holding charge, replaced.

[rocksteady_racer]

Ah gotcha. I just bumped it and put it in my 91 and it seems to be running ok right now. Maybe it was a short I fixed when I swapped the radio in the 90.