10.3V isn't a healthy battery, regardless of a glowing light.
What alarm have you got fitted?
And what 'accoutrements' have you got that are / may be draining the battery? That turntable below the rear glass, for example - battery or wired-in??? LEDs / Neons / big Subwoofer behind the passenger seat?!?
...and has anyone checked your alternator?
If it's always doing it, and it's always OEM batteries, then one (or more) of:-
- your alternator isn't doing the required job, or is doing so but only partly / intermittently;
- there's something else providing a drain on the battery (alarm / other modification - think there may be a few to choose from), which a 'new' battery can deal with but which after a couple of years becomes too much.
- you've an intermittent short-to-earth, perhaps?
- your CTEK is faulty and not really charging / conditioning?
- ...or someone with better electrical knowledge can come up with another idea?
I would GUESS that if you've got an a-market alarm + LEDs + neons + turntable + ??? all turned on, then the overall draw when driving might be similar to / more than the alternator can provide, which means you could be draining the battery (slightly) while driving - a long journey could undo all the good that the trickle charge has done. A new battery has sufficient peak juice to cope with this, a slightly older battery may not...although I'd expect a CTEK to do better than that...how old is the CTEK?
"No man with a good car needs to be justified"
Blue '08 FD2 CTR - big, ITR-sized shoes to fill...
Yellow '96 NSX 3.0 - oh was it worth the wait!
Black '99 ITR - well, I had to have another one, the first was so much fun. Miss this one even more than #1...
Blue '03 S2000 - SOLD, flawed but fun
Blue '04 Focus TDCi Sport - SOLD, very good fun for a diesel!
Black '00 ITR - SOLD, still missed
Red '98 Civic VTi - SOLD, probably still bombproof