Andrew, it's not making sense to me either.
1) The Battery Terminal doesn't say what (amp or volts), but I'm pretty sure it's in volts. They're a Jaycar unit,
like this but not exactly like it. 2) Yes, I do have a battery charger, bought a new one as I couldn't find mine earlier this year. It's a trickle charger, with the auto cutout/top up feature.
The battery that's in the car now is only a couple of weeks old. But the previous one I didn't know how old that one was and I had to charge it about half a dozen times since last year. I took a punt on that the battery was terminal (pun intended
), so bought a new one. Could hear the difference in how the engine was running at idle, 100% better. So I thought that was the problem. It seems it was just the tip of the iceberg.
I have no idea what the starter motor is, other than it's a VW unit. It's tucked down under the drivers side of the engine, nice and accessible to hit it with a piece of lumber & a hammer. lol So it's certainly not mounted in the gearbox.
Battery terminals & posts are new and clean.
Anyway, I went out and started the car this morning. Started second turn (had to get in and goose the loud pedal, fairly typical). No jump pack used, in fact it's still charging from being used the other day. I checked the readout on the terminal before I started it, was 12.8, went to 13.8 when the car was up and running. Also I didn't need to hit the starter motor with a piece of wood & a hammer.
Trying Darren's suggestion, I flicked on the headlights, and there was a slight drop in revs, but just slightly. I tried it several times and noticed the drop in revs about 1/2 the time.
You do have one thing correct Andrew, the stereo is very temperamental (Yes Simon, it's still the same unit, lol). And I have noticed that it's been worse than usual lately, finally making me think I should replace it. But surely if I drove the car to the petrol station, filled it up, paid and came back out to the car, it shouldn't have drained a car battery in that time?
Actually, same with the alarm. Hmm. Been meaning to get that sorted out as well. That's more likely the issue.
Thanks for the PM Andrew.