Battery flat from working on stereo but was disconnected?

[Kol12]

I have been installing my new stereo and have disconnected the battery while doing so. When I hooked the battery back up the car started fine so I turned it off then sat there listening to the radio for a few minutes then tried to start the car again but it didn't. Somehow it went flat and I don't have any idea why? Once jump started it has no trouble starting on it's own again.

I have to leave my key in the ignition when I disconnect the battery because it's the only way to get the gear stick out of the way of the dash for removal. Don't know if this has anything to do with it?

[gotasuby]

Low capacity battery?

[Kol12]

Low capacity, how do I know? It's pretty new, has no trouble starting again after being jumped.

[DRFVDR]

well is it the same size as the battery that you took out, didnt cheap out and buy a smaller battery, these should have a NS70 or ZZ50 in them

[Kol12]

No same size I think, it's a Century 530 cca...

[cods4]

How long were you listening for with the car off? It sounds like something is drawing a lot more current than it should be. Maybe there is a partial short somewhere. The easiest way to solve this is to use a dc clamp ammeter which you can clamp over any cable and see what is drawing high current. But you would need to borrow one off a sparky friend as they are expensive.

Alternatively you could start by checking supply voltage at the battery and then at your head unit and your amps. If there is a large difference (greater than 0.2v) between these voltages (with the volume on low to medium) then there may be a wiring fault somewhere.

[DRFVDR]

 Kol12 said:

No same size I think, it's a Century 530 cca...

And there it is

Century Batteries in my experience are crap

I have tested NEW century against both Exide/Marshall and supercharge and they come up short every time

[Kol12]

 DRFVDR said:

And there it is

Century Batteries in my experience are crap

I have tested NEW century against both Exide/Marshall and supercharge and they come up short every time

Hmm, I put no thought into what sort of battery at the time, the guy at the shop just replaced it with this.

I was listening for only a minute or so after I turned the engine off. As I've said the battery has no trouble at all after it's been jumpered.