So, went to start my car on Wednesday morning and it wouldn't start, battery dead. Brother gave me a jump Wed night and I left the engine running for about 20mins and haven't driven it since. Went out just now and it's dead again. I know the battery is probably on its way out so I will replace when I get the money (no job) but I'm guessing leaving it running for 20mins didn't do it any favours as it's prob not long enough. Would this be correct?