88 crx hf, the battery will not charge unless the a/c is on or the lights are on. otherwise the battery will only put out 12 volts. without those two on the idle will be really low, like 200rpms, turn the lights on and the idle picks up. also the past two days it takes at least 10 times to fire up. it'll try to start then die. finally it'll catch and run fine. theres lots of knocking in the engine when under a load. other than that its a fine car. any ideas? i've changing the alternator, no help. thanks.