So I have lurked these forums for a number of years now and they have always solved my problems but this time the search function doesn't seem to be helping me. My stock VT Calais head unit recently died and so I bought a pioneer head unit to put in instead while leaving all of the stock speakers in place. In the past, I was able to leave the engine off but run the radio for extended periods of time (ie at the drive in or while I am washing my car). I went to the drive in once after getting the head unit and all was fine. I went a second time and the battery died after about 50 minutes of the movie. And then, earlier today, I washed my car which took about 20 minutes and had the radio on playing my iPod. I didn't have it on overly loud. I then went to start my car but the battery was too flat to start the car. Is this merely something as simple as my battery dying or is it something more sinister with the head unit? Or is this a common thing with after market head units? The only things I could find in search were relating to the battery going flat over night when they have amps and subs and everything as well but my battery is fine for over night. Any help would be greatly appreciated.
Does the headdeck remember radio stations etc? You could have +ve and ignition (red and yellow) the wrong was around. This will cause some additional current draw when off. I'd get your battery load tested. Some do fail early. With your car idling and headlights on measure the battery voltage. If it's under 13 your alternator may be giving up the ghost.
Hey, yes it does remember the radio stations. I have checked that and with everything turned on it doesn't drop below 13.8V.
So it's wired correctly and your alternator is charging. Aftermarket headunits have similar current draw to the factory ones do its unlikely to be due to the headunit. Your local battery place or auto sparkie can load test your battery (usually free). They basically put a large load (say 100a) on the battery and measure the voltage. As batteries degrade the internal resistance rises and as a result under load the output voltage decreases.
is it a high watt head unit? is the battery good quality or the cheapest one they had at super cheap winter is always hard on car batteries get the battery tested properly and the alternator
No, it was a normal head unit. I went to super cheap and got them to test the battery and the alternator. It said the alternator was fine and the battery needed replacing. The results were: Initial Volts: 12.76V Battery Rating: -23.6% S. Loaded Volts: 9.36V Battery Ohms: 6.3mj Post/Clamp Drop: 0.00V Accumulated Chg: 0.00Ah So I bought a new battery and am going to the drive in tonight so will test it then. Judging from those results would it be the battery? I'm not sure how reliable those century battery testers are and how bad the battery has to be before they say to replace it?
Nope. No idea what the load was. Well I'm hoping this is the problem. I was really hoping there wasn't a short or something in the head unit.
Well your alternator sounds fine, possibly dud battery but you have a new one now, if you still have problems then get your multimeter and measure the amperage draw at the battery, ideally should be around 50-100 milliamps with nothing on. If it's over this then process of removing fuses to find the item drawing current. If it's all normal then you also try with your radio on and see what it draws and then you can idea of what time length it should last.
