New Kenwood draining battery

i just replaced a pioneer with a new Kenwood and overnight my battery drained, wouldn't start in the morning. All wires are connected color for color, the only addition is a Kenwood powered sub under the seat that was connected to the pioneer with no issues for months. Any ideas are welcome, please help.

 

May be it's just a dead battery? The simplest explanation?

 

Sounds like the amp turn on wire is somehow getting constant power.

 

The battery is the original as far as I know, about 8 years old. After charging with my trickle charger it started so I'm going to go for a dive to advance auto and have them check it. Hopefully that's all it is, I didn't even think about it but I was playing the new stereo for at least 20 or 30 mins with the truck off, could be that was all it took to finally kill the old battery?

 

Uh, yeah. 8 year old battery, probably a 250 watt amp drawing XX amps for what you think was 20 or 30 minutes, which we all know is like internet time, so it was probably actually 1 1/2 hours of real time. Pretty good chance that's probably your problem. Still would be a good idea to do a parasitic draw test.

 

went to advance auto and their battery test said my old battery was definitely dead. I bought a new battery so I'll see tomorrow morning if things are good or not. The old battery read 12.4 on a voltmeter and the new reads 12.8, that's with everything off. I haven't done a parasitic test on it yet, but if it's dead again tomorrow I'll definitely do that.

 

After 2 days with the new battery it's all good, just an old battery that didn't enjoy life. Question, when the battery was disconnected (about 10 mins give or take) did my ecu reset itself or was that not a long enough time frame. I'm trying to figure out if my shifting feels odd or if I'm just making things up in my mind.