defurr

Although I have pulled the HFL unit, I need to know if my battery is cooked, or if I have some other form of residual battery drain.

About a year ago, I stopped driving my 2006 TL every day. During this period, I began to notice that my battery would drain dead if left idle for, say, three or more days. I had the battery replaced, but this phenomenon continued.

A year has passed, during which time I mostly managed the symptoms rather than addressing the root cause: I started driving the Acura more frequently, and bought a float charger. As long as I drove it every single day, things were fine. Still, I didn’t always drive it, and I wasn’t always vigilant with the charger, and so sometimes the battery would run down to the point where she needed a jump. This happened maybe 5 to 10 times since I replaced the battery.

Finally, yesterday, I took the bull by the horns and removed the HFL BlueTooth unit, which had stopped working around the same time this issue started, and which by all accounts frequently produces this kind of issue, draining the battery while it tries to continually reboot. When I was done at 3:00 p.m., the voltage on the battery read 12.5v. This morning, 16 hours later, I checked it again, and it had dropped to 12.1v.

So do I have something else besides the HFL draining my batter, or is it so cooked after another year of abuse that it just isn't going to hold a charge like it should? And if it's the former, how do I chase that down?

ZOMGVTEK

The HFL is gone, and you're sure no dome lights, trunk lights, or whatever is left on?

From there, about the only obvious move is to check how much juice the car is drawing with everything off and all the doors closed. You'd need an amp meter or multi meter with an amp range. Break the battery connection, red or black, and put your meter in series with it. You should expect to see something under 0.1A if all is well, more than that and something is still on. Pull fuses one by one, and jumper the fuse with your meter until you find whats taking power. Be aware some things might turn on when the power is removed then comes back, so give it a second to stabilize.

If you don't feel comfortable doing this, you need to take it somewhere, replace the battery and hope, or leave it alone. Be aware, totally draining the battery even once is going to cut a HUGE amount of life off your battery. Typical lead starting batteries never really come back after you drain them low.

defurr

Thanks, Z. I have an idea that might answer the question about the battery itself: I'm about to go out of town on Wednesday. I could charge it up to 12.6V before I leave, and then break the battery connection. In theory, if it's still north of 12V upon my return in a week, then the battery itself isn't completely shot, since there will have been no possibility for exiguous drain during my absence. Is that sound logic?

ZOMGVTEK

Yeah, that works.

If the battery is healthy the car should be able to sit for ~2 weeks before its a problem. Under ideal conditions it might last closer to a month, but thats pushing it.

Disconnected, the battery should be able to start the car after several months of sitting. How many months depends on the battery, but generally it will still self discharge with absolutely no external load in under a year.

One thing to note, ~12.65V is where you want to see the battery sit. ~12.2V is DEAD. Typically you need to float about 14.2-14.6V on the battery for a few days to fully charge it. It can take even longer to 'fully' charge an older battery thats fairly sulfated. It can't be done much faster. Typical lead starting batteries are just junk. They work fine when used daily, or at least a few times a week. Let them sit and they don't last.

defurr

Here recently, the highest I've seen the battery in the morning is ~12.3V, and it always starts fine at that level. Seems like I've even started it as low as 12.2V or 12.1V. Granted, in that range, it starts to struggle...

Wharbone

I had a similar parasitic drain that wasn't my HFL. My drain was from my stock radio. I took my car to a trusted mechanic to figure it out and that was their diagnosis.

I was skeptical that was my problem, but I found a new radio for $199 at replacementradios.com and swapped it in. Solved my problem.

This may or may not be your drain. Try pulling the radio fuse and see how that affects your draw. There are other components like amp on that same fuse as well which may be causing it instead. If that doesn't solve your draw, go through your fuses one by one to figure out what is causing it.

Also, get your battery checked for free at Autozone or other parts store so you know for sure that it's good.

toantran99

It could also be your ac compressor relay

defurr

Turns out Mr. Z's lead appears to have been the right one. I charged the battery on my 6 amp charger for about 6 hours @ ~14V. Then I left it on the float charger the rest of the night. The next day, I parked it all day. When I got back after 10 hours of inactivity, for the first time it was sitting at 12.6V. I floated it that night, and its LED finally went to green in forever (which signifies fully charged and monitoring for drain). The true test will have been having it sit idle for almost a week, as I'm outta town at the moment.