Looking for someone with any insight who has knowledge about car batteries and electrical systems.

Vehicle is a 2008 MDX. The battery is an OEM Acura battery, about 2.5 years old. These vehicles have issues with the hands free Bluetooth causing parasitic battery drain, like all Acuras of this era. That should be solved in this case, as we have removed the wire that provides power to the system after the ignition is off.

I don't drive this vehicle everyday. After letting it sit for 3 or 4 days that battery was close to dead and could just barley start the car.The Nav system and radio both reset. I charged the battery and took a reading with the multi-meter. After charge it was roughly 12.85. After sitting overnight it was at about 12.47. I let it sit for a few days, periodically testing it with a multi-meter, and it went down to about 12.37.

I charged the battery again, and used a recondition program on the Ctek charger. When I pulled the charger, I was around 12.87. The next morning battery was back around 12.47. Doing a parasitic draw test with the multi-meter, it will jump showing there is draw when first connecting the multi-meter and the negative post of about 3.25, but it immediately comes down to 0.02 on a 10 Amp scale within about 2 seconds. I assume the initial numbers are just the vehicle "waking up".

I then pulled the battery out of the vehicle thinking I would see if the volts dropped overnight when it wasn't connected. However out of the vehicle, it immediately tests at 12.65 volts. Put it back in the car and hook it up, and it shows 12.47 Volts.

Whats going on here? Battery on the way out? Seems strange for a battery under 3 years old.

Any knowledgeable help is appreciated.

 

You'll need to do both a conductance and load test on the battery to determine its true health.

If it passes both tests, you'll need to connect, in series with your battery, a scope, GMM or DMM with a record feature and let it record over night to see if there is a draw. It is not uncommon for a module to awaken when it isnt supposed to.

 

Thanks for this.

I haven't done a load test yet, but that was next on the list. To be honest everything you have after that is beyond my scope of tools and or ability.

I Let the MDX sit again for two days, battery showed 12.40 when tested.

Getting a bit annoyed, but I guess its time to unhook the Bluetooth and see if that cures it. I was really thinking pulling out the constant power would fix it. I'm kinda of hoping it still looses power so I can blame it on the battery.

 

Darn,I ment to ask you about this. I was wondering what power wire you were referring too.

Yeah I agree, just completely unplug the BT module,before anything else.

Its what we normally do for the customers that dont want to pay $400+ for an ancient BT system....

 

LOL its funny you know exactly what I'm talking about. I'm surprised this isn't something Acura just agreed to replace for everyone.

The power wire I'm talking about, a bit hard to explain I guess, but its a white wire next to a purple wire on the harness that plugs into the Hands free/Bluetooth unit. The white wire provides constant power. The purple wire only has power when ignition on. So we unplugged the white wire, then ran a wire from the purple into the white wire position. So now power is ONLY provided to the Bluetooth system with ignition on. in theory, that should eliminate the power drain.

I got the idea from someone on MDXERs.org. It seemed to work for him.

I haven't tried sorting this yet, but i'm starting to wonder if it isn't a combination of battery packing it in, and very short drives or just moving the vehicle in the driveway a bunch.

 

If anyone is looking this up. Solution was a new Battery. Apparently the factory Acura battery isn't known for long life.

Also the Bluetooth fix is still working well, no problems yet.

 

You seem to be a fairly competent DIYer.

I suggest buying yourself a conductance battery tester. They are relatively inexpensive and will give you a head start on any automotive electrical issue(a battery test is almost always the first place to start)

This seems to be decent: