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Acura TL 2009-2014 and MDX: Why is My Battery Not Charging?

Sometimes battery problems can be caused by something other than the battery. This diagnostic will show you what to look for.

By Jared Hammond - May 4, 2016

This article applies to the Acura TL and MDX (2009-2014).

When your car doesn't start or it suffers from failing gauges, lights, and other accessories, it's easy to just throw a new battery in and call it a day. But you don't want to waste money on new batteries unless you are absolutely sure that it's the battery. Check out the instructions below to learn more on the possibilities of battery drain, and what can cause it.

Acura TL 2009-2014 and MDX: Why is My Battery Not Charging?

Materials Needed

  • Multimeter
  • Battery tender
  • Ratchet with socket set and extension

Step 1 – Checking the battery

It's true that the battery is the most likely culprit and should be checked first. Batteries tend to lose charge, especially during winter.

There's a quick test you can do using a multimeter. Set the multimeter to volts and insert the probes to the battery posts. When the car is off, the battery should hold 12.2 to 12.8 volts. Now try starting the engine. There should be a slight drop in voltage as the engine cranks. If it drops below 10 volts, then that could mean your battery isn't holding a charge. But the multimeter test isn't conclusive. If you want a truly conclusive test, you need to take the battery to an auto parts store or battery supplier and have them put the battery through a load test.

ACURA TL MDX BATTERY CABLE ALTERNATOR STARTER NOT CHARGING DIAGNOSE
Figure 1. Check the battery.

Step 2 – Is the battery getting charged?

Batteries get charged by the alternator, but if you don't drive the vehicle regularly, then there's a good chance that the battery is not getting recharged. This can also happen if you only ever take the car on short trips. If your battery needs to be charged, or you haven't driven it in a while, then you should take the battery out and hook it up to a battery tender so that it gets a full charge.

ACURA TL MDX BATTERY CABLE ALTERNATOR STARTER NOT CHARGING DIAGNOSE
Figure 2. Use a battery tender to charge a battery not in use.

Step 3 – Is there something draining the battery?

When you buy a luxury brand vehicle like Acura, you're getting more electronic features than a typical car. These features can be a greater burden on the battery, but only when something goes wrong.

Have you recently added an aftermarket part or accessory to your vehicle? Then it's possible that could be causing an excessive drain. There have also been cases where the HomeLink computer created an open circuit, causing an excessive draw. In this case, replacing the computer can fix the problem. There have also been cases where the liftgate and backup camera wiring harness got damaged and caused an excessive draw. The wiring harness can be fixed by splicing the wires back together. You can test these things by having your multimeter set to amps. If it's drawing more amps than needed, then you've found the problem.

  • ACURA TL MDX BATTERY CABLE ALTERNATOR STARTER NOT CHARGING DIAGNOSE
    Figure 3. HomeLink module circuit board.
  • ACURA TL MDX BATTERY CABLE ALTERNATOR STARTER NOT CHARGING DIAGNOSE
    Figure 4. Check the backup camera/liftgate wiring harness for damage.

Step 4 – Is it the battery cables?

Battery cables go through more wear than any other cable. A loose or corroded battery cable can cause all kinds of battery problems.

Firstly, make sure that the cables are securely connected to the terminals. Then make sure there isn't any corrosion on the battery terminals. Inspect the cable for any signs of corrosion, especially around the end points. To test the cables with your multimeter, set the multimeter to ohms and touch one probe to the battery post and another probe to the battery cable itself. It should indicate little or no resistance. If there is a significant amount of resistance or full resistance, then you have a bad battery cable.

ACURA TL MDX BATTERY CABLE ALTERNATOR STARTER NOT CHARGING DIAGNOSE
Figure 5. Check the battery cable for corrosion.

Step 5 – Is it the alternator?

A bad alternator could be failing to charge the battery.

To test the alternator with your multimeter you'll need a partner. Have the multimeter set to volts. Like the battery test touch, the black probe to the negative battery post and the red probe to the positive battery post. Have your partner turn on the lights and other accessories, then have him/her rev the engine up to 1,500 rpms. You should get a reading between 14.2 and 14.8 volts. This is the alternator charging the battery. If it's less than 14, then your alternator may not be sufficiently charging your battery.

ACURA TL MDX BATTERY CABLE ALTERNATOR STARTER NOT CHARGING DIAGNOSE
Figure 6. Check if it's the alternator.

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