Owners of other Honda or Acura vehicles such as the Accord, Insight, Clarity, Fit, HR-V, CR-V, Pilot, Passport, Odyssey, Ridgeline, ILX, MDX, RDX, NSX, RLX and TLX may also find these DIY instructions to be helpful.

The symptoms of a weak or failing 12V battery include slow cranking, sluggish starting and possibly also a warning light on the gauge cluster.

To make sure the alternator is working properly, test the voltage while the engine is running with a digital multimeter. The alternator should be charging the battery at least over 13 volts to as high as just over 14 volts.

The OEM battery in this 2016 Civic is a "Group Size" 51R.

A few compatible replacement aftermarket 51R sized 12V batteries include the following: Optima 8073-167 D51R YellowTop, Exide Edge FP-AGM51R and EverStart MAXX-51R (at Walmart).

The tools needed to complete this procedure include a 10mm socket and a 1/4" drive ratchet or a standard 10mm wrench.

The first two steps are to open the hood and then move to the right (driver) side of the engine bay.

The 12V battery is located to the right of the brake fluid reservoir and in front of the black plastic cowl near the windshield.

First, loosen the nut on the "-" negative terminal by turning it in the counterclockwise direction with a 10mm socket and a 1/4" drive ratchet or a 10mm wrench.

Wrap the terminal in a small towel and tuck it away on the right side of the battery near the suspension tower to help prevent accidental electrical contact.

To remove the battery hold down bar or "clamp", remove the two nuts on the top of the threaded bars by turning them in the counterclockwise direction with a deep well 10mm socket or a 10mm wrench.

Set the two 10mm nuts aside in a safe place.

Pull the hold down bar off the top of the old battery and set it aside with the two nuts.

Loosen the terminal nut by rotating it in the counterclockwise direction a few turns.

You do not need to fully remove the nut.

Pull the positive terminal off the battery post.

Close the red cover over the positive terminal and tuck it away on the left side of the battery.

Set the battery cover aside for re-installation later.

Carefully lift the old battery straight out of the engine bay.

Gently set the old battery on the ground.

Try to avoid tipping over or dropping the old battery since that could cause acid to leak out.

Be sure to take the old battery with you to the auto parts store or Walmart to possibly avoid having to pay a "core", "recycling", "disposal" or "environmental" fee.

Clean off any debris on the black plastic battery tray so that the new battery will rest evenly on it.

Carefully lower the new 12V battery down into the engine bay.

The positive post should be situated closer to the front of the car and the negative post should be located near the cowl by the windshield.

If you've had a problem with corrosion (white or blue powder) building up on the terminals or cables, consider installing some felt anti-corrosion washers over the battery posts.

Push the positive terminal over the "+" battery post.

Try to avoid over tightening the terminal nut to prevent from cracking the battery post which could lead to an acid leak.

Flip the red plastic cover closed over the positive terminal.

You should feel or hear the cover "click" securely into place.

Next, push the negative terminal over the "-" battery post.

Avoid over tightening the terminal nut to prevent from damaging the battery post which could lead to an acid leak.

Replace the two nuts by tightening them in the clockwise direction with the 10mm wrench until they are snug.

Check to see if the new battery can be moved, rocked or slid around.

If the new battery can be moved, tighten the two hold down bar nuts an extra turn or two.

To test the new battery, start the engine, turn on the headlights and flash the high beams.

Please remember to adjust the time on the clock and program your favorite radio station presets before you start driving.

If you often don't drive your car for a week or two at a time, I highly recommend using a trickle charger to keep the 12V battery fully charged while you are away. Lead-acid batteries have a much longer useful life when they are kept fully charged.

I personally use and can recommend the Battery Tender Junior smart trickle charger.

Be sure to record the 12V battery change in your car's service records.

Please check out all of my 2016-2019 Honda Civic DIY Repair & Maintenance Guides.