If your Infiniti is starting to have trouble holding a charge or if it's just been a while since you've replaced the battery, it's probably time for a new one. Depending on the model of your Infiniti, batteries can range in price from $100-$200. Some factors that will affect the cost of replacement include the age and model of your vehicle and whether you choose to do it yourself or have it done by a professional.
If you're comfortable working with cars, replacing the battery is a relatively easy job that you can do yourself with just a few tools. You'll need to purchase the correct battery for your car (make sure to check the size and voltage), disconnect the old battery, clean off any corrosion, connect the new battery, and test to make sure everything is working properly. The whole process should take less than an hour.
If you'd rather not do it yourself, most auto shops will be able to replace your Infiniti's battery for you. Prices will vary depending on where you go, but expect to pay around $75-$100 for labor. So all in all, replacing an Infiniti battery should cost between $175-$300.