Which battery type you have determines how you install it
Most consumer devices use one of three battery types: replaceable alkaline batteries (AA, AAA, 9V), rechargeable lithium-ion batteries built into the device, or rechargeable batteries you can swap out yourself. The steps differ completely depending on which one you own. Alkaline batteries slide or snap into a battery compartment. Built-in lithium-ion batteries require opening the device and disconnecting the old one before soldering or clipping in a new one — a task most people should not attempt. Swappable rechargeable batteries (common in cameras, power tools, and some phones) slide into a charging dock or slot on the device itself.
Before you start, check your device manual or the manufacturer's website to confirm which type your device uses. The manual will also tell you the correct orientation, voltage, and capacity your device needs. Installing the wrong battery type or size can damage your device or create a safety hazard.
Key Takeaways
- Alkaline batteries (AA, AAA, 9V) slide or snap into a compartment on the outside of your device and require no tools.
- Built-in lithium-ion batteries are soldered to the circuit board and should only be replaced by a manufacturer or professional repair shop.
- Swappable rechargeable batteries slide into a slot or dock on your device and can be replaced by the user without tools.
- Always check your device manual for the correct battery type, size, and orientation before installation.
- Alkaline batteries have a positive (+) and negative (−) end; installing them backwards will prevent your device from working.
Installing alkaline batteries in a battery compartment
Locate the battery compartment on your device. This is usually on the back, bottom, or inside a door or panel. The compartment will have a small latch, screw, or sliding cover. If there is a screw, use a screwdriver (usually Phillips head) to remove it. If there is a latch or tab, slide or flip it to open the compartment. Some compartments have a small indentation you can press with your fingernail to pop the cover open.
Look inside the compartment. You will see metal contact points (usually two or more) and often a diagram showing how many batteries fit and which direction they go. The diagram shows a + (positive) end and a − (negative) end. The positive end is the flat or slightly raised side; the negative end is the spring-loaded side or the side with a dimple.
Insert the battery with the positive end facing the direction the diagram shows. Usually this means the positive end faces toward the back of the compartment and the negative end faces toward the spring or contact point. Push gently until the battery sits flat and the spring makes contact with the negative end. If your device uses more than one battery, install them all in the same orientation.
Close the compartment by sliding the cover back, flipping the latch, or replacing and tightening the screw. Do not force the cover; if it does not close easily, check that the batteries are sitting flat and facing the correct direction.
Installing swappable rechargeable batteries
Swappable rechargeable batteries are common in digital cameras, cordless power tools, wireless mice, and some portable speakers. These batteries slide into a slot on the device or into a separate charging dock. Check your manual to see whether your device charges the battery while it is inside the device or whether you remove the battery and place it in a separate charger.
To install a swappable battery, locate the battery slot or compartment. On cameras, this is often on the side or bottom. On power tools, it is usually on the handle. Slide the battery into the slot with the contacts (the metal pads on the battery) facing toward the device. You will feel a slight resistance as the contacts align. Push until you hear a click or feel the battery lock into place. Do not force it; if it does not slide smoothly, remove it and check that the contacts are clean and facing the right direction.
If your device uses a separate charging dock, place the battery into the dock with the contacts facing down or toward the dock, depending on your model. The dock will hold the battery in place while it charges. Most docks have an indicator light that shows charging status.
When you should not install a battery yourself
If your device has a built-in lithium-ion battery that is soldered or glued to the circuit board, do not attempt to replace it yourself. These batteries are found in smartphones, tablets, laptops, and many modern wireless earbuds. Removing and replacing a soldered battery requires specialized tools, training, and a clean workspace to avoid damaging the device or creating a fire hazard.
If your device is still under warranty, contact the manufacturer or an authorized repair center. If the warranty has expired, you can take the device to an independent repair shop that specializes in your device type. Many shops can replace a built-in battery for a flat fee, usually between $50 and $150 depending on the device.
Never attempt to pry open a device with a soldered battery using a screwdriver or knife. You risk puncturing the battery, which can cause it to overheat, catch fire, or release toxic chemicals. If you see a battery that is swollen, leaking, or has a burnt smell, stop and take the device to a professional immediately.
Checking battery contacts and troubleshooting
If your device does not turn on after you install a battery, the contacts may be dirty or corroded. Remove the battery and look at both the metal contacts on the battery and the metal contact points inside the device. If you see white, green, or blue corrosion or a dull film, clean them gently with a dry cotton swab or a pencil eraser. Rub lightly until the metal is shiny again. Do not use water or liquid cleaners, which can damage the device.
Reinsert the battery and try again. If the device still does not work, try a fresh battery of the same type to rule out a dead battery. If a fresh battery does not work, the problem is likely with the device itself, not the battery installation.
For swappable rechargeable batteries, make sure the battery is fully charged before troubleshooting. Plug the battery into its charger and wait for the indicator light to show a full charge. If the battery will not charge, try cleaning the contacts on both the battery and the charger with a dry cotton swab.
Battery safety and storage
Store alkaline batteries in a cool, dry place away from metal objects. Do not store batteries in a drawer with loose coins, keys, or paperclips, which can touch both the positive and negative ends at the same time and cause the battery to discharge or overheat.
Never mix old and new batteries in the same device. Old batteries have less charge and can cause the device to work poorly or damage the new batteries. If your device uses multiple batteries, replace them all at the same time.
Rechargeable batteries degrade over time. If a rechargeable battery no longer holds a charge after a full charge cycle, it is time to replace it. Do not throw batteries in the trash. Take them to a battery recycling program or a retailer that accepts used batteries. Best Buy, Home Depot, and most electronics stores have battery recycling bins near the entrance.
Frequently Asked Questions
What happens if I install a battery backwards?
Your device will not work. The electrical circuit requires the positive and negative ends to connect in the correct order. Simply remove the battery, flip it around, and reinsert it. No damage occurs from a single backwards installation, but leaving it backwards for a long time can damage the battery compartment contacts.
Can I use a rechargeable battery in a device that takes alkaline batteries?
Yes, but it may not work as well. Rechargeable batteries (usually 1.2 volts) have a lower voltage than alkaline batteries (1.5 volts). Devices designed for alkaline batteries may work slowly or not at all with rechargeable batteries. Check your device manual to see if it supports rechargeable batteries.
How do I know if my battery is dead?
For alkaline batteries, the only way to know is to test them in a device or use a battery tester (a small handheld device sold at hardware stores for $5 to $15). For rechargeable batteries, plug them into their charger. If the indicator light does not turn on or the battery will not hold a charge after a full charge cycle, the battery is dead.
Is it safe to leave batteries in a device I am not using?
Alkaline batteries can stay in a device indefinitely if the device is off. However, if you plan to store a device for more than a few months, remove the batteries to prevent leakage. Rechargeable batteries should be removed and stored in a cool place if you will not use the device for more than a month.
What should I do if a battery is leaking?
Remove the battery immediately and do not touch the leaked material. Wash your hands thoroughly. Wipe the inside of the battery compartment with a dry paper towel. If the leaked material has damaged the device contacts, take the device to a repair shop. Do not attempt to clean the inside of the device with water or liquid cleaners.