Your car key fob is dead. You pop open the battery compartment, and it says CR1620. The only spare you have in the drawer is a CR1616. The numbers look close—just two digits off. Will it work?

Short answer: maybe. The two batteries share the same 16 mm diameter and the same 3 V voltage, but the CR1620 is 0.4 mm thicker and packs roughly 40–50% more capacity. Whether that 0.4 mm matters depends entirely on how much room your device has.

This guide breaks down every real difference between the CR1616 and CR1620. We will compare specifications, run through brand options, list exact equivalent models, show you how to install them safely, and tell you which car key fobs accept which battery. If you are looking for a quick reference chart or a step-by-step replacement guide, you will find both here.

• C = Lithium-based chemistry
• R = Round (coin) form factor
• 16 = 16 mm diameter
• 16 = 1.6 mm thickness

Trade-off: the thin profile comes at the cost of capacity. A 55 mAh cell will not last as long as thicker alternatives in devices that draw frequent current, such as key fobs with remote-start buttons.

The CR1620 follows the same naming convention, but the trailing 20 indicates a thickness of 2.0 mm. Like the CR1616, it is a 3 V lithium manganese dioxide coin cell, but its extra 0.4 mm of material translates to higher capacity.

• Nominal voltage: 3.0 V
• Typical capacity: 70–80 mAh (some industrial-grade units reach 85 mAh)
• Weight: roughly 1.3 g
• Temperature range: –30 °C to +60 °C
• Shelf life: up to 10 years at room temperature

The extra capacity makes the CR1620 the default choice for car key fobs, small LED lights, and medical devices that need longer runtime without increasing the device size. The diameter is still 16 mm, so the footprint on the PCB is identical. The only difference is height.

Key takeaway: same voltage, same diameter, different height, different capacity. That 0.4 mm and the extra 20–25 mAh are the entire story.

A note on capacity claims: some low-quality web sources list CR1620 capacity as high as 120–150 mAh. Those numbers are inaccurate. The physical volume of a 16 mm × 2.0 mm coin cell limits practical capacity to the 70–80 mAh range for standard LiMnO₂ chemistry. If you see a claim above 90 mAh, it is either a marketing exaggeration or a different chemistry (such as Li-SOCl₂, which is not sold as a drop-in CR1620 replacement).

The 0.4 mm height difference is the single most important factor when deciding whether you can swap these batteries. Here is how to think about it.

• The battery will be 0.4 mm taller than the space it is designed for.
• In devices with a spring-loaded battery clip, the extra thickness may be absorbed by the spring. The back cover or battery door may still close, though it may bulge slightly.
• In devices with a rigid plastic battery tray, the CR1620 may not fit at all, or it may warp the tray when you force the cover shut.
• The positive terminal on the CR1620 may press harder against the device contact. This is usually fine, but in rare cases it can deform the contact spring over time.

• The battery will sit 0.4 mm lower than designed.
• The negative terminal may lose contact with the spring or flat plate in the battery compartment.
• The device may work intermittently, reset when shaken, or fail to power on at all.
• This is the more problematic direction of the swap. A loose CR1616 in a CR1620 compartment can cause erratic behavior.

1. Open the battery compartment and measure the depth. If there is visible clearance around the existing battery, a CR1620 might fit.
2. Check the battery door or cover. If it snaps shut with no resistance and sits flush, the device is likely tolerant of minor height differences. If it requires force to close, stop.
3. Test the device after installation. Press every button and check that the device does not lose power when tapped or shaken.

The CR1620’s extra capacity does not come from better chemistry per unit volume. The two cells are roughly equal in energy density. The CR1620 simply has more material inside the cell, so it stores more total charge.

In practice, that means a car key fob that runs on a CR1620 will usually outlast the same fob running on a CR1616 by roughly one year. If you are replacing a CR1616 with a CR1620 and the fit is good, you gain runtime. If you are replacing a CR1620 with a CR1616, you lose runtime and risk contact problems.

Both batteries have a self-discharge rate below 1% per year at 20 °C. If you leave a spare in a drawer, it will still hold most of its charge after five years. Shelf life is rated at 10 years for both.

Not all CR1616 or CR1620 cells are identical. Different brands use slightly different cathode formulations, sealing methods, and quality control standards. Here is how the major players compare.

Panasonic is the reference standard for coin cells. Their CR1616 and CR1620 are widely used in OEM medical devices and automotive key fobs because of tight dimensional tolerances and consistent capacity. If your device specifies a Panasonic battery, there is usually a reason related to contact geometry.

Duracell and Energizer dominate retail shelves. You will pay more per cell at a pharmacy or hardware store, but the packaging is consumer-friendly, and the quality is solid. Both brands perform within spec, but their capacity ratings are sometimes rounded up in marketing materials.

Maxell is the go-to for bulk buyers and OEMs. The cells are reliable, the price is lower, and the lead times are typically shorter than those of Western brands. If you are sourcing 1,000+ units for a production run, Maxell is worth evaluating.

Car Key Fob Compatibility Quick Reference

If your key fob is not on this list, check the owner’s manual or open the battery compartment. The battery type is usually molded into the plastic tray or printed on the back cover.

Spring-loaded battery contacts can absorb the 0.4 mm difference. Devices with rigid tray mounts usually cannot. Some manufacturers deliberately design the battery compartment with a slight tolerance so that either cell works, reducing supply chain risk.

Scenario 1: Your device needs a CR1616, and you only have a CR1620.

• Check whether the battery compartment has visible clearance above the existing battery.
• If the device uses a spring contact on the negative side, the spring will compress to accommodate the extra 0.4 mm. The positive contact will press slightly harder. This is usually fine.
• If the device uses a rigid plastic tray, the CR1620 may not fit, or the back cover may bulge.
• If the back cover snaps shut flush and the device powers on reliably, the swap works. You gain extra capacity and longer runtime.
• If the back cover requires force to close, or the device resets when shaken, do not use the CR1620. The risk of contact damage or battery deformation is not worth it.

• This is the riskier direction. The CR1616 is thinner than the device expects.
• The negative contact spring may not press firmly against the battery. The cell can rattle, shift, or lose contact.
• If the device has a flat plate contact instead of a spring, the CR1616 may sit too low to make reliable contact at all.
• Use the CR1616 only in an emergency, and replace it with the correct CR1620 as soon as possible.

• If you are stuck at a parking lot with a dead key fob and only a CR1616 in your wallet, the CR1616 may get you home. Slide it in, press the battery down firmly, and test the buttons. If the car responds, drive home and order the correct battery.
• Do not leave an emergency substitute in place for weeks. Intermittent contact can cause the device to draw irregular current, which may shorten the replacement battery's life or confuse the device’s power-management circuit.

Summary rule: CR1620 into a CR1616 device is usually safe if it fits. CR1616 into a CR1620 device is only a temporary fix. When in doubt, use the battery specified by the manufacturer.

Manufacturers use different prefixes for the same physical cell. Here is the complete cross-reference.

CR vs BR: The BR series uses carbon monofluoride (CF) chemistry instead of manganese dioxide. BR cells excel in high-temperature environments (up to +125 °C) and have extremely low self-discharge, making them ideal for long-term memory backup. However, they handle pulse discharge poorly compared to CR cells. For car key fobs and active devices, stick with CR. For CMOS backup batteries in industrial equipment, BR is the better choice.

ML1616 / ML1620: These are rechargeable lithium manganese coin cells. They have lower capacity (typically 10–20 mAh) and are not drop-in replacements for standard CR cells. Do not use an ML cell in a device designed for CR unless the device explicitly supports rechargeable coin cells.

• A small flat-head screwdriver, a coin, or a plastic pry tool
• A soft cloth or tissue
• Optional: a pair of tweezers for handling the battery

1. Open the battery compartment. Most car key fobs have a small notch or seam along the edge. Insert the edge of a coin or screwdriver and twist gently to pop the two halves apart. For watches and small devices, look for a screw-on back or a sliding tray.
2. Note the orientation. Before you remove the old battery, note which side faces up. The positive (+) terminal is the raised side with the brand label. The negative (–) terminal is the flat bottom.
3. Remove the old battery. Use tweezers or a fingernail to lift the battery out. Do not use metal tools to pry against the circuit board. If the battery is stuck, gently push from the side to slide it out of the tray.
4. Clean the contacts. Wipe the metal contacts in the battery compartment with a soft cloth. If you see corrosion (white or green residue), clean it with a cotton swab lightly dampened with rubbing alcohol. Let the compartment dry completely before inserting the new battery.
5. Insert the new battery. Place the new battery with the positive (+) side facing the same direction as the old one. In most devices, the positive side faces up toward the cover. Press the battery gently into place until it sits flat in the tray.
6. Close the compartment. Snap the cover back on or screw it down. The cover should close without force. If you need to press hard, the battery may be too thick for the compartment.
7. Test the device. Press every button and confirm the device responds. For a car key fob, test the lock, unlock, trunk, and panic buttons. Some vehicles require a resynchronization step after battery replacement; check the owner’s manual if the fob does not work immediately.
8. Dispose of the old battery. Coin cells contain lithium and should not go in the regular trash. Drop it at a battery recycling bin (most electronics retailers and hardware stores have them) or a household hazardous waste facility.

Users searching for CR1620 information often wonder about the next size up. Here is how the three most common 3 V coin cells stack up.

Can you swap a CR1620 with a CR1632? No. The CR1632 is 1.2 mm thicker than the CR1620. It will not fit in a CR1620 compartment unless the device was specifically designed with extra clearance.

Can you swap a CR1620 with a CR2032? No. The CR2032 is 4 mm wider. It physically will not fit into a 16 mm battery tray.

Bottom line: within the 16 mm family, the CR1616 and CR1620 are the only pair that can sometimes be swapped, and only in one direction (CR1620 into a CR1616 device, if space allows). The CR1632 and CR2032 are entirely different sizes.

Counterfeit warning: Fake coin cells are common on marketplace platforms. Red flags include:

• Brand labels that look off-center or poorly printed
• Prices significantly below market rate (e.g., $0.20 per cell for "Panasonic")
• No safety vent markings on the positive terminal
• Packaging that lacks a manufacturing date or batch code

If you are buying in volume for a commercial product, source through an authorized distributor (DigiKey, Mouser, Arrow, or WellLinkChips) to guarantee authenticity and traceability.

Coin cells are small, sealed, and generally safe, but there are a few rules worth following.

Keep them away from children. Ingestion of a lithium coin cell can cause severe internal burns within two hours. The battery can generate hydroxide when it comes into contact with body fluids, which can lead to perforation of the esophagus or intestines. Store spare batteries in a locked drawer or a child-resistant container. If a child swallows a battery, seek emergency medical help immediately. Do not induce vomiting.

Do not mix old and new batteries. When cells of different charge levels are placed in series, the weaker cell can be forced into reverse polarity, which can cause leakage or rupture. Always replace all batteries in a multi-cell device at the same time.

Do not short the terminals. A coin cell can deliver enough current to heat up rapidly if the positive and negative terminals touch a metal object. Do not carry loose batteries in a pocket with keys or coins.

Store dry and cool. Lithium manganese cells self-discharge slowly, but high humidity can corrode the terminals. Store in a sealed container at room temperature.

Recycle, do not trash. Lithium batteries contain reactive materials. Most municipalities require drop-off at a recycling center or hazardous waste facility. Many electronics retailers offer free battery recycling bins at the entrance.

If you have replaced the battery and the device still does not work, the problem is likely not the battery. Check for a blown fuse, damaged circuit board, or failed component. For car key fobs, the transponder chip itself may be damaged, in which case the fob needs professional reprogramming or replacement.

Often, yes. The CR1620 is 0.4 mm thicker than the CR1616, but many key fobs have enough spring travel in the battery contact to absorb the difference. If the back cover snaps shut flush and the buttons work reliably, the swap is safe. You will get longer battery life. If the cover bulges or the fob resets when shaken, use the correct CR1616 instead.

The CR1616 is thinner, so it may sit too low in the battery compartment. The negative contact spring may not press firmly against the cell, causing intermittent power loss or complete failure. Use a CR1616 only as a temporary emergency fix. Replace it with the correct CR1620 as soon as possible.

Yes. Both are 3 V lithium manganese dioxide cells. The voltage is identical. The difference is physical size and capacity.

Under typical use (a few button presses per day), a CR1620 lasts about 2–3 years. Heavy users who press remote-start or trunk buttons daily may see 1.5–2 years. The CR1616 in the same fob would last roughly 1.5–2 years under light use and 1 year under heavy use.

No. The CR1632 is 1.2 mm thicker and will not fit in a CR1620 compartment. The diameter is the same (16 mm), but the extra height makes it incompatible.

Panasonic is the industry standard for tight-tolerance applications. Duracell and Energizer are excellent for retail purchases. Maxell offers the best value for bulk orders. For most consumers, any major brand will perform within spec. Avoid unbranded cells from unknown marketplace sellers.

Three common causes: (1) the battery is counterfeit and has far less capacity than rated; (2) the device has a parasitic drain that keeps drawing current in standby; (3) you mixed an old and new battery in a multi-cell device, and the old one is dragging the new one down. Test with a genuine fresh cell from an authorized source. If it still dies fast, the device likely needs repair.

Yes, the ML1620 is a rechargeable lithium manganese coin cell with the same 16 mm × 2.0 mm dimensions. However, it has much lower capacity (typically 10–20 mAh) and is only suitable for devices that explicitly support rechargeable coin cells. Do not use an ML1620 in a device designed for a standard CR1620.

Authorized distributors such as DigiKey, Mouser, Arrow, and WellLinkChips sell CR1620 cells in bulk (100-packs, 500-packs, and 1,000-packs). For prototype quantities, 10-packs from Amazon or Walmart are convenient. For production volumes, contact an authorized distributor for the best pricing and guaranteed authenticity.

"C" indicates a lithium-based chemistry (specifically lithium manganese dioxide). "R" indicates a round (coin) form factor. The full code is defined in IEC 60086. The "DL" prefix used by Duracell follows the same physical standard but uses the manufacturer’s own product code.

The CR1616 and CR1620 are close cousins: same diameter, same voltage, different thickness, different capacity. Whether you can swap them depends on one question—does the thicker CR1620 fit in your device’s battery compartment?

If it fits and the cover closes without force, the CR1620 is the better choice. It gives you 40–50% more capacity and longer runtime. If the device was designed for a CR1620, do not downgrade to a CR1616. The thinner cell will rattle, lose contact, and leave you with a dead remote.

For the best results, always buy genuine cells from authorized sources. Counterfeit coin cells are common, and a fake battery will cost you more in frustration than you saved in price.

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