If you’re designing a medical device and choosing between AG13/LR44 alkaline, SR44 silver oxide, and CR2032 lithium button cells, here’s the direct answer: AG13/LR44 is the cheapest but carries the highest leakage risk and voltage instability; SR44 provides the best voltage accuracy for diagnostic precision; CR2032 offers the safest leakage protection and longest shelf life but requires voltage regulation.

The “right” choice depends on your device’s criticality level, accuracy requirements, expected service life, and regulatory pathway. A $5 blood pressure monitor can tolerate alkaline voltage drift. A $500 glucose meter cannot.

I’ve spent 15 years manufacturing button cell batteries for medical device companies, and I’ve seen the consequences of wrong chemistry choices. The glucose meter manufacturer whose devices showed inconsistent readings because they used alkaline instead of silver oxide. The pulse oximeter company that faced FDA queries about their battery leakage risk assessment. The thermometer brand that had to recall devices after alkaline electrolyte corroded the sensor contacts.

This guide breaks down the real engineering tradeoffs so you can select the right chemistry for your medical device’s accuracy, safety, and regulatory requirements.

Understanding the Three Chemistries: What the Part Numbers Actually Mean

Before comparing performance, let’s clarify what these part numbers represent, because the naming conventions confuse even experienced engineers.

AG13 vs LR44: Same Battery, Different Names

AG13 and LR44 are the same physical battery with identical specifications. Both are 11.6mm diameter × 5.4mm height alkaline manganese dioxide button cells with 1.5V nominal voltage and 110-150mAh capacity. The different designations come from regional naming conventions:

• AG13: “Alkaline” designation, commonly used in Asian markets
• LR44: IEC (International Electrotechnical Commission) standard designation, used globally
• Other equivalents: A76, 357, 157 (all cross-reference to the same dimensions and chemistry)

When sourcing for medical devices, always specify the IEC LR44 designation to avoid confusion across international supply chains.

SR44: Silver Oxide, Not Alkaline

SR44 uses silver oxide chemistry (zinc-silver oxide) with the same physical dimensions as AG13/LR44, but delivers different electrical characteristics. The “SR” designation indicates silver oxide chemistry per IEC standards. Key differences:

• Nominal voltage: 1.55V (vs 1.5V for alkaline)
• Capacity: 150-200mAh (vs 110-150mAh for alkaline)
• Discharge curve: Flat at 1.55V until near end-of-life (vs declining from 1.5V to 0.9V for alkaline)
• Leakage risk: Lower than alkaline due to improved seal design
• Cost: 2-4× more expensive than alkaline AG13/LR44

The “SR” in SR44 stands for “Silver oxide Round” per IEC 60086-3 (the international standard for primary lithium and silver oxide button cells).

CR2032: Lithium, Different Form Factor

CR2032 is a 3.0V lithium manganese dioxide coin cell with larger dimensions (20mm diameter × 3.2mm height) and different electrical characteristics. The “CR” designation indicates lithium chemistry per IEC standards. Key characteristics:

• Nominal voltage: 3.0V (double the voltage of AG13/LR44/SR44)
• Capacity: 210-240mAh (highest of the three)
• Discharge curve: Flat at 3.0V with excellent stability
• Leakage risk: Lowest due to hermetic laser-welded sealing
• Self-discharge: 2-3% per year (vs 2-5% per month for alkaline/silver oxide)
• Cost: Moderate—more expensive than alkaline, comparable to silver oxide

The “CR2032″ designation follows IEC naming: “C” = lithium, “R” = round, “20″ = 20mm diameter, “32″ = 3.2mm height.

Voltage Characteristics: Why Medical Devices Care

Voltage isn’t just about “does it power the device?” For medical devices, voltage stability directly impacts measurement accuracy.

AG13/LR44 Alkaline: Progressive Voltage Decline

Alkaline AG13/LR44 batteries show continuous voltage decline from 1.5V (fresh) to 0.9V (end-of-life) during discharge. This declining voltage curve creates problems for medical devices that rely on stable reference voltage for sensor accuracy.

Consider a glucose meter using an electrochemical test strip. The meter measures current flow through the strip, which is proportional to blood glucose concentration. But the measurement circuit needs a stable reference voltage to convert current to concentration accurately. If the battery voltage drops from 1.5V to 1.2V during use, the reference voltage shifts, introducing measurement error.

According to ISO 15197:2013 (the international standard for blood glucose monitoring systems), measurement accuracy must be within ±15% of reference values. Voltage instability is a contributor to measurement drift.

I worked with a glucose meter manufacturer who switched from alkaline to silver oxide after field complaints about inconsistent readings. Their analysis showed that 23% of accuracy complaints correlated with battery voltage below 1.3V—something that happens inevitably with alkaline chemistry after 30-40% of capacity is used.

SR44 Silver Oxide: Flat Voltage for Precision

SR44 silver oxide batteries maintain 1.55V ±0.05V throughout 90% of their discharge cycle, then drop rapidly at end-of-life. This flat discharge curve ensures consistent measurement accuracy from first use to last.

For medical devices requiring diagnostic precision—glucose meters, pulse oximeters, digital thermometers, blood pressure monitors—SR44 silver oxide provides voltage stability that alkaline simply cannot match.

The voltage difference between fresh alkaline (1.5V) and silver oxide (1.55V) is negligible for most medical circuits designed with 10% tolerance. However, if your device was originally designed for alkaline and you switch to silver oxide, verify that the 0.05V difference doesn’t affect voltage-sensitive components (some voltage regulators have narrow input ranges).

CR2032 Lithium: High Voltage Requires Conversion

CR2032 lithium delivers 3.0V nominal with excellent stability, but most medical devices designed for AG13/LR44/SR44 operate at 1.5V. Using CR2032 requires a voltage regulator or DC-DC converter to step down from 3.0V to 1.5V.

This adds complexity, cost, and power consumption (voltage regulators are not 100% efficient). However, the conversion provides a stable 1.5V output regardless of battery voltage decline, potentially improving accuracy over even silver oxide.

CR2032 makes sense when:

• Your device has higher power requirements (CR2032 capacity is 210-240mAh vs 150-200mAh for SR44)
• You need long shelf life (CR2032 self-discharge is 2-3% per year vs 2-5% per month for silver oxide)
• Your device is designed from scratch and can accommodate the voltage regulator

Capacity and Service Life: How Long Will Your Battery Last?

Capacity determines how long your battery lasts before replacement. For medical devices, this affects user experience and maintenance schedules.

Comparing Capacity Across Chemistries

Capacity varies by discharge rate and temperature, but here are typical values at low drain (0.1mA continuous, 20°C):

• AG13/LR44 alkaline: 110-150mAh
• SR44 silver oxide: 150-200mAh (30-50% higher than alkaline)
• CR2032 lithium: 210-240mAh (highest, but at 3.0V = 630-720mWh energy vs 225-300mWh for SR44)

CR2032′s energy advantage is even larger than the mAh comparison suggests, because energy (in mWh) = capacity (mAh) × voltage (V). At 3.0V, CR2032 delivers 2-3× the energy of SR44.

Self-Discharge: The Hidden Capacity Killer

For medical devices that sit unused between measurements (emergency equipment, backup devices, seasonal equipment), self-discharge matters more than rated capacity.

• AG13/LR44 alkaline: 2-5% capacity loss per month
• SR44 silver oxide: 2-5% capacity loss per month (similar to alkaline)
• CR2032 lithium: 2-3% capacity loss per year (10× better than alkaline/silver oxide)

If your medical device is stored for 6 months between uses, alkaline/silver oxide loses 12-30% capacity during storage. CR2032 lithium loses only 1-1.5%.

For a defibrillator stored in an emergency kit for a year, this difference is critical. You want to open the kit and have the device work reliably—not discover the battery is depleted.

Leakage Risk: The Medical Device Dealbreaker

Battery leakage is the #1 reliability concern for medical device batteries. Electrolyte leakage can corrode device circuitry, cause measurement errors, or—worst case—expose patients to harmful chemicals.

Why Alkaline AG13/LR44 Has the Highest Leakage Risk

Alkaline AG13/LR44 batteries use aqueous potassium hydroxide (KOH) electrolyte, which is corrosive to copper, aluminum, and other common electronics materials. If the battery seal fails, leaked KOH can:

• Corrode battery contacts and PCB traces
• Create conductive paths causing short circuits
• Degrade sensor accuracy (glucose test strip contacts, thermistor leads)
• Pose chemical exposure risk if the device contacts patient skin

Alkaline battery leakage is caused by:

• Internal pressure buildup from hydrogen gas generation during discharge
• Seal degradation from prolonged storage or high-temperature exposure
• Physical damage to the battery can (denting, puncture)
• Deep discharge below 0.8V, which accelerates seal degradation

According to IEEE research on battery leakage in medical devices, alkaline button cells show 2-5% leakage incidence after 2 years of storage at 25°C, increasing to 8-12% at 40°C. For medical devices with 5-year expected service life, this is unacceptable for critical applications.

SR44 Silver Oxide: Lower Leakage Risk

SR44 silver oxide batteries also use alkaline KOH electrolyte, but feature improved seal design and lower gas generation during discharge, reducing leakage probability. Silver oxide chemistry generates less hydrogen gas than alkaline manganese dioxide, resulting in lower internal pressure.

Premium SR44 cells from reputable manufacturers use triple-seal designs (mechanical crimp + gasket + epoxy) to prevent leakage even under temperature cycling and vibration. Leakage incidence for premium SR44 is typically <1% after 2 years at 25°C.

For medical devices where leakage would cause measurement errors but not patient safety risks (glucose meters, thermometers), SR44 provides acceptable leakage protection.

CR2032 Lithium: Hermetic Sealing for Maximum Protection

CR2032 lithium batteries use organic electrolyte (not aqueous KOH) and feature hermetic laser-welded metal can sealing, providing the lowest leakage risk of all three chemistries. The lithium manganese dioxide chemistry generates virtually no gas during normal discharge, eliminating internal pressure buildup.

CR2032 leakage incidence is <0.1% even after 5 years at 40°C. The organic electrolyte is also less corrosive than KOH, so even in the unlikely event of leakage, damage to device electronics is less severe.

For implantable medical devices, patient-contact devices, or applications where battery leakage could cause patient injury, CR2032 lithium provides the safest leakage profile.

Regulatory Compliance: Meeting Medical Device Standards

Medical device batteries must comply with safety, performance, and biocompatibility standards. Here’s how the three chemistries compare.

IEC 60086 Safety Standards

All three chemistries must comply with IEC 60086 (primary batteries standard) for safety testing:

• Short circuit resistance
• Forced discharge tolerance
• Leakage resistance
• Mechanical shock and vibration

Premium manufacturers test beyond IEC minimums for medical applications. For example, IEC requires 1 hour at 70°C for high-temperature testing, but medical-grade cells often undergo 1000 hours at 60°C to simulate long-term storage.

Biocompatibility for Patient-Contact Devices

If your medical device contacts patient skin (wearable monitors, skin-probe thermometers), battery materials must comply with ISO 10993-5 (cytotoxicity) and ISO 10993-10 (irritation) biocompatibility standards.

All three chemistries can meet biocompatibility requirements if the battery is enclosed and does not directly contact patient skin. However, if battery leakage could result in patient contact with electrolyte:

• Alkaline KOH (AG13/LR44, SR44) is a known skin irritant and requires risk mitigation
• Lithium organic electrolyte (CR2032) is less irritating but still requires evaluation

For implantable devices, battery materials must meet even stricter biocompatibility requirements (ISO 10993-6 for local tissue effects). Most implantable devices use custom lithium cells, not standard button cells.

FDA Documentation Requirements

FDA 510(k) submissions for battery-powered medical devices must include:

• Battery specifications and chemistry justification
• Battery life analysis (expected service life under typical use conditions)
• Leakage risk assessment and mitigation strategies
• Battery replacement instructions (if user-replaceable)
• Electrical safety testing with battery at end-of-life voltage

I recommend working with your battery supplier early in the design process to obtain test reports and compliance documentation. Reputable medical-grade battery manufacturers can provide IEC test reports, material declarations, and leakage risk data to support your FDA submission.

For questions about medical battery sourcing, our team at ZSCells can provide the technical documentation you need.

Head-to-Head Comparison: AG13/LR44 vs SR44 vs CR2032 for Medical Devices

How to Choose the Right Chemistry for Your Medical Device

Here’s a practical decision framework based on device type and requirements:

Choose AG13/LR44 Alkaline When:

• Your device is disposable or single-patient-use (e.g., disposable thermometers)
• Measurement accuracy requirements are low (±10% or worse)
• Battery replacement is frequent (monthly or more often)
• Device cost is the primary constraint and battery is a small fraction of total cost
• Leakage consequences are minor (device damage but no patient risk)

Choose SR44 Silver Oxide When:

• Your device requires high measurement accuracy (glucose meters, pulse oximeters, precision thermometers)
• Battery replacement is infrequent (6-24 months)
• Voltage stability is critical for sensor accuracy
• You need a direct drop-in replacement for AG13/LR44 (same dimensions)
• Leakage risk must be minimized but hermetic sealing is not required

Choose CR2032 Lithium When:

• Your device is used intermittently or stored for long periods (emergency equipment, backup devices)
• Leakage risk must be minimized to the lowest possible level
• Your device has higher power requirements or longer service life needs
• You can accommodate voltage regulation from 3.0V to 1.5V
• Patient safety requires the lowest possible leakage probability

Real-World Medical Device Applications

Glucose Meters: SR44 Wins on Accuracy

Blood glucose monitoring requires ±15% accuracy per ISO 15197. Alkaline voltage drift can introduce measurement errors as the battery discharges. SR44 silver oxide provides flat voltage for consistent readings throughout battery life.

Most major glucose meter brands (Accu-Chek, OneTouch, Contour) specify SR44 or equivalent silver oxide batteries for this reason.

Digital Thermometers: SR44 for Precision

Digital thermometers use thermistors or thermocouples that require stable reference voltage for accurate temperature measurement. SR44 silver oxide ensures consistent accuracy across the battery’s service life.

For clinical thermometers requiring ±0.1°C accuracy, SR44 is strongly recommended. Alkaline is acceptable only for low-precision consumer thermometers (±0.5°C or worse).

Pulse Oximeters: SR44 or CR2032

Pulse oximeters measure blood oxygen saturation (SpO2) using light absorption. The LED and photodetector circuits require stable voltage for accurate readings.

SR44 silver oxide provides voltage stability for accuracy. CR2032 lithium is chosen when longer battery life or lower leakage risk is needed (hospital equipment with infrequent battery changes).

Blood Pressure Monitors: CR2032 for Memory Backup

Digital blood pressure monitors often use CR2032 lithium cells for memory backup (storing measurement history) even if the main device uses AA or AAA batteries. CR2032′s low self-discharge ensures memory retention during long storage periods.

Emergency Medical Devices: CR2032 for Reliability

Defibrillators, emergency glucose meters, and rescue breathing monitors must work reliably after long storage periods. CR2032 lithium’s low self-discharge (2-3% per year) and hermetic sealing make it the safest choice for life-critical applications.

Expert Perspective: Trends in Medical Device Battery Selection

From my experience supplying batteries to medical device companies, I see three clear trends:

Silver oxide is becoming the default for diagnostic devices. As accuracy requirements tighten and regulatory scrutiny increases, more device manufacturers are switching from alkaline to silver oxide to eliminate voltage-related measurement errors.

Lithium is expanding beyond memory backup. As medical devices become more portable and wireless, the energy density and low self-discharge of CR2032 lithium are driving adoption even in applications that previously used alkaline or silver oxide.

Alkaline is being pushed to disposable applications only. For reusable medical devices, alkaline’s leakage risk and voltage instability are increasingly seen as unacceptable. Alkaline remains cost-effective only for truly disposable devices where the battery is discarded with the device.

For medical device designers, the question is no longer “which chemistry is cheapest?” but “which chemistry delivers the accuracy, reliability, and safety that your device and your patients require?”

Need medical-grade battery specifications or compliance documentation? Our engineering team at ZSCells button battery division can support your medical device design. For direct technical consultation, contact us.