When consulting with experienced riders about their Harley battery needs, one requirement consistently topped their list: reliability under vibration and cold starts. I’ve tested these units in rain, heat, and long hauls, and I’ll cut to what matters. You want clean starts, maintenance-free use, and a battery that won’t quit mid-ride.
From compact lithium options to robust AGM packs, the best Harley battery should feel like a ready-to-roll partner. After weighing fit, capacity, weight, and durability, I’ve found a clear standout that balances performance with value and plugs into Harley models with ease. After extensive testing, I found the TYKOOL LFP20L-BS-STD Lithium Battery, Replaces YTX20L-BS to be the standout choice.
Top Recommendation: TYKOOL LFP20L-BS-STD Lithium Battery, Replaces YTX20L-BS
Why We Recommend It: This option delivers superior cranking with 480CCA and a lightweight profile (about 3.3 lb), improving handling and cold starts. It’s a drop-in replacement for YTX20L-BS with a rugged, IP66-sealed case to resist water and debris, plus a built-in BMS for over-charge and short-circuit protection. Compared to AGM rivals, it reduces weight by a factor of ~4 and offers a longer cycle life with lower self-discharge, addressing both performance and longevity for Harley touring and fast-moving daily rides.
Best harley battery: Our Top 5 Picks
- Pirate Battery YTX20HL-BS 310 CCA Maintenance-Free 12V 19Ah – Best Harley Battery Replacement
- Energizer TX20HL AGM Bike/ATV 12V Battery 310CCA 18Ah Black – Best Harley Battery Brand
- Banshee YTX30L-BS AGM Battery for Harley Touring, 12V 30Ah – Best for Touring Harley
- TYKOOL LFP20L-BS-STD Lithium Battery, Replaces YTX20L-BS – Best Premium Option
- Lithium YTX20L-BS 12V 10Ah Motorcycle Battery (ATV/UTV) – Best for Lightweight/Less Maintenance
Pirate Battery YTX20HL-BS 310 CCA Maintenance-Free 12V 19Ah
- ✓ Solid, durable build
- ✓ Fully charged out of the box
- ✓ Spill-proof, seal-protected posts
- ✕ Slightly heavier than some peers
- ✕ Needs venting clearance on tight fits
| Battery Type | YTX20HL-BS AGM |
| Voltage | 12V |
| Capacity | 19Ah |
| Cold Cranking Amps (CCA) | 310 CCA |
| Maintenance | Maintenance-free |
| Technology | Absorbed Glass Mat (AGM) with sealed post construction |
You pop the Pirate Battery YTX20HL-BS onto the bench, and the first thing that hits you is the solid heft and the clean, matte case texture. It feels durable, with those sturdy Nut & Bolt terminals that bite a little when you twist in a wrench.
The AGM seal sits proudly, kind of like a small shield around the posts.
As you unbox it, you notice it ships fully charged, which is a relief after a late-night project. The battery has a compact, brick-like shape that fits snugly under Harley’s seat and most sports-bike hatches.
It’s compact enough to swap in without wrestling cables loose for hours.
Plug-in feels smooth when you connect it to the bike’s terminals, and the post design avoids any odd corrosion drama you’ve seen with other batteries. The absence of leaks is real—no curious puddle, no sour plug odor.
You’ll appreciate the spill-proof promise when you’re juggling a tight garage space.
In daily riding, it starts clean and quick, even after a few cold mornings. The low-maintenance profile means you won’t be chasing electrolyte tweaks or frequent top-ups.
It’s ready to go right out of the box, which is exactly what you want when you’re rushing to beat dawn and roll out with the crew.
For longer rides or weekend adventures, the performance feels steady, with consistent cranking power. The anti-corrosion post design matters when you’re swapping batteries in dusty, gravel roads.
Overall, you get reliable starts, minimal upkeep, and a straightforward install that doesn’t demand a degree in battery science.
If you’re upgrading a Harley or another sport bike, this one checks the essential boxes: dependable starts, sealed post protection, and spill-proof design. It’s a practical, all-terrain battery that won’t complicate your day when you’re chasing miles instead of maintenance.
Energizer TX20HL AGM Bike/ATV 12V Battery 310CCA 18Ah Black
- ✓ Maintenance-free design
- ✓ Strong cold-start power
- ✓ Easy to install
- ✕ Heavier than some competitors
- ✕ Higher upfront price relative to basic batteries
| Battery Chemistry | Absorbent Glass Mat (AGM) |
| Battery Type | 12V maintenance-free motorcycle/ATV battery |
| Cold Cranking Amps (CCA) | 310 CCA |
| Capacity (Ah) | 18 Ah |
| Dimensions (L x W x H) | 175 mm (6-7/8 in) x 87 mm (3-7/16 in) x 155 mm (6-1/8 in) |
| Weight | 6.2 kg (13.67 lbs) |
You pull this Energizer TX20HL out of the box and immediately notice the heft—just under 14 pounds of solid, solid battery. The glossy black case feels sturdy, with clean edges and a factory-sealed finish that screams maintenance-free reliability.
It sits there cool and ready, not a leak or a drop of juice in sight.
First tilt of the battery, you appreciate the dimensions—6-7/8 inches long, 3-7/16 inches wide, and 6-1/8 inches tall. It fits snugly in the Harley and other big-bore bikes I’ve got, with a non-spill AGM design that doesn’t waver when you move it around the shed.
It looks purpose-built, like it’s seen a few cold starts and still kept its cool.
Hooking it up was straightforward. The terminals are solid, not sharp, and the connector leads felt firm without any wobble.
The description says “performance ready out of the box,” and you can feel that when you crank: fast ignition, steady cold-start torque, and no hesitation at all on the first week of rides.
In daily riding, you notice the smooth voltage delivery even after long highway stints. It’s whisper-quiet during starting, which is a nice contrast to some bulkier batteries that creak under load.
AGM tech means you can drain and recharge without worrying about foul smells or spills—hands stay clean, workshop stays calm.
Real-world use matters: it fits older Harleys and newer models alike, with a weight you’ll notice during installation but not in operation. It’s reliable on chilly mornings, and your bike starts cleanly after evenings parked in damp garages.
If you’re chasing that dependable start every time, this TX20HL does the job without drama.
Bottom line? It’s a solid, maintenance-free choice that blends strength with practical size and easy fit.
You’ll appreciate the peace of mind that comes with a sealed, AGM battery that’s ready to go right out of the box.
Banshee YTX30L-BS AGM Battery for Harley Touring, 12V 30Ah
- ✓ Solid, dense build
- ✓ Maintenance-free
- ✓ Strong cold starts
- ✕ Heavier than some
- ✕ Limited OEM-fit list
| Battery Type | Maintenance-free, sealed AGM |
| Voltage | 12 V |
| Capacity | 30 Ah |
| CCA (Cold Cranking Amps) | 500 CCA |
| Dimensions (L x W x H) | 6.54 x 4.96 x 6.89 inches |
| Weight | 22 lb |
You pop the Banshee YTX30L-BS into your ride and immediately notice the solid heft in your hands—about 22 pounds of dense, maintenance-free promise. The sealed AGM design feels clean and modern, with flush heavy-duty terminals that sit snug in their posts, no messy acid smell in sight.
The battery sits compact for a 30Ah unit, measuring 6.54 by 4.96 by 6.89 inches, and it slides into the Harley touring battery tray with just a touch of wobble before the terminals line up perfectly. The black case has a no-nonsense, rugged look that matches a lot of aftermarket chrome and matte plastics alike.
In use, you’ll like the low-maintenance nature—no topping off, no corroded caps, just a clean, sealed unit that doesn’t mind the vibrations of highway miles. The 500 CCA rating gives you reliable cold starts, even when the bike sits for a while or in cooler mornings.
Installation is straightforward: you’ll swap in the included terminal bolts and snug the terminals until they click, then fire up the bike and hear that reassuring turn of the motor. It’s especially reassuring on longer rides when you don’t want to worry about battery health after parking in the sun or a garage with a stray charger plugged in.
Real-world use shows the versatility of this battery beyond Harleys—ATVs and jet skis could also benefit from the same maintenance-free setup, which keeps you from worrying about electrolyte levels. If you’re upgrading from an older lead-acid, you’ll notice crisper starts and less voltage sag on throttle bursts.
Overall, you get a robust, reliable 12V battery that keeps vibrations at bay and starts on demand. It’s a practical upgrade for touring riders who value reliability and ease of maintenance.
TYKOOL LFP20L-BS-STD Lithium Battery, Replaces YTX20L-BS
- ✓ Lightweight and compact
- ✓ Strong cold-crank power
- ✓ IP66 ruggedness
- ✕ Needs LiFePO4 charger
- ✕ Higher upfront cost
| Battery Type | Lithium Iron Phosphate (LiFePO4) |
| Cranking Power (CCA) | 480 CCA |
| Weight | 3.3 lbs (1.50 kg) |
| Dimensions (L x W x H) | 6.89 x 3.43 x 6.10 in (175 x 87 x 155 mm) |
| Replacement/Compatibility | Direct drop-in replacement for YTX20L-BS and models 65989-97C, GYZ20HL, GYZ20L, ETX20L |
| Battery Management System (BMS) Features | Onboard digital readout LCD, cell balancing, over-charge and deep-discharge protection, 2500+ cycle life |
You’re at a sun-warmed curb, cranking the engine of your Harley just after a winter layup, and the TYKOOL LFP20L-BS-STD sits snugly in the battery tray like a compact, ready-for-action spark. The moment the starter taps, you notice a crisp, confident turn as the 480 CCA delivers a quick, clean swing of the big V-Twin.
It’s noticeably lighter in your hands than the old lead-acid block, almost like swapping a dumbbell for a focused kettlebell in the same weight class.
Placing the drop-in unit is straightforward, and the terminals feel solid with vibration-isolated mounts. The rugged casing handles road heat and dampens the bite of the engine’s thump, even as you roll through a rough stretch of highway.
The digital readout on the BMS lights up with a calm blue glow, showing SOC at a glance without fiddling with gauges.
You’ll value the ultra-low self-discharge during winter storage, so come spring you’re not staring at a dead bike. The IP66 sealing keeps rain and grit from gnawing at the electronics, which is a relief after months of soggy rides.
It’s designed for Harleys—Softail, Fat Boy, V-Rod, and the rest—so you don’t have to wonder if you bought the right size or fit.
In daily use, the bike fires with ease in any weather, and you’ll notice the center of gravity feels lighter on corners, helping with flickability. The BMS balances cells and guards against over-charge, giving you peace of mind as you rack up miles.
If you’re swapping from a heavy AGM, you’ll appreciate the long-term durability and the reliable voltage stability on those long highway treks. It’s a thoughtful upgrade that respects the bike’s power needs and your riding routine.
Lithium YTX20L-BS 12V 10Ah Motorcycle Battery (ATV/UTV)
- ✓ Lighter than lead-acid
- ✓ Quick starts even in cold
- ✓ Ready to install out of the box
- ✕ Requires correct fitment check
- ✕ Slightly higher upfront cost
| Battery Type | Lithium LiFePO4 (LifePO4) motorcycle battery |
| Voltage | 12.8V |
| Capacity | 10Ah |
| Cold Cranking Amps (CCA) | 700 CCA |
| Weight | 3.7 pounds (1.68 kg) |
| Dimensions | L 6.89 in × W 3.43 in × H 6.1 in |
You pull your Harley out of the garage and notice that the old battery’s been a stubborn starter in the cold mornings. The moment you swap in the Forgetyo YTX20L-BS, the bike fires up with a confident growl, not a whimper.
It’s lighter, and you can feel the balance shift as you lift it into place—no sweaty wrestle required.
Measuring 6.89 by 3.43 by 6.1 inches, it drops into the battery tray like it was designed for your model. The left negative and right positive terminals sit exactly where you expect them, making the install feel almost plug-and-play.
It’s fully charged out of the box, so you’re not chasing a charger before your next ride.
During a chilly morning commute, the 700 CCA kicks in hard, giving you instant torque on that first crank. The built-in BMS protects against overcharge and short circuits, which gives you peace of mind when you’re riding in variable weather.
You’ll appreciate the steady, predictable starts even after long park sessions.
The weight drop is noticeable too—about a third lighter than a traditional lead-acid battery—which makes maneuvering the bike during maintenance a breeze. It also charges efficiently on a 2A to 5A charger, so quick top-offs on the road aren’t out of the question.
If you’ve got a charger handy, you’ll be back on the throttle in no time.
In everyday use, it’s compatible with a wide range of Harley and other 12V setups, which means you won’t be stuck hunting for a replacement niche battery. It’s a solid, no-fuss upgrade that just works when you need it to.
If you’re tired of heavy, finicky batteries that refuse to crank, this is the one you’ll want to try.
What Factors Should You Consider When Choosing the Best Harley Battery?
When choosing the best Harley battery, several factors should be taken into account to ensure optimal performance and longevity.
- Battery Type: It’s essential to consider the type of battery that suits your Harley. Common types include lead-acid, AGM (Absorbent Glass Mat), and lithium-ion batteries. AGM batteries are popular for their maintenance-free operation and resistance to vibration, while lithium-ion batteries offer lightweight performance and faster charging times.
- Cold Cranking Amps (CCA): This measurement indicates the battery’s ability to start an engine in cold temperatures. A higher CCA rating is crucial for Harley motorcycles, especially in colder climates, as it ensures reliable starts without straining the electrical system.
- Size and Fit: The physical dimensions of the battery must match the specifications of your Harley model. An improperly sized battery can lead to installation issues and may not provide the necessary power. Always check the owner’s manual for the correct battery size.
- Brand Reputation: Choosing a battery from a reputable brand can significantly impact reliability and performance. Brands like Harley Davidson, Yuasa, and Odyssey have established trust within the motorcycle community for producing high-quality batteries that meet the demands of riders.
- Warranty: A good warranty can provide peace of mind and protection against manufacturing defects. Look for batteries that offer at least a one-year warranty, as this indicates the manufacturer’s confidence in their product’s durability.
- Maintenance Requirements: Some batteries require regular maintenance, such as checking fluid levels and cleaning terminals, while others are sealed and maintenance-free. If you prefer a hassle-free experience, an AGM or lithium-ion battery may be the best choice for you.
- Price: While it can be tempting to opt for the cheapest option, it’s important to balance cost with quality. Investing in a reliable battery can save you money in the long run by reducing the frequency of replacements and avoiding unexpected failures on the road.
How Do Cold Cranking Amps (CCA) Impact Battery Performance in Harley Davidson?
Cold Cranking Amps (CCA) are a critical factor in determining battery performance, especially for motorcycles like Harley Davidson.
- Definition of CCA: Cold Cranking Amps refers to the amount of current a battery can provide at 0°F (-18°C) for 30 seconds while maintaining a voltage of at least 7.2 volts.
- Importance in Start-Up: CCA is crucial for starting the engine, particularly in colder environments where the oil is thicker and requires more power to crank the engine.
- Battery Size and Compatibility: The CCA rating must match or exceed the specifications recommended for Harley Davidson models to ensure reliable performance.
- Lifespan and Durability: Batteries with higher CCA ratings tend to have better durability and longevity, as they can handle the demands of high-performance engines.
- Impact on Electrical Systems: A battery with an adequate CCA rating ensures that all electrical components, including lights and electronics, function optimally during start-up and while running.
- Selection of the Best Harley Battery: When selecting the best Harley battery, considering the CCA rating is essential, as it directly correlates with the battery’s ability to perform in various weather conditions.
The definition of CCA is foundational to understanding battery performance; it quantifies the cranking power available in cold conditions, ensuring that the motorcycle starts reliably in adverse weather. For Harley Davidson motorcycles, which often feature larger engines, a higher CCA rating is beneficial as it guarantees enough power to crank the engine smoothly, even in freezing temperatures.
The importance of CCA during start-up cannot be overstated, especially for motorcycles that may sit idle for extended periods. When temperatures drop, oil thickens, making it more challenging for the engine to turn over; thus, a battery with a higher CCA provides the necessary boost to initiate the ignition process effectively.
Compatibility with battery size is also a vital consideration; Harley Davidson models have specific CCA requirements, and choosing a battery that meets or exceeds these recommendations is crucial for optimal performance and engine reliability.
Batteries with higher CCA ratings are often more robust and durable, capable of withstanding the rigors of high-performance demands. This durability translates into a longer lifespan, which is especially valuable for riders who rely on their motorcycles for both leisure and transportation.
The impact of CCA on electrical systems is significant, as a battery with sufficient cranking power ensures that all associated electrical components function correctly during start-up and while the motorcycle is in operation. This includes everything from lights to advanced electronic systems that enhance the riding experience.
Finally, when selecting the best Harley battery, it’s essential to prioritize the CCA rating alongside other specifications. A battery that meets the necessary CCA requirements will provide peace of mind, knowing that the motorcycle will start reliably under various conditions, enabling a better riding experience.
What Are the Differences Between AGM and Lithium Batteries for Harley Davidson?
| Aspect | AGM Battery | Lithium Battery |
|---|---|---|
| Cost | Generally cheaper, ranging from $100 to $200. | More expensive, typically $300 to $600. |
| Weight | Heavier, adds more weight to the bike. | Lightweight, significantly reduces overall bike weight. |
| Lifespan | Lasts about 3-5 years with proper care. | Can last up to 10 years or more with optimal conditions. |
| Maintenance | Requires regular checks and maintenance. | Low maintenance; often maintenance-free. |
| Charging time | Typically takes 4-6 hours to fully charge. | Can charge in 1-2 hours depending on the charger. |
| Self-discharge rate | Self-discharge rate is about 3-5% per month. | Very low self-discharge rate, around 1-2% per month. |
| Temperature performance | Performs well in a wide temperature range, but may lose capacity in extreme cold. | Performs well in cold weather, but can be affected by extreme heat. |
| Environmental impact | Less environmentally friendly; contains lead and acid. | More environmentally friendly but requires careful recycling. |
| Compatibility with Harley Davidson models | Compatible with most Harley models; check specifications. | Compatible with many models, but may require specific adapters. |
What Are the Top Recommendations for Harley Davidson Batteries?
The top recommendations for Harley Davidson batteries are:
- Yuasa YTX20HL-BS: This is a popular choice for its high-performance capabilities and reliability.
- Antigravity AG-1201: Known for its lightweight design and advanced lithium technology, this battery offers impressive power and longevity.
- Deka ETX20L: Renowned for its durability and maintenance-free design, it provides consistent performance even in harsh conditions.
- Shorai LFX14A4-BS12: A lithium iron phosphate option, this battery boasts fast charging and long life, making it an excellent upgrade.
- Odyssey PC680: This battery is celebrated for its deep cycle capabilities and robust construction, ensuring a long lifespan and strong cranking power.
The Yuasa YTX20HL-BS is a sealed lead-acid battery that delivers high power, making it suitable for various Harley models. Its maintenance-free design means riders can enjoy peace of mind without the hassle of regular upkeep, and its reliable performance under different weather conditions makes it a top choice.
The Antigravity AG-1201 is a lightweight lithium battery that provides a significant weight reduction compared to traditional lead-acid batteries. It offers a high cranking amperage, ensuring quick starts, and its compact size allows for flexible installation options, which is particularly beneficial for customizing Harley bikes.
The Deka ETX20L is designed for optimal performance and longevity, featuring a completely sealed and maintenance-free design. Its robust build quality ensures that it can withstand vibrations and harsh environments, making it ideal for riders who frequently take their Harleys on challenging rides.
The Shorai LFX14A4-BS12 leverages lithium iron phosphate technology, which results in a much lighter battery that also charges faster than traditional options. This battery not only offers impressive weight savings but also has a longer cycle life, making it a smart investment for performance-oriented riders.
The Odyssey PC680 stands out for its deep cycle capabilities, allowing it to provide reliable starting power and sustained performance even after multiple discharges. Its rugged construction ensures it can handle the demands of high-performance bikes, and its ability to hold a charge for extended periods makes it a favorite among serious Harley enthusiasts.
How Do Batteries Differ Between Harley Davidson Sportster, Softail, Touring, and Trike Models?
The batteries in Harley Davidson motorcycles vary significantly across models like the Sportster, Softail, Touring, and Trike, each designed to meet specific power needs and performance characteristics.
- Sportster Batteries: Sportster models typically use smaller, lighter batteries, often in the range of 12V and 20Ah. These batteries are designed for quick starts and to support the lightweight frame, providing sufficient power for the smaller engine and electrical systems.
- Softail Batteries: Softail models feature larger batteries, usually around 12V and 24Ah, designed to accommodate more robust electrical systems and accessories. The increased capacity ensures reliable starting power and supports additional features like advanced lighting and infotainment systems.
- Touring Batteries: Touring models require high-capacity batteries, often around 12V and 28Ah or higher, to support the extensive electronic features and comfort options. These batteries are built for longevity and consistent performance under heavy loads, making them ideal for long-distance riding.
- Trike Batteries: Trike models also utilize high-capacity batteries similar to those in Touring bikes, generally around 12V and 28Ah. The unique design and additional weight of Trikes demand batteries that can deliver strong starting power and handle the electrical demands of multiple systems, ensuring reliability on the road.
What Maintenance Tips Can Maximize the Lifespan of Your Harley Battery?
To maximize the lifespan of your Harley battery, consider the following maintenance tips:
- Regular Charging: Keeping your battery charged is crucial, especially if your motorcycle is not in regular use.
- Clean Terminals: Regularly inspect and clean the battery terminals to prevent corrosion that can lead to poor performance.
- Check Fluid Levels: For lead-acid batteries, ensure that the electrolyte levels are adequate to prevent damage and maintain optimal performance.
- Store Properly: If storing your Harley for an extended period, remove the battery and store it in a cool, dry place while keeping it charged.
- Avoid Deep Discharges: Try to avoid letting your battery discharge completely, as this can significantly shorten its lifespan.
Regular charging helps ensure that your battery maintains a full charge, which is essential for starting your motorcycle and powering its electrical systems. If you do not ride often, consider using a battery maintainer or trickle charger to keep it at the optimal charge level.
Corrosion can build up on battery terminals, leading to poor electrical connections and reduced battery efficiency. Cleaning the terminals with a mixture of baking soda and water can help maintain a good connection and prolong battery life.
For lead-acid batteries, it’s important to periodically check the fluid levels in the cells, as low levels can cause the battery to overheat and sustain permanent damage. Top off with distilled water as necessary, but be careful not to overfill.
Proper storage is key to battery longevity. When not in use for a long time, remove the battery from the motorcycle, and store it in a location that avoids extreme temperatures, which can negatively impact its performance and lifespan.
Deep discharges can severely damage a battery, leading to sulfation and reduced capacity. To prevent this, make it a practice to recharge your battery before it drops below 50% capacity to ensure it remains healthy and functional.
What Common Signs Indicate That Your Harley Battery is Failing?
Common signs that indicate your Harley battery is failing include:
- Slow Engine Crank: When you turn the key, the engine takes longer than usual to crank or may not start at all, indicating that the battery is losing its ability to hold a charge.
- Dim Lights: If the headlights or dashboard lights appear dimmer than normal while the engine is off or while riding, it may suggest that the battery is not providing sufficient power.
- Corrosion on Terminals: Visible corrosion or buildup on the battery terminals can hinder the connection and indicate that the battery is reaching the end of its lifespan.
- Frequent Jump Starts: If you find yourself needing to jump-start your Harley frequently, it’s a clear sign that the battery may be failing and unable to retain a charge.
- Swollen Battery Case: A swollen or misshapen battery case can occur due to overcharging or internal damage, signaling that the battery needs to be replaced.
- Old Age: Most Harley batteries have a lifespan of 3 to 5 years; if your battery is older than that, it’s wise to monitor for signs of failure as it may be nearing the end of its useful life.
Each of these signs can help you identify potential battery issues before they lead to a breakdown on the road, allowing you to replace your battery with one of the best Harley batteries available.
How Long Can You Expect a Quality Harley Davidson Battery to Last?
The lifespan of a quality Harley Davidson battery can vary based on several factors, including type, usage, and maintenance.
- Lead-Acid Batteries: Typically, these batteries last between 3 to 5 years. They are the traditional type used in many Harley models and can be affected by factors such as temperature extremes and maintenance practices like keeping them charged.
- AGM (Absorbent Glass Mat) Batteries: These usually have a longer lifespan, ranging from 4 to 7 years. They are sealed and maintenance-free, providing better resistance to vibration and deep cycling, which makes them suitable for demanding riding conditions.
- Lithium-Ion Batteries: Known for their lightweight and high performance, these batteries can last anywhere from 5 to 10 years. They charge faster and have a higher energy density, but may require a specific charging system to ensure longevity.
- Battery Maintenance: Regular maintenance can significantly extend battery life. This includes keeping terminals clean, ensuring proper charging levels, and using a battery tender during long periods of inactivity.
- Environmental Factors: Extreme temperatures, both hot and cold, can adversely affect battery life. Storing the bike in a controlled environment and avoiding long exposure to extreme weather can help maximize the longevity of the battery.