Subaru owners ask two questions over and over: “What battery size do I actually need?” and “Can I upgrade to AGM?” The right answer depends on your specific Subaru model (Outback vs. WRX vs. Ascent), if you have start-stop/Auto Start-Stop, local climate, and how many electronics you run with the engine off (heated seats, stereo, light bars, etc.). This full guide breaks down battery types, fitment groups, cold-weather specs, pricing, what not to cheap out on, and how to install and maintain your next battery without frying your Subaru’s electronics. When you’re ready to compare real products, here are live search shortcuts for common Subaru sizes:
Group 35 AGM (Forester / Outback / Crosstrek), Group 24F AGM (Ascent / larger SUVs), and Group 25 AGM (WRX / turbo builds). Those links open searches filtered to the correct BCI group number so you’re not guessing at fitment.
Table of Contents
- Quick Picks for Subaru Owners (By Use Case)
- Top Battery Types for Subarus (What to Choose & Why)
- Subaru Model-Specific Buying Tips
- Subaru Battery Fitment Cheat Sheet (Most-Common Sizes)
- Spec Targets: CCA, RC, and Warranty
- Best Car Battery Brands for Subaru & Where-to-Buy
- Subaru Car Battery Installation Guide (DIY or Shop)
- Subaru Car Battery Maintenance & Longevity
- Signs You Need a New Battery
- Contact Subaru Customer Service & Support
Quick Picks for Subaru Owners (By Use Case)
- Daily driver (Impreza / Crosstrek / Outback), no start-stop: A quality Flooded/Lead-Acid or EFB with solid Reserve Capacity (RC). You’re usually in Group 35. Browse current Group 35 batteries. Typical street price: ~$120–$200 Flooded, $160–$250 EFB
- Subaru with Auto Start-Stop (newer Forester / Outback / Ascent): Subaru uses EFB or AGM from the factory because the battery gets hammered by constant restarts. Do not downgrade to a basic flooded battery or you’ll kill it early and may trigger warning lights. For many trims that means AGM Group 35 or AGM Group 24F. See Group 35 AGM and Group 24F AGM. ~$180–$350
- Electronics-heavy / short-trip city driving (heater seats, Apple CarPlay, dash cam always on): AGM is the smart upgrade. AGM handles frequent partial charging better and resists vibration (nice for gravel, roof racks, light off-road). Check AGM best sellers. ~$200–$350
- Cold climate / snow state: You want higher CCA (Cold Cranking Amps) for winter starts. AGMs often deliver higher CCA in the same footprint. Look at high-CCA listings for Group 35 AGM: High-CCA Group 35 AGM.
- Hot climate / desert / long idling with A/C: Heat cooks batteries. Step up from budget flooded to EFB or AGM with strong RC so lights, blower fan, and A/C clutch cycling don’t drain you while parked. Compare EFB batteries.
- WRX / WRX STI / tuned turbo builds: These often run Group 25 or Group 35 depending on year and aftermarket intercooler piping. Many owners upgrade to AGM Group 25 for vibration resistance. See Group 25 AGM. ~$190–$300
- Subaru Ascent / 3-row family hauler: Heavy electrical load (3-zone climate, rear charging ports). Go AGM in Group 24F. Browse 24F AGM options. ~$200–$330
Weize Platinum AGM Battery BCI Group 35 Automotive Battery, 100RC, 650CCA, 36 Months Warranty, Dimensions 9.06" L x 6.89" W x 8.82" H
Weize Platinum AGM Battery BCI Group 47-12v 60ah H5 Size 47 Automotive Battery, 100RC, 680CCA, 36 Months Warranty, Dimensions 9.52" L x 6.89" W x 7.48" H
Weize Platinum AGM Battery BCI Group 48-12v 70ah H6 Size 48 Automotive Battery, 120RC, 760CCA, 36 Months Warranty, Dimensions 10.94" L x 6.89" W x 7.48" H
Top Battery Types for Subarus (What to Choose & Why)
| Type | What It Is | When It’s OK | Why Upgrade? | Typical Subaru Price |
|---|---|---|---|---|
| Flooded / Lead-Acid | Traditional liquid-electrolyte battery. Cheapest upfront. | Older Subarus without Auto Start-Stop and with lighter accessory loads. | It’s fine if you do long highway drives that keep it fully charged, and you don’t blast accessories with engine off. | ~$120–$180 for Group 35 shop Group 35 flooded |
| EFB (Enhanced Flooded Battery) | Stronger plates + improved cycle life vs basic flooded. Often OEM in start-stop cars. | Newer Crosstrek / Outback / Forester with Auto Start-Stop where Subaru originally spec’d EFB. | Handles repeated engine restarts better than standard flooded, delays voltage dip that triggers warning lights. | ~$160–$250 for Subaru-sized groups compare EFB |
| AGM (Absorbent Glass Mat) | Electrolyte is absorbed in glass mat. Sealed, spill-resistant, vibration-resistant, fast recharge. | Auto Start-Stop, cold climates, short-trip city driving, or high electrical load (heated seats, rear defrost, cameras, sound system). | Higher CCA in the same footprint. Better deep-cycle behavior so it won’t die early from accessories on while parked. | ~$200–$350 for Group 35 / 24F / 25 browse AGM |
Subaru Model-Specific Buying Tips
- Outback / Forester / Crosstrek (most 2014+): You’re usually in Group 35. Many trims with Auto Start-Stop expect EFB or AGM. Budget: ~$180–$260 for EFB, ~$220–$320 for AGM. Check Group 35 AGM.
- Impreza: Base/non-start-stop Impreza can still run a standard flooded Group 35, but upgrading to AGM gives you better winter starts and longer life if you do short trips. Expect ~$150–$250 depending on chemistry.
- WRX / WRX STI: Higher vibration and often more electrical draw from gauges, fuel pumps, fans, etc. Go AGM in Group 25 or Group 35 (depends on year and intercooler piping/aftermarket mounts). ~$200–$300. Try Group 25 AGM.
- Ascent (3-row SUV): Heavier electrical load (rear-seat climate, USB everywhere) and frequent around-town trips. Most owners should stick with a strong AGM Group 24F. ~$220–$330. Browse Group 24F AGM.
- Legacy: Similar to Outback for equivalent years. Many late-model Legacy trims use Group 35 with Start-Stop, so AGM/EFB is recommended. ~$200–$300.
- Older NA (non-turbo) Subarus (pre-2010-ish): These cars typically don’t have start-stop, so a good-quality flooded battery can still be cost-effective. Still, if you live where winters are brutal, AGM = easier cold starts and fewer “click-click-no-start” mornings. ~$140–$220.
Subaru Battery Fitment Cheat Sheet (Most-Common Sizes)
| Subaru Model (Typical Years) | Common BCI / JIS Group | Factory Tech | Recommended Upgrade |
|---|---|---|---|
| Outback (2015–present) | Group 35 | Flooded or EFB (Start-Stop trims) | AGM Group 35 for stronger CCA and better cycle life see options |
| Forester (2014–present) | Group 35 | EFB/AGM on Start-Stop models | Stay AGM if you have Auto Start-Stop |
| Crosstrek (2018–present incl. Hybrid) | Group 35 | EFB on many trims w/ Start-Stop | AGM Group 35 for city/short-trip use |
| Impreza (2017–present) | Group 35 | Flooded (base) / EFB (Start-Stop) | AGM Group 35 if you do winter starts or lots of accessories |
| Legacy (2015–present) | Group 35 | Often EFB with Start-Stop | AGM Group 35 for best reliability |
| WRX / WRX STI (varies by gen) | Group 25 or Group 35 | Flooded from factory on many years | AGM Group 25 or 35, higher vibration resistance shop Group 25 AGM |
| Ascent (2019–present) | Group 24F | AGM / EFB due to Start-Stop and heavy load | Premium AGM Group 24F check Group 24F AGM |
Spec Targets: CCA, RC, and Warranty
CCA: Cold Cranking Amps
RC: Reserve Capacity
Tech: Flooded / EFB / AGM
- CCA (Cold Cranking Amps): Match or exceed Subaru’s spec. If you live where winters dip below freezing, aim for +50–100 CCA above stock. Easier cold starts, less strain on starter motor.
- RC (Reserve Capacity): RC tells you how long the battery can power essentials (lights, blower, infotainment) with the engine off. Higher RC is great if you camp in your Subaru, sit in ski-lodge parking with heated seats on, or wait in school pickup lines with hazards flashing.
- Battery Technology: If your Subaru shipped with EFB or AGM, do not downgrade. Start-Stop systems expect stronger cycling performance. Downgrading often means early failure, dim lights at idle, and potential warning messages.
- Warranty: Look for at least a 36-month free replacement window. Longer warranties usually come with better internal build quality (thicker plates, better separators).
- Terminal orientation / height: Subaru engine bays can be tight, especially on turbo cars with aftermarket intercoolers. Make sure the positive post lands on the correct side (often “R” versions in some group sizes mean reversed layout).
Best Car Battery Brands for Subaru & Where-to-Buy
| Brand / Line | Why Subaru Owners Like It | Good For | Where to Look |
|---|---|---|---|
| OEM Subaru / Panasonic / Yuasa (varies by region) | Matched to Subaru’s charging profile and Start-Stop demands. | Keeping the car 100% stock, less guesswork. | Subaru dealer parts counter, dealership service |
| AGM “Premium” lines from major retailers | Usually high CCA, solid RC, and 3+ yr free replacement warranties. | Cold climates, lots of accessories, short trips. | AGM high-CCA search |
| EFB lines | Cheaper than AGM but tougher than basic flooded. Great for Start-Stop if you’re cost-sensitive. | Newer Outback / Forester / Crosstrek with Auto Start-Stop. | Compare EFB |
| Performance AGM / deep-cycle style | Extra vibration resistance. Popular with WRX/STI owners and overlanders running lights, fridge, radios. | Rally/gravel roads, roof racks with light bars, dash cams that record while parked. | Group 25 AGM |
- Dealership / OEM: Easiest fitment match, but often not cheapest.
- Big-box / Auto parts chains: Fast warranty swaps, sometimes free install/testing.
- Online (Amazon, etc.): You can compare CCA, RC, and warranty across multiple brands in the same group size side by side. Example: Group 24F AGM for Ascent.
How to Check Freshness & Authenticity
- Date code: Batteries have a build date stamped/printed. Fresher is better. Try to buy something manufactured within the last 3–6 months, not something that sat discharged on a shelf for a year.
- Case condition: No bulges, cracks, leaks, or white corrosion crust around posts.
- Seals / caps: AGM and many EFBs are sealed. Avoid anything that looks opened, refilled, or tampered with.
- Labeling: Make sure the label actually matches the group size you ordered (35 vs 24F vs 25). A wrong-height battery can smash into your hood insulation.
Car Battery Warranty Tips
- Free replacement period matters more than “pro-rated”: A true 36-month free replacement is strong. A 12-month free + long prorate is weaker.
- Keep your receipt (paper or digital). You’ll need proof of purchase for warranty swap.
- Some retailers test/print voltage and CCA at install. Save that slip — it proves baseline health if you claim early failure.
- Abuse (like using a starting battery as a camping deep-cycle for hours every weekend) can void warranties. Be honest about use and choose AGM if you idle with accessories a lot.
Weize Platinum AGM Battery BCI Group 48-12v 70ah H6 Size 48 Automotive Battery, 120RC, 760CCA, 36 Months Warranty, Dimensions 10.94" L x 6.89" W x 7.48" H
Weize Platinum AGM Battery BCI Group 47-12v 60ah H5 Size 47 Automotive Battery, 100RC, 680CCA, 36 Months Warranty, Dimensions 9.52" L x 6.89" W x 7.48" H
Weize Platinum AGM Battery BCI Group 49-12v 95ah H8 Size 49 Automotive Battery, 160RC, 900CCA, 36 Months Warranty, Dimensions 13.9" L x 6.89" W x 7.48" H
Subaru Car Battery Installation Guide (DIY or Shop)
- Prep the car: Engine off, key out, headlights off, dome lights off. On newer Subarus with a ton of modules, leave doors closed so you don’t keep waking up control units.
- Save radio presets / memory (optional): If you’re worried about losing settings, you can use a 12V memory saver through the OBD-II port or cigarette lighter. If you don’t, it’s not the end of the world — you might just have to re-set auto-up windows or radio favorites.
- Locate the battery hold-down: Subaru usually uses a top clamp with two small vertical J-bolts. Spray penetrating lube if they’re rusty.
- Disconnect negative (–) first: Loosen the negative terminal and remove it. Tuck it safely so it can’t snap back onto the post. Then remove the positive (+).
- Remove the old battery: Lift straight up. They’re heavy (35–50+ lb depending on group/AGM). Keep it upright.
- Clean terminals and tray: Use a battery terminal brush or light sandpaper to clean corrosion. Wipe dirt out of the tray so the new battery sits flat.
- Drop in the new battery: Make sure the positive and negative posts line up exactly like the old one. Wrong orientation = cables don’t reach or you’ll stretch them across hot components. Reinstall the hold-down snugly — not gorilla tight, just no wobble.
- Reconnect positive (+) first, then negative (–): Tighten until the terminals don’t twist by hand. Loose terminals cause intermittent “Christmas tree dash lights” and weird sensor codes in Subarus.
- Start the car and check voltage: Confirm quick, strong crank. Watch for warning lights. Some newer Start-Stop Subarus may briefly “relearn” idle RPM and auto start-stop timing — that’s normal.
- Recycle the old battery: Don’t trash it. Parts stores and recycling centers take cores, and some pay a small credit.
Subaru Car Battery Maintenance & Longevity
- Drive long enough to recharge: Constant 5-minute errands starve the battery. Mix in 20+ minute drives so the alternator can top it off.
- Keep terminals tight and clean: Subaru ECUs hate low voltage. Loose/corroded posts can trigger AWD, EyeSight, or “battery weak” alerts.
- Use a smart maintainer if you park for weeks: A low-amp intelligent charger keeps AGM/EFB healthy, especially in winter or if you work from home and barely drive. Search AGM smart maintainer.
- Avoid deep discharges: Sitting in accessory mode blasting the stereo with engine off can pull voltage down fast. Repeated deep drains kill even good AGMs.
- Watch alternator health: Weak charging systems cook batteries by undercharging or overcharging. If your lights flicker at idle, test both battery and alternator.
Signs You Need a New Battery
- Slow crank: Engine turns over lazier than normal, especially first start of the morning.
- Dash lights flicker / multiple warnings at once: Subaru ECUs throw random system warnings when system voltage dips.
- Start-Stop disabled more often than usual: If your Auto Start-Stop suddenly “won’t engage” and you haven’t changed driving style or climate, the battery may be weak.
- Visible corrosion / swelling: Battery case looks bloated or you see a fuzzy white/green crust around terminals.
- Age: 3–5 years is normal life for many flooded/EFB batteries in mixed weather. AGM can last longer, but if you’re past 5 years, test it.
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Contact Subaru Customer Service & Support
Your regional Subaru customer service line can confirm the original battery group size, cold cranking amps spec, and warranty status on newer vehicles. They can also check if your VIN is under any battery-related service bulletins or software updates (for things like Start-Stop charging logic). In many markets, you can start from Subaru’s official Customer Support page or the broader Owner Support section and then navigate to your region.
A dealer can scan your car for voltage-related trouble codes, verify alternator output, and “register” or initialize a new battery if required on newer Start-Stop systems. If you’re not comfortable swapping the battery yourself, this is the safest route. Use Subaru’s official Find a Retailer tool to locate an authorized Subaru service department near you.
- Subaru USA (owner resources) / regional Subaru site for your country
- “Subaru dealer near me” for parts counter availability and VIN lookup
- Owner’s manual / maintenance schedule PDFs for your exact model year (look up “Subaru [year model] owner manual battery spec”)
Subaru Car Battery FAQs
Can I upgrade from a standard flooded battery to AGM in my Subaru?
Yes, in most Subaru models AGM is considered an upgrade. AGM batteries deliver better cranking power, accept charge faster, and tolerate deep cycling and accessory load better than basic flooded batteries. You can safely upgrade from flooded → AGM, but you should not downgrade from AGM → basic flooded in vehicles with start-stop, high electrical demand, or sensitive voltage monitoring.
Do I need a special battery for start-stop in my Subaru?
If your Subaru uses auto start-stop (common in newer Outback, Forester, Crosstrek, etc.), you should be running either EFB (Enhanced Flooded Battery) or AGM, depending on trim. Those chemistries are built to handle repeated engine restarts and deeper discharge. Dropping in a cheaper standard flooded battery can shorten life, trigger battery or charging warnings, and cause sluggish restarts.
How long should a Subaru car battery last?
Most Subaru batteries last around 3–5 years in normal use. Lots of short trips, cold-climate starts, long idling with lights/heater/audio running, or frequent start-stop cycling can bring that down to 2–3 years. A Subaru that sees mostly longer highway drives (meaning the alternator can fully recharge the battery) and occasionally gets maintained with a smart charger can make it past 5 years.
How much is a Subaru car battery?
On average, expect roughly $100–$180 USD for a standard flooded replacement in older/non-start-stop Subaru models, $150–$230 USD for EFB in Subaru models with start-stop, and about $200–$350 USD for AGM in higher-demand or premium trims. Larger battery group sizes with higher Cold Cranking Amps (CCA) and longer Reserve Capacity generally cost more.
What size battery does my Subaru need?
You should match the OEM group size (examples commonly used in Subaru vehicles include Group 25, Group 35, or H6/Group 48 depending on model/year), make sure the terminals are oriented the same way, and meet or exceed the factory Cold Cranking Amps (CCA). Easiest path: read the label on the existing battery or check the owner’s manual before you buy.
When should I replace the battery instead of just recharging it?
If the engine cranks slowly first thing in the morning, the battery keeps dropping below ~12.4V even after a proper drive, or you’re getting weird electrical behavior (dim dome lights on startup, radio presets resetting, random warning lights), it’s usually time to replace rather than keep jump-starting or trying to top it off.
Does warranty matter when choosing a Subaru battery?
Yes. Look for a strong free-replacement warranty window (commonly 24–36 months). A better warranty usually means better internal plate construction, better vibration resistance, and longer expected cycle life under Subaru’s AWD drivetrain loads, winter starts, and accessory draw.
Bottom line: For most modern Subarus, the “best battery” is not just the cheapest thing that physically fits. Match the correct group size (35, 24F, 25, etc.), keep or upgrade the technology (EFB → EFB or AGM, AGM → AGM), and pay attention to CCA and RC if you live in extreme temps or camp in the car. Spending a little more on an AGM with solid warranty is cheaper than getting stranded in a ski resort parking lot with warning lights lit up and a Subaru that won’t crank.
Weize Platinum AGM Battery BCI Group 48-12v 70ah H6 Size 48 Automotive Battery, 120RC, 760CCA, 36 Months Warranty, Dimensions 10.94" L x 6.89" W x 7.48" H
Weize Platinum AGM Battery BCI Group 47-12v 60ah H5 Size 47 Automotive Battery, 100RC, 680CCA, 36 Months Warranty, Dimensions 9.52" L x 6.89" W x 7.48" H