Ever since the average car became a ‘rolling computer’, car battery related breakdowns skyrocketed (obviously).
Nowadays, cars are equipped with over 30 different control modules that are constantly exchanging information with each other, therefore a healthy and powerful battery is extremely important.
How to Choose the Best Battery for Mazda 3
Before we dive in, let’s take a look at what you should look for when buying a battery for your Mazda 3. Remember, each car is different, therefore different cars need different size, type and capacity batteries.
Battery Group Size (BCI)
Different engine bays can only fit a certain size battery, therefore engineers had to come up with a way to categorize batteries by their size. Make that sure the size of your battery of choice is as close to your car’s OEM battery as possible. That way, you won’t face any problems when installing the new battery.
Here is the BCI group size chart in imperial and metric:
| Group Size | LxWxH (inches) | LxWxH (cm) |
| Group 24 | 10.25 x 6.8125 x 8.875 | 26 x 17.3 x 22.5 |
| Group 27 | 12.0625 x 6.8125 x 8.875 | 30.6 x 17.3 x 22.5 |
| Group 31 | 13 x 6.8125 x 9.4375 | 33 x 17.3 x 24 |
| Group 51 | 9.374 x 5.0625 x 8.8125 | 23.8 x 12.9 x 22.3 |
| Group 65 | 12.0625 x 7.5 x 7.5625 | 30.6 x 19 x 19.2 |
| Group 78 | 10.25 x 7.0625 x 7.6875 | 26 x 17.9 x 19.6 |
Cold Cranking Amps (CCA)
Cold Cranking Amps is the single most important metric for cold weather. It’s a measure of the discharge load in amperes that a battery in 0oF temperature can deliver for 30 seconds, while still maintaining terminal voltage to or higher than 1.20V per cell. To put it simply, the higher the CCA, the better the batter will perform in cold weather.
Reserve Capacity (RC)
RC is the number of minutes a fully charged battery will discharge constant 25 amps until the battery voltage drops below 10.5 Volts. This is supposed to simulate a complete charging system failure, meaning that only the reserve power on the battery is powering all electrical demands of the car. Similarly to CCA, the higher the Reserve Capacity, the better.
Ampere Hour (Ah)
Ampere hour is how you measure the flow of energy in amperes over one hour. For example, a 60Ah battery (the most common for Mazda 3), can supply 1 amp of current for 60 hours before it dies. Just like the ratings above, the higher the ampere hour rating of a battery, the better.
EFB vs AGM for i-stop
Now, changing your car’s battery when it’s going bad is easy, however, it becomes a headache once your car comes with a start-stop function and needs a special (and very expensive) battery. Unfortunately, this is the case with some Mazda 3’s.
Some of these Japanese beauties run a special Q85 EFB battery, in this case, EFB stands for Enhanced Flooded Lead-Acid Battery. The Q85 EFB was specially designed to work with the i-stop function as it introduced frequent charging and discharging cycles.
However, you don’t need to spend a fortune on a new Q85 battery. Even though the original OEM Q85 is still the recommended replacement, there are plenty of much cheaper and better-performing alternatives for cars with start-stop functions on the market right now.
Of course, EFB performs better than a conventional lead-acid battery, but as long as you get an AGM (Absorbed Glass Mat) battery, your Mazda’s electrical system should work just as well or even better. An AGM battery is a better-performing, maintenance-free upgrade to the EFB.
Enough with the technical mumbo-jumbo, let’s get your Mazda 3 back on the streets.
Here are our Top 4 Best Batteries for Mazda 3:
The 4 Best Batteries for Mazda 3
 Advertising | Best Overall 1. NorthStar NSB-AGM-35 |
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 Advertising | Best Value 3. Deka 9A35/85 Intimidator AGM |
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 Advertising | Maximum Reserve 4. Odyssey 35-PC1400T AGM |
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 Advertising | Quick Charging 5. Optima Batteries 8040-218 |
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1. NorthStar NSB-AGM-35 – Best Overall
NorthStar batteries are designed to provide both high reserve capacity and cranking amps – the perfect combination for all performance and start-stop applications.
- Type: AGM
- BCI Group Size: 35
- Amp Hour: 60
- Cold Cranking Amperage: 740
- Reserve Capacity: 115
Proudly made in the USA, the NSB-AGM-35 features 1400 pulse cranking amps for the first five seconds of operation, which later drops down to consistent 880 CA. Because of these features, your Mazda 3 will keep starting quickly for years.
The cycling life on the NSB-AGM-35 is unmatched by rival battery manufacturers. The battery is able to cycle over 900 times at 50% depth of discharge, which makes it the most durable and long-lasting AGM battery on the market right now.
Not only is the NSB-AGM-35 durable when it comes to maintaining charge, it’s also durable on the outside, as the battery is made from high-quality ABS plastic. Keep in mind it’s a sealed AGM battery – this means it is virtually maintenance-free too.
The only negative aspect of the NorthStar is that it probably won’t fit with the factory battery insulation sleeve, however, the factory sleeve won’t be needed anyway, since the NSB-AGM-35 is heat resistant.
Pros
- Cycles over 900 times at 50% depth of charge
- Pure Lead AGM Technology gives great reserve capacity, cycling ability, and CCA ratings
- High cranking amps allow for consistent quick starting
- Housed in durable and heat resistant ABS plastics
- AGM construction means you won’t need to add water or clean the terminals
Cons
- Might be a tight fit on some Mazda 3’s
2. Deka 9A35/85 Intimidator AGM – Best Value
Proudly made in the USA by hard-working men and women, The Deka Intimidator is an AGM battery designed for extreme starting and deep cycle applications.
- Type: AGM
- BCI Group Size: 35/85
- Amp Hour: 50
- Cold Cranking Amperage: 640
- Reserve Capacity: 100
Made by East Penn Manufacturing, the Deka AGM Intimidator is engineered with a premium glass mat that has a perfect balance of absorbency, compressibility, and electrical resistance. This results in superior performance and long life.
The low internal resistance of the Intimidator allows for quick power delivery, which is very important for start-stop systems. Of course, the low internal resistance also gives the ability to recharge faster than conventional batteries.
With an Enhanced Electrolyte Suspension System, the Intimidator is able to absorb more electrolytes and protect the internal components, while special micro-porous glass separators prevent acid spills and terminal corrosion.
The Intimidator is equipped for the toughest operating conditions thanks to its advanced durability design. The addition of fortified battery posts, straps, and welds combined with extremely vibration-resistant glass mat provides ultimate durability.
Pros
- Is BCI Group Size 35/85, which makes it the same size as OEM Q85 battery
- Very low internal resistance allows for high instantaneous power and quick starts
- Fast recharge time
- Enhanced Electrolyte Suspension system gives higher power density and durability
- Fortified posts, straps and welds for added vibration resistance
Cons
- The Amp Hour ratings are on the lower side
3. Odyssey 35-PC1400T AGM – Maximum Reserve Power
Odyssey batteries are renowned for their quality and this one is no exception. It has the highest recharge efficiency of any sealed lead battery on the market right now.
- Type: AGM
- BCI Group Size: 35
- Amp Hour: 65
- Cold Cranking Amperage: 850
- Reserve Capacity: 130
The Odyssey 35-PC1400T is full of high starting power. Even by AGM standards, this battery has an astonishing reserve capacity and CCA.
Such high power is achieved by using plates made up of virgin lead instead of lead alloy. This allows to fit a greater number of plates into the battery, increasing the surface area of the plates and allowing to store more power.
The ability to contain large amounts of stored power is impressive, but discharge durability is also important, therefore Odyssey designed the 35-PC1400T to reliably discharge up to 400 cycles at 80% depth of discharge.
Lastly, you’ll be amazed by the service life of this AGM: it’s up to 10 years with a 3-4 year replacement warranty.
Pros
- Exceptionally high CCA and long Reserve Capacity
- Very long service life
- 4-year warranty
- Up to 400 cycles at 80%
- Massive starting power of 1400 Pulse Hot Cranking Amps
Cons
- On the expensive side
- Heavy
4. Optima Batteries 8040-218 D35 YellowTop – Quick Charging
The AGM YelllowTop Optima is one of the only true dual-purpose car batteries available right now. It has a really strong 5-second starting burst, which is exactly what your Mazda 3 needs.
- Type: AGM
- BCI Group Size: 35
- Amp Hour: 48
- Cold Cranking Amperage: 620
- Reserve Capacity: 98
There really is nothing the YellowTop can’t do. It’s used in competition audio cars, competition hydraulic systems, off-roaders with winches, and even diesel trucks. So, it’s safe to say this AGM battery cranks out enough power to satisfy even the most demanding vehicles.
The YellowTop can really take a beating with repeated deep discharges but will still start your Mazda 3 up time after time. To add to that, the YellowTop has an incredibly small internal resistance of 0.003 ohms, which means it features fast recharging capabilities you’ve never seen before.
Optima’s YellowTop has a very distinct exterior design due to its Spiracell technology. The heart of the battery consists of a series of individual spiral-wound cells that are made from two 99.99% lead plates that are coated in lead oxide. This allows for ultra low internal resistance, lighting fast output, and nearly twice the lifespan of traditional car batteries.
Pros
- Lightweight for an AGM
- Decent CCA
- 3-year Warranty
- Exceptionally small internal resistance allows for quick recharge times
Cons
- Low Amp Hour and CCA rating
How to Reset i-stop After Battery Replacement
On Mazda 3’s and CX5’s with the i-stop system, the i-stop may not reactivate after disconnecting or changing the battery. If that happens, you need to visit your dealership to reset it or you can try to do it yourself, here’s the whole procedure:
- First, warm up the engine and reach the operating temperature. Remember to turn off all the electrical accessories you can, like A/C and radio.
- Switch off the ignition.
- Now switch the ignition on but don’t start the engine. Press and hold the i-stop OFF switch for 3s within the 5s window after switching the ignition ON.
- Start the engine.
- Press the i-stop OFF switch again. Verify that the green i-stop indicator light is now flashing and stays flashing. If it does not flash, you have to go back to step 3 and try again.
- Allow the car to idle until the green i-stop indicator light turns off. If it doesn’t turn off automatically, proceed to step 7 after the car has been idling for 10 minutes.
- Now switch the engine off and wait a few minutes.
- Start the engine back up. Go for a drive, and check that the i-stop system is working as it should. You may need to drive a mile or two until it will activate. Keep in mind that it may take more time if you’ve replaced the battery with a new one, so go for a decent drive to fully charge the battery.
- If i-stop works normal, it means that you’ve successfully reset the system. Congratulations!
Mazda 3 Battery Frequently Asked Questions (FAQ)
Will a bigger battery hurt my car?
A bigger battery will not hurt your car, it might actually increase the life of your alternator.
You see, the battery doesn’t provide the car with electrical current when the engine is running at rpms higher than idle – that’s solely the job of the alternator.
A bigger battery might act as a buffer and decrease the workload from the alternator on some rare occasions by serving its reserve power when needed.
Does it matter what kind of battery you put in your car?
It absolutely does matter. There are three main types of car batteries: Conventional, EFB, and AGM. A car that has an EFB battery can only be replaced with another EFB or upgraded to an AGM, while cars that run AGM batteries need to be replaced with another AGM battery – no downgrades in battery technology are possible.
Lastly, batteries come in various sizes, configurations, and ratings, therefore picking the right battery is crucial.
How do you keep a car battery charged when not in use?
You need a trickle charger, which will keep your car’s battery charged, in turn increasing its lifetime.
Do car batteries charge while idling?
Yes, but not as fast as compared to driving. When cars used to have generators instead of alternators, the generators were unable to provide enough power at idle RPMs. Nowadays, cars use alternators that are very efficient at low RPMs and are able to charge the battery while idling.
However, the alternator provides significantly more charging power when the RPMs are raised, i.e. diving.
Eddie is the co-founder of CarCareCamp.com, and the site’s primary contributor.
Under his belt, Eddie has a bachelor’s degree in Automotive Electronics Engineering and almost a decade of experience working as a semi-truck technician (specializing in electrics).
