Mighty Max Battery MM-AUX12 Auxiliary Battery 12V 12Ah, 20RC, 200 CCA Rechargeable AGM Car Battery
Condition: New
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FREE 30-day refund/replacement
To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.
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Availability:
In Stock.
Arrives
Monday, Mar 2
Style: AUX12
Features
- Reliable Backup Power: This 12V 12Ah AGM battery delivers dependable performance in any weather and supports critical systems when the engine is off.
- Made to Last: With its 20-minute Reserve Capacity supports longer run times and a longer overall battery lifespan.
- All Power, No Mess AGM Design: Sealed and spill-proof, the MM-AUX12 is built with high discharge output and deep discharge recovery to keep power steady when it counts.
- Strength That Starts on the Inside: The rugged construction resists shock, vibration, and harsh conditions, delivering reliable performance across a wide range of temperatures and tough environments.
- Tested Tough & Certified Safe: Mighty Max batteries are built in an ISO-certified facility and meet CE standards for quality, safety, and reliability.
- Rechargeable and Versatile: Mounts in multiple positions (excluding upside down) for flexible vehicle installation.
- Dimensions: Sized at 5.93 x 3.50 x 5.75 inches, ready to fit your ride with ease. Polarity is easy to spot, with the positive terminal on the left and the negative on the right.
- Included: Each battery includes mounting screws for quick, hassle-free installation.
- Not Included: Wire harness and mounting accessories are not included.
- 3 Year Warranty: Mighty Max strength, long-haul protection, and confidence that youre powered to the max.
Brand: Mighty Max Battery
Vehicle Service Type: Passenger Car
Size: Standard
Voltage: 12 Volts
Battery Cell Composition: Lead Acid
Product Dimensions: 5.81"D x 3.38"W x 5.63"H
Resistance: 144 Ohms
Terminal: Bolt Terminal
Battery Capacity: 12 Amp Hours
Automotive Fit Type: Universal Fit
Brand: Mighty Max Battery
Size: Standard
Battery Cell Composition: Lead Acid
Product Dimensions: 5.81"D x 3.38"W x 5.63"H
Resistance: 144 Ohms
Terminal: Bolt Terminal
Battery Capacity: 12 Amp Hours
Automotive Fit Type: Universal Fit
Manufacturer: Mighty Max Battery
UPC: 810185370030
Model: MM-AUX12
Item Weight: 11 pounds
Item model number: MM-AUX12
Batteries: 1 Nonstandard Battery batteries required.
Manufacturer Part Number: MM-AUX12
Date First Available: May 9, 2025
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Monday, Mar 2
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Learn more about financing & leasing here.
Similar Products
Top Amazon Reviews
Style: Group 49
I’ve been running the Mighty Max battery in my 2006 Mercedes S430 for a few weeks now, and I honestly couldn’t be happier. I was a little hesitant at first because it’s priced lower than some of the big-name options, but it’s held up exceptionally well, even in eventfull weather and after sitting for a few days. Cranks strong every time. What really impressed me was the fitment. It dropped right into place with no modifications needed, which can be tricky with older luxury cars. Voltage stays consistent, and I haven’t noticed any electrical hiccups or drain issues since the swap. For the price and performance, I definitely recommend if you're looking for a reliable, budget-friendly battery without cutting corners.
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Reviewed in the United States on August 5, 2025 by PaperLanternShelf
Style: Group 47
This battery is a great replacement for AGM OEM batteries. Size is correct for group 47 H5 battery. Functional and came with 55% charge. I fully charged before use. Heavy duty durable battery. Awesome value for the money. Easy to replace. includes some instruction and warranty card.
Reviewed in the United States on November 15, 2025 by BigB BigB
Style: Group 35
Great battery! Exact match to size and description. Fit the car perfectly and fired it right up. Excited to have the extra CCA’s for my cold winters coming, as the AGM of Mighty Max has better CCA’s than the one issued with the car. All that at a much more reasonable price! Well worth it!
Reviewed in the United States on November 12, 2025 by flashdance flashdance
Style: Group 47
The battey failed in less than THREE months so beware of this battery and the customer service you will receive... I was told by Amazon that it has a ONE year manufactures warranty and to contact the company who sold it through Amazon... I contacted the company with the phone number provided by Amazon and was told from this company that I need to jump thru so many hurdles to prove that the battery was indeed defective... They even are nice enough to send you a link to explain all the hurdles you need to go thru... It's not enough that the dead battery left us stranded and not even a concern that this had happened to us from the seller. Finally after giving in to the seller and not wanting to jump thru all the hurdles that they place in front of you because it would just take to much time and effort... I believe they want so many things from you so that you do just give up on trying to get a return at no cost for their defective battery... So do yourself a favor and just go to an auto store and pay a little bit more because if the battery goes bad this soon they replace it with no problem at these stores... Also to prove this battery is bad they want you to use one of these auto part stores to use their tester to show that the battery is no good anyway and they also want the auto sotre to provide you with documentation LOL... You may also be told as I was that you are responsible for shipping cost to return the defective battery to them. So you don't save anything if a problem arises with this battery... I hope this helps with your decision to purchase this battery because it should have ZERO stars...
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Reviewed in the United States on December 10, 2025 by MFRYE
Style: AUX14
Put this in my wifes volvo that has that stop start feature (which of course is deactivated) yet is still needs 2 batteries to not kick a code. One is used for all the electrical bs and the main battery in the back is used for starting. If this small aux battery under the hood isnt working properly or is dead it puts a strain on the main battery in the back of the car. This was a little talller and has more cranking amps than the original volvo battery and took a little altering of the battery cover but it is a great battery , no codes now and easy starts. Much less than OEM battery as well.
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Reviewed in the United States on January 16, 2026 by floyd george
Style: Group 26R
Bought as a replacement for my Generac Guardian 14kw home generator. "26R" fits properly, hooked up and generator cranks just fine (though honestly not appreciably faster than the old lead acid battery). Fired up today no problem in ~10*F weather, though.
Reviewed in the United States on December 26, 2025 by Andrew
Style: Group 47
Packaging and battery look great. Waiting to install but for the price it seems to be a great deal. I got this for my 2021 Nissan Kicks
Reviewed in the United States on August 27, 2025 by Tesia garcia Tesia garcia
Style: Group 47
Arrived fully charged. Perfect fit in my Subaru Outback. Easy to install and the car started right up! Original Subaru battery only lasted 3 years hopefully Mighty Max lasts alot longer! Thanks Mighty Max
Reviewed in the United States on December 20, 2025 by Joseph S. Joseph S.