Mighty Max Battery MM-G31 Start and Stop Car BCI Group 31 12V 100AH, 140RC, 900 CCA, Rechargeable AGM Car battery
Condition: New
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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
Tuesday, Oct 20
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Style: Group 31
Features
- Fast Starting Power: This 12V 100Ah 900 CCA delivers strong, steady starts is ready for any weather in any season.
- Made to Last: With its 140-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-G31 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 12.88 x 6.75 x 9.50 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: Group 31
Voltage: 12 volts
Battery Cell Composition: Lead Acid
Item Weight: 57.6 pounds
Product Dimensions: 12.88"D x 6.75"W x 9.5"H
Number Of Cells: 6
Resistance: 12 ohm
Terminal: Bolt Terminal
Compatible with Vehicle Type: Passenger Car
Voltage: 12 volts
Number Of Cells: 6
Resistance: 12 ohm
Terminal: Bolt Terminal
Battery Capacity: 100 amp_hours
Automotive Fit Type: Universal Fit
Size: Group 31
Item Weight: 57.6 pounds
Item Dimensions D x W x H: 12.88"D x 6.75"W x 9.5"H
Battery Type: Lead Acid
Brand Name: Mighty Max Battery
Manufacturer Part Number: MM-G31
Model Number: MM-G31
Manufacturer: Mighty Max Battery
UPC: 810185371167
Number of Items: 1
Included Components: Battery
Item Type Name: Battery
Manufacturer Warranty Description: 1 Year Manufacturers Warranty
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Tuesday, Oct 20
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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Top Amazon Reviews
Style: Group 35
If you are looking for a rock-solid, high-performance AGM battery that won't break the bank, the Mighty Max MM-G35 is an absolute home run. The difference in starting power is night and day. Here is why this Group 35 battery easily earns a full 5-star rating: 🚀 Key Highlights & Performance Flawless Start-Stop Performance: This battery handles start-stop cycles effortlessly. AGM (Absorbent Glass Mat) technology is a must-have for modern, high-draw vehicles, and this unit manages the constant on-and-off cycling without breaking a sweat. Massive Cranking Power: With 650 CCA (Cold Cranking Amps), the engine turns over instantly and aggressively, even on freezing cold mornings. There is zero hesitation or sluggishness. Impressive Reserve & Capacity: The 55Ah rating and 100RC (Reserve Capacity) mean you have plenty of reliable power to run accessories, dash cams, and electronics without worrying about draining your main power supply. Built Like a Tank: True to premium AGM design, it is completely sealed, spill-proof, and highly resistant to intense engine vibration. You can install it and completely forget about maintenance, venting issues, or terminal corrosion. 🛠️ Fit and Installation The BCI Group Size 35 form factor is a precise, standard fit. The terminals are cleanly molded, solid, and accept heavy-duty vehicle clamps perfectly. It has a reassuring weight to it, which is a great indicator of the quality and density of the internal lead plates.
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Reviewed in the United States on July 12, 2026 by Reviewer2765
Style: Group 48
Bought this to replace the battery in my Jeep and so far it has been great. It arrived well packaged, fit like it was supposed to, and had plenty of power right out of the box. The Jeep starts strong and I haven't had any issues with it. Considering what some of the name brand AGM batteries cost, this was a much better deal. So far I'm very happy with it and would buy it again.
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Reviewed in the United States on September 2, 2026 by James Williams
Style: Group 48
Absolutely TERRIBLE product. The first one I ordered arrived dead and wouldn't take a charge at all, not even a single volt. I guessed it might have been damaged in shipping. Amazon customer service was great though. They missed an immediate refund and didn't require I return it, and they advised the easiest solution was to simply order again. I did so and the second one arrived and worked fine... For a while. The second one lasted just over a year and was outside of Amazons warranty window so I was told I would need to contact MightyMax directly. They first made me jump through a bunch of hoops including taking it to Autozone to get a scan and a print out of the result (which was "bad" of course, as I had already told them). Every time I emailed them to answer their question or jump through another hoop, it took them 24 to 48 hours to reply, so by the time they agreed it was indeed bad and under warranty, a week had gone by and I needed my car working so I just bought one locally. I told MightyMax I would prefer a refund at this point but they said it was out of the question and advised they would send a replacement (that I don't need at this point). Well, here it is 2 weeks later and still nothing from them. No battery, no email, nothing. Yesterday I sent an email asking for an update and here we are 24 hours later and still nothing. DONT BUY THIS BATTERY! DONT DEAL WITH THIS COMPANY! YOUVE BEEN WARNED.
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Reviewed in the United States on August 4, 2026 by Peter S.
Style: Group 151R
No complaints it's a battery fits in tractor and works
Reviewed in the United States on September 7, 2026 by brendon
Style: Group 35
The cost of this MM-G35 battery was a big factor in my decision to purchase it, as it costs literally half of what some of the big name brands do! I am a great fan of AGM batteries. I’ve used the “yellow top” brand in my heavily modified 2002 Silverado one ton diesel truck since it was just a year old. My first set (Diesel engines require two batteries) lasted an unbelievable 14 years! AGM batteries typically have a much greater service life than lead-acid batteries. I also use an AGM battery in my heavily modified 2005 Jeep TJ. So when my wife’s 2021 Subaru Ascent Touring was ready to a new battery, it was a no-brainer decision that I was going to purchase another AGM battery. The battery was delivered within 36 hours of my purchasing it with zero damage to neither the battery, nor even to the outer packaging. It also arrived fully charged and ready to install. The fit was perfect and installation took less than 10 minutes. I’m very happy to be done with my wife’s old lead acid battery and I hope she has many, many years of trouble free service from her new Mighty-Max battery. 😀 Also, simply by registering your purchase, via the included QR code, the manufacturer’s warranty will be extended an additional three months, 👍 I will also be adding a photo of the installed battery to this review very soon, as the warranty period will be increased by an additional three months by the manufacturer, just for doing so. 👍 I’m very happy with this purchase and I highly recommend this AGM battery!!! 😀
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Reviewed in the United States on February 15, 2026 by Kevin C.
Style: Group 35
Battery is junk had dead cell in two months
Reviewed in the United States on August 21, 2026 by Willy Simkins
Style: Group 35
This battery worked swimmingly for my Lancer
Reviewed in the United States on September 14, 2026 by Paul Vallez
Style: Group 94R
AGM class 94 battery failed after 7 weeks. Despite contacting customer service for warranty replacement 5 times they have yet to provide promised communication nor shipped a replacement after 5 days. Customer service says 9a to 5p pst but it is actually 9a to 5p est however Amazon won't connect you until 9a pst (12noon est) and they won't answer after 5p est. So customer service is only available noon to 5p est in actuality Monday to Friday. If you work you are out of luck. Car is my primary means of transportation and being down for a week is ridiculous. In reality much longer as they haven't corresponded, called or provided any useful correspondence. Going to go to autozone and buy a new battery and remember never to buy a car battery on Amazon or thru these useless twits again. Absolutely pathetic. 42 a day in Uber while I wait for the worst customer service to get their act together. No savings just heartache and pain. Crappy battery lasted weeks and useless warranty. Absolute contempt for their customers
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Reviewed in the United States on September 16, 2026 by Albert V