Exide MC-31 and XMC-31 MEGACYCLE AGM-200 Sealed Maintenance Free (AGM) Marine Batteries

Exide MC-31 and XMC-31 MEGACYCLE AGM-200 Sealed Maintenance Free (AGM) Marine Batteries are two very similar, dual-purpose marine batteries.

Being lead acid AGM batteries, they are rather heavy when compared with similar lithium marine batteries, but they are much cheaper, have very good vibration resistance, and are generally very robust and reliable.

They can be used as main boat batteries, as trolling batteries, and in any application requiring good starting power combined with deep cycle tolerance.

Updated: November 22, 2022.

The actual capacity of these batteries is 100 Ah when discharged for 20 hours. They are advertised as "Megacycle AGM-200":

• "AGM" stands for Absorbed Glass Mat, meaning that these batteries use electrolyte that is held in the glass mats made out of woven, very thin glass fibers.
• "200" stands for minutes of reserved capacity, which is how long (in minutes) a new, fully charged, 12V battery, at 80°F (~25°C), can deliver 25A current and maintain at least 10.5V of voltage.

We had to emphasize this right away since many people are confused with "AGM-200" and often believe that this is the actual capacity of these batteries in Ampere-hours (Ah). To aid the confusion, some online stores have photos of these batteries mixed-up :)

Specifications of these batteries are given in the following table:

Name	Exide MC-31 MEGACYCLE AGM-200 Sealed Maintenance Free (AGM) Marine Battery	Exide XMC-31 MEGACYCLE AGM-200 Sealed Maintenance Free (AGM) Marine Battery
Photo
BCI Battery Group	31	31
Dimensions LxWxH	13 x 6.6 x 9.4 inches 33 x 16.8 x 23.9 cm	13 x 6.6 x 9.4 inches 33 x 16.8 x 23.9 cm
Weight	72 lbs (~32.6 kg)	71 lbs (~32.2 kg)
Cold Cranking Amps (CCA)	700 A	925 A
Cranking Amps (CA)	840 A	1110 A
Reserve Capacity	200 min	200 min
Capacity (20h)	100 Ah	100 Ah
Maximum 5s Discharging Current	1400 A	1400 A
Battery Terminals (Dual)	1:9 SAE Post 3/8" – 16 Positive Stud 5/16"– 18 Negative Stud	1:9 SAE Post 3/8" – 16 Positive Stud 5/16"– 18 Negative Stud
Battery Type	Absorbed Glass Mat (AGM)	Absorbed Glass Mat (AGM)
Grid Alloy	Lead Calcium (both positive and negative)	Lead Calcium (both positive and negative)
Warranty	24 months	24 months
Amazon Link	Exide MC-31	Exide XMC-31

Note: Amazon links in the table are affiliate links. Height is given to the top of the terminals.

As one can see, battery dimensions are practically the same, just the XMC-31 is one pound lighter. Both batteries have the same capacity, maximum allowed 5s discharge current (IMHO, not recommended), reserve capacity, terminal types, etc., but the most significant differences are cold cranking amps (CCA) and cranking amps (CA), where XMC-31 is better than MC-31.

This also means that XMC-31 costs slightly more than MC-31, but personally, the difference in amperes more than justifies the difference in the price.

However, if you need an electric trolling motor battery that must, from time to time, start a smaller gas or even diesel engine, the cheaper MC-31 is also a good choice, especially if you need a bank of several batteries - in that case, the price difference can be important.

Note: When connecting batteries in the battery bank in parallel (larger capacity) or series (larger voltage), or even both, be sure to use not only the batteries of the same type (flooded, AGM, Gel Cell, etc.) but the batteries of the same manufacturer, preferably of the same series, bought at the same time.

This way, slight differences in voltage and capacity between individual batteries are minimized, avoiding additional stress of individual batteries in the battery pack - the battery pack lasts longer.

Exide XMC-31 vs. Optima D31M BlueTop vs. VMAXTANKS MR137-120

A comparison of these BCI Group Size 31 batteries is given in the following table:

Note: Amazon links in the table are affiliate links. Also, the Cold Cranking Amps (CCA) of the VMAXTANKS MR137-120 battery are calculated values, not the exact values provided by the manufacturer.

As one can see, physical dimensions are very similar, after all, they are all BCI Group Size 31.

However, Optima D31M BlueTop is some 11 pounds lighter than Exide XMC-31 and some 15 pounds lighter than VMAXTANKS MR137-120 battery.

Also, Optima D31M BlueTop has the lowest 20h capacity - 75Ah, compared with 100 Ah of Exide XMC-31 and 120 Ah capacity of VMAXTANKS MR137-120.

Although lighter and having a smaller capacity, Optima D31M BlueTop has CCA and CA ratings very similar to Exide XMC-31, while VMAXTANKS MR137-120 lags behind with its maximum values (CCA for VMAXTANKS MR137-120 is calculated value!).

VMAXTANKS MR137-120 has the largest Reserve Capacity - 230 minutes vs. 200 minutes of Exide XMC-120 and 155 minutes of Optima D31M BlueTop.

Price comparison - Optima D31M BlueTop is the cheapest of these three batteries, while VMAXTANKS MR137-120 is the most expensive. The price difference is not big, so choose the battery according to your needs:

• dual-purpose marine battery with good starting power - go for Optima D31M BlueTop,
• dual-purpose marine battery with good deep cycle performance - VMAXTANKS MR137-120,
• dual-purpose marine battery with both good starting power and good deep cycle performance (having in mind all the differences between the three of them) - Exide XMC-31.

Long story short - Optima D31M BlueTop is dual purpose battery with excellent starting power, VMAXTANKS MR137-120 is dual purpose battery with excellent deep cycle performance, while Exide XMC-31, with its characteristics, fits between them.

As BCI Group 31 battery, Exide XMC-31 competes with some of the best lead-acid batteries on the market.

If You are looking for a deep cycle group 31 battery, be sure to check other models as well, especially since this battery is not always available in local shops and online stores.

For more reviews and recommendations, feel free to check Exide XMC-31 AGM-200 Amazon link (link opens in the new window).