Mighty Max ML4D 12V 200Ah 4D SLA AGM Battery

Mighty Max ML4D is a large, heavy and sturdy Sealed Lead Acid (SLA) Absorbent Glass Mat (AGM) battery, belonging to BCI Group Size 4D.

It is maintenance free battery, suitable for deep discharge applications like trolling motor battery, RV house battery, golf carts and other electric vehicles, garden tools, solar, hobby, off-the-grid applications, security devices, standby applications etc.

Despite having 20h capacity of 200Ah, maximum allowed current of Mighty Max ML4D is 'only' 1000 Amps for 5 seconds. But, this battery is not even intended for such applications.

mighty max ml4d agm 1

Mighty Max ML4D Features and Specifications

Mighty Max ML4D is BCI Group Size 4D AGM battery and its dimensions are (L x W x H) 20.9 x 8.23 x 8.46/8.66 inches (530 x 209 x 215/220 mm) and it weighs 114.6 pounds (~52 kg).

Mighty Max ML4D features two side handles for carrying it around by two adults - one can carry it, or at least lift it and put it down, but with the risk of injuries. IMHO, of course.

Its nominal voltage is 12V and nominal (20h) capacity is 200Ah. As the battery is discharged faster, so does its capacity drops, too:

- 20h rate, 10 Amps, down to 10.5 volts: 200 Ah capacity,

- 10h rate, 17.6 Amps, down to 10.5 volts: 176 Ah capacity,

- 5h rate, 31.5 Amps, down to 10.5 volts: 157.5 Ah capacity,

- 1h rate, 115 Amps, down to 9.6(!) volts: 115 Ah capacity.

This capacity loss is typical for SLA AGM batteries and Mighty Max ML4D is not an exception, although its capacity loss is rather acceptable.

Note: 1h discharge is down to 9.6 volts (1.6 volts per cell), which is rather low. But, this discharge rate is 'just' for an hour, after which the battery must be recharged.

Fully charged battery at 77°F (25°C) features internal resistance of <4.3 mΩ, with the short circuit current of 3430 Amps and the maximum allowed 5s discharge rate of 1000 Amps.

Mighty Max ML4D is designed to have standby service life of 10 years with the six months shelf life at 20°C with the 3% capacity loss per month.

Maximum allowed charging current is 52.5 Amps, with the recommended charging voltage for cycle use in the 14.4 - 14.7 volts range and with the recommended charging voltage or standby use in the 13.2 - 13.8 volts range.

Mighty Max ML4D is maintenance free AGM battery, featuring diluted sulfuric acid as electrolyte, absorbed by glass mat. If the battery is overcharged and if the oxygen and hydrogen are created, one-way valves release the gasses out of the battery, preventing pressure build-up.

Nonetheless, it is highly recommended to charge Mighty Max ML4D battery with the smart AGM battery chargers that also act as battery maintainers.

mighty max ml4d agm terminals

Mighty Max ML4D features terminals in the form of nuts and bolts, allowing simple, but firm connection between the battery and the cables.

Mighty Max ML4D Discharge Characteristics

Constant current discharge values are listed in the following table (Amps, at 77%°, 25°C):

End Cell Voltage End Battery Voltage 15 min 30 min 45 min 2h 3h 5h 10h
1.60V 9.6V 324 195 141 67.1 51.1 33.5 18.0
1.65V 9.9V 309 187 137 65.3 49.9 32.7 17.9
1.70V 10.2V 298 183 134 64.1 49.4 32.1 17.7
1.75V 10.5V 280 178 130 62.6 48.4 31.5 17.6
1.80V 10.8V 246 169 125 60.3 46.2 31.0 17.5

Personally, AGM batteries should not be drained below 10.5 volts (they tend to last longer).

Note that this table doesn't list values below 15 minutes (like 10 min, 5 min) - this is because ML4D battery is simply not intended for such strong currents.

Constant power discharge values for Mighty Max ML4D battery are listed in the following table (watts, at 77%°, 25°C):

End Cell Voltage End Battery Voltage 15 min 30 min 45 min 2h 3h 5h 10h
1.60V 9.6V 3504 2208 1614 750 580.8 385.2 212.4
1.65V 9.9V 3324 2082 1566 738 573 378.6 205.8
1.70V 10.2V 3168 2046 1524 726 565.2 373.2 202.2
1.75V 10.5V 3066 1998 1494 711 549.6 367.2 198.6
1.80V 10.8V 2940 1962 1476 696 361.2 361.2 193.8

Again, these are values are for whole ML4D battery, not just single cell.

Mighty Max ML4D Cycles vs. Depth of Discharge (DoD)

Deep discharge cycle operations shorten the operating life of Mighty Max ML4D battery. Following list shows dependency between DoD, number of cycles and capacity loss:

- 100% DoD, 80% capacity after ~190 cycles, 60% capacity after ~210 cycles,

- 50% DoD, 80% capacity after ~380 cycles, 60% capacity after 450 cycles,

- 30% DoD, 80% capacity after ~900 cycles, 60% capacity after ~1210 cycles.

These values shows that Mighty Max ML4D tolerates deep discharges well, but it could be better.

Note: some manufacturers doesn't release actual data of 'cycles vs DoD vs capacity'. Personally, I would rather buy battery with actual data known than the battery that is 'said to be good'!

mighty max ml4d agm 2

Mighty Max ML4D as Trolling Motor Battery

First of all, Mighty Max ML4D is rather large and heavy battery and having one in smaller boat is significant weight penalty.

But the energy stored in a single battery allow the fisherman to push the 60 Amps trolling motor for up to 2h, even with some energy left.

Since trolling motors are rarely pushed to the limit all the time, actual trolling time can be significantly longer, for example, 30 Amps trolling motor can be powered for 5(!) hours, with some energy left for safety reasons and for periods of short burst of power.

Note: these values are for an end battery voltage of 10.5 volts.

For short, Mighty Max ML4D can be used as an excellent AGM trolling motor battery.

 Mighty Max ML4D as RV House Battery

For RVs with two batteries electrical systems, single Mighty Max ML4D battery can provide plenty of power/energy for onboard devices and appliances.

With the voltage not dropping below 10.5 volts, Mighty Max ML4D can provide ~200 watts for 10 hours, which is enough for LED lights, ventilation, smaller flat screen TV and perhaps a fridge - actual values depends on the devices being used, because it is not the same if the user has 3x1W LEDs or 5x5W LEDs, 10" TV or 30" TV etc.

If more energy is required, Mighty Max ML4D can be easily connected in parallel to create 400Ah (2 batteries), 600Ah (3 batteries) etc. battery packs.

Similarly, Mighty Max ML4D battery can be used in other off-the-grid, solar, standby and similar applications.

Mighty Max ML4D vs VMAXTANKS MR197-200 AGM Batteries

Both Mighty Max ML4D and VMAXTANKS MR197-200 are large, sturdy and heavy duty AGM batteries. They both belong to the BCI Group 4D and feature 12V nominal voltage and 200Ah nominal capacity.

Their most important features and specifications are given in the following table:

Model Mighty Max ML4D VMAXTANKS MR197-200
Photo mighty max ml4d agm table vmaxtanks mr197 200 table
Chemistry Type SLA AGM SLA AGM
Nominal Voltage 12V 12V
Nominal Capacity 200 Ah 200 Ah
Reserve Capacity ? 450 min
MCA - 1400 Amps
PHCA 1000 Amps 2900 Amps
Short Circuit Current 3430 Amps -
Internal Resistance <4.3 mΩ -
Dimensions (L x W x H) 20.9 x 8.23 x 8.66 19.1 x 6.8 x 9.5
Weight 114.6 pounds 112 pounds
 Charging Current 52.5 Amps max. 15 - 60 Amps
Cycle Charging Voltage 14.4 - 14.7 volts 14.4 - 14.9 volts
Float Charging Voltage 13.2 - 13.8 volts 13.5 - 13.8 volts
Warranty 1 year 2 years
Compare the Prices
Amazon Links Mighty Max ML4D VMAXTANKS MR197-200

Note: Amazon links open in the new windows, feel free to check them for most up-to-date offers and prices.

Both Mighty Max ML4D and VMAXTANKS MR197-200 are deep cycle batteries, with the VMAXTANKS MR197-200 having also 'some' starting abilities - we say 'some' since 1400 MCA Amps is not especially good value for 200 Ah battery.

But, this also means that VMAXTANKS MR197-200 can be used in dual applications, while Mighty Max ML4D is intended only for deep discharge applications.

VMAXTANKS MR197-200 is also slightly lighter and more compact battery, featuring longer warranty period and of course, it costs more - you win some, you lose some :)


mighty max ml4d agm mLong Story Short: If you are looking for 12V 200Ah AGM deep cycle battery that is relatively cheap and reliable, consider Mighty Max ML4D battery - if treated properly, it will serve you well.

For dual purpose applications, VMAXTANKS MR197-200 is better choice, although it costs more.

For more review and recommendations, check Mighty Max ML4D 12V 200Ah 4D SLA AGM Battery and VMAXTANKS MR197-200 12V 200Ah AGM SLA Battery Amazon links (links open in the new window).