Battery Equivalents and Replacements

VMAXTANKS MR127-100 AGM Deep Cycle Battery

VMAXTANKS MR127-100 battery is AGM SLA, 12V 100 Ah, deep cycle, high performance battery, often used for marine, automotive and other off-the-grid applications.

VMAXTANKS MR127-100 battery is BCI Group 27 battery, featuring robust, spill-proof design, heavy duty lead tin plates, long shelf life, low self-discharge rate etc.

Updated: October 16, 2019.

vmaxtanks mr127 100 1

VMAXTANKS MR127-100 Battery Features and Specifications

VMAXTANKS MR127-100 battery is very popular BCI Group 27 battery, optimized for deep cycle applications.

It is spill-proof maintenance-free Sealed Lead Acid (SLA) Absorbed Glass Matt (AGM) battery, with physical dimensions of (W x D x H) 12.1 x 6.7 x 8.2 (8.46 with terminal posts) inches (~30.7 x 17 x 20.8 (21.5 with terminal posts) cm).

It is anything but light battery and it weighs 68 pounds (~30.8 kg) - it is light enough to be carried by single adult at short distances, but two adults are recommended.

VMAXTANKS MR127-100 battery features nominal voltage of 12 volts and 20h capacity of 100 Ah.

Reserve capacity (RC) value of 200 minutes ensures good deep discharge performances - VMAXTANKS MR127-100 battery is able to provide 25 Amps for 200 minutes (3h 20 minutes) for effective capacity of ~83 Ah.

Although it is not intended for staring applications, it is good to know that it is able to provide 800 MCA. Also, its 3 sec PHCA (Pulse Hot Cranking Amps) is 1580 Amps.

Recommended charging current is 7-30 Amps, with end charging voltage between 14.4 and 12.9 volts. When being used in standby applications, its recommended float voltage range is between 13.5 and 13.8 volts.

Number of Cycles vs. Depth of Discharge (DoD)

VMAXTANKS MR127-100 battery's average number of charging/discharging cycles depends on the DoD, and is given in the following table:

DoD Capacity Loss Down To 80% Capacity Loss Down To 60%
10% ~2400 cycles ~3500 cycles
25% ~1150 cycles ~1600 cycles
50% ~680 cycles ~900 cycles
80% ~460 cycles  ~550 cycles
100% ~280 cycles ~300 cycles

vmaxtanks mr127 100 2As one can see, when the VMAXTANKS MR127-100 battery is being used for deep cycle applications, it can withstand ~460 cycles when it is being discharged down to 80% DoD, while still retaining 80% of its nominal 100 Ah capacity.

Personally, I don't like when the battery is used below its 80% of nominal capacity (it should be replaced then), but some people use such batteries even until the capacity loss is down to 60% - AGM SLA batteries lose capacity slowly, but one never knows when the battery will actually 'die'.

In order not to overdischarge your battery, it is important to know actual DoD (or remaining capacity %) depending on the battery voltage and temperature.

The following table lists battery voltages, depending on the temperature and remaining capacity:

Capacity % at 20°C DoD % at 20°C Battery Voltage at Different Temperature
32°F, 0°C 50°F, 10°C 68°F, 20°C 86°F, 30°C 104°F, 40°C
100% 0% 13.20 13.14 13.08 13.02 12.96
80% 20% 12.90 12.84 12.78 12.72 12.66
60% 40% 12.60 12.54 12.48 12.42 12.36
40% 60% 12.30 12.24 12.18 12.12 12.06
20% 80% 12.00 11.94 11.82 11.76 11.70

For example, if you don't want to discharge the battery below 20% of nominal capacity (80% DoD) at 68°F (20°C), don't discharge the battery below 11.82 volts.

Note: never discharge AGM SLA batteries in general below 10.5 volts (below 1.75 volts per cell) unless absolutely required - such discharging can decreased number of charging/discharging cycles significantly.

How to Charge VMAXTANKS MR127-100 Battery

According to the manufacturer, VMAXTANKS MR127-100 battery should be charged with current in 7 and 30 Amps range. Anything less than 7 Amps or more than 30 Amps can shorten operating life of the battery.

Note: feel free to use advanced AGM battery maintainers to keep the battery charged, but only AFTER the battery is fully charged.

The use of intelligent AGM battery chargers is highly recommended and one of the most popular chargers is VMAXTANKS BC1220 battery charger.

vmaxtanks bc1220 charger

VMAXTANKS BC1220 is 7 stage, 12 volts, 20 Amps intelligent charger, intended for AGM, Gel-cell, or wet lead-acid batteries, ranging from 60 to 300 Ah.

VMAXTANKS BC1220 is designed not only to charge the batteries, but also to recondition them and maintain them over longer period of time.

For more info about this charger, check VMAXTANKS BC1220 Smart Battery Charger Amazon link (link opens in the new window).

If you intend to use your VMAXTANKS MR127-100 battery in the boat or vehicle, just let onboard alternator/wind-turbine/solar panels to do the job - again, keep the charging current in the 7 to 30 Amps range.

Battery Box - Power Center

For applications where the VMAXTANKS MR127-100 battery is used as standalone, single battery, the use of battery box as power center is highly recommended.

Battery box protects the battery from sun and water, often featuring built-in battery meter, manual reset circuit breakers, USB chargers, accessory plugs etc.

One of the most popular battery boxes that are used alongside VMAXTANKS MR127-100 battery is Minn Kota Trolling Motor Power Center battery box.

minn kota trolling motor power center

Minn Kota Trolling Motor Power Center is designed to fit BCI Group 24- and 27-size batteries, it features built-in battery meter, circuit breakers, and it protects the battery from the mechanical impacts, sun, water and similar.

Although VMAXTANKS MR127-100 battery features carrying handles, carrying 68 pound battery around is much easier when it is stored in the battery box with suitable handles/straps.

For more info about this battery box, check MinnKota Trolling Motor Power Center Amazon link (link opens in the new window).

Long Story Short: VMAXTANKS MR127-100 offers great features and performances at affordable price.

Designed as deep cycle battery, in the single battery electric system it can be even used as starting battery (MCA 800 Amps), although such use is not recommended on regular basis, at least not for larger diesel engines.

VMAXTANKS MR127-100 battery can be used in off-the-grid applications, as great trolling motor battery, as RV Deep Cycle Battery and for other similar applications.

For more reviews and recommendations, check VMAXTANKS MR127-100 Deep Cycle Battery Amazon link (link opens in the new window).