ExpertPower EXP12120 12 Volt 12 Ah AGM SLA Battery

ExpertPower EXP12120 12 Volt 12 Ah AGM SLA Battery is very popular AGM battery. It can operate in any position, it has very good vibration resistance, it is almost maintenance-free battery, tolerates well deep discharges, have low-self discharge rate, acceptable price, long float service life etc. Because of this, ExpertPower EXP12120 battery is commonly used in both standby applications (UPS battery, for example) and for cyclic use (fish finder battery, for example).

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ExpertPower EXP12120 AGM SLA Battery - Features and Specifications

As its name says, ExpertPower EXP12120 12 Volt 12 Ah AGM SLA Battery is AGM SLA battery with nominal voltage of 12 volts and 12 Ah capacity when discharged for 20 hours.

Its physical dimensions are 3.9x5.94x3.86 inches (~10 x 15 x 9.8 cm) and it weighs around 7.61 pounds (~3.45 kg).

Battery is made using the high impact resistant, non-conductive ABS plastic, making the battery itself very resistant to shocks, vibration, chemicals and heat.

Nonetheless, use your battery, but don't abuse it!

The acid is absorbed and immobilized between lead plates by very fine fiberglass mat - hence the name AGM. To prevent issues with gassing, battery is also valve regulated. All these features means that the battery can operate in any position, it is spill-proof and almost maintenance-free. We say almost, but occasionally it is recommended to check connections between battery's F2 style terminals and wires connected with the battery.

Typical applications of EXP12120 battery include alarm systems, communication equipment, security systems, medical and control equipment, UPS, power tools and of course, as good and reliable fish finder battery.

ExpertPower EXP12120 AGM SLA Battery Capacity

The capacity of the lead-acid batteries mainly depends on temperature and discharging current. There are other factors that influence the capacity, but not as much.

Nominal capacity of the EXP1212o battery is 12 Ah, when the battery is being discharged for 20 hours at 77°F (25°C). Capacity/discharge hours dependency is given in the following table - note that the battery is being discharged down to 10.5V (1.75V per cell):

Discharge Conditions Capacity (Ah; 77°F, 25°C)
20h (0.60A) 12.00 Ah
10h (1.155A) 11.55 Ah
5h (2.16A) 10.80 Ah
1h (7.23A) 7.23 Ah
15 min (19A) 4.75 Ah
5 min (40.96A) 3.41 Ah

As the discharge current increases, so does the capacity decreases. This capacity loss is typical for lead acid batteries, and EXP12120 is not an exception, although there aren't many batteries in this class (capacity/price/warranty) with better results. On a contrary...

Capacity also depends on the temperature and its dependency is given in the following table:

Temperature 5°F (-15°C) 32°F (0°C) 77°F (25°C) 104°F (40°C)
Relative Capacity 65% 85% 100% 102%

Although the increase in temperature leads to increase in capacity, higher temperatures shorten the lifespan of the battery.

When temperatures drop below freezing, consider warming up your battery, or at least insulate it, but monitor its temperature, since during the use, its temperature increases and again, high temperatures are not good for SLA AGM batteries.

Battery self-discharge rate is ~3-4% per month (temperature dependent), allowing the battery to be stored for longer period of time without trickle-charge. However, if the user needs the battery to be ready on the moment notice, smart SLA AGM battery charger with trickle charge and float voltage of 13.6-13.8 volts is recommended.

Note: storing the battery above 77°F (25°C) leads to higher self-discharge rate. For example:

Capacity Retention (%) at Temperature 41°F (5°C) 77°F (25°C) 86°F (30°C) 104°F (40°C)
80% ~10 months ~3 months ~50 days ~40 days
70% ~20 months ~6 1/2 months ~100 days ~60 days
60% - ~10 months ~6 months ~95 days
50% - ~15 months ~9 months ~5 months

Note: when the battery charge drops to 50%, charge it - it will last longer.

When the battery is used as cycling battery, it can be charged up to 14.4-15.0 volts, just keep the current below 3.6 Amps.

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 ExpertPower EXP12120 AGM SLA Battery Charging Cycles

ExpertPower EXP12120 AGM SLA Battery comes with 1-Year Limited Warranty. But, if treated properly, this battery can last much longer.

When the battery is kept at 68-77°F (20-25°C), its float service life is 3 to 5 years. However, if the battery is kept at 122°F (50°C), its expected float service life is shortened to one year - and this is very good value for battery in this class.

When the battery is used as cycling battery, depth of discharge (DoD) plays major role in the number of cycles that the battery can withstand. The following table lists average number of charge/discharge cycles, depending on the DoD and relative capacity.

Nominal Capacity (%) 100% DoD 50% DoD 30% DoD
80% ~160-200 ~330-410 ~790-920
60% ~190-280 ~410-510 ~1050-1250

For example, if the battery is regularly discharged down to 50%, one can expect 330-410 charging/discharging cycles, before actual capacity of the battery drops down to 80% of its nominal value (from 12Ah down to 9.6Ah).

 ExpertPower EXP12120 AGM SLA Battery Discharging Characteristics

In real life, batteries are rarely discharged using continuous current or power. However, charts showing battery's current and power in relation to time and end voltage are two common way to present what new, fully charged battery can do - when being discharged at 77°F (25°C).

Constant Current Discharge (Amps) at 77°F (25°C)
Volts/Cell Volts/Battery 5 min 10 min 15 min 30 min 1h 2h 3h 4h 5h 6h 10h 20h
1.85V 11.1V 39.45 23.29 18.31 11.93 6.96 4.03 3.09 2.538 2.080 1.696 1.112 0.578
1.80V 10.8V  40.21  23.74  18.65  12.16  7.10  4.10  3.15  2.587  2.120  1.728  1.133  0.589
1.75V 10.5V  40.96  24.18  19.00  12.39  7.23  4.18  3.21  2.635  2.160  1.761  1.155  0.600
1.70V 10.2V  44.65  25.63  20.14  12.88  7.36  4.25  3.27  2.682  2.196  1.792  1.175  0.611
1.65V 9.9V  49.15  27.81  21.86  13.60  7.44  4.30  3.30  2.711  2.221  1.811  1.187  0.617
1.60V 9.6V  53.25  29.26  23.00  14.18  7.52  4.34  3.34  2.740  2.245  1.830  1.200  0.624

 For example, when the battery is discharged for 20 hours down to 1.75 volts per cell (10.50 volts total), new, fully charged battery is capable of providing 0.60 Amps of constant current - and that is native battery capacity:

20h * 0.60 Amps = 12 Ah (at 77°F/25°C down to 10.50 volts)

Similarly, when the battery is discharged with constant power:

Constant Power Discharge (Watts) at 77°F (25°C)
Volts/Cell Volts/Battery 5 min 10 min 15 min 30 min 1h 2h 3h 4h 5h 6h 10h 20h
1.85V 11.1V 461.64 272.52 214.14 139.62 81.48 47.10 36.18 29.70 24.36 19.86 13.02 6.78
1.80V 10.8V  470.40 277.68 218.28 142.26 83.04 48.00 36.84 30.24 24.78 20.22 13.26 6.90
1.75V 10.5V 479.22 282.90 222.36 144.96 84.60 48.90 37.56 30.84 25.26 20.58 13.50 7.02
1.70V 10.2V 522.36 299.88 235.68 150.72 86.10 49.74 38.22 31.38 25.74 20.94 13.74 7.14
1.65V 9.9V 575.10 325.32 255.72 159.12 87.00 50.28 38.64 31.74 25.98 21.18 13.92 7.20
1.60V 9.6V 623.04 342.30 269.04 165.96 87.96 50.82 39.06 32.04 26.28 21.42 14.04 7.32

experpower exp12120 sla battery 3For example, when the battery is discharged for 20 hours, down to 1.75 volts per cell (10.50 volts total), new, fully charged battery is capable of providing 7.02 watts of constant power.

Also:

- if you have 7W LED light, ExpertPower EXP12120 battery will provide 20h of light, without the battery voltage dropping below 10.50 volts.

- if you have fish finder that requires 0.70 Amps of current and at least 10.50 volts, then you can expect some 16-17 hours of operation on a single battery charge.

- if you have small trolling motor that requires 20 Amps at full throttle and you don't mind draining the battery really deep (down to 9.6 volts, for example), you can expect some 17-18 minutes of operation at full throttle - just be aware that draining the battery very low significantly reduces number of its charging/discharging cycles.


Long Story Short: ExpertPower EXP12120 12 Volt 12 Ah AGM SLA Battery is cheap and durable battery and thus very popular. It is commonly used as fish finder battery, providing many hours of constant and reliable power in compact and mechanically very resistant case.

Like all lead-acid batteries, it is not the lightest battery - it provides 18.9 Wh/pound (41.77 Wh/kg) which is very good.

If you need affordable battery in this class (12V, 12Ah), consider ExpertPower EXP12120 battery.

For more reviews and recommendations, check ExpertPower EXP12120 12 Volt 12 Ah SLA AGM Battery Amazon link (link opens in the new window).