Deep Cycle Marine Battery

ExpertPower EXP12330 12 Volt 33 Ah AGM SLA Battery

ExpertPower EXP12330 is medium size, general purpose Absorbent Glass Mat (AGM) Sealed Lead Acid (SLA) battery, intended for the broad range of deep cycle and standby/float applications. Thanks to its rugged and durable design, it can be even used as the starting/cranking battery of small internal combustion engines commonly found in the ride-on lawn mowers, small boats, ATVs, and similar vehicles - it should NOT be used as car starting battery.

ExpertPower EXP12330 is group U1 size battery, and is suitable for applications like security systems, backups, medical instruments, smaller wheelchair battery, solar battery, large fish finder battery, etc.

Published: November 18, 2019.

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ExpertPower EXP12330 Features and Specifications

Physical dimensions of the ExpertPower EXP12330 are (L x W x H) 7.72 x 5.16 x 6.34 (with terminals 7.09) inches (196 x 131 x 161/180 mm) and it weighs 23.81 pounds (10.80 kg).

ExpertPower EXP12330 battery comes with the carrying handle and considering its relatively low weight, it may be safely carried around by an adult.

ExpertPower EXP12330 labeled 20h capacity is 33 Ah, but actual capacity depends on the discharge time and the end voltage:

- 20 hours, 1.72 Amps, down to 10.8 volts: 34.40 Ah

- 10 hours, 3.30 Amps, down to 10.8 volts: 33.0 Ah

- 5 hours, 6.30 Amps, down to 10.5 volts: 31.50 Ah

- 1 hours, 21.09 Amps, down to 10.5 volts: 21.09 Ah

As the discharge current is increased, actual capacity drops, which is typical for lead-acid batteries. Also note that as the discharge rate is increased, the end voltage may be lower without additional adverse effects on the battery.

When the new ExpertPower EXP12330 is fully charged, its internal resistance is <8.5 mΩ at 77°F (25°C) - ExpertPower EXP12330 may be used as a strong battery for various applications (check the discharge tables later in the this article), but it is not suitable as the starting battery for cars, trucks, larger boats and similar.

ExpertPower EXP12330 features low self-discharge rate which depends on the storage temperature:

- 104°F (40°C): down to 80% in ~40 days, 70% in 2 months, 60% in 3 months and few days (on average),

- 86°F (30°C): down to 80% in slightly less than 2 months, 70% in 3.5 months and 60% in 6 months,

- 77°F (25°C): down to 80% in 3 months, 70% in slightly more than 6 months and 60% in 10 months,

- 41°F (5°C): down to 80% in ~10 months, 70% in ~20 months.

Note: when the AGM SLA battery is stored, in order to avoid any damage to the battery, don't let its charge drop below 80%. Of course, the best way to store these batteries is to charge them fully using intelligent AGM battery charger and than to leave the battery connected to the intelligent battery maintainer (practically all intelligent AGM battery chargers can also operate as the battery maintainers).


ExpertPower EXP12330 battery comes with B2 terminal posts (M6 bolts), ensuring firm connection between the battery and the power cables.

Charging voltage depends on the intended battery use:

- float use: 13.5 - 13.8 volts (-20 mV/°C),

- cycle use: 14.40 - 15.00 volts (-30 mV/°C).

Maximum allowed charging current varies even on the official ExpertPower site and is between 8.25 and 9.90 Amps - personally, keep it below 8 Amps and the battery will be jsut fine.

Note: When the battery is discharged down to 50% DoD, 5 Amps AGM battery charger will fully charge the ExpertPower EXP12330 battery in ~4 hours. Personally, there is no need to charge the 33-35 Ah battery faster ...

ExpertPower EXP12330 AGM battery is spill-proof, maintenance free battery designed for 3-5 years of float/standby use or to be able to withstand cyclic use:

- 100% DoD: capacity loss down to 80% - 180-200 cycles, capacity loss down to 60% - 200-260 cycles,

- 50% DoD: capacity loss down to 80% - 330-410 cycles, capacity loss down to 60% - 410-500 cycles,

- 30% DoD: capacity loss down to 80% - 780-920 cycles, capacity loss down to 60% - 1050-1220 cycles.

This list shows that by avoiding too deep discharges, number of cycles of ExpertPower EXP12330 battery may be significantly increased.

ExpertPower EXP12330 AGM SLA Battery Current and Power Discharging Characteristics

In the real life, batteries are rarely discharged using continuous current or continuous power.

However, charts showing battery's current and power in relation to time and end voltage are two most common ways to present what new, fully charged battery can do (measured at 77°F/25°C):

ExpertPower EXP12330 Constant Current Discharge (Amps)

Cell End Voltage Battery End Voltage 5 min 10 min 15 min 30 min 1 hour 2 hours 3 hours 4 hours 5 hours 6 hours 10 hours 20 hours
1.85 V 11.1 V 115.09 67.94 53.40 34.81 20.32 11.74 9.02 7.41 6.07 4.95 3.24 1.69
1.80 V 10.8 V 117.29 69.24 54.42 35.47 20.70 11.97 9.19 7.55 6.18 5.04 3.30 1.72
1.75 V 10.5 V 119.49 70.54 55.44 36.14 21.09 12.19 9.36 7.69 6.30 5.14  3.37 1.75
1.70 V 10.2 V 130.25 74.77 58.77 37.58 21.46 12.41 9.53 7.82 6.41 5.23 3.43 1.78
1.67 V 10.02 V 143.39 81.12 63.76 39.68 21.69 12.54 9.63 7.91 6.48 5.28 3.46 1.80

ExpertPower EXP12330 Constant Power Discharge (Watts)

Cell End Voltage Battery End Voltage 5 min 10 min 15 min 30 min 1 hour 2 hours 3 hours 4 hours 5 hours 6 hours 10 hours 20 hours
1.85 V 11.1 V 1346.58 794.94 624.78 407.28 237.66 137.4 105.48 86.64 70.98 57.9 37.92 19.74
1.80 V 10.8 V 1372.32 810.12 636.72 415.02 242.22 140.04 107.52 88.32 72.36 58.98 38.64 20.1
1.75 V 10.5 V 1398.06 825.3 648.66 422.82 246.78 142.62 109.56 89.94 73.68 60.12 39.36 20.46
1.70 V 10.2 V 1523.88 874.8 687.54 439.68 251.1 145.14 111.48 91.56 75 61.14 40.08 20.82
1.67 V 10.02 V 1677.66 949.08 745.92 464.28 253.8 146.7 112.68 92.52  75.84 61.8 40.5 21.06

Thanks to its discharge characteristics, ExpertPower EXP12330 may be used for various applications like fish finder battery, kayak fish finder/trolling motor battery, backup battery, wheel chair battery etc.

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ExpertPower EXP12330 As Fish Finder Battery

ExpertPower EXP12330 may be used as high-capacity fish finder battery, regradless if it is used as standalone battery or as a part of electric system on the boat.

When being powered from 12V battery, smaller fish finders often require currents in the range of 0.2 - 0.3 Amps, while larger GPS/Chart Plotter units require 2-3 Amps, rarely more, even if they are network enabled units.

ExpertPower EXP12330 may power smaller fish finders for 110-170 hours (4-7 days of constant use), while larger units may be powered for 10-15 hours.

Of course, before settling for a fish finder battery, check the exact power requirements of your unit.

ExpertPower EXP12330 As Kayak Battery

ExpertPower EXP12330 is relatively lightweight AGM SLA battery, being able to power LED navigation lights, kayak fish finder, smaller trolling motor, navigation equipment, multimedia/entertainment devices and similar.

Kayak's LED navigation lights require just few watts of power, which is not a problem for ExpertPower EXP12330 battery.

In order to save space and weight, kayak fish finders are usually smaller and lightweight units, not requiring more than 0.2 - 0.4 Amps (model dependent). Such units may be powered for days with ExpertPower EXP12330 battery.

Electric trolling motors for kayaks require at most 20-30 Amps, and such devices may be powered for 40-60 minutes at full throttle, which is in most cases enough to quickly get to shore and safety, or to change fishing location. However, if you need longer operating times for your kayak trolling motor and you don't want heavier battery, go for lithium trolling batteries.

ExpertPower EXP12330 As Backup Battery

When used as standby/float battery, ExpertPower EXP12330 features 3-5 years life and when required, it is able to provide for example:

- ~950 watts for 10 minutes,

- ~250 watts for 1 hour,

- ~90 watts for 4 hours, etc.

Note: these values are for new, fully charged ExpertPower EXP12330 battery. As the battery gets older, it loses its capacity - it is recommended to make a run-test of every UPS battery every 2-4 months in order to asset the battery actual capabilities.

ExpertPower EXP12330 As the Wheelchair Battery

While larger wheelchairs use batteries in the 50-75Ah range, some smaller and lighter wheelchairs operate using smaller 33-35 Ah batteries.

Since ExpertPower EXP12330 is able to provide 2x150 watts for ~40 minutes continuosly, it may be used for such wheelchairs, as rather lightweight battery (12 volts systems).

Some wheelchairs use 24V electric systems, and such wheelchairs (commonly 2x250 watts) may be powered for ~1 hour.

Note: wheelchairs are rarely used at full power all the time, which significantly prolongs the operating time of its battery/batteries.

expertpower exp12330 mLong Story Short: ExpertPower EXP12330 is well balanced, deep cycle/standby AGM SLA battery, one of the most popular batteries in its class.

It is able to reliably store the energy, and release it when required, even after years of waiting. And when being used in cycle applications, it may endure large number of cycles, especially when not being drained below 50% DoD.

For more reviews and recommendations, check ExpertPower EXP12330 AGM Battery Amazon link (link opens in the new window).

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